CHM Hc11d3 MC68HC11D3 (Freescale)

User Manual: CHM MC68HC11D3 (Freescale)

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HC11
MC68HC11D3
Technical Data
Freescale Semiconductor, I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
nc...
Freescale Semiconductor, I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
nc...
TECHNICAL DATA iii
TABLE OF CONTENTS
Paragraph
Number
Page
Number
Section 1
INTRODUCTION
1.1 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.2 Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Section 2
PIN DESCRIPTIONS
2.1 VDD, VSS, and EVSS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
2.2 Reset (RESET) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
2.3 Crystal Driver and External Clock Input (XTAL, EXTAL) . . . . . . . . . . . . . . . . . . . . 2-3
2.4 E-Clock Output (E). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
2.5 Interrupt Request (IRQ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
2.6 Non-Maskable Interrupt (XIRQ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
2.7 MODA and MODB (MODA/LIR,and MODB/VSTBY). . . . . . . . . . . . . . . . . . . . . . . . 2-5
2.8 PD6/AS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
2.9 PD7/R/W . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
2.10 Port Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
2.10.1 Port A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
2.10.2 Port B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
2.10.3 Port C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
2.10.4 Port D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
Section 3
CENTRAL PROCESSING UNIT
3.1 CPU Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3.1.1 Accumulators A, B, and D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
3.1.2 Index Register X (IX) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
3.1.3 Index Register Y (IY) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
3.1.4 Stack Pointer (SP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
3.1.5 Program Counter (PC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
3.1.6 Condition Code Register (CCR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
3.1.6.1 Carry/Borrow (C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
3.1.6.2 Overflow (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
3.1.6.3 Zero (Z). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
3.1.6.4 Negative (N) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
3.1.6.5 Interrupt Mask (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
3.1.6.6 Half Carry (H) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
3.1.6.7 X Interrupt Mask (X) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
3.1.6.8 Stop Disable (S) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
3.2 Data Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
3.3 Opcodes and Operands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
3.4 Addressing Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
3.4.1 Immediate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
3.4.2 Direct . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
3.4.2.1 Extended . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
3.4.2.2 Indexed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
3.4.2.3 Inherent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
3.4.2.4 Relative. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
3.5 Instruction Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8
Freescale Semiconductor, I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
nc...
iv TECHNICAL DATA
Table of Contents (Cont.)
Paragraph
Number
Page
Number
Section 4
OPERATING MODES AND ON-CHIP MEMORY
4.1 Operating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.1.1 Single-Chip Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.1.2 Expanded Multiplexed Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.1.3 Special Test Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
4.1.4 Bootstrap Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
4.2 Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
4.2.1 Priority and Mode Select Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
4.2.2 System Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8
4.2.2.1 CONFIG Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8
4.2.2.2 INIT Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9
4.2.2.3 OPTION Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10
Section 5
RESETS AND INTERRUPTS
5.1 Resets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
5.1.1 Power-On Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
5.1.2 External Reset (RESET). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
5.1.3 COP Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
5.1.4 Clock Monitor Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
5.1.5 Option Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
5.1.6 CONFIG Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
5.2 Effects of Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
5.2.1 CPU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
5.2.2 Memory Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
5.2.3 Parallel I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
5.2.4 Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
5.2.5 Real-Time Interrupt. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
5.2.6 Pulse Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
5.2.7 COP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6
5.2.8 SCI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6
5.2.9 SPI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6
5.2.10 System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6
5.3 Reset and Interrupt Priority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6
5.3.1 Highest Priority Interrupt and Miscellaneous Register . . . . . . . . . . . . . . . . . 5-7
5.4 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8
5.4.1 Interrupt Recognition and Register Stacking . . . . . . . . . . . . . . . . . . . . . . . . 5-9
5.4.2 Non-Maskable Interrupt Request XIRQ . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10
5.4.3 Illegal Opcode Trap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10
5.4.4 Software Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11
5.4.5 Maskable Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11
5.4.6 Reset and Interrupt Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11
5.5 Low-Power Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-16
5.5.1 WAIT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-16
5.5.2 STOP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-17
Section 6
PARALLEL I/O
6.1 Port A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
6.2 Port B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
6.3 Port C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2
Freescale Semiconductor, I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
nc...
TECHNICAL DATA v
Table of Contents (Cont.)
Paragraph
Number
Page
Number
6.4 Port D. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2
6.5 Parallel I/O Control Register (PIOC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4
Section 7
SERIAL COMMUNICATIONS INTERFACE
7.1 Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
7.2 Transmit Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
7.3 Receive Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2
7.4 Wake-up Feature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4
7.4.1 Idle-Line Wakeup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4
7.4.2 Address-Mark Wakeup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4
7.5 SCI Error Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5
7.6 SCI Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5
7.6.1 Serial Communications Data Register (SCDR) . . . . . . . . . . . . . . . . . . . . . . 7-5
7.6.2 Serial Communications Control Register 1 (SCCR1) . . . . . . . . . . . . . . . . . . 7-5
7.6.3 Serial Communications Control Register 2 (SCCR2) . . . . . . . . . . . . . . . . . . 7-6
7.6.4 Serial Communication Status Register (SCSR) . . . . . . . . . . . . . . . . . . . . . . 7-7
7.6.5 Baud Rate Register (BAUD). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-8
7.7 Status Flags and Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-10
Section 8
SERIAL PERIPHERAL INTERFACE
8.1 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1
8.2 SPI Transfer Formats. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2
8.2.1 Clock Phase and Polarity Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3
8.3 SPI Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3
8.3.1 Master In Slave Out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4
8.3.2 Master Out Slave In . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4
8.3.3 Serial Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4
8.3.4 Slave Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4
8.4 SPI System Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4
8.5 SPI Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-5
8.5.1 Serial Peripheral Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-6
8.5.2 Serial Peripheral Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-7
8.5.3 Serial Peripheral Data I/O. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-7
Section 9
TIMING SYSTEM
9.1 Timer Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3
9.2 Input Capture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4
9.2.1 Timer Control 2 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-5
9.2.2 Timer Input Capture Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-6
9.2.3 Timer Input Capture 4/Output Compare 5 Register . . . . . . . . . . . . . . . . . . . 9-6
9.3 Output Compare. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-6
9.3.1 Timer Output Compare Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-7
9.3.2 Timer Compare Force Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-8
9.3.3 Output Compare Mask Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-8
9.3.4 Output Compare 1 Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-9
9.3.5 Timer Counter Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-9
9.3.6 Timer Control 1 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-9
9.3.7 Timer Interrupt Mask 1 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-10
9.3.8 Timer Interrupt Flag 1 Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-10
Freescale Semiconductor, I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
nc...
vi TECHNICAL DATA
Table of Contents (Cont.)
Paragraph
Number
Page
Number
9.3.9 Timer Interrupt Mask 2 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-11
9.3.10 Timer Interrupt Flag 2 Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-12
9.4 Real-Time Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-12
9.4.1 Timer Interrupt Flag 2 Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-13
9.4.2 Pulse Accumulator Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-14
9.5 Computer Operating Properly Watchdog Function . . . . . . . . . . . . . . . . . . . . . . . 9-15
9.6 Pulse Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-15
9.6.1 Pulse Accumulator Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-17
9.6.2 Pulse Accumulator Count Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-17
9.6.3 Pulse Accumulator Status and Interrupt Bits . . . . . . . . . . . . . . . . . . . . . . . 9-18
Appendix A
ELECTRICAL CHARACTERISTICS
Appendix B
MECHANICAL DATA AND ORDERING INFORMATION
B.1 Pin Assignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1
B.2 Package Dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-3
B.3 Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-3
Appendix C
DEVELOPMENT SUPPORT
C.1 Development System Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1
C.2 MC68HC11D3 Development Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1
INDEX
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MC68HC11D3
TA
Figure Title Page
LIST OF ILLUSTRATIONS
1-1 MC68HC11D3 Block Diagram ........................................................................ 1-2
2-1 Pin Assignments for 44-Pin PLCC ................................................................. 2-1
2-2 Pin Assignments for 40-Pin DIP ..................................................................... 2-2
2-3 External Reset Circuit ..................................................................................... 2-3
2-4 Common Crystal Connections ........................................................................ 2-3
2-5 External Oscillator Connections ..................................................................... 2-4
2-6 One Crystal Driving Two MCUs ..................................................................... 2-4
3-1 Programming Model ....................................................................................... 3-1
3-2 Stacking Operations ....................................................................................... 3-3
4-1 Address/Data Demultiplexing ......................................................................... 4-2
4-2 MC68HC11D3 Memory Map .......................................................................... 4-3
4-3 RAM Standby MODB/VSTBY Connections ...................................................... 4-6
5-1 Processing Flow out of Reset (1 of 2) .......................................................... 5-12
5-2 Interrupt Priority Resolution (1 of 2) ............................................................. 5-14
5-3 Interrupt Source Resolution within SCI ........................................................ 5-16
7-1 SCI Transmitter Block Diagram ...................................................................... 7-2
7-2 SCI Receiver Block Diagram .......................................................................... 7-3
7-3 SCI Baud Rate Diagram ............................................................................... 7-10
7-4 Interrupt Source Resolution within SCI ........................................................ 7-12
8-1 SPI Block Diagram ......................................................................................... 8-2
8-2 SPI Transfer Format ....................................................................................... 8-3
9-1 Timer Clock Divider Chains ............................................................................ 9-2
9-2 Capture/Compare Block Diagram .................................................................. 9-4
9-3 Pulse Accumulator ....................................................................................... 9-16
A-1 Test Methods ..................................................................................................A-3
A-2 Timer Inputs ...................................................................................................A-4
A-3 POR and External Reset Timing Diagram ......................................................A-5
A-4 STOP Recovery Timing Diagram ...................................................................A-6
A-5 WAIT Recovery Timing Diagram ....................................................................A-7
A-6 Port Write Timing Diagram .............................................................................A-8
A-7 Port Read Timing Diagram .............................................................................A-8
A-8 Multiplexed Expansion Bus Timing Diagram ................................................A-10
A-9 SPI Master Timing (CPHA = 0) ....................................................................A-12
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MOTOROLA
TECHNI
(Continued)
Figure Title Page
LIST OF ILLUSTRATIONS
A-10 SPI Master Timing (CPHA = 1) ....................................................................A-12
A-11 SPI Slave Timing (CPHA = 0) ......................................................................A-13
A-12 SPI Slave Timing (CPHA = 1) ......................................................................A-13
B-1 40-Pin DIP ......................................................................................................B-1
B-2 44-Pin PLCC ..................................................................................................B-2
B-3 44-Pin QFP .....................................................................................................B-3
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MC68HC11D3
TA
Table Title Page
LIST OF TABLES
2-1 Port Signal Functions............................................................................................. 2-6
3-2 Instruction Set........................................................................................................ 3-8
4-1 Register and Control Bit Assignments ................................................................. 4-4
4-2 Hardware Mode Select Summary.......................................................................... 4-6
4-3 RAM Mapping........................................................................................................ 4-9
4-4 Register Mapping................................................................................................... 4-9
5-1 COP Time-out........................................................................................................ 5-2
5-2 Reset Cause, Reset Vector, and Operating Mode ................................................ 5-4
5-3 Highest Priority Interrupt Selection ........................................................................ 5-8
5-4 Interrupt and Reset Vector Assignments............................................................... 5-9
5-5 Stacking Order on Entry to Interrupts .................................................................. 5-10
7-1 Baud Rate Prescale Selects.................................................................................. 7-8
7-2 Baud Rate Selects................................................................................................ 7-9
9-1 Timer Summary ..................................................................................................... 9-3
9-2 Timer Control Configuration................................................................................... 9-5
9-3 Pulse Accumulator Timing................................................................................... 9-16
A-1 Maximum Ratings..................................................................................................A-1
A-2 Thermal Characteristics ........................................................................................A-1
A-3 DC Electrical Characteristics.................................................................................A-2
A-4 Control Timing.......................................................................................................A-4
A-5 Peripheral Port Timing...........................................................................................A-8
A-6 Expansion Bus Timing...........................................................................................A-9
A-7 Serial Peripheral Interface Timing.......................................................................A-11
B-1 Ordering Information .............................................................................................B-3
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INTRODUCTION
TECHNICAL DATA 1-1
SECTION 1
INTRODUCTION
The MC68HC11D3 and MC68HC11D0 are ROM-based high-performance microcon-
trollers (MCUs) based on the MC68HC11E9 design. Members of the Dx series are de-
rived from the same mask and feature a high speed multiplexed bus capable of
running at up to 3 MHz, and a fully static design that allows operations at frequencies
to dc.
The only difference between the MCUs in the Dx series is whether or not the ROM has
been tested and guaranteed.
1.1 Features
• MC68HC11 CPU
• Power Saving STOP and WAIT Modes
• 4 Kbytes of On-Chip ROM
• 192 Bytes of On-Chip RAM (All Saved During Standby)
• 16-Bit Timer System
— 3 Input Capture (IC) Channels
— 4 Output Compare (OC) Channels
— One IC or OC Channel (Software Selectable)
• 8-Bit Pulse Accumulator
• Real-Time Interrupt Circuit
• Computer Operating Properly (COP) Watchdog System
• Synchronous Serial Peripheral Interface (SPI)
• Asynchronous Nonreturn to Zero (NRZ) Serial Communications Interface (SCI)
• 26 Input/Output (I/O) Pins
— 16 Bidirectional I/O Pins
— 3 Input Only Pins
— 3 Output Only Pins (One Output Only Pin in the 40-Pin Package)
• Available in a 44-Pin Plastic Leaded Chip Carrier (PLCC) and 40-Pin Dual In-Line
Package (DIP)
1.2 Structure
Refer to Figure 1-1, which shows the structure of the MC68HC11D3 MCU.
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INTRODUCTION
1-2 TECHNICAL DATA
Figure 1-1 MC68HC11D3 Block Diagram
SPI SCI
PORT D
CONTROL
EXTALXTAL E
OSCILLATOR
CLOCK LOGIC INTERRUPT LOGIC
MODA/
LIR MODB/
VSTBY
TIMER
SYSTEM
CPU
COP
PULSE ACCUMULATOR
STROBE AND HANDSHAKE
PORT B
PB7/A15
PB6/A14
PB5/A13
PB4/A12
PB3/A11
PB2/A10
PB1/A9
PB0/A8
PORT C
PC7/A7/D7
PC6/A6/D6
PC5/A5/D5
PC4/A4/D4
PC3/A3/D3
PC2/A2/D2
PC1/A1/D1
PC0/A0/D0
PD7/R/W
PD6/AS
PD5/SS
PD4/SCK
PD3/MOSI
PD2/MISO
PD1/TxD
PD0/RxD
CONTROL
PORT A
PA7/PAI/OC1
PA6/OC2/OC1
PA5/OC3/OC1
PA4/OC4/OC1
PA3/OC5/OC1
PA2/IC1
PA1/IC2
PA0/IC3
BUS EXPANSION
PARALLEL I/O
ADDRESS ADDRESS/DATA
R/W
AS
SS
SCK
PERIODIC INTERRUPT
MODE
CONTROL
XIRQ
IRQ/RESET
MOSI
MISO
192 BYTES RAM
4 KBYTES ROM
VSS
VDD
TxD
RxD
CONTROL
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PIN DESCRIPTIONS
TECHNICAL DATA 2-1
SECTION 2
PIN DESCRIPTIONS
The MC68HC11D3 is available packaged as a 40-pin dual in-line package (DIP), a 44-
pin plastic leaded chip carrier (PLCC), or a 44-pin quad flat pack (QFP). Most pins on
this MCU serve two or more functions, as described in the following paragraphs. Refer
to Figure 2-1 and Figure 2-2, which shows the MC68HC11D3 pin assignments.
Figure 2-1 Pin Assignments for 44-Pin PLCC
PC4/ADDR4
PC5/ADDR5
PC6/ADDR6
PC7/ADDR7
XIRQ/VPP
PD7/R/W
PD6/AS
RESET
IRQ
PD0/RxD
PD1/TxD
PB2/ADDR10
PB3/ADDR11
PB4/ADDR12
PB5/ADDR13
PB6/ADDR14
PB7/ADDR15
NC
PA0/IC3
PA1/IC2
PC3/ADDR3
PC2/ADDR2
PC1/ADDR1
PC0/ADDR0
VSS
EVSS
XTAL
EXTAL
E
MODA/LIR
MODB/VSTBY
PD2/MISO
PD3/MOSI
PD4/SCK
PD5/SS
VDD
PA7/PAI/OC1
PA6/OC2/OC1
PA5/OC3/OC1
PA4/OC4/OC1
PA3/IC4/OC5/OC1
PA2/IC1
7
8
9
10
11
12
13
14
15
16
37
36
35
34
33
32
31
30
29
18
19
20
21
22
23
24
25
26
27
28
6
5
4
3
2
1
44
43
42
41
40
17
PB1/ADDR9
38
PB0/ADDR8
39
MC68HC(7)11D3
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PIN DESCRIPTIONS
2-2 TECHNICAL DATA
Figure 2-2 Pin Assignments for 40-Pin DIP
2.1 VDD, VSS, and EVSS
Power is supplied to the MCU through VDD and VSS. VSS is the power supply, and
VSS is ground. EVSS, available on the 44-pin PLCC, is an additional ground pin that
must be grounded with VSS. The MCU operates from a single 5-volt (nominal) power
supply. Very fast signal transitions occur on the MCU pins. The short rise and fall times
place high, short duration current demands on the power supply. To prevent noise
problems, provide good power supply bypassing at the MCU. Also, use bypass capac-
itors that have good high-frequency characteristics and situate them as close to the
MCU as possible. Bypass requirements vary, depending on how heavily the MCU pins
are loaded.
2.2 Reset (RESET)
An active low bidirectional control signal, RESET, acts as an input to initialize the MCU
to a known startup state. It also acts as an open-drain output to indicate that an internal
failure has been detected in either the clock monitor or COP watchdog circuit. The
CPU distinguishes between internal and external reset conditions by sensing whether
the reset pin rises to a logic one in less than two E-clock cycles after a reset has oc-
curred. It is not advisable to connect an external resistor-capacitor (RC) power-up de-
lay circuit to the reset pin of M68HC11 devices because the circuit charge time
PC7/ADDR7
XIRQ/VPP
PD7/R/W
PD6/AS
RESET
IRQ
PD0/RxD
PD1/TxD
PD2/MISO
PD3/MOSI
9
10
11
12
13
14
15
16
17
18
PD4/SCK 19
PD5/SS 20
PC6/ADDR6 8
PC5/ADDR5 7
PC4/ADDR4 6
PC3/ADDR3 5
PC2/ADDR2 4
PC1/ADDR1 3
PC0/ADDR0 2
VSS 1
PB5/ADDR13
PB6/ADDR14
PB7/ADDR15
PA0/IC3
PA1/IC2
PA2/IC1
PA3/IC4/OC5/OC1
PA5/OC3/OC1
PA7/PAI/OC1
VDD
30
29
28
27
26
25
24
23
22
21
PB4/ADDR1231
PB3/ADDR1132
PB2/ADDR1033
PB1/ADDR934
PB0/ADDR835
MODB/VSTBY
36
MODA/LIR37
E38
EXTAL39
XTAL40
MC68HC(7)11D3
D3 40-PIN DIP
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PIN DESCRIPTIONS
TECHNICAL DATA 2-3
constant can cause the device to misinterpret the type of reset that occurred. Refer to
SECTION 5 RESETS AND INTERRUPTS for further information.
Figure 2-3 illustrates a reset circuit that uses an external switch. Use a low voltage
interrupt circuit, however, to prevent corruption of RAM.
Figure 2-3 External Reset Circuit
2.3 Crystal Driver and External Clock Input (XTAL, EXTAL)
These two pins provide the interface for either a crystal or a CMOS compatible clock
to control the internal clock generator circuitry. The frequency applied to these pins is
four times higher than the desired E-clock rate.
The XTAL pin is normally left unterminated when an external CMOS compatible clock
input is connected to the EXTAL pin. However, a 10 kΩ to 100 kΩ load resistor con-
nected from XTAL to ground can be used to reduce RFI noise emission. The XTAL
output is normally intended to drive only a crystal. The XTAL output can be buffered
with a high impedance buffer, or it can be used to drive the EXTAL input of another
M68HC11.
In all cases, use caution around the oscillator pins. Load capacitances shown in the
oscillator circuits include all stray layout capacitances. Refer to Figure 2-4, Figure 2-
5, and Figure 2-6.
Figure 2-4 Common Crystal Connections
EXT RESET CIRCUIT
4.7 kΩ
TO RESET
VDD
MC34(0/1)64
RESET
GND
IN
OF M68HC11
2
1
3
V
DD
10 MΩ
* THIS VALUE INCLUDES ALL STRAY CAPACITANCES.
MCU
25 pF *
25 pF *
EXTAL
XTAL
4 x E
CRYSTAL
COMMON XTAL CONN
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PIN DESCRIPTIONS
2-4 TECHNICAL DATA
Figure 2-5 External Oscillator Connections
Figure 2-6 One Crystal Driving Two MCUs
2.4 E-Clock Output (E)
E is the output connection for the internally generated E clock. The signal from E is
used as a timing reference. The frequency of the E-clock output is one fourth that of
the input frequency at the XTAL and EXTAL pins. When E-clock output is low, an in-
ternal process is taking place. When it is high, data is being accessed. All clocks, in-
cluding the E clock, are halted when the MCU is in STOP mode. The E clock can be
turned off in single-chip modes to reduce the effects of radio frequency interference
(RFI).
2.5 Interrupt Request (IRQ)
The IRQ input provides a means of applying asynchronous interrupt requests to the
MCU. Either negative edge-sensitive triggering or level-sensitive triggering is program
selectable (OPTION register). IRQ is always configured to level-sensitive triggering at
reset. Connect an external pullup resistor, typically 4.7 kΩ, to VDD when IRQ is used
in a level sensitive wired-OR configuration.
2.6 Non-Maskable Interrupt (XIRQ)
The XIRQ input provides a means of requesting a nonmaskable interrupt after reset
initialization. During reset, the X bit in the condition code register (CCR) is set and any
interrupt is masked until MCU software enables it. Because the XIRQ input is level-
NC
MCU
EXTAL
XTAL
4 x E
CMOS-COMPATIBLE
EXT EXTAL CONN
EXTERNAL OSCILLATOR
10 MΩ
* THIS VALUE INCLUDES ALL STRAY CAPACITANCES.
FIRST
25 pF *
25 pF *
EXTAL
XTAL
4 x E
CRYSTAL
DUAL-MCU XTAL CONN
NC
SECOND
EXTAL
XTAL
220 Ω
MCU
MCU
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PIN DESCRIPTIONS
TECHNICAL DATA 2-5
sensitive, it can be connected to a multiple-source wired-OR network with an external
pullup resistor to VDD. XIRQ is often used as a power loss detect interrupt.
Whenever XIRQ or IRQ are used with multiple interrupt sources (IRQ must be config-
ured for level-sensitive operation if there is more than one source of IRQ interrupt),
each source must drive the interrupt input with an open-drain type of driver to avoid
contention between outputs. There should be a single pullup resistor near the MCU
interrupt input pin (typically 4.7 kΩ). There must also be an interlock mechanism at
each interrupt source so that the source holds the interrupt line low until the MCU rec-
ognizes and acknowledges the interrupt request. If one or more interrupt sources are
still pending after the MCU services a request, the interrupt line will still be held low
and the MCU will be interrupted again as soon as the interrupt mask bit in the MCU is
cleared (normally upon return from an interrupt). Refer to SECTION 5 RESETS AND
INTERRUPTS.
2.7 MODA and MODB (MODA/LIR,and MODB/VSTBY)
During reset, MODA and MODB select one of the four operating modes. Refer to SEC-
TION 4 OPERATING MODES AND ON-CHIP MEMORY.
After the operating mode has been selected, the LIR pin provides an open-drain output
to indicate that execution of an instruction has begun. A series of E-clock cycles occurs
during execution of each instruction. The LIR signal goes low during the first E-clock
cycle of each instruction (opcode fetch). This output is provided for assistance in pro-
gram debugging.
The VSTBY pin is used to input RAM standby power. When the voltage on this pin is
more than one MOS threshold (about 0.7 volts) above the VDD voltage, the internal
192-byte RAM and part of the reset logic are powered from this signal rather than the
VDD input. This allows RAM contents to be retained without VDD power applied to the
MCU. Reset must be driven low before VDD is removed and must remain low until VDD
has been restored to a valid level.
2.8 PD6/AS
This pin performs either of two separate functions, depending on the operating mode.
In single-chip and bootstrap modes, the pin functions as input/output port D bit 6. In
the expanded multiplexed and test modes, it provides an address strobe (AS) function.
The AS can demultiplex the address and data signals at port C. Refer to SECTION 4
OPERATING MODES AND ON-CHIP MEMORY for further information.
2.9 PD7/R/W
This pin provides two separate functions, depending on the operating mode. In single-
chip and bootstrap modes, PD7/R/W acts as input/output port D bit 7. Refer to SEC-
TION 6 PARALLEL I/O for further information.
In expanded multiplexed and test modes, PD7/R/W performs a read/write function.
PD7/R/W controls the direction of transfers on the external data bus. A high on this pin
indicates that a read cycle is in progress.
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PIN DESCRIPTIONS
2-6 TECHNICAL DATA
2.10 Port Signals
In the 44-pin PLCC package, 32 input/output lines are arranged into four 8-bit ports:
A, B, C, and D. The lines of ports B, C, and D are fully bidirectional. Each of these four
ports serves a purpose other than I/O, depending on the operating mode or peripheral
functions selected. Note that ports B, C, and two bits of port D are available for I/O
functions only in single-chip and bootstrap modes. Refer to Table 2-1 for details about
the 32 port signals' functions within different operating modes.
*In the 40-pin package, pins PA4 and PA6 are not bonded. Their associated I/O and output compare functions are
not available externally. They can still be used as internal software timers, however.
Table 2-1 Port Signal Functions
Port/Bit Single-Chip and
Bootstrap Mode Expanded Multiplexed and
Special Test Mode
PA0 PA0/IC3
PA1 PA1/IC2
PA2 PA2/IC1
PA3 PA3/OC5/IC4/OC1
PA4* PA4/OC4/OC1
PA5 PA5/OC3/OC1
PA6* PA6/OC2/OC1
PA7 PA7/PAI/OC1
PB0 PB0 ADDR8
PB1 PB1 ADDR9
PB2 PB2 ADDR10
PB3 PB3 ADDR11
PB4 PB4 ADDR12
PB5 PB5 ADDR13
PB6 PB6 ADDR14
PB7 PB7 ADDR15
PC0 PC0 ADDR0/DATA0
PC1 PC1 ADDR1/DATA1
PC2 PC2 ADDR2/DATA2
PC3 PC3 ADDR3/DATA3
PC4 PC4 ADDR4/DATA4
PC5 PC5 ADDR5/DATA5
PC6 PC6 ADDR6/DATA6
PC7 PC7 ADDR7/DATA7
PD0 PD0/RxD
PD1 PD1/TxD
PD2 PD2/MISO
PD3 PD3/MOSI
PD4 PD4/SCK
PD5 PD5/SS
PD6 PD6 AS
PD7 PD7 R/W
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PIN DESCRIPTIONS
TECHNICAL DATA 2-7
2.10.1 Port A
Port A can be read at any time. Inputs return the pin level; outputs return the pin driver
input level. If written, port A stores the data in an internal latch. It drives the pins only
if they are configured as outputs. Writes to port A do not change the pin state when
the pins are configured for timer output compares.
Out of reset, port A bits 7 and [3:0] are general high impedance inputs, while bits [6:4]
are outputs, driving low. Bidirectional lines PA7 and PA3 in PACTL are not changed
and do not have any effect on those bits. When the output compare functions associ-
ated with these pins are disabled, the DDR bits in PACTL govern the I/O state.
Refer to SECTION 6 PARALLEL I/O.
2.10.2 Port B
Port B is an 8-bit general-purpose I/O port with a data register (PORTB) and a data
direction register (DDRB). In single-chip mode, port B pins are general-purpose I/O
pins (PB[7:0]). In the expanded multiplexed mode, all of the port B pins act as the high-
order address bits (ADDR[15:8]) of the address bus.
Port B can be read at any time. Inputs return the sensed levels at the pin, while outputs
return the input level of the port B pin drivers. If port B is written, the data is stored in
an internal latch and can be driven only if port B is configured as general-purpose out-
puts in single-chip or bootstrap modes.
Port B pins are general-purpose inputs out of reset in single-chip and bootstrap
modes. These pins are outputs (the high order address bits) out of reset in expanded
multiplexed and test modes.
Refer to SECTION 6 PARALLEL I/O.
2.10.3 Port C
Port C is an 8-bit general-purpose I/O port with a data register (PORTC) and a data
direction register (DDRC). In the single-chip mode, port C pins are general-purpose I/
O pins (PC[7:0]). In the expanded multiplexed mode, port C pins are configured as
multiplexed address/data pins. During the address cycle, bits [7:0] of the address are
output on PC[7:0]. During the data cycle, bits [7:0] (PC[7:0]) are bidirectional data pins
controlled by the R/W signal.
Port C can be read at any time. Inputs return the sensed levels at the pin, while outputs
return the input level of the port C pin drivers. If port C is written, the data is stored in
an internal latch and can be driven only if port C is configured for general-purpose out-
puts in single-chip or bootstrap mode. Port C pins are general-purpose inputs out of
reset in single-chip and bootstrap modes. These pins are multiplexed low-order ad-
dress and data bus lines out of reset in expanded multiplexed and test modes.
The CWOM control bit in the PIOC register disables port C's P-channel output driver.
CWOM simultaneously affects all eight bits of port C. Because the N-channel driver is
not affected by CWOM, setting CWOM causes port C to become an open-drain-type
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PIN DESCRIPTIONS
2-8 TECHNICAL DATA
output port suitable for wired-OR operation. In wired-OR mode (a port C bit is at logic
level zero), it is actively driven low by the N-channel driver. When a port C bit is at logic
level one, the associated pin has high impedance, as neither the N- nor the P-channel
devices are active. It is customary to have an external pullup resistor on lines that are
driven by open-drain devices. Port C can only be configured for wired-OR operation
when the MCU is in single-chip mode. Refer to SECTION 6 PARALLEL I/O for addi-
tional information about port C functions.
2.10.4 Port D
Port D, an 8-bit, general-purpose I/O port has a data register (PORTD) and a data di-
rection register (DDRD). The eight port D bits (D[7:0]) can be used for general-purpose
I/O, for the serial communications interface (SCI) and serial peripheral interface (SPI)
subsystems, or for bus data direction control.
Port D can be read at any time and inputs return the sensed levels at the pin; whereas,
the outputs return the input level of the port D pin drivers. If PORTD is written, the data
is stored in an internal latch, and can be driven only if port D is configured for general-
purpose output. This port shares functions with the on-chip SCI and SPI subsystems,
while bits 6 and 7 control the direction of data flow on the bus in expanded and special
test modes.
Refer to SECTION 6 PARALLEL I/O.
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SECTION 3
CENTRAL PROCESSING UNIT
This section presents information on M68HC11 central processing unit (CPU) archi-
tecture, data types, addressing modes, the instruction set, and special operations,
such as subroutine calls and interrupts.
The CPU is designed to treat all peripheral, I/O, and memory locations identically as
addresses in the 64 Kbyte memory map. This is referred to as memory-mapped I/O.
There are no special instructions for I/O that are separate from those used for memory.
This architecture also allows accessing an operand from an external memory location
with no execution-time penalty.
3.1 CPU Registers
M68HC11 CPU registers are an integral part of the CPU and are not addressed as if
they were memory locations. The seven registers, discussed in the following para-
graphs, are shown in Figure 3-1.
Figure 3-1 Programming Model
8-BIT ACCUMULATORS A & B
7070
15 0
AB
D
IX
IY
SP
PC
70
CVZNIHXS
OR 16-BIT DOUBLE ACCUMULATOR D
INDEX REGISTER X
INDEX REGISTER Y
STACK POINTER
PROGRAM COUNTER
CARRY/BORROW FROM MSB
OVERFLOW
ZERO
NEGATIVE
I-INTERRUPT MASK
HALF CARRY (FROM BIT 3)
X-INTERRUPT MASK
STOP DISABLE
CONDITION CODES
HC11 PROG MODEL
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3.1.1 Accumulators A, B, and D
Accumulators A and B are general-purpose 8-bit registers that hold operands and re-
sults of arithmetic calculations or data manipulations. For some instructions, these two
accumulators are treated as a single double-byte (16-bit) accumulator called accumu-
lator D. Although most operations can use accumulators A or B interchangeably, the
following exceptions apply:
The ABX and ABY instructions add the contents of 8-bit accumulator B to the contents
of 16-bit register X or Y, but there are no equivalent instructions that use A instead of B.
The TAP and TPA instructions transfer data from accumulator A to the condition code
register, or from the condition code register to accumulator A, however there are no
equivalent instructions that use B rather than A.
The decimal adjust accumulator (DAA) instruction is used after binary-coded decimal
(BCD) arithmetic operations, but there is no equivalent BCD instruction to adjust ac-
cumulator B.
The add, subtract, and compare instructions associated with both A and B (ABA, SBA,
and CBA) only operate in one direction, making it important to plan ahead to ensure
the correct operand is in the correct accumulator.
3.1.2 Index Register X (IX)
The IX register provides a 16-bit indexing value that can be added to the 8-bit offset
provided in an instruction to create an effective address. The IX register can also be
used as a counter or as a temporary storage register.
3.1.3 Index Register Y (IY)
The 16-bit IY register performs an indexed mode function similar to that of the IX reg-
ister. However, most instructions using the IY register require an extra byte of machine
code and an extra cycle of execution time because of the way the opcode map is im-
plemented. Refer to 3.3 Opcodes and Operands for further information.
3.1.4 Stack Pointer (SP)
The M68HC11 CPU has an automatic program stack. This stack can be located any-
where in the address space and can be any size up to the amount of memory available
in the system. Normally the SP is initialized by one of the first instructions in an appli-
cation program. The stack is configured as a data structure that grows downward from
high memory to low memory. Each time a new byte is pushed onto the stack, the SP
is decremented. Each time a byte is pulled from the stack, the SP is incremented. At
any given time, the SP holds the 16-bit address of the next free location in the stack.
Figure 3-2 is a summary of SP operations.
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Figure 3-2 Stacking Operations
SP
STACK
CCR
SP+1
ACCB
SP+2
ACCA
SP+3
IXH
SP+4
IXL
SP+5
IYH
SP+6
IYL
SP+7
RTNH
SP+8
➩ SP+9
70
RTNL
PC
MAIN PROGRAM
$9D = JSR
JSR, JUMP TO SUBROUTINE
dd
NEXT MAIN INSTR.
RTN
DIRECT
PC
MAIN PROGRAM
$AD = JSR
ff
NEXT MAIN INSTR.
RTN
INDEXED, X
PC
MAIN PROGRAM
$18 = PRE
ff
NEXT MAIN INSTR.
RTN
INDEXED, Y $AD = JSR
PC
MAIN PROGRAM
$BD = PRE
ll
NEXT MAIN INSTR.
RTN
INDEXED, Y hh
JMP, JUMP
PC
MAIN PROGRAM
$6E = JMP
ff
NEXT MAIN INSTR.
X + ff
INDEXED, X
INDEXED, Y
EXTENDED
PC
MAIN PROGRAM
$18 = PRE
$6E = JMP
NEXT MAIN INSTR.
X + ff
ff
PC
MAIN PROGRAM
$7E = JMP
hh
NEXT MAIN INSTR.
hh ll
ll
SP
STACK
CCR
SP+1
ACCB
SP+2
ACCA
SP+3
IXH
SP+4
IXL
SP+5
IYH
SP+6
IYL
SP+7
RTNH
SP+8
➩ SP+9
70
RTNL
PC
INTERRUPT ROUTINE
$3E = WAI
➩ SP–9
STACK
CCR
SP–8
ACCB
SP–7
ACCA
SP–6
IXH
SP–5
IXL
SP–4
IYH
SP–3
IYL
SP–2
RTNH
SP–1
SP
70
RTNL
PC
MAIN PROGRAM
$3F = SWI
PC
MAIN PROGRAM
$3E = WAI
SWI, SOFTWARE INTERRUPT
WAI, WAIT FOR INTERRUPT
WAI, WAIT FOR INTERRUPT
➩ SP–2
STACK
RTNH
SP–1
RTNL
SP
70
PC
MAIN PROGRAM
$8D = BSR
PC
MAIN PROGRAM
$39 = RTS
BSR, BRANCH TO SUBROUTINE
RTS, RETURN FROM
SUBROUTINE
SP
STACK
RTNH
SP+1
RTNL
➩ SP+2
70
LEGEND:
RTN = ADDRESS OF NEXT INSTRUCTION IN MAIN PROGRAM TO
BE EXECUTED UPON RETURN FROM SUBROUTINE
RTNH = MOST SIGNIFICANT BYTE OF RETURN ADDRESS
RTNL = LEAST SIGNIFICANT BYTE OF RETURN ADDRESS
➩ = STACK POINTER POSITION AFTER OPERATION IS COMPLETE
dd = 8-BIT DIRECT ADDRESS ($0000–$00FF) (HIGH BYTE ASSUMED
TO BE $00)
ff = 8-BIT POSITIVE OFFSET $00 (0) TO $FF (256) IS ADDED TO INDEX
hh = HIGH-ORDER BYTE OF 16-BIT EXTENDED ADDRESS
ll = LOW-ORDER BYTE OF 16-BIT EXTENDED ADDRESS
rr= SIGNED RELATIVE OFFSET $80 (–128) TO $7F (+127) (OFFSET
RELATIVE TO THE ADDRESS FOLLOWING THE MACHINE CODE
OFFSET BYTE)
HC11 STACK OPERATIONS
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When a subroutine is called by a jump to subroutine (JSR) or branch to subroutine
(BSR) instruction, the address of the instruction after the JSR or BSR is automatically
pushed onto the stack, least significant byte first. When the subroutine is finished, a
return from subroutine (RTS) instruction is executed. The RTS pulls the previously
stacked return address from the stack, and loads it into the program counter. Execu-
tion then continues at this recovered return address.
When an interrupt is recognized, the current instruction finishes normally, the return
address (the current value in the program counter) is pushed onto the stack, all of the
CPU registers are pushed onto the stack, and execution continues at the address
specified by the vector for the interrupt. At the end of the interrupt service routine, an
RTI instruction is executed. The RTI instruction causes the saved registers to be pulled
off the stack in reverse order. Program execution resumes at the return address.
There are instructions that push and pull the A and B accumulators and the X and Y
index registers. These instructions are often used to preserve program context. For ex-
ample, pushing accumulator A onto the stack when entering a subroutine that uses ac-
cumulator A, and then pulling accumulator A off the stack just before leaving the
subroutine, ensures that the contents of a register will be the same after returning from
the subroutine as it was before starting the subroutine.
3.1.5 Program Counter (PC)
The program counter, a 16-bit register, contains the address of the next instruction to
be executed. After reset, the program counter is initialized from one of six possible
vectors, depending on operating mode and the cause of reset.
3.1.6 Condition Code Register (CCR)
This 8-bit register contains five condition code indicators (C, V, Z, N, and H), two inter-
rupt masking bits, (IRQ and XIRQ) and a stop disable bit (S). In the M68HC11 CPU,
condition codes are automatically updated by most instructions. For example, load ac-
cumulator A (LDAA) and store accumulator A (STAA) instructions automatically set or
clear the N, Z, and V condition code flags. Pushes, pulls, add B to X (ABX), add B to
Y (ABY), and transfer/exchange instructions do not affect the condition codes. Refer
to Table 3-2, which shows what condition codes are affected by a particular instruc-
tion.
3.1.6.1 Carry/Borrow (C)
The C bit is set if the arithmetic logic unit (ALU) performs a carry or borrow during an
arithmetic operation. The C bit also acts as an error flag for multiply and divide opera-
Table 3-1 Reset Vector Comparison
POR or Pin Clock Monitor COP Watchdog
Normal $FFFE, F $FFFC, D $FFFA, B
Test or Boot $BFFE, F $BFFC, D $BFFA, B
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tions. Shift and rotate instructions operate with and through the carry bit to facilitate
multiple-word shift operations.
3.1.6.2 Overflow (V)
The overflow bit is set if an operation causes an arithmetic overflow. Otherwise, the V
bit is cleared.
3.1.6.3 Zero (Z)
The Z bit is set if the result of an arithmetic, logic, or data manipulation operation is
zero. Otherwise, the Z bit is cleared. Compare instructions do an internal implied sub-
traction and the condition codes, including Z, reflect the results of that subtraction. A
few operations (INX, DEX, INY, and DEY) affect the Z bit and no other condition flags.
For these operations, only = and - conditions can be determined.
3.1.6.4 Negative (N)
The N bit is set if the result of an arithmetic, logic, or data manipulation operation is
negative (MSB = 1). Otherwise, the N bit is cleared. A result is said to be negative if its
most significant bit (MSB) is a one. A quick way to test whether the contents of a mem-
ory location has the MSB set is to load it into an accumulator and then check the status
of the N bit.
3.1.6.5 Interrupt Mask (I)
The interrupt request (IRQ) mask (I bit) is a global mask that disables all maskable in-
terrupt sources. While the I bit is set, interrupts can become pending, but the operation
of the CPU continues uninterrupted until the I bit is cleared. After any reset, the I bit is
set by default and can only be cleared by a software instruction. When an interrupt is
recognized, the I bit is set after the registers are stacked, but before the interrupt vector
is fetched. After the interrupt has been serviced, a return from interrupt instruction is
normally executed, restoring the registers to the values that were present before the
interrupt occurred. Normally, the I bit is zero after a return from interrupt is executed.
Although the I bit can be cleared within an interrupt service routine, “nesting” interrupts
in this way should only be done when there is a clear understanding of latency and of
the arbitration mechanism. Refer to SECTION 5 RESETS AND INTERRUPTS.
3.1.6.6 Half Carry (H)
The H bit is set when a carry occurs between bits 3 and 4 of the arithmetic logic unit
during an ADD, ABA, or ADC instruction. Otherwise, the H bit is cleared. Half carry is
used during BCD operations.
3.1.6.7 X Interrupt Mask (X)
The XIRQ mask (X) bit disables interrupts from the pin. After any reset, X is set by de-
fault and must be cleared by a software instruction. When an interrupt is recognized,
the X and I bits are set after the registers are stacked, but before the interrupt vector
is fetched. After the interrupt has been serviced, an RTI instruction is normally execut-
ed, causing the registers to be restored to the values that were present before the in-
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terrupt occurred. The X interrupt mask bit is set only by hardware (or acknowledge). X
is cleared only by program instruction (TAP, where the associated bit of A is 0; or RTI,
where bit 6 of the value loaded into the CCR from the stack has been cleared). There
is no hardware action for clearing X.
3.1.6.8 Stop Disable (S)
Setting the STOP disable (S) bit prevents the STOP instruction from putting the
M68HC11 into a low-power stop condition. If the STOP instruction is encountered by
the CPU while the S bit is set, it is treated as a no-operation (NOP) instruction, and
processing continues to the next instruction. S is set by reset —STOP disabled by de-
fault.
3.2 Data Types
The M68HC11 CPU supports the following data types:
• Bit data
• 8-bit and 16-bit signed and unsigned integers
• 16-bit unsigned fractions
• 16-bit addresses
A byte is eight bits wide and can be accessed at any byte location. A word is composed
of two consecutive bytes with the most significant byte at the lower value address. Be-
cause the M68HC11 is an 8-bit CPU, there are no special requirements for alignment
of instructions or operands.
3.3 Opcodes and Operands
The M68HC11 family of microcontrollers uses 8-bit opcodes. Each opcode identifies
a particular instruction and associated addressing mode to the CPU. Several opcodes
are required to provide each instruction with a range of addressing capabilities. Only
256 opcodes would be available if the range of values were restricted to the number
able to be expressed in 8-bit binary numbers.
A four-page opcode map has been implemented to expand the number of instructions.
An additional byte, called a prebyte, directs the processor from page 0 of the opcode
map to one of the other three pages. As its name implies, the additional byte precedes
the opcode.
A complete instruction consists of a prebyte, if any, an opcode, and zero, one, two, or
three operands. The operands contain information the CPU needs for executing the
instruction. Complete instructions can be from one to five bytes long.
3.4 Addressing Modes
Six addressing modes; immediate, direct, extended, indexed, inherent, and relative,
detailed in the following paragraphs, can be used to access memory. All modes except
inherent mode use an effective address. The effective address is the memory address
from which the argument is fetched or stored, or the address from which execution is
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to proceed. The effective address can be specified within an instruction, or it can be
calculated.
3.4.1 Immediate
In the immediate addressing mode an argument is contained in the byte(s) immediate-
ly following the opcode. The number of bytes following the opcode matches the size
of the register or memory location being operated on. There are two-, three-, and four-
(if prebyte is required) byte immediate instructions. The effective address is the ad-
dress of the byte following the instruction.
3.4.2 Direct
In the direct addressing mode, the low-order byte of the operand address is contained
in a single byte following the opcode, and the high-order byte of the address is as-
sumed to be $00. Addresses $00–$FF are thus accessed directly, using two-byte in-
structions. Execution time is reduced by eliminating the additional memory access
required for the high-order address byte. In most applications, this 256-byte area is re-
served for frequently referenced data. In M68HC11 MCUs, the memory map can be
configured for combinations of internal registers, RAM or external memory to occupy
these addresses.
3.4.2.1 Extended
In the extended addressing mode, the effective address of the argument is contained
in two bytes following the opcode byte. These are three-byte instructions (or four-byte
instructions if a prebyte is required). One or two bytes are needed for the opcode and
two for the effective address.
3.4.2.2 Indexed
In the indexed addressing mode, an 8-bit unsigned offset contained in the instruction
is added to the value contained in an index register (IX or IY) — the sum is the effective
address. This addressing mode allows referencing any memory location in the 64
Kbyte address space. These are from two- to five-byte instructions, depending on
whether or not a prebyte is required.
3.4.2.3 Inherent
In the inherent addressing mode, all the information necessary to execute the instruc-
tion is contained in the opcode. Operations that use only the index registers or accu-
mulators, as well as control instructions with no arguments, are included in this
addressing mode. These are one- or two-byte instructions.
3.4.2.4 Relative
The relative addressing mode is used only for branch instructions. If the branch con-
dition is true, an 8-bit signed offset included in the instruction is added to the contents
of the program counter to form the effective branch address. Otherwise, control pro-
ceeds to the next instruction. These are usually two-byte instructions.
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3.5 Instruction Set
Refer to Table 3-2, which shows all the M68HC11 instructions in all possible address-
ing modes. For each instruction, the table shows the operand construction, the number
of machine code bytes, and execution time in CPU E-clock cycles.
Table 3-2 Instruction Set (Sheet 1 of 7)
Mnemonic Operation Description Addressing Instruction Condition Codes
Mode Opcode Operand Cycles S X H I N Z V C
ABA Add
Accumulators A + B ⇒ AINH1B—2——
∆—∆∆∆∆
ABX Add B to X IX + (00 : B) ⇒ IX INH 3A — 3 ————————
ABY Add B to Y IY + (00 : B) ⇒ IY INH 18 3A — 4 ————————
ADCA (opr) Add with Carry
to A A + M + C ⇒ A A IMM
ADIR
A EXT
AIND,X
AIND,Y
89
99
B9
A9
18 A9
ii
dd
hh ll
ff
ff
2
3
4
4
5
—— ∆—∆∆∆∆
ADCB (opr) Add with Carry
to B B + M + C ⇒ B B IMM
BDIR
B EXT
BIND,X
BIND,Y
C9
D9
F9
E9
18 E9
ii
dd
hh ll
ff
ff
2
3
4
4
5
—— ∆—∆∆∆∆
ADDA (opr) Add Memory
to A A + M ⇒ A A IMM
ADIR
A EXT
AIND,X
AIND,Y
8B
9B
BB
AB
18 AB
ii
dd
hh ll
ff
ff
2
3
4
4
5
—— ∆—∆∆∆∆
ADDB (opr) Add Memory
to B B + M ⇒ BB IMM
BDIR
B EXT
BIND,X
BIND,Y
CB
DB
FB
EB
18 EB
ii
dd
hh ll
ff
ff
2
3
4
4
5
—— ∆—∆∆∆∆
ADDD (opr) Add 16-Bit to D D + (M : M + 1) ⇒ DIMM
DIR
EXT
IND,X
IND,Y
C3
D3
F3
E3
18 E3
jj kk
dd
hh ll
ff
ff
4
5
6
6
7
———— ∆∆∆∆
ANDA (opr) AND A with
Memory A • M ⇒ A A IMM
A DIR
A EXT
AIND,X
AIND,Y
84
94
B4
A4
18 A4
ii
dd
hh ll
ff
ff
2
3
4
4
5
———— ∆∆0—
ANDB (opr) AND B with
Memory B • M ⇒ B B IMM
BDIR
B EXT
BIND,X
BIND,Y
C4
D4
F4
E4
18 E4
ii
dd
hh ll
ff
ff
2
3
4
4
5
———— ∆∆0—
ASL (opr) Arithmetic
Shift Left EXT
IND,X
IND,Y
78
68
18 68
hh ll
ff
ff
6
6
7
———— ∆∆∆∆
ASLA Arithmetic
Shift Left A A INH 48 — 2 ———— ∆∆∆∆
ASLB Arithmetic
Shift Left B B INH 58 — 2 ———— ∆∆∆∆
ASLD Arithmetic
Shift Left D INH 05 — 3 ———— ∆∆∆∆
ASR Arithmetic
Shift Right EXT
IND,X
IND,Y
77
67
18 67
hh ll
ff
ff
6
6
7
———— ∆∆∆∆
ASRA Arithmetic
Shift Right A A INH 47 — 2 ———— ∆∆∆∆
ASRB Arithmetic
Shift Right B B INH 57 — 2 ———— ∆∆∆∆
BCC (rel) Branch if Carry
Clear ? C = 0 REL 24rr 3 ————————
C0
b7 b0
C0
b7 b0
C0
b7 b0
C0
b7 b0
AB
b7
b0
C
b7 b0
C
b7 b0
C
b7 b0
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BCLR (opr)
(msk) Clear Bit(s) M • (mm) ⇒ MDIR
IND,X
IND,Y
15
1D
18 1D
dd mm
ff mm
ff mm
6
7
8
———— ∆∆0—
BCS (rel) Branch if Carry
Set ? C = 1 REL 25rr 3 ————————
BEQ (rel) Branch if =
Zero ? Z = 1 REL 27rr 3 ————————
BGE (rel) Branch if ∆
Zero ? N ⊕ V = 0 REL 2Crr 3 ————————
BGT (rel) Branch if >
Zero ? Z + (N ⊕ V) = 0 REL 2Err 3 ————————
BHI (rel) Branch if
Higher ? C + Z = 0 REL 22rr 3 ————————
BHS (rel) Branch if
Higher or
Same
? C = 0 REL 24rr 3 ————————
BITA (opr) Bit(s) Test A
with Memory A • M A IMM
ADIR
A EXT
AIND,X
AIND,Y
85
95
B5
A5
18 A5
ii
dd
hh ll
ff
ff
2
3
4
4
5
———— ∆∆0—
BITB (opr) Bit(s) Test B
with Memory B • M B IMM
BDIR
B EXT
BIND,X
BIND,Y
C5
D5
F5
E5
18 E5
ii
dd
hh ll
ff
ff
2
3
4
4
5
———— ∆∆0—
BLE (rel) Branch if ∆
Zero ? Z + (N ⊕ V) = 1 REL 2F rr 3————————
BLO (rel) Branch if
Lower ? C = 1 REL 25 rr 3————————
BLS (rel) Branch if
Lower or
Same
? C + Z = 1 REL 23 rr 3————————
BLT (rel) Branch if <
Zero ? N ⊕ V = 1 REL 2D rr 3————————
BMI (rel) Branch if
Minus ? N = 1 REL 2B rr 3————————
BNE (rel) Branch if not =
Zero ? Z = 0 REL 26 rr 3————————
BPL (rel) Branch if Plus ? N = 0 REL 2A rr 3————————
BRA (rel) Branch Always ? 1 = 1 REL 20 rr 3————————
BRCLR(opr)
(msk)
(rel)
Branch if
Bit(s) Clear ? M • mm = 0 DIR
IND,X
IND,Y
13
1F
18 1F
dd mm rr
ff mm rr
ff mm rr
6
7
8
————————
BRN (rel) Branch Never ? 1 = 0 REL 21 rr 3————————
BRSET(opr)
(msk)
(rel)
Branch if Bit(s)
Set ? (M) • mm = 0 DIR
IND,X
IND,Y
12
1E
18 1E
dd mm rr
ff mm rr
ff mm rr
6
7
8
————————
BSET (opr)
(msk) Set Bit(s) M + mm ⇒ M DIR
IND,X
IND,Y
14
1C
18 1C
dd mm
ff mm
ff mm
6
7
8
———— ∆∆0—
BSR (rel) Branch to
Subroutine See Figure 3–2 REL 8D rr 6————————
BVC (rel) Branch if
Overflow Clear ? V = 0 REL 28 rr 3————————
BVS (rel) Branch if
Overflow Set ? V = 1 REL 29 rr 3————————
CBA Compare A to
BA – B INH 11 — 2———— ∆∆∆∆
CLC Clear Carry Bit 0 ⇒ CINH 0C — 2——————— 0
CLI Clear Interrupt
Mask 0 ⇒ IINH 0E — 2——— 0 ————
CLR (opr) Clear Memory
Byte 0 ⇒ M EXT
IND,X
IND,Y
7F
6F
18 6F
hh ll
ff
ff
6
6
7
———— 0100
Table 3-2 Instruction Set (Sheet 2 of 7)
Mnemonic Operation Description Addressing Instruction Condition Codes
Mode Opcode Operand Cycles S X H I N Z V C
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CENTRAL PROCESSING UNIT
3-10 TECHNICAL DATA
CLRA Clear
Accumulator A 0 ⇒ A A INH 4F — 2 ———— 0100
CLRB Clear
Accumulator B 0 ⇒ B B INH 5F — 2 ———— 0100
CLV Clear Overflow
Flag 0 ⇒ V INH 0A — 2 —————— 0 —
CMPA (opr) Compare A to
Memory A – M A IMM
ADIR
A EXT
AIND,X
AIND,Y
81
91
B1
A1
18 A1
ii
dd
hh ll
ff
ff
2
3
4
4
5
———— ∆∆∆∆
CMPB (opr) Compare B to
Memory B – M B IMM
BDIR
B EXT
BIND,X
BIND,Y
C1
D1
F1
E1
18 E1
ii
dd
hh ll
ff
ff
2
3
4
4
5
———— ∆∆∆∆
COM (opr) Ones
Complement
Memory Byte
$FF – M ⇒ M EXT
IND,X
IND,Y
73
63
18 63
hh ll
ff
ff
6
6
7
———— ∆∆01
COMA Ones
Complement
A
$FF – A ⇒ A A INH 43 — 2 ———— ∆∆01
COMB Ones
Complement
B
$FF – B ⇒ B B INH 53 — 2 ———— ∆∆01
CPD (opr) Compare D to
Memory 16-Bit D – M : M + 1 IMM
DIR
EXT
IND,X
IND,Y
1A 83
1A 93
1A B3
1A A3
CD A3
jj kk
dd
hh ll
ff
ff
5
6
7
7
7
———— ∆∆∆∆
CPX (opr) Compare X to
Memory 16-Bit IX – M : M + 1 IMM
DIR
EXT
IND,X
IND,Y
8C
9C
BC
AC
CD AC
jj kk
dd
hh ll
ff
ff
4
5
6
6
7
———— ∆∆∆∆
CPY (opr) Compare Y to
Memory 16-Bit IY – M : M + 1 IMM
DIR
EXT
IND,X
IND,Y
18 8C
18 9C
18 BC
1A AC
18 AC
jj kk
dd
hh ll
ff
ff
5
6
7
7
7
———— ∆∆∆∆
DAA Decimal Adjust
AAdjust Sum to BCD INH 19 — 2 ———— ∆∆∆∆
DEC (opr) Decrement
Memory Byte M – 1 ⇒ M EXT
IND,X
IND,Y
7A
6A
18 6A
hh ll
ff
ff
6
6
7
———— ∆∆∆
—
DECA Decrement
Accumulator
A
A – 1 ⇒ A A INH 4A — 2 ———— ∆∆∆
—
DECB Decrement
Accumulator
B
B – 1 ⇒ B B INH 5A — 2 ———— ∆∆∆
—
DES Decrement
Stack Pointer SP – 1 ⇒ SP INH 34 — 3 ————————
DEX Decrement
Index Register
X
IX – 1 ⇒ IX INH 09 — 3 ————— ∆——
DEY Decrement
Index Register
Y
IY – 1 ⇒ IY INH 18 09 — 4 ————— ∆——
EORA (opr) Exclusive OR
A with Memory A ⊕ M ⇒ AA IMM
ADIR
A EXT
AIND,X
AIND,Y
88
98
B8
A8
18 A8
ii
dd
hh ll
ff
ff
2
3
4
4
5
———— ∆∆0—
EORB (opr) Exclusive OR
B with Memory B ⊕ M ⇒ BB IMM
BDIR
B EXT
BIND,X
BIND,Y
C8
D8
F8
E8
18 E8
ii
dd
hh ll
ff
ff
2
3
4
4
5
———— ∆∆0—
FDIV Fractional
Divide 16 by
16
D / IX ⇒ IX; r ⇒ D INH 03 — 41 ————— ∆∆∆
IDIV Integer Divide
16 by 16 D / IX ⇒ IX; r ⇒ D INH 02 — 41 ————— ∆0∆
Table 3-2 Instruction Set (Sheet 3 of 7)
Mnemonic Operation Description Addressing Instruction Condition Codes
Mode Opcode Operand Cycles S X H I N Z V C
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CENTRAL PROCESSING UNIT
TECHNICAL DATA 3-11
INC (opr) Increment
Memory Byte M + 1 ⇒ M EXT
IND,X
IND,Y
7C
6C
18 6C
hh ll
ff
ff
6
6
7
———— ∆∆∆
—
INCA Increment
Accumulator
A
A + 1 ⇒ A A INH 4C — 2 ———— ∆∆∆
—
INCB Increment
Accumulator
B
B + 1 ⇒ B B INH 5C — 2 ———— ∆∆∆
—
INS Increment
Stack Pointer SP + 1 ⇒ SP INH 31 — 3 ————————
INX Increment
Index Register
X
IX + 1 ⇒ IX INH 08 — 3 ————— ∆——
INY Increment
Index Register
Y
IY + 1 ⇒ IY INH 18 08 — 4 ————— ∆——
JMP (opr) Jump See Figure 3–2 EXT
IND,X
IND,Y
7E
6E
18 6E
hh ll
ff
ff
3
3
4
————————
JSR (opr) Jump to
Subroutine See Figure 3–2 DIR
EXT
IND,X
IND,Y
9D
BD
AD
18 AD
dd
hh ll
ff
ff
5
6
6
7
————————
LDAA (opr) Load
Accumulator
A
M ⇒ AAIMM
A DIR
A EXT
A IND,X
A IND,Y
86
96
B6
A6
18 A6
ii
dd
hh ll
ff
ff
2
3
4
4
5
———— ∆∆0—
LDAB (opr) Load
Accumulator
B
M ⇒ BBIMM
B DIR
B EXT
B IND,X
B IND,Y
C6
D6
F6
E6
18 E6
ii
dd
hh ll
ff
ff
2
3
4
4
5
———— ∆∆0—
LDD (opr) Load Double
Accumulator
D
M ⇒ A,M + 1 ⇒ BIMM
DIR
EXT
IND,X
IND,Y
CC
DC
FC
EC
18 EC
jj kk
dd
hh ll
ff
ff
3
4
5
5
6
———— ∆∆0—
LDS (opr) Load Stack
Pointer M : M + 1 ⇒ SP IMM
DIR
EXT
IND,X
IND,Y
8E
9E
BE
AE
18 AE
jj kk
dd
hh ll
ff
ff
3
4
5
5
6
———— ∆∆0—
LDX (opr) Load Index
Register
X
M : M + 1 ⇒ IX IMM
DIR
EXT
IND,X
IND,Y
CE
DE
FE
EE
CD EE
jj kk
dd
hh ll
ff
ff
3
4
5
5
6
———— ∆∆0—
LDY (opr) Load Index
Register
Y
M : M + 1 ⇒ IY IMM
DIR
EXT
IND,X
IND,Y
18 CE
18 DE
18 FE
1A EE
18 EE
jj kk
dd
hh ll
ff
ff
4
5
6
6
6
———— ∆∆0—
LSL (opr) Logical Shift
Left EXT
IND,X
IND,Y
78
68
18 68
hh ll
ff
ff
6
6
7
———— ∆∆∆∆
LSLA Logical Shift
Left A A INH 48 — 2 ———— ∆∆∆∆
LSLB Logical Shift
Left B B INH 58 — 2 ———— ∆∆∆∆
LSLD Logical Shift
Left Double INH 05 — 3 ———— ∆∆∆∆
LSR (opr) Logical Shift
Right EXT
IND,X
IND,Y
74
64
18 64
hh ll
ff
ff
6
6
7
———— 0 ∆∆∆
LSRA Logical Shift
Right A A INH 44 — 2 ———— 0 ∆∆∆
Table 3-2 Instruction Set (Sheet 4 of 7)
Mnemonic Operation Description Addressing Instruction Condition Codes
Mode Opcode Operand Cycles S X H I N Z V C
C0
b7 b0
C0
b7 b0
C0
b7 b0
C0
b7 b0AB
b7
b0
C
0b7 b0
C
0b7 b0
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CENTRAL PROCESSING UNIT
3-12 TECHNICAL DATA
LSRB Logical Shift
Right B B INH 54 — 2 ———— 0 ∆∆∆
LSRD Logical Shift
Right Double INH 04 — 3 ———— 0 ∆∆∆
MUL Multiply 8 by 8 A ∗ B ⇒ D INH 3D — 10 ——————— ∆
NEG (opr) Two’s
Complement
Memory Byte
0 – M ⇒ M EXT
IND,X
IND,Y
70
60
18 60
hh ll
ff
ff
6
6
7
———— ∆∆∆∆
NEGA Two’s
Complement
A
0 – A ⇒ A A INH 40 — 2 ———— ∆∆∆∆
NEGB Two’s
Complement
B
0 – B ⇒ B B INH 50 — 2 ———— ∆∆∆∆
NOP No operation No Operation INH 01 — 2 ————————
ORAA (opr) OR
Accumulator
A (Inclusive)
A + M ⇒ A A IMM
ADIR
A EXT
AIND,X
AIND,Y
8A
9A
BA
AA
18 AA
ii
dd
hh ll
ff
ff
2
3
4
4
5
———— ∆∆0—
ORAB (opr) OR
Accumulator
B (Inclusive)
B + M ⇒ B B IMM
BDIR
B EXT
BIND,X
BIND,Y
CA
DA
FA
EA
18 EA
ii
dd
hh ll
ff
ff
2
3
4
4
5
———— ∆∆0—
PSHA Push A onto
Stack A ⇒ Stk,SP = SP – 1 A INH 36 — 3 ————————
PSHB Push B onto
Stack B ⇒ Stk,SP = SP – 1 B INH 37 — 3 ————————
PSHX Push X onto
Stack (Lo
First)
IX ⇒ Stk,SP = SP – 2 INH 3C — 4 ————————
PSHY Push Y onto
Stack (Lo
First)
IY ⇒ Stk,SP = SP – 2 INH 18 3C — 5 ————————
PULA Pull A from
Stack SP = SP + 1, A ⇐ StkA INH 32 — 4 ————————
PULB Pull B from
Stack SP = SP + 1, B ⇐ StkB INH 33 — 4 ————————
PULX Pull X From
Stack (Hi
First)
SP = SP + 2, IX ⇐
Stk INH 38 — 5 ————————
PULY Pull Y from
Stack (Hi
First)
SP = SP + 2, IY ⇐
Stk INH 18 38 — 6 ————————
ROL (opr) Rotate Left EXT
IND,X
IND,Y
79
69
18 69
hh ll
ff
ff
6
6
7
———— ∆∆∆∆
ROLA Rotate Left A A INH 49 — 2 ———— ∆∆∆∆
ROLB Rotate Left B B INH 59 — 2 ———— ∆∆∆∆
ROR (opr) Rotate Right EXT
IND,X
IND,Y
76
66
18 66
hh ll
ff
ff
6
6
7
———— ∆∆∆∆
RORA Rotate Right A A INH 46 — 2 ———— ∆∆∆∆
RORB Rotate Right B B INH 56 — 2 ———— ∆∆∆∆
RTI Return from
Interrupt See Figure 3–2 INH 3B — 12 ∆↓∆∆∆∆∆∆
RTS Return from
Subroutine See Figure 3–2 INH 39 — 5 ————————
SBA Subtract B
from A A – B ⇒ A INH 10 — 2 ———— ∆∆∆∆
Table 3-2 Instruction Set (Sheet 5 of 7)
Mnemonic Operation Description Addressing Instruction Condition Codes
Mode Opcode Operand Cycles S X H I N Z V C
C
0b7 b0
C
0b7 b0
AB
b7
b0
Cb7 b0
Cb7 b0
Cb7 b0
C
b7 b0
C
b7 b0
C
b7 b0
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CENTRAL PROCESSING UNIT
TECHNICAL DATA 3-13
SBCA (opr) Subtract with
Carry from A A – M – C ⇒ A A IMM
ADIR
A EXT
AIND,X
AIND,Y
82
92
B2
A2
18 A2
ii
dd
hh ll
ff
ff
2
3
4
4
5
———— ∆∆∆∆
SBCB (opr) Subtract with
Carry from B B – M – C ⇒ B B IMM
BDIR
B EXT
BIND,X
BIND,Y
C2
D2
F2
E2
18 E2
ii
dd
hh ll
ff
ff
2
3
4
4
5
———— ∆∆∆∆
SEC Set Carry 1 ⇒ C INH 0D — 2 ——————— 1
SEI Set Interrupt
Mask 1 ⇒ I INH 0F — 2 ——— 1 ————
SEV Set Overflow
Flag 1 ⇒ V INH 0B — 2 —————— 1 —
STAA (opr) Store
Accumulator
A
A ⇒ MADIR
A EXT
AIND,X
AIND,Y
97
B7
A7
18 A7
dd
hh ll
ff
ff
3
4
4
5
———— ∆∆0—
STAB (opr) Store
Accumulator
B
B ⇒ MBDIR
B EXT
BIND,X
BIND,Y
D7
F7
E7
18 E7
dd
hh ll
ff
ff
3
4
4
5
———— ∆∆0—
STD (opr) Store
Accumulator
D
A ⇒ M, B ⇒ M + 1 DIR
EXT
IND,X
IND,Y
DD
FD
ED
18 ED
dd
hh ll
ff
ff
4
5
5
6
———— ∆∆0—
STOP Stop Internal
Clocks — INH CF — 2 ————————
STS (opr) Store Stack
Pointer SP ⇒ M : M + 1 DIR
EXT
IND,X
IND,Y
9F
BF
AF
18 AF
dd
hh ll
ff
ff
4
5
5
6
———— ∆∆0—
STX (opr) Store Index
Register X IX ⇒ M : M + 1 DIR
EXT
IND,X
IND,Y
DF
FF
EF
CD EF
dd
hh ll
ff
ff
4
5
5
6
———— ∆∆0—
STY (opr) Store Index
Register Y IY ⇒ M : M + 1 DIR
EXT
IND,X
IND,Y
18 DF
18 FF
1A EF
18 EF
dd
hh ll
ff
ff
5
6
6
6
———— ∆∆0—
SUBA (opr) Subtract
Memory from
A
A – M ⇒ A A IMM
ADIR
A EXT
AIND,X
AIND,Y
80
90
B0
A0
18 A0
ii
dd
hh ll
ff
ff
2
3
4
4
5
———— ∆∆∆∆
SUBB (opr) Subtract
Memory from
B
B – M ⇒ B A IMM
ADIR
A EXT
AIND,X
AIND,Y
C0
D0
F0
E0
18 E0
ii
dd
hh ll
ff
ff
2
3
4
4
5
———— ∆∆∆∆
SUBD (opr) Subtract
Memory from
D
D – M : M + 1 ⇒ DIMM
DIR
EXT
IND,X
IND,Y
83
93
B3
A3
18 A3
jj kk
dd
hh ll
ff
ff
4
5
6
6
7
———— ∆∆∆∆
SWI Software
Interrupt See Figure 3–2 INH 3F — 14 ——— 1 ————
TAB Transfer A to B A ⇒ B INH 16 — 2 ———— ∆∆0—
TAP Transfer A to
CC Register A ⇒ CCR INH 06 — 2 ∆↓∆∆∆∆∆∆
TBA Transfer B to A B ⇒ A INH 17 — 2 ———— ∆∆0—
TEST TEST (Only in
Test Modes) Address Bus Counts INH 00 — * ————————
TPA Transfer CC
Register to A CCR ⇒ A INH 07 — 2 ————————
TST (opr) Test for Zero
or Minus M – 0 EXT
IND,X
IND,Y
7D
6D
18 6D
hh ll
ff
ff
6
6
7
———— ∆∆00
TSTA Test A for Zero
or Minus A – 0 A INH 4D — 2 ———— ∆∆00
TSTB Test B for Zero
or Minus B – 0 B INH 5D — 2 ———— ∆∆00
Table 3-2 Instruction Set (Sheet 6 of 7)
Mnemonic Operation Description Addressing Instruction Condition Codes
Mode Opcode Operand Cycles S X H I N Z V C
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CENTRAL PROCESSING UNIT
3-14 TECHNICAL DATA
TSX Transfer Stack
Pointer to X SP + 1 ⇒ IX INH 30 — 3 ————————
TSY Transfer Stack
Pointer to Y SP + 1 ⇒ IY INH 18 30 — 4 ————————
TXS Transfer X to
Stack Pointer IX – 1 ⇒ SP INH 35 — 3 ————————
TYS Transfer Y to
Stack Pointer IY – 1 ⇒ SP INH 18 35 — 4 ————————
WAI Wait for
Interrupt Stack Regs & WAIT INH 3E — ** ————————
XGDX Exchange D
with X IX ⇒ D, D ⇒ IX INH 8F — 3 ————————
XGDY Exchange D
with Y IY ⇒ D, D ⇒ IY INH 18 8F — 4 ————————
Table 3-2 Instruction Set (Sheet 7 of 7)
Mnemonic Operation Description Addressing Instruction Condition Codes
Mode Opcode Operand Cycles S X H I N Z V C
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OPERATING MODES AND ON-CHIP MEMORY
TECHNICAL DATA 4-1
SECTION 4
OPERATING MODES AND ON-CHIP MEMORY
This section contains information about the modes that define MC68HC11D3 operat-
ing conditions, and about the on-chip memory that allows the MCU to be configured
for various applications.
4.1 Operating Modes
The values of the mode select inputs MODB and MODA during reset determine the
operating mode. Single chip and expanded multiplexed are the normal modes. With
single-chip mode only on-board memory is available. Expanded multiplexed mode,
however, allows access to external memory. Each of these two normal modes is
paired with a special mode. Bootstrap, a variation of the single-chip mode, is a special
mode that executes a bootloader program in an internal bootstrap ROM. Test is a spe-
cial mode that allows privileged access to internal resources.
4.1.1 Single-Chip Mode
In single-chip mode, ports B and C are available for general-purpose parallel I/O. In
expanded multiplexed mode the MCU can access a 64 Kbyte address space. The total
address space includes the same on-chip memory addresses used for single-chip
mode plus external memory and peripheral devices.
4.1.2 Expanded Multiplexed Mode
Expanded memory access is achieved by providing multiplexed external data and ad-
dress buses on two of the M68HC11 ports; therefore only 18 pins are needed for an
8-bit data bus, a 16-bit address bus and two bus control lines. Port B is designated for
ADDR[15:8], while port C is multiplexed ADDR[7:0]/DATA[7:0]. The address, R/W,
and AS signals are active and valid for all bus cycles including accesses to internal
memory locations. Refer to Figure 4-1, which illustrates a recommended method of
demultiplexing low order addresses from data at port C.
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OPERATING MODES AND ON-CHIP MEMORY
4-2 TECHNICAL DATA
Figure 4-1 Address/Data Demultiplexing
4.1.3 Special Test Mode
Special test, a variation of the expanded multiplexed mode, is primarily used during
Motorola's internal production testing; however, it is accessible for programming the
CONFIG register, and supporting emulation and debugging during development.
4.1.4 Bootstrap Mode
When the MCU is reset in special bootstrap mode, a small amount of on-chip ROM is
enabled at address $BF00–$BFFF. The ROM contains a bootloader program and a
special set of interrupt and reset vectors. The MCU fetches the reset vector, then ex-
ecutes the bootloader.
For normal use of the bootloader program, send $FF to the SCI receiver at either E
clock ÷16, or E clock ÷104 (1200 baud for E clock equals 2 MHz). Then download up
to 192 bytes of program data, which is put into RAM starting at $0040. These charac-
ters are echoed through the transmitter. When loading is complete, the program jumps
to location $0040 and begins executing the code. The bootloader program ends the
download after 192 bytes, or when the received data line is idle for at least four char-
acter times. Use of an external pullup resistor is required when using the SCI transmit-
ter pin because port D pins are configured for wired-OR operation by the bootloader.
In bootstrap mode, the interrupt vectors are directed to RAM. This allows the use of
interrupts through a jump table. Refer to Motorola application note AN1060,
MC68HC11 Bootstrap Mode.
HC373
MCU
ADDR/DATA DEMUX
ADDR14
ADDR13
ADDR12
ADDR11
ADDR10
ADDR9
ADDR8
ADDR15
ADDR6
ADDR5
ADDR4
ADDR3
ADDR2
ADDR1
ADDR0
ADDR7
DATA6
DATA5
DATA4
DATA3
DATA2
DATA1
DATA0
DATA7
D2
D3
D4
D5
D6
D7
D8
D1 Q2
Q3
Q4
Q5
Q6
Q7
Q8
Q1
OE
LE
PC6
PC5
PC4
PC3
PC2
PC1
PC0
PC7
AS
PB6
PB5
PB4
PB3
PB2
PB1
PB0
PB7
R/W
EWE
OE
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OPERATING MODES AND ON-CHIP MEMORY
TECHNICAL DATA 4-3
4.2 Memory Map
The operating mode determines memory mapping and whether memory is addressed
on- or off-chip. Refer to Figure 4-2, which illustrates the memory maps for each of the
four modes of operation. Memory locations for on-chip resources are the same for both
expanded multiplexed and single-chip modes. 192-byte RAM is mapped to $0040 af-
ter reset. It can be placed at any other 4K boundary ($x040) by writing an appropriate
value to the INIT register. The 64-byte register block is mapped to $0000 after reset
and can also be placed at any 4K boundary ($x000) by writing an appropriate value to
the INIT register. Refer to Table 4-1, which details the MCU register and control bit
assignments.
Figure 4-2 MC68HC11D3 Memory Map
SINGLE
CHIP
BOOTSTRAP SPECIAL
TEST
EXPANDED
NORMAL
MODES
INTERRUPT
VECTORS
192 BYTES STATIC RAM
64-BYTE REGISTER BLOCK
$0000
$0040
$7000
$F000
$FFFF
SPECIAL MODES
INTERRUPT
VECTORS
4 KBYTES ROM
4 KBYTES ROM
BOOT
ROM
D3 MEM MAP
FFC0
FFFF
BFC0
BFFF
FFFF
BF00
BFFF
7000
7FFF
0040
00FF
0000
003F
EXT EXT
F000
FFFF
EXT
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OPERATING MODES AND ON-CHIP MEMORY
4-4 TECHNICAL DATA
Table 4-1 Register and Control Bit Assignments
Bit 7654321Bit 0
$0000 PA7 PA6 PA5 PA4 PA3 PA2 PA1 PA0 PORTA
$0001 Reserved
$0002 CWOM PIOC
$0003 PC7 PC6 PC5 PC4 PC3 PC2 PC1 PC0 PORTC
$0004 PB7 PB6 PB5 PB4 PB3 PB2 PB1 PB0 PORTB
$0005 Reserved
$0006 DDB7 DDB6 DDB5 DDB4 DDB3 DDB2 DDB1 DDB0 DDRB
$0007 DDC7 DDC6 DDC5 DDC4 DDC3 DDC2 DDC1 DDC0 DDRC
$0008 PD7 PD6 PD5 PD4 PD3 PD2 PD1 PD0 PORTD
$0009 DDD7 DDD6 DDD5 DDD4 DDD3 DDD2 DDD1 DDD0 DDRD
$000A Reserved
$000B FOC1 FOC2 FOC3 FOC4 FOC5 0 0 0 CFORC
$000C OC1M7 OC1M6 OC1M5 OC1M4 OC1M3 0 0 0 OC1M
$000D OC1D7 OC1D6 OC1D5 OC1D4 OC1D3 0 0 0 OC1D
$000E Bit 15 14 13 12 11 10 9 Bit 8 TCNT (High)
$000FBit 7654321Bit 0TCNT (Low)
$0010 Bit 15 14 13 12 11 10 9 Bit 8 TIC1 (High)
$0011Bit 7654321Bit 0TIC1 (Low)
$0012 Bit 15 14 13 12 11 10 9 Bit 8 TIC2 (High)
$0013Bit 7654321Bit 0TIC2 (Low)
$0014 Bit 15 14 13 12 11 10 9 Bit 8 TIC3 (High)
$0015Bit 7654321Bit 0TIC3 (Low)
$0016 Bit 15 14 13 12 11 10 9 Bit 8 TOC1(High)
$0017Bit 7654321Bit 0TOC1 (Low)
$0018 Bit 15 14 13 12 11 10 9 Bit 8 TOC2 (High)
$0019Bit 7654321Bit 0TOC2 (Low)
$001A Bit 15 14 13 12 11 10 9 Bit 8 TOC3 (High)
$001BBit 7654321Bit 0TOC3 (Low)
$001C Bit 15 14 13 12 11 10 9 Bit 8 TOC4 (High)
$001DBit 7654321Bit 0TOC4 (Low)
$0023 OC1F OC2F OC3F OC4F I4/O5F IC1F IC2F IC3F TFLG1
$0024 TOI RTII PAOVI PAII 0 0 PR1 PR0 TMSK2
$0025TOFRTIFPAOVFPAIF0000TFLG2
$0026 DDRA7 PAEN PAMOD PEDGE DDRA3 I4/O5 RTR1 RTR0 PACTL
$0027Bit 7654321Bit 0PACNT
$0028 SPIE SPE DWOM MSTR CPOL CPHA SPR1 SPR0 SPCR
$0029SPIFWCOL0MODF0000SPSR
$002ABit 7654321Bit 0SPDR
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OPERATING MODES AND ON-CHIP MEMORY
TECHNICAL DATA 4-5
The bootloader program is contained in the 192-byte bootstrap ROM. This ROM,
which appears as internal memory space at locations $BF40–$BFFF, is enabled only
if the MCU is reset in special bootstrap mode.
Memory locations are the same for expanded multiplexed and single-chip modes, ex-
cept for ROM in expanded mode and the bootloader ROM in special bootstrap mode.
The on-board 192-byte RAM is initially located at $0040 after reset, but can be placed
at any other 4K boundary ($x040) by writing an appropriate value to the INIT register.
The 4 Kbyte ROM is located at $F000 through $FFFF in all modes except expanded
multiplexed, in which it is located at $7000. ROM can be located at $F000 in expanded
multiplexed by entering single-chip mode out of reset and setting the MDA bit in the
HPRIO register to 1, thereby entering expanded mode from internal ROM. Disable
ROM by clearing the ROMON bit in the CONFIG register.
Hardware priority is built into RAM and I/O remapping. Registers and RAM have prior-
ity over ROM. In the event of conflicts, the higher priority resource takes precedence.
The 192 bytes of fully static RAM store instructions, variables, and temporary data.
The direct addressing mode can access RAM locations using a one-byte address op-
erand, saving program memory space and execution time, depending on the applica-
tion. RAM contents are preserved during periods of processor inactivity by two
methods, both of which reduce power consumption.
In the software-based STOP mode, the clocks are stopped while VDD powers the
MCU. Because power supply current is directly related to operating frequency in
CMOS integrated circuits, only a very small amount of leakage exists when the clocks
are stopped.
$002B TCLR 0 SCP1 SCP0 RCKB SCR2 SCR1 SCR0 BAUD
$002C R8 T8 0 M WAKE 0 0 0 SCCR1
$002D TIE TCIE RIE ILIE TE RE RWU SBK SCCR2
$002E TDRE TC RDRF IDLE OR NF FE 0 SCSR
$002F R7/T7 R6/T6 R5/T5 R4/T4 R3/T3 R2/T2 R1/T1 R0/T0 SCDR
$0030 Reserved
to
$0038 Reserved
$0039 0 0 IRQE DLY CME 0 CR1 CR0 OPTION
$003ABit 7654321Bit 0COPRST
$003B Reserved
$003C RBOOT SMOD MDA IRVNE PSEL3 PSEL2 PSEL1 PSEL0 HPRIO
$003D RAM3 RAM2 RAM1 RAM0 REG3 REG2 REG1 REG0 INIT
$003E TILOP 0 OCCR CBYP DISR FCM FCOP 0 TEST1
$003F00000NOCOPROMON0CONFIG
Table 4-1 Register and Control Bit Assignments (Continued)
Bit 7654321Bit 0
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OPERATING MODES AND ON-CHIP MEMORY
4-6 TECHNICAL DATA
In the second method, the MODB/VSTBY pin can supply RAM power from a battery
backup or from a second power supply, as shown in Figure 4-3. Using the MODB/
VSTBY pin may require external hardware, but can be justified when a significant
amount of external circuitry is operating from VDD. If VSTBY is used to maintain RAM
contents, reset must be held low whenever VDD is below normal operating level. Refer
to SECTION 5 RESETS AND INTERRUPTS.
Figure 4-3 RAM Standby MODB/VSTBY Connections
4.2.1 Priority and Mode Select Register
The four operating modes are selected with the logic states of the mode A (MODA)
and mode B (MODB) pins during reset. The MODA and MODB logic levels determine
the logic state of the special mode (SMOD) and mode A (MDA) control bits in the
HPRIO register.
After reset is released, the mode select pins no longer influence the MCU operating
mode. For single-chip mode, the MODA pin is connected to a logic zero. For expanded
mode, MODA is normally connected to VDD through a pull-up resistor of 4.7 kΩ. The
MODA pin also functions as the load instruction register (LIR) pin when the MCU is not
in reset. The open drain active low LIR output pin drives low during the first E cycle of
each instruction. The MODB pin also functions as standby power input, VSTBY, which
maintains RAM contents in the absence of VDD. Refer to Table 4-2 for information
about hardware mode selection.
Table 4-2 Hardware Mode Select Summary
Inputs Mode Latched at Reset
MODB MODA RBOOT SMOD MDA
1 0 Single-Chip 0 0 0
1 1 Expanded Multiplexed 0 0 1
0 0 Special Bootstrap 1 1 0
0 1 Special Test 0 1 1
MODB/VSTBY CONN
4.7k
MAX
690
VBATT
+
4.8 V
NiCd
VDD
VDD
VOUT TO MODB/VSTBY
OF M68HC11
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OPERATING MODES AND ON-CHIP MEMORY
TECHNICAL DATA 4-7
The values of the RBOOT, SMOD, IRVNE, and MDA at reset depend on the mode dur-
ing initialization. Refer to Table 4-2.
RBOOT — Read Bootstrap ROM
Has meaning only when the SMOD bit is a one (special bootstrap mode or special test
mode). At all other times this bit is clear and cannot be written.
0 = Bootloader ROM disabled and not in map
1 = Bootloader ROM enabled and located in map at $BF40–$BFFF
SMOD — Special Mode Select
This bit reflects the inverse of the MODB input pin at the rising edge of reset. It is set
if the MODB input pin is low during reset. If MODB is high during reset, it is cleared.
SMOD can be cleared under software control from the special modes, thus changing
the operating mode of the MCU. SMOD can never be set by software.
0 = Normal mode variation in effect
1 = Special mode variation in effect
MDA — Mode Select A
The mode select A bit reflects the status of the MODA input pin at the rising edge of
reset. While the SMOD bit is set (special bootstrap or special test mode in effect), the
MDA bit can be written, thus changing the operating mode of the MCU. When the
SMOD bit is clear, the MODA bit is read-only and the operating mode cannot be
changed without going through a reset sequence.
0 = Normal single-chip or special bootstrap mode in effect
1 = Normal expanded or special test mode in effect
IRVNE — Internal Read Visibility/Not E
The IRVNE control bit allows internal read accesses to be available on the external
data bus during factory testing or emulation. If this capability is used for other purpos-
es, bus conflicts can occur because the bidirectional data bus is driven out during a
read of internal addresses, even though the R/W line suggests a high impedance
read mode.
0 = No internal read visibility on external bus
1 = Internal read data driven out data bus
In single-chip modes, this bit determines whether the E clock drives out of the chip.
0 = E driven out
1 = E pin driven low
HPRIO — Highest Priority I-Bit Interrupt and Miscellaneous $003C
Bit 7654321Bit 0
RBOOT SMOD MDA IRVNE PSEL3 PSEL2 PSEL1 PSEL0
RESET:— — — —0101
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OPERATING MODES AND ON-CHIP MEMORY
4-8 TECHNICAL DATA
PSEL[3:0] — Priority Select Bits
Refer to SECTION 5 RESETS AND INTERRUPTS.
4.2.2 System Initialization
Registers and bits that control initialization and the basic configuration of the MCU are
protected against writes except under special circumstances. The protection mecha-
nism, overridden in special operating modes, permits writing these bits only within the
first 64 bus cycles after any reset, and then only once after each reset. If the MCU is
going to be changed to a normal mode after being reset in a special mode, write to the
protected registers before writing the SMOD control bit to zero.
4.2.2.1 CONFIG Register
The CONFIG register consists of static latches that control the startup configuration of
the MCU. CONFIG is writable only once in expanded and single-chip modes (SMOD
= 0). In these modes, the COP watchdog timer is enabled out of reset.
Bits [7:3] and 0 — Not implemented
Always read zero
NOCOP — COP System Disable
This bit is cleared out of reset in normal modes (COP enabled). Refer to SECTION 5
RESETS AND INTERRUPTS.
0 = COP system enabled
1 = COP system disabled
ROMON — ROM Enable
In all modes, ROMON is forced to one out of reset. Writable once in normal modes and
writable at any time in special modes.
0 = ROM removed from the memory map
1 = ROM present in the memory map
Mode IRVNE Out
of Reset E Clock Out
of Reset IRV Out of
Reset IRVNE
Affects Only
Single-Chip 0 On Off E
Expanded 0 On Off IRV
Boot 0 On Off E
Special Test 1 On On IRV
CONFIG — System Configuration $003F
Bit 7654321Bit 0
00000NOCOPROMON0
RESET:00000— —0
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OPERATING MODES AND ON-CHIP MEMORY
TECHNICAL DATA 4-9
NOTE
In expanded mode, ROM is located at $7000–$7FFF out of reset. In
all other modes, ROM is located at $F000–$FFFF.
4.2.2.2 INIT Register
The internal registers used to control the operation of the MCU can be relocated on 4K
boundaries within the memory space with the use of INIT. This 8-bit special-purpose
register can change the default locations of the RAM and control registers within the
MCU memory map. It can be written to only once within the first 64 E-clock cycles after
a reset, and then it becomes a read-only register.
RAM[3:0] — RAM Map Position
These four bits, which specify the upper hexadecimal digit of the RAM address, control
position of RAM in the memory map. RAM can be positioned at the beginning of any
4K page in the memory map. It is initialized to address $0040 out of reset. Refer to
Table 4-3.
REG[3:0] — 64-Byte Register Block Position
These four bits specify the upper hexadecimal digit of the address for the 64-byte block
of internal registers. The register block, positioned at the beginning of any 4K page in
the memory map, is initialized to address $0000 out of reset. Refer to Table 4-4.
INIT — RAM and I/O Mapping Register $003D
Bit 7654321Bit 0
RAM3 RAM2 RAM1 RAM0 REG3 REG2 REG1 REG0
RESET:00000001
Table 4-3 RAM Mapping Table 4-4 Register Mapping
RAM[3:0] Address REG[3:0] Address
0000 $0040–$00FF 0000 $0000–$003F
0001 $1040–$10FF 0001 $1000–$103F
0010 $2040–$20FF 0010 $2000–$203F
0011 $3040–$30FF 0011 $3000–$303F
0100 $4040–$40FF 0100 $4000–$403F
0101 $5040–$50FF 0101 $5000–$503F
0110 $6040–$60FF 0110 $6000–$603F
0111 $7040–$70FF 0111 $7000–$703F
1000 $8040–$80FF 1000 $8000–$803F
1001 $9040–$90FF 1001 $9000–$903F
1010 $A040–$A0FF 1010 $A000–$A03F
1011 $B040–$B0FF 1011 $B000–$B03F
1100 $C040–$C0FF 1100 $C000–$C03F
1101 $D040–$D0FF 1101 $D000–$D03F
1110 $E040–$E0FF 1110 $E000–$E03F
1111 $F040–$F0FF 1111 $F000–$F03F
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OPERATING MODES AND ON-CHIP MEMORY
4-10 TECHNICAL DATA
4.2.2.3 OPTION Register
The 8-bit special-purpose OPTION register sets internal system configuration options
during initialization. The time protected control bits, IRQE, DLY, and CR[1:0] can be
written to only once after a reset and then they become read-only. This minimizes the
possibility of any accidental changes to the system configuration.
*Can be written only once in first 64 cycles out of reset in normal modes, or at any time in special modes
Bits [7:6] and 2 — Not implemented
Always read zero
IRQE — IRQ Select Edge Sensitive only
0 = IRQ is configured for level sensitive operation
1 = IRQ is configured for edge sensitive only operation
DLY — Enable Oscillator Startup Delay
0 = The oscillator startup delay coming out of STOP is bypassed and the MCU re-
sumes processing within about four bus cycles.
1 = A delay of approximately 4000 E-clock cycles is imposed as the MCU is started
up from the STOP power-saving mode. This delay allows the crystal oscillator
to stabilize.
CME — Clock Monitor Enable
Refer to SECTION 5 RESETS AND INTERRUPTS.
CR[1:0] — COP Timer Rate Select Bits
The internal E clock is first divided by 215 before it enters the COP watchdog system.
These control bits determine a scaling factor for the watchdog timer. Refer to SEC-
TION 5 RESETS AND INTERRUPTS.
OPTION — System Configuration Options $0039
Bit 7654321Bit 0
0 0 IRQE* DLY* CME 0 CR1* CR0*
RESET:00010000
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RESETS AND INTERRUPTS
TECHNICAL DATA 5-1
SECTION 5
RESETS AND INTERRUPTS
Resets and interrupt operations load the program counter with a vector that points to
a new location from which instructions are to be fetched. A reset immediately stops
execution of the current instruction and forces the program counter to a known starting
address. Internal registers and control bits are initialized so the MCU can resume ex-
ecuting instructions. An interrupt temporarily suspends normal program execution
while an interrupt service routine is being executed. After an interrupt has been ser-
viced, the main program resumes as if there had been no interruption.
5.1 Resets
There are four possible sources of reset. Power-on reset (POR) and external reset
share the normal reset vector. The computer operating properly (COP) system and the
clock monitor each has its own vector.
5.1.1 Power-On Reset
A positive transition on VDD generates a power-on reset (POR), which is used only for
power-up conditions. POR cannot be used to detect drops in power supply voltages.
A 4064 tCYC (internal clock cycle) delay after the oscillator becomes active allows the
clock generator to stabilize. If RESET is at logical zero at the end of 4064 tCYC, the
CPU remains in the reset condition until goes to logical one.
It is important to protect the MCU during power transitions. Most M68HC11 systems
need an external circuit that holds the RESET pin low whenever VDD is below the min-
imum operating level. This external voltage level detector, or other external reset cir-
cuits, are the usual source of reset in a system. The POR circuit only initializes internal
circuitry during cold starts. Refer to Figure 2-3.
5.1.2 External Reset (RESET)
The CPU distinguishes between internal and external reset conditions by sensing
whether the reset pin rises to a logic one in less than two E-clock cycles after an inter-
nal device releases reset. When a reset condition is sensed, the RESET pin is driven
low by an internal device for four E-clock cycles, then released. Two E-clock cycles
later it is sampled. If the pin is still held low, the CPU assumes that an external reset
has occurred. If the pin is high, it indicates that the reset was initiated internally by ei-
ther the COP system or the clock monitor. It is not advisable to connect an external
resistor capacitor (RC) power-up delay circuit to the reset pin of M68HC11 devices be-
cause the circuit charge time constant can cause the device to misinterpret the type of
reset that occurred.
5.1.3 COP Reset
The MCU includes a COP system to help protect against software failures. When the
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RESETS AND INTERRUPTS
5-2 TECHNICAL DATA
COP is enabled, the software is responsible for keeping a free-running watchdog timer
from timing out. When the software is no longer being executed in the intended se-
quence, a system reset is initiated.
The state of the NOCOP bit in the CONFIG register determines whether the COP sys-
tem is enabled or disabled. In normal modes, COP is enabled out of reset and does
not depend on software action. To disable the COP system, set the NOCOP bit in the
CONFIG register. In the special test and bootstrap operating modes, the COP system
is initially inhibited by the disable resets (DISR) control bit in the TEST1 register. The
DISR bit can subsequently be written to zero to enable COP resets.
The COP timer rate control bits CR[1:0] in the OPTION register determine the COP
time-out period. The system E clock is divided by 215 and then further scaled by a fac-
tor shown in Table 5-1. After reset, these bits are zero, which selects the fastest time-
out period. In normal operating modes, these bits can only be written once within 64
bus cycles after reset.
Complete the following reset sequence to service the COP timer. Write $55 to CO-
PRST to arm the COP timer clearing mechanism. Then write $AA to COPRST to clear
the COP timer. Performing instructions between these two steps is possible as long as
both steps are completed in the correct sequence before the timer times out.
5.1.4 Clock Monitor Reset
The clock monitor circuit is based on an internal RC time delay. If no MCU clock edges
are detected within this RC time delay, the clock monitor can optionally generate a sys-
tem reset. The clock monitor function is enabled or disabled by the CME control bit in
the OPTION register. The presence of a time-out is determined by the RC delay, which
allows the clock monitor to operate without any MCU clocks.
Clock monitor is used as a backup for the COP system. Because the COP needs a
clock to function, it is disabled when the clocks stop. Therefore, the clock monitor sys-
tem can detect clock failures not detected by the COP system.
Table 5-1 COP Time-out
CR[1:0]
Divide
E/215
By
XTAL = 4.0 MHz
Time-out
–0/+32.8 ms
XTAL = 8.0 MHz
Time-out
–0/+16.4 ms
XTAL = 12.0 MHz
Time-out
–0/+10.9 ms
0 0 1 32.768 ms 16.384 ms 10.923 ms
0 1 4 131.072 ms 65.536 ms 43.691 ms
1 0 16 524.288 ms 262.140 ms 174.76 ms
1 1 64 2.097 sec 1.049 sec 699.05 ms
E = 1.0 MHz 2.0 MHz 3.0 MHz
COPRST — Am/Reset COP Timer Circuitry $003A
Bit 7654321Bit 0
76543210
RESET:00000000
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RESETS AND INTERRUPTS
TECHNICAL DATA 5-3
Semiconductor wafer processing causes variations of the RC time-out values between
individual devices. An E-clock frequency below 10 kHz is detected as a clock monitor
error. An E-clock frequency of 200 kHz or more prevents clock monitor errors. Using
the clock monitor function when the E clock is below 200 kHz is not recommended.
Special considerations are needed when a STOP instruction is executed and the clock
monitor is enabled. Because the STOP function causes the clocks to be halted, the
clock monitor function generates a reset sequence if it is enabled at the time the STOP
mode was initiated. Before executing a STOP instruction, clear the CME bit in the OP-
TION register to zero to disable the clock monitor. After recovery from STOP, set the
CME bit to logic one to enable the clock monitor.
5.1.5 Option Register
*Can be written only once in first 64 cycles out of reset in normal modes, or at any time in special modes.
Bits [7:6] and 2 — Not implemented
Always read zero
IRQE — Configure IRQ for Edge Sensitive Only Operation
This bit can be written only once during the first 64 E-clock cycles after reset in normal
modes.
0 = Low level recognition
1 = Falling edge recognition
DLY — Enable Oscillator Startup Delay
This bit is set during reset and can be written only once during the first 64 E-clock cy-
cles after reset in normal modes. If an external clock source rather than a crystal is
used, the stabilization delay can be inhibited because the clock source is assumed to
be stable.
0 = No stabilization delay on exit from STOP
1 = Stabilization delay enabled on exit from STOP
CME — Clock Monitor Enable
This control bit can be read or written at any time and controls whether or not the in-
ternal clock monitor circuit triggers a reset sequence when the system clock is slow or
absent. When it is clear, the clock monitor circuit is disabled. When it is set, the clock
monitor circuit is enabled. Reset clears the CME bit.
CR[1:0] — COP Timer Rate Select
These control bits determine a scaling factor for the watchdog timer.
OPTION — System Configuration Options $0039
Bit 7654321Bit 0
0 0 IRQE* DLY* CME 0 CR1* CR0*
RESET:00010000
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RESETS AND INTERRUPTS
5-4 TECHNICAL DATA
5.1.6 CONFIG Register
Bits [7:4] and 0 — Not implemented
Always read zero
NOCOP — COP System Disable
This bit is cleared out of reset in normal modes, enabling the COP system. It is set out
of reset in special modes. NOCOP is writable once in normal modes and at any time
in special modes.
0 = The COP system is enabled as the MCU comes out of reset.
1 = The COP system is disabled and does not generate system resets.
ROMON — Enable On-Chip ROM
Refer to SECTION 4 OPERATING MODES AND ON-CHIP MEMORY.
5.2 Effects of Reset
When a reset condition is recognized, the internal registers and control bits are forced
to an initial state. Depending on the cause of the reset and the operating mode, the
reset vector can be fetched from any of six possible locations. Refer to Table 5-2.
These initial states then control on-chip peripheral systems to force them to known
startup states, as follows:
5.2.1 CPU
After reset, the CPU fetches the restart vector from the appropriate address during the
first three cycles, and begins executing instructions. The stack pointer and other CPU
registers are indeterminate immediately after reset; however, the X and I interrupt
mask bits in the condition code register (CCR) are set to mask any interrupt requests.
Also, the S bit in the CCR is set to inhibit the STOP mode.
5.2.2 Memory Map
After reset, the INIT register is initialized to $00, putting the 192 bytes of RAM at loca-
tions $0040 through $00FF, and the control registers at locations $0000 through
$003F.
CONFIG
— Configuration Control Register $003F
Bit 7654321Bit 0
00000NOCOPROMON0
RESET:00000— —0
Table 5-2 Reset Cause, Reset Vector, and Operating Mode
Cause of Reset Normal Mode Vector Special Test or Bootstrap
POR or RESET Pin $FFFE, FFFF $BFFE, BFFF
Clock Monitor Failure $FFFC, FFFD $BFFC, $BFFD
COP Watchdog Time-out $FFFA, FFFB $BFFA, BFFB
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RESETS AND INTERRUPTS
TECHNICAL DATA 5-5
5.2.3 Parallel I/O
When a reset occurs in expanded multiplexed operating modes, the pins used for par-
allel I/O are dedicated to the expansion bus. In single-chip and bootstrap modes, all
ports are parallel I/O data ports. In expanded multiplexed and test modes, ports B, C,
and lines DATA6/AS and DATA7/R/W are a memory expansion bus with port B as a
high-order address bus, port C as a multiplexed address and data bus, AS as the de-
multiplexing signal, and R/as the data bus direction control. The CWOM bit in PIOC is
cleared so that port C is not in wired-OR mode. Port A, bits [0:3] and 7; and ports B,
C, and D are general-purpose I/O at reset and set for input. For this reason the pins
are configured as high impedance upon reset. Port A bits [4:6] are outputs, so high im-
pedance protection is not necessary.
NOTE
Do not confuse pin function with the electrical state of the pin at reset.
All general-purpose I/O pins configured as inputs at reset are in a
high impedance state. Port data registers reflect the port's functional
state at reset. The pin function is mode dependent.
5.2.4 Timer
During reset, the timing system is initialized to a count of $0000. The prescaler bits are
cleared, and all output compare registers are initialized to $FFFF. All input capture reg-
isters are indeterminate after reset. The output compare 1 mask (OC1M) register is
cleared so that successful OC1 compares do not affect any I/O pins. The other four
output compares are configured so that they do not affect any I/O pins on successful
compares. All input capture edge-detector circuits are configured for capture disabled
operation. The timer overflow interrupt flag and all eight timer function interrupt flags
are cleared. All nine timer interrupts are disabled because their mask bits have been
cleared.
The I4/O5 bit in the PACTL register is cleared to configure the I4/O5 function as OC5;
however, the OM5:OL5 control bits in the TCTL1 register are clear so OC5 does not
control the PA3 pin.
5.2.5 Real-Time Interrupt
The real-time interrupt flag (RTIF) is cleared and automatic hardware interrupts are
masked. The rate control bits are cleared after reset and can be initialized by software
before the real-time interrupt (RTI) system is used. After reset, a full RTI period elaps-
es before the first RTI interrupt.
5.2.6 Pulse Accumulator
The pulse accumulator system is disabled at reset so that the PAI input pin defaults to
being a general-purpose input pin (PA7).
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RESETS AND INTERRUPTS
5-6 TECHNICAL DATA
5.2.7 COP
The COP watchdog system is enabled if the NOCOP control bit in the CONFIG regis-
ter is clear, and disabled if NOCOP is set. The COP rate is set for the shortest duration
time-out.
5.2.8 SCI
The reset condition of the SCI system is independent of the operating mode. At reset,
the SCI baud rate is indeterminate and must be established by a software write to the
BAUD register. All transmit and receive interrupts are masked and both the transmitter
and receiver are disabled so the port pins default to being general-purpose I/O lines.
The SCI frame format is initialized to an 8-bit character size. The send break and re-
ceiver wake-up functions are disabled. The TDRE and TC status bits in the SCI status
register are both set, indicating that there is no transmit data in either the transmit data
register or the transmit serial shift register. The RDRF, IDLE, OR, NF, and FE receive-
related status bits are cleared.
5.2.9 SPI
The SPI system is disabled by reset. The port pins associated with this function default
to being general-purpose I/O lines.
5.2.10 System
The memory system is configured for normal read operation. PSEL[3:0] are initialized
with the value $0101, causing the external IRQ pin to have the highest I-bit interrupt
priority. The IRQ pin is configured for level sensitive operation (for wired-OR systems).
The RBOOT, SMOD, and MDA bits in the HPRIO register reflect the status of the
MODB and MODA inputs at the rising edge of reset. The DLY control bit in OPTION is
set to specify that an oscillator start-up delay is imposed upon recovery from STOP.
The clock monitor system is disabled by CME equals zero.
5.3 Reset and Interrupt Priority
Resets and interrupts have a hardware priority that determines which reset or interrupt
is serviced first when simultaneous requests occur. Any maskable interrupt can be giv-
en priority over other maskable interrupts.
The first six interrupt sources are not maskable. The priority arrangement for these
sources is as follows:
1. POR or RESET pin
2. Clock monitor reset
3. COP watchdog reset
4. XIRQ interrupt
5. Illegal opcode interrupt
6. Software interrupt (SWI)
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TECHNICAL DATA 5-7
The maskable interrupt sources have the following priority arrangement:
1. IRQ
2. Real-time interrupt
3. Timer input capture 1
4. Timer input capture 2
5. Timer input capture 3
6. Timer output compare 1
7. Timer output compare 2
8. Timer output compare 3
9. Timer output compare 4
10. Timer input capture 4/output compare 5
11. Timer overflow
12. Pulse accumulator overflow
13. Pulse accumulator input edge
14. SPI transfer complete
15. SCI system
Any one of these interrupts can be assigned the highest maskable interrupt priority by
writing the appropriate value to the PSEL bits in the HPRIO register. Otherwise, the
priority arrangement remains the same. An interrupt that is assigned highest priority is
still subject to global masking by the I bit in the CCR, or by any associated local bits.
Interrupt vectors are not affected by priority assignment. To avoid race conditions,
HPRIO can be written only while I-bit interrupts are inhibited.
5.3.1 Highest Priority Interrupt and Miscellaneous Register
The values of the RBOOT, SMOD, IRVNE, and MDA reset bits depend on the mode
during initialization. Refer to Table 5-3.
RBOOT — Read Bootstrap ROM
Has meaning only when the SMOD bit is a one (special bootstrap mode or special test
mode). At all other times this bit is clear and cannot be written. Refer to SECTION 4
OPERATING MODES AND ON-CHIP MEMORY for more information.
SMOD — Special Mode Select
This bit reflects the inverse of the MODB input pin at the rising edge of reset. Refer to
SECTION 4 OPERATING MODES AND ON-CHIP MEMORY for more information.
MDA — Mode Select A
The mode select A bit reflects the status of the MODA input pin at the rising edge of
reset. Refer to SECTION 4 OPERATING MODES AND ON-CHIP MEMORY for more
information.
IRVNE — Internal Read Visibility Enable/Not E
HPRIO — Highest Priority I-Bit Interrupt and Miscellaneous $003C
Bit 7654321Bit 0
RBOOT SMOD MDA IRVNE PSEL3 PSEL2 PSEL1 PSEL0
RESET:— — — —0101
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5-8 TECHNICAL DATA
The IRVNE control bit allows internal read accesses to be available on the external
data bus during factory testing or emulation. Refer to SECTION 4 OPERATING
MODES AND ON-CHIP MEMORY for more information.
PSEL[3:0] — Priority Select Bits
These bits select one interrupt source to be elevated above all other I-bit-related
sources and can be written to only while the I bit in the CCR is set (interrupts disabled).
5.4 Interrupts
The MCU has 18 interrupt vectors that support 22 interrupt sources. The 19 maskable
interrupts are generated by on-chip peripheral systems. These interrupts are recog-
nized when the global interrupt mask bit (I) in the condition code register (CCR) is
clear. The three non-maskable interrupt sources are illegal opcode trap, software in-
terrupt, and XIRQ pin. Refer to Table 5-4, which shows the interrupt sources and vec-
tor assignments for each source.
Table 5-3 Highest Priority Interrupt Selection
PSEL[3:0] Interrupt Source Promoted
0 0 0 0 Timer Overflow
0 0 0 1 Pulse Accumulator Overflow
0 0 1 0 Pulse Accumulator Input Edge
0 0 1 1 SPI Serial Transfer Complete
0 1 0 0 SCI Serial System
0 1 0 1 Reserved (Default to IRQ)
0 1 1 0 IRQ (External Pin)
0 1 1 1 Real-Time Interrupt
1 0 0 0 Timer Input Capture 1
1 0 0 1 Timer Input Capture 2
1 0 1 0 Timer Input Capture 3
1 0 1 1 Timer Output Compare 1
1 1 0 0 Timer Output Compare 2
1 1 0 1 Timer Output Compare 3
1 1 1 0 Timer Output Compare 4
1 1 1 1 Timer Input Capture 4/Output Compare 5
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TECHNICAL DATA 5-9
5.4.1 Interrupt Recognition and Register Stacking
An interrupt can be recognized at any time after it is enabled by its local mask, if any,
and by the global mask bit in the CCR. Once an interrupt source is recognized, the
CPU responds at the completion of the instruction being executed. Interrupt latency
varies according to the number of cycles required to complete the current instruction.
When the CPU begins to service an interrupt, the contents of the CPU registers are
pushed onto the stack in the order shown in Table 5-5. After the CCR value is stacked,
the I bit and the X bit, if XIRQ is pending, are set to inhibit further interrupts. The inter-
rupt vector for the highest priority pending source is fetched, and execution continues
at the address specified by the vector. At the end of the interrupt service routine, the
return from interrupt instruction is executed and the saved registers are pulled from the
stack in reverse order so that normal program execution can resume. Refer to SEC-
TION 3 CENTRAL PROCESSING UNIT for further information.
Table 5-4 Interrupt and Reset Vector Assignments
Vector Address Interrupt Source CCR Mask Local
Mask
FFC0, C1 — FFD4, D5 Reserved — —
FFD6, D7 SCI Serial System I Bit —
• SCI Transmit Complete TCIE
• SCI Transmit Data Register Empty TIE
• SCI Idle Line Detect ILIE
• SCI Receiver Overrun RIE
• SCI Receive Data Register Full RIE
FFD8, D9 SPI Serial Transfer Complete I Bit SPIE
FFDA, DB Pulse Accumulator Input Edge I Bit PAII
FFDC, DD Pulse Accumulator Overflow I Bit PAOVI
FFDE, DF Timer Overflow I Bit TOI
FFE0, E1 Timer Input Capture 4/Output Compare 5 I Bit I4/O5I
FFE2, E3 Timer Output Compare 4 I Bit OC4I
FFE4, E5 Timer Output Compare 3 I Bit OC3I
FFE6, E7 Timer Output Compare 2 I Bit OC2I
FFE8, E9 Timer Output Compare 1 I Bit OC1I
FFEA, EB Timer Input Capture 3 I Bit IC3I
FFEC, ED Timer Input Capture 2 I Bit IC2I
FFEE, EF Timer Input Capture 1 I Bit IC1I
FFF0, F1 Real Time Interrupt I Bit RTII
FFF2, F3 IRQ (External Pin) I Bit None
FFF4, F5 XIRQ Pin X Bit None
FFF6, F7 Software Interrupt None None
FFF8, F9 Illegal Opcode Trap None None
FFFA, FB COP Failure None NOCOP
FFFC, FD Clock Monitor Fail None CME
FFFE, FF RESET None None
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5-10 TECHNICAL DATA
5.4.2 Non-Maskable Interrupt Request XIRQ
Non-maskable interrupts are useful because they can always interrupt CPU opera-
tions. The most common use for such an interrupt is for serious system problems, such
as program runaway or power failure. The XIRQ input is an updated version of the
nonmaskable NMI input of earlier MCUs.
Upon reset, both the X bit and I bits of the CCR are set to inhibit all maskable interrupts
and XIRQ. After minimum system initialization, software can clear the X bit by a TAP
instruction, enabling XIRQ interrupts. Thereafter, software cannot set the X bit. Thus,
an XIRQ interrupt is a nonmaskable interrupt. Because the operation of the I-bit-relat-
ed interrupt structure has no effect on the X bit, the internal XIRQ pin remains non-
masked. In the interrupt priority logic, the XIRQ interrupt has a higher priority than any
source that is maskable by the I bit. All I-bit-related interrupts operate normally with
their own priority relationship.
When an I-bit-related interrupt occurs, the I bit is automatically set by hardware after
stacking the CCR byte. The X bit is not affected. When an X-bit-related interrupt oc-
curs, both the X and I bits are automatically set by hardware after stacking the CCR.
A return from interrupt instruction restores the X and I bits to their pre-interrupt request
state.
5.4.3 Illegal Opcode Trap
Because not all possible opcodes or opcode sequences are defined, the MCU in-
cludes an illegal opcode detection circuit, which generates an interrupt request. When
an illegal opcode is detected and the interrupt is recognized, the current value of the
program counter is stacked. After interrupt service is complete, reinitialize the stack
pointer so repeated execution of illegal opcodes does not cause stack underflow. Left
uninitialized, the illegal opcode vector can point to a memory location that contains an
illegal opcode. This condition causes an infinite loop that causes stack underflow. The
stack grows until the system crashes.
The illegal opcode trap mechanism works for all unimplemented opcodes on all four
opcode map pages. The address stacked as the return address for the illegal opcode
interrupt is the address of the first byte of the illegal opcode. Otherwise, it would be
almost impossible to determine whether the illegal opcode had been one or two bytes.
Table 5-5 Stacking Order on Entry to Interrupts
Memory Location CPU Registers
SP PCL
SP – 1 PCH
SP –2 IYL
SP – 3 IYH
SP – 4 IXL
SP – 5 IXH
SP – 6 ACCA
SP – 7 ACCB
SP – 8 CCR
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TECHNICAL DATA 5-11
The stacked return address can be used as a pointer to the illegal opcode so the illegal
opcode service routine can evaluate the offending opcode.
5.4.4 Software Interrupt
SWI is an instruction, and thus cannot be interrupted until complete. SWI is not inhib-
ited by the global mask bits in the CCR. Because execution of SWI sets the I mask bit,
once an SWI interrupt begins, other interrupts are inhibited until SWI is complete, or
until user software clears the I bit in the CCR.
5.4.5 Maskable Interrupts
The maskable interrupt structure of the MCU can be extended to include additional ex-
ternal interrupt sources through the IRQ pin. The default configuration of this pin is a
low-level sensitive wired-OR network. When an event triggers an interrupt, a software
accessible interrupt flag is set. When enabled, this flag causes a constant request for
interrupt service. After the flag is cleared, the service request is released.
5.4.6 Reset and Interrupt Processing
Figure 5-1 and Figure 5-1 illustrate the reset and interrupt process. Figure 5-1 illus-
trates how the CPU begins from a reset and how interrupt detection relates to normal
opcode fetches. Figure 5-1 is an expansion of a block in Figure 5-1 and illustrates in-
terrupt priorities. Figure 5-2 shows the resolution of interrupt sources within the SCI
subsystem.
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5-12 TECHNICAL DATA
Figure 5-1 Processing Flow out of Reset (1 of 2)
2A
BIT X IN
Y
N
XIRQ Y
N
PIN LOW?
CCR = 1?
BEGIN INSTRUCTION
SEQUENCE
1A
STACK CPU
REGISTERS
SET BITS I AND X
FETCH VECTOR
$FFF4, $FFF5
SET BITS S, I, AND X
RESET MCU
HARDWARE
POWER-ON RESET
(POR)
EXTERNAL RESET
CLOCK MONITOR FAIL
(WITH CME = 1)
COP WATCHDOG
TIMEOUT
(WITH NOCOP = 0)
DELAY 4064 E CYCLES
LOAD PROGRAM COUNTER
WITH CONTENTS OF
$FFFE, $FFFF
(VECTOR FETCH)
LOAD PROGRAM COUNTER
WITH CONTENTS OF
$FFFC, $FFFD
(VECTOR FETCH)
LOAD PROGRAM COUNTER
WITH CONTENTS OF
$FFFA, $FFFB
(VECTOR FETCH)
HIGHEST
PRIORITY
LOWEST
PRIORITY
FLOW OUT OF RESET P1
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TECHNICAL DATA 5-13
Figure 5-1 Processing Flow out of Reset (2 of 2)
BIT I IN
CCR = 1?
2A
Y
N
ANY I-BIT
INTERRUPT Y
N
PENDING?
FETCH OPCODE
ILLEGAL
OPCODE?
Y
N
WAI Y
N
INSTRUCTION?
SWI
INSTRUCTION?
Y
N
RTI
INSTRUCTION?
Y
N
EXECUTE THIS
INSTRUCTION
STACK CPU
REGISTERS
ANY
N
Y
INTERRUPT
PENDING?
SET BIT I IN CCR
RESOLVE INTERRUPT
PRIORITY AND FETCH
VECTOR FOR HIGHEST
PENDING SOURCE
STACK CPU
REGISTERS
SET BIT I IN CCR
FETCH VECTOR
$FFF8, $FFF9
STACK CPU
REGISTERS
SET BIT I IN CCR
FETCH VECTOR
$FFF6, $FFF7
RESTORE CPU
REGISTERS
FROM STACK
1A
STACK CPU
REGISTERS
SEE FIGURE 5–2
FLOW OUT OF RESET P2
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5-14 TECHNICAL DATA
Figure 5-2 Interrupt Priority Resolution (1 of 2)
INT PRIORITY RES P1
2A
BEGIN
SET X BIT IN CCR
FETCH VECTOR
$FFF4, FFF5
X BIT
IN CCR
SET ?
YES
NO
XIRQ PIN
LOW ?
YES
NO
HIGHEST
PRIORITY
INTERRUPT
?
YES
NO
IRQ ? YES
NO
FETCH VECTOR
$FFF2, FFF3
FETCH VECTOR
$FFF0, FFF1
RTII = 1 ? YES
NO
REAL-TIME
INTERRUPT
?
YES
NO
FETCH VECTOR
$FFEE, FFEF
IC1I = 1 ? YES
NO
TIMER
IC1F ?
YES
NO
FETCH VECTOR
$FFEC, FFED
IC2I = 1 ? YES
NO
TIMER
IC2F ?
YES
NO
FETCH VECTOR
$FFEA, FFEB
IC3I = 1 ? YES
NO
TIMER
IC3F ?
YES
NO
FETCH VECTOR
$FFE8, FFE9
OC1I = 1 ? YES
NO
TIMER
OC1F ?
YES
NO
2B
FETCH VECTOR
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TECHNICAL DATA 5-15
Figure 5-2 Interrupt Priority Resolution (2 of 2)
TOI = 1? Y
N
Y
N
PAOVI = 1?
PAII = 1? Y
N
SPIE = 1? Y
N
Y
N
FLAG Y
N
Y
N
FLAG
FLAG Y
N
FLAGS Y
N
PAIF = 1?
SPIF = 1? OR
TOF = 1?
PAOVF = 1
FETCH VECTOR
$FFDE, $FFDF
FETCH VECTOR
$FFDC, $FFDD
FETCH VECTOR
$FFDA, $FFDB
FETCH VECTOR
$FFD6, $FFD7
FETCH VECTOR
$FFD8, $FFD9
OC2I = 1? Y
N
Y
N
OC3I = 1?
OC4I = 1? Y
N
OC5I = 1? Y
N
FLAG Y
N
Y
N
FLAG
FLAG Y
N
FLAG Y
N
OC4F = 1?
OC5F = 1?
OC2F = 1?
OC3F = 1
FETCH VECTOR
$FFE6, $FFE7
FETCH VECTOR
$FFE4, $FFE5
FETCH VECTOR
$FFE2, $FFE3
FETCH VECTOR
$FFE0, $FFE1
MODF = 1?
INTERRUPT?
SEE FIGURE
9–7
2A 2B
END
FETCH VECTOR
$FFF2, $FFF3
SCI
INT PRI RES P2
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5-16 TECHNICAL DATA
Figure 5-3 Interrupt Source Resolution within SCI
5.5 Low-Power Operation
Both STOP and WAIT suspend CPU operation until a reset or interrupt occurs. The
WAIT condition suspends processing and reduces power consumption to an interme-
diate level. The STOP condition turns off all on-chip clocks and reduces power con-
sumption to an absolute minimum while retaining the contents of all 192 bytes of RAM.
5.5.1 WAIT
The WAI opcode places the MCU in the WAIT condition, during which the CPU regis-
ters are stacked and CPU processing is suspended until a qualified interrupt is detect-
ed. The interrupt can be an external IRQ, an XIRQ, or any of the internally generated
interrupts, such as the timer or serial interrupts. The on-chip crystal oscillator remains
active throughout the WAIT standby period.
The reduction of power in the WAIT condition depends on how many internal clock sig-
FLAG Y
N
OR = 1? Y
N
Y
N
TDRE = 1?
TC = 1? Y
N
IDLE = 1? Y
N
Y
N
Y
N
Y
N
ILIE = 1?
RIE = 1?
TIE = 1?
BEGIN
RE = 1? Y
N
Y
N
TE = 1?
TCIE = 1? Y
N
RE = 1? Y
N
RDRF = 1?
VALID SCI REQUEST
NO
VALID SCI REQUEST
INT SOURCE RES
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TECHNICAL DATA 5-17
nals driving on-chip peripheral functions can be shut down. The CPU is always shut
down during WAIT. While in the wait state, the address/data bus repeatedly runs read
cycles to the address where the CCR contents were stacked. The MPU leaves the wait
state when it senses any interrupt that has not been masked.
The free-running timer system is shut down only if the I bit is set to one and the COP
system is disabled by NOCOP being set to one. Several other systems can also be in
a reduced power consumption state depending on the state of software-controlled
configuration control bits. The SPI system is enabled or disabled by the SPE control
bit. The SCI transmitter is enabled or disabled by the TE bit, and the SCI receiver is
enabled or disabled by the RE bit. Therefore the power consumption in WAIT is de-
pendent on the particular application.
5.5.2 STOP
Executing the STOP instruction while the S bit in the CCR is equal to zero places the
MCU in the STOP condition. If the S bit is not zero, the STOP opcode is treated as a
no-op (NOP). The STOP condition offers minimum power consumption because all
clocks, including the crystal oscillator, are stopped while in this mode. To exit STOP
and resume normal processing, a logic low level must be applied to one of the external
interrupts (IRQ or XIRQ), or to the RESET pin. A pending edge-triggered IRQ can also
bring the CPU out of STOP.
Because all clocks are stopped in this mode, all internal peripheral functions also stop.
The data in the internal RAM is retained as long as VDD power is maintained. The CPU
state and I/O pin levels are static and are unchanged by STOP. Therefore, when an
interrupt comes to restart the system, the MCU resumes processing as if there were
no interruption. If reset is used to restart the system a normal reset sequence results
where all I/O pins and functions are also restored to their initial states.
To use the IRQ pin as a means of recovering from STOP, the I bit in the CCR must be
clear (IRQ not masked). The XIRQ pin can be used to wake up the MCU from STOP
regardless of the state of the X bit in the CCR, although the recovery sequence de-
pends on the state of the X bit. If X is set to zero (XIRQ not masked), the MCU starts
up, beginning with the stacking sequence leading to normal service of the XIRQ re-
quest. If X is set to one (XIRQ masked or inhibited), then processing continues with
the instruction that immediately follows the STOP instruction, and no XIRQ interrupt
service is requested or pending.
Because the oscillator is stopped in STOP mode, a restart delay may be imposed to
allow oscillator stabilization upon leaving STOP. If the internal oscillator is being used,
this delay is required; however, if a stable external oscillator is being used, the DLY
control bit can be used to bypass this startup delay. The DLY control bit is set by reset
and can be optionally cleared during initialization. If the DLY equal to zero option is
used to avoid startup delay on recovery from STOP, then reset should not be used as
the means of recovering from STOP, as this causes DLY to be set again by reset, im-
posing the restart delay. This same delay also applies to power-on-reset, regardless
of the state of the DLY control bit, but does not apply to a reset while the clocks are
running.
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5-18 TECHNICAL DATA
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PARALLEL I/O
TECHNICAL DATA 6-1
SECTION 6
PARALLEL I/O
The MC68HC11D3 has four 8-bit I/O ports; A, B, C, and D. In single-chip and bootstrap
modes, all ports are parallel I/O data ports. In expanded multiplexed and test modes,
ports B and C, and lines DATA6/AS and DATA7/R/W are a memory expansion bus
with port B as the high order address bus, port C as the multiplexed address and data
bus, AS as the demultiplexing signal, and R/W as the data bus direction control. Refer
to Table 6-1, which is a summary of the ports and their shared functions:
6.1 Port A
Port A bits handle the timer functions and can also be used as general-purpose I/O. In
both the normal operating modes, port A can be configured for four timer input capture
(IC) and three timer output compare (OC) functions, or four OC and three IC functions
with either a pulse accumulator input (PAI) or a fifth OC function.
*This pin is not bonded in the 40-pin version.
6.2 Port B
In single-chip mode, all port B pins are general-purpose I/O (PB[7:0]). In expanded
multiplexed mode, all port B pins act as high-order address bits (ADDR[15:8]).
Table 6-1 I/O Ports
Port Input Pins Output Pins Bidirectional Pins Shared Functions
Port A 3 3 2 TImer
Port B — — 8 High Order Address
Port C — — 8 Low Order Address and Data Bus
Port D — — 8 SCI, SPI, AS, and R/
PORTA — Port A Data $0000
Bit 7654321Bit 0
PA7 PA6* PA5 PA4* PA3 PA2 PA1 PA0
RESET: HiZ 0 0 0 HiZ HiZ HiZ HiZ
Alt. Func: PAI OC2 OC3 OC4 IC4/OC5 IC1 IC2 IC3
And/or: OC1 OC1 OC1 OC1 OC1 — — —
PORTB — Port B Data $0004
Bit 7654321Bit 0
PB7 PB6 PB5 PB4 PB3 PB2 PB1 PB0
S. Chip
or Boot: PB7 PB6 PB5 PB4 PB3 PB2 PB1 PB0
RESET: Reset configures pins as HiZ inputs
Expan.
or Test: ADDR15 ADDR14 ADDR13 ADDR12 ADDR11 ADDR10 ADDR9 ADDR8
RESET: Reset configures pins as high-order address outputs
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6-2 TECHNICAL DATA
DDB[7:0] — Data Direction for Port B
0 = Corresponding port B pin configured for input only
1 = Corresponding port B pin configured as output
6.3 Port C
Port C pins are general-purpose I/O (PC[7:0]) in single-chip mode. In expanded mul-
tiplexed mode, port C pins are configured as multiplexed address/data pins. During the
data cycle, bits [7:0] (PC[7:0]) are bidirectional data pins controlled by the R/W signal.
DDC[7:0] — Data Direction for Port C
0 = Input
1 = Output
6.4 Port D
The eight port D bits (PD[7:0]) can be used for general-purpose I/O, for the SCI and
SPI subsystems, or for bus data direction control. Port D can be read at any time. In-
puts return the sensed levels at the pin; outputs return the input level of the port D pin
drivers. If port D is written, the data is stored in an internal latch, and can be driven only
if port D is configured for general-purpose output. This port shares functions with the
on-chip SCI and SPI subsystems, while bits 6 and 7 control the direction of data flow
on the bus in expanded and special test modes.
DDRB — Data Direction Register for Port B $0006
Bit 7654321Bit 0
DDB7 DDB6 DDB5 DDC4 DDB3 DDB2 DDB1 DDB0
RESET:00000000
PORTC — Port C Data $0003
Bit 7654321Bit 0
PC7 PC6 PC5 PC4 PC3 PC2 PC1 PC0
S. Chip
or Boot: PC7 PC6 PC5 PC4 PC3 PC2 PC1 PC0
RESET: Reset configures pins as HiZ inputs
Expan.
or Test: ADDR7/
DATA7 ADDR6/
DATA6 ADDR5/
DATA5 ADDR4/
DATA4 ADDR3/
DATA3 ADDR2/
DATA2 ADDR1/
DATA1 ADDR0/
DATA0
RESET: Reset configures pins as multiplexed, low-order address/data I/O
DDRC — Data Direction Register for Port C $0007
Bit 7654321Bit 0
DDC7 DDC6 DDC5 DDC4 DDC3 DDC2 DDC1 DDC0
RESET:00000000
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TECHNICAL DATA 6-3
DDD[7:0] — Data Direction for Port D
When port D is a general-purpose I/O port, the DDRD register controls the direction of
the I/O pins as follows:
0 = Configures the corresponding port D pin for input
1 = Configures the corresponding port D pin for output
In expanded and test modes, bits 6 and 7 are dedicated AS and R/W outputs.
When port D is functioning with the SPI system enabled, bit 5 is dedicated as the slave
select (SS) input. In SPI slave mode, DDD5 has no meaning or effect. In SPI master
mode, DDD5 affects port D bit 5 as follows:
0 = Port D bit 5 is an error-detect input to the SPI.
1 = Port D bit 5 is configured as a general-purpose output line.
If the SPI is enabled and expects port D bits 2, 3, and 4 (MISO, MOSI, and SCK) to be
inputs, then they are inputs, regardless of the state of DDRD bits 2, 3, and 4. If the SPI
expects port D bits 2, 3, and 4 to be outputs, they are outputs only if DDRD bits 2, 3,
and 4 are set.
DDRA7 — Data Direction Control for Port A Bit 7
Refer to SECTION 9 TIMING SYSTEM.
PAEN — Pulse Accumulator System Enable
Refer to SECTION 9 TIMING SYSTEM.
PAMOD — Pulse Accumulator Mode
Refer to SECTION 9 TIMING SYSTEM.
PEDGE — Pulse Accumulator Edge Control
Refer to SECTION 9 TIMING SYSTEM.
DDRA3 — Data Direction for Port A Bit 3
Overridden if an output compare function is configured to control the PA3 pin.
0 = Input only
1 = Output
PORTD — Port D Data $0008
Bit 7654321Bit 0
PD7 PD6 PD5 PD4 PD3 PD2 PD1 PD0
RESET:00000000
Alt. Func.: R/W AS SCK MOSI MISO TxD RxD
DDRD — Data Direction Register for Port D $0009
Bit 7654321Bit 0
DDD7 DDD6 DDD5 DDD4 DDD3 DDD2 DDD1 DDD0
RESET:00000000
PACTL — Pulse Accumulator Control $0026
Bit 7654321Bit 0
DDRA7 PAEN PAMOD PEDGE DDRA3 I4/O5 RTR1 RTR0
RESET:00000000
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PARALLEL I/O
6-4 TECHNICAL DATA
I4/O5 — Configure TI4/O5 register for IC4 or OC5
0 = OC5 function enabled
1 = IC4 function enabled
RTR[1:0] — Real-Time Interrupt (RTI) Rate
Refer to SECTION 9 TIMING SYSTEM.
6.5 Parallel I/O Control Register (PIOC)
PIOC configures and controls handshake I/O functions in MCUs where this function is
available. In the MC68HC11D3, however, only the CWOM bit in the PIOC register is
usable. The CWOM bit is cleared so that port C is not in wired-OR mode.
CWOM — Port C Wired-OR Mode (affects all eight port C pins)
0 = Port C outputs are normal CMOS outputs
1 = Port C outputs are open-drain outputs
PIOC— Parallel I/O Control $0002
Bit 7654321Bit 0
00CWOM00000
RESET:00000000
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SERIAL COMMUNICATIONS INTERFACE
TECHNICAL DATA 7-1
SECTION 7
SERIAL COMMUNICATIONS INTERFACE
The serial communications interface (SCI) is a universal asynchronous receiver trans-
mitter (UART), one of two independent serial I/O subsystems in the MC68HC11D3. It
has a standard nonreturn to zero (NRZ) format (one start, eight or nine data, and one
stop bit). Several baud rates are available. The SCI transmitter and receiver are inde-
pendent, but use the same data format and bit rate.
7.1 Data Format
The serial data format requires the following conditions:
1. An idle line in the high state before transmission or reception of a message
2. A start bit, logic zero, transmitted or received, that indicates the start of each
character
3. Data that is transmitted and received least significant bit (LSB) first
4. A stop bit, logic one, used to indicate the end of a frame (A frame consists of a
start bit, a character of eight or nine data bits, and a stop bit.)
5. A break (defined as the transmission or reception of a logic zero for some mul-
tiple number of frames).
Selection of the word length is controlled by the M bit of SCI control register SCCR1.
7.2 Transmit Operation
The SCI transmitter includes a parallel transmit data register (SCDR) and a serial shift
register. The contents of the serial shift register can only be written through the SCDR.
This double buffered operation allows a character to be shifted out serially while an-
other character is waiting in the SCDR to be transferred into the serial shift register.
The output of the serial shift register is applied to TxD as long as transmission is in
progress or the transmit enable (TE) bit of serial communication control register 2
(SCCR2) is set. The block diagram, Figure 7-1, shows the transmit serial shift register,
and the buffer logic at the top of the figure.
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SERIAL COMMUNICATIONS INTERFACE
7-2 TECHNICAL DATA
Figure 7-1 SCI Transmitter Block Diagram
7.3 Receive Operation
During receive operations, the transmit sequence is reversed. The serial shift register
receives data and transfers it to a parallel receive data register (SCDR) as a complete
word. Refer to Figure 7-2. This double buffered operation allows a character to be
shifted in serially while another character is already in the SCDR. An advanced data
11 SCI TX BLOCK
FE
NF
OR
IDLE
RDRF
TC
TDRE
SCSR
INTERRUPT STATUS
SBK
RWU
RE
TE
ILIE
RIE
TCIE
TIE
SCCR2
SCI CONTROL 2
TRANSMITTER
CONTROL LOGIC
TCIE
TC
TIE
TDRE
SCI Rx
REQUESTS
SCI INTERRUPT
REQUEST
INTERNAL
DATA BUS
PIN BUFFER
AND CONTROL
H(8)76543210L
10 (11) - BIT Tx SHIFT REGISTER
DDD1
PD1
TxD
SCDR
Tx BUFFER
TRANSFER Tx BUFFER
SHIFT ENABLE
JAM ENABLE
PREAMBLE—JAM 1s
BREAK—JAM 0s
(WRITE ONLY)
FORCE PIN
DIRECTION (OUT)
SIZE 8/9
WAKE
M
T8
R8
SCCR1
SCI CONTROL 1
TRANSMITTER
BAUD RATE
CLOCK
8
8
8
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SERIAL COMMUNICATIONS INTERFACE
TECHNICAL DATA 7-3
recovery scheme distinguishes valid data from noise in the serial data stream. The
data input is selectively sampled to detect receive data, and a majority voting circuit
determines the value and integrity of each bit.
Figure 7-2 SCI Receiver Block Diagram
11 SCI RX BLOCK
FE
NF
OR
IDLE
RDRF
TC
TDRE
SCSR
SCI STATUS 1
SBK
RWU
RE
TE
ILIE
RIE
TCIE
TIE
SCCR2
SCI CONTROL 2
WAKE
M
T8
R8
WAKEUP
LOGIC
RIE
OR
ILIE
IDLE
SCI Tx
REQUESTS
SCI INTERRUPT
REQUEST INTERNAL
DATA BUS
PIN BUFFER
AND CONTROL
DDD0
PD0
RxD
SCDR Rx BUFFER
STOP
(8)76543210
10 (11) - BIT
Rx SHIFT REGISTER
(READ ONLY)
SCCR1
SCI CONTROL 1
RIE
RDRF
START
MSB ALL ONES
DATA
RECOVERY
÷16
RWU
RE
M
DISABLE
DRIVER
RECEIVER
BAUD RATE
CLOCK
8
8
8
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SERIAL COMMUNICATIONS INTERFACE
7-4 TECHNICAL DATA
7.4 Wake-up Feature
The wake-up feature reduces SCI service overhead in multiple receiver systems. Soft-
ware for each receiver evaluates the first character of each message. The receiver is
placed in wakeup mode by writing a one to the RWU bit in the SCCR2 register. While
RWU is one, all of the receiver-related status flags (RDRF, IDLE, OR, NF, and FE) are
inhibited (cannot become set). Although RWU can be cleared by a software write to
SCCR2, to do so would be unusual. Normally RWU is set by software and is cleared
automatically with hardware. Whenever a new message begins, logic alerts the sleep-
ing receivers to wake up and evaluate the initial character of the new message.
Two methods of wake-up are available: idle line wake-up and address mark wake-up.
During idle line wake-up, a sleeping receiver awakens as soon as the RxD line be-
comes idle. In the address mark wake-up, logic one in the most significant bit (MSB)
of a character wakes up all sleeping receivers.
7.4.1 Idle-Line Wakeup
To use the receiver wake-up method, establish a software addressing scheme to allow
the transmitting devices to direct a message to individual receivers or to groups of re-
ceivers. This addressing scheme can take any form as long as all transmitting and re-
ceiving devices are programmed to understand the same scheme. Because the
addressing information is usually the first frame(s) in a message, receivers that are not
part of the current task do not become burdened with the entire set of addressing
frames. All receivers are awake (RWU = 0) when each message begins. As soon as
a receiver determines that the message is not intended for it, software sets the RWU
bit (RWU = 1), which inhibits further flag setting until the RxD line goes idle at the end
of the message. As soon as an idle line is detected by receiver logic, hardware auto-
matically clears the RWU bit so that the first frame of the next message can be re-
ceived. This type of receiver wakeup requires a minimum of one idle-line frame time
between messages, and no idle time between frames in a message.
7.4.2 Address-Mark Wakeup
The serial characters in this type of wakeup consist of seven (eight if M = 1) information
bits and an MSB, which indicates an address character (when set to one — mark). The
first character of each message is an addressing character (MSB = 1). All receivers in
the system evaluate this character to determine if the remainder of the message is di-
rected toward this particular receiver. As soon as a receiver determines that a mes-
sage is not intended for it, the receiver activates the RWU function by using a software
write to set the RWU bit. Because setting RWU inhibits receiver-related flags, there is
no further software overhead for the rest of this message. When the next message be-
gins, its first character has its MSB set, which automatically clears the RWU bit and
enables normal character reception. The first character whose MSB is set is also the
first character to be received after wakeup because RWU gets cleared before the stop
bit for that frame is serially received. This type of wakeup allows messages to include
gaps of idle time, unlike the idle-line method, but there is a loss of efficiency because
of the extra bit time for each character (address bit) required for all characters.
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SERIAL COMMUNICATIONS INTERFACE
TECHNICAL DATA 7-5
7.5 SCI Error Detection
Three error conditions, SCDR overrun, received bit noise, and framing can occur dur-
ing generation of SCI system interrupts. Three bits (OR, NF, and FE) in the serial com-
munications status register (SCSR) indicate if one of these error conditions exists. The
overrun error (OR) bit is set when the next byte is ready to be transferred from the re-
ceive shift register to the SCDR and the SCDR is already full (RDRF bit is set). When
an overrun error occurs, the data that caused the overrun is lost and the data that was
already in SCDR is not disturbed. The OR is cleared when the SCSR is read (with OR
set), followed by a read of the SCDR.
The noise flag (NF) bit is set if there is noise on any of the received bits, including the
start and stop bits. The NF bit is not set until the RDRF flag is set. The NF bit is cleared
when the SCSR is read (with FE equal to one) followed by a read of the SCDR.
When no stop bit is detected in the received data character, the framing error (FE) bit
is set. FE is set at the same time as the RDRF. If the byte received causes both fram-
ing and overrun errors, the processor only recognizes the overrun error. The framing
error flag inhibits further transfer of data into the SCDR until it is cleared. The FE bit is
cleared when the SCSR is read (with FE equal to one) followed by a read of the SCDR.
7.6 SCI Registers
There are five addressable registers in the SCI.
7.6.1 Serial Communications Data Register (SCDR)
SCDR is a parallel register that performs two functions. It is the receive data register
when it is read, and the transmit data register when it is written. Reads access the re-
ceive data buffer and writes access the transmit data buffer. Receive and transmit are
double buffered.
*U = Unaffected
7.6.2 Serial Communications Control Register 1 (SCCR1)
The SCCR1 register provides the control bits that determine word length and select
the method used for the wake-up feature.
R8 — Receive Data Bit 8
If M bit is set, R8 stores the ninth bit in the receive data character.
SCDR — SCI Data Register $002F
Bit 7654321Bit 0
R7/T7 R6/T6 R5/T5 R4/T4 R3/T3 R2/T2 R1/T1 R0/T0
RESET:U*UUUUUUU
SCCR1 — SCI Control Register 1 $002C
Bit 7654321Bit 0
R8 T8 0 M WAKE 0 0 0
RESET:UU000000
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SERIAL COMMUNICATIONS INTERFACE
7-6 TECHNICAL DATA
T8 — Transmit Data bit 8
If M bit is set, T8 stores ninth bit in transmit data character.
M — Mode (Select Character Format)
0 = Start bit, 8 data bits, 1 stop bit
1 = Start bit, 9 data bits, 1 stop bit
WAKE — Wake-up by Address Mark/Idle
0 = Wake-up by IDLE line recognition
1 = Wake-up by address mark (most significant data bit set)
7.6.3 Serial Communications Control Register 2 (SCCR2)
The SCCR2 register provides the control bits that enable or disable individual SCI
functions.
TIE — Transmit Interrupt Enable
0 = TDRE interrupts disabled
1 = SCI interrupt requested when TDRE status flag is set
TCIE — Transmit Complete Interrupt Enable
0 = TC interrupts disabled
1 = SCI interrupt requested when TC status flag is set
RIE — Receiver Interrupt Enable
0 = RDRF and OR interrupts disabled
1 = SCI interrupt requested when RDRF flag or the OR status flag is set
ILIE — Idle Line Interrupt Enable
0 = IDLE interrupts disabled
1 = SCI interrupt requested when IDLE status flag is set
TE — Transmitter Enable
When TE goes from zero to one, one unit of idle character time (logic one) is queued
as a preamble.
0 = Transmitter disabled
1 = Transmitter enabled
RE — Receiver Enable
0 = Receiver disabled
1 = Receiver enabled
RWU — Receiver Wake-Up Control
0 = Normal SCI receiver
1 = Wake-up enabled and receiver interrupts inhibited
SCCR2 — SCI Control Register 2 $002D
Bit 7654321Bit 0
TIE TCIE RIE ILIE TE RE RWU SBK
RESET:00000000
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SERIAL COMMUNICATIONS INTERFACE
TECHNICAL DATA 7-7
SBK — Send Break
At least one character time of break is queued and sent each time SBK is written to
one. More than one break may be sent if the transmitter is idle at the time the SBK bit
is toggled on and off, as the baud rate clock edge could occur between writing the one
and writing the zero to SBK.
0 = Break generator off
1 = Break codes generated as long as SBK = 1
7.6.4 Serial Communication Status Register (SCSR)
The SCSR provides inputs to the interrupt logic circuits for generation of the SCI sys-
tem interrupt.
TDRE — Transmit Data Register Empty Flag
This flag is set when SCDR is empty. Clear the TDRE flag by reading SCSR with
TDRE set and then writing to SCDR.
0 = SCDR busy
1 = SCDR empty
TC — Transmit Complete Flag
This flag is set when the transmitter is idle (no data, preamble, or break transmission
in progress). Clear the TC flag by reading SCSR with TC set and then writing to SCDR.
0 = Transmitter busy
1 = Transmitter idle
RDRF — Receive Data Register Full Flag
This flag is set if a received character is ready to be read from SCDR. Clear the RDRF
flag by reading SCSR with RDRF set and then reading SCDR.
0 = SCDR empty
1 = SCDR full
IDLE — Idle Line Detected Flag
This flag is set if the RxD line is idle. Once cleared, IDLE is not set again until the RxD
line has been active and becomes idle again. The IDLE flag is inhibited when RWU =
1. Clear IDLE by reading SCSR with IDLE set and then reading SCDR.
0 = RxD line is active
1 = RxD line is idle
OR — Overrun Error Flag
OR is set if a new character is received before a previously received character is read
from SCDR. Clear the OR flag by reading SCSR with OR set and then reading SCDR.
0 = No overrun
1 = Overrun detected
SCSR — SCI Status Register $002E
Bit 7654321Bit 0
TDRE TC RDRF IDLE OR NF FE 0
RESET:11000000
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SERIAL COMMUNICATIONS INTERFACE
7-8 TECHNICAL DATA
NF — Noise Error Flag
NF is set if majority sample logic detects anything other than a unanimous decision.
Clear NF by reading SCSR with NF set and then reading SCDR.
0 = Unanimous decision
1 = Noise detected
FE — Framing Error
FE is set when a 0 is detected where a stop bit was expected. Clear the FE flag by
reading SCSR with FE set and then reading SCDR.
0 = Stop bit detected
1 = 0 detected
7.6.5 Baud Rate Register (BAUD)
Use this register to select different baud rates for the SCI system. The SCP[1:0] bits
function as a prescaler for the SCR[2:0] bits. Together, these five bits provide multiple
baud rate combinations for a given crystal frequency. Normally, this register is written
once during initialization. The prescaler is set to its fastest rate by default out of reset,
and can be changed at any time. Refer to Table 7-1 and Table 7-2 for normal baud
rate selections.
TCLR — Clear Baud Rate Counters (Test)
RCKB — SCI Baud Rate Clock Check (Test)
SCP1, SCP0 — SCI Baud Rate Prescaler Selects
These two bits select a prescale factor for the SCI baud rate generator that determines
the highest possible baud rate.
SCR[2:0] — SCI Baud Rate Selects
These three bits select receiver and transmitter bit rate based on output from baud rate
prescaler stage.
BAUD — Baud Rate $002B
Bit 7654321Bit 0
TCLR 0 SCP1 SCP0 RCKB SCR2 SCR1 SCR0
RESET:00000UUU
Table 7-1 Baud Rate Prescale Selects
SCP[1:0] Divide Crystal Frequency in MHz
Internal Clock
By 4.0 MHz
(Baud) 8.0 MHz
(Baud) 10.0 MHz
(Baud) 12.0 MHz
(Baud)
0 0 1 62.50 K 125.0 K 156.25 K 187.5 K
0 1 3 20.83 K 41.67 K 52.08 K 62.5 K
1 0 4 15.625 K 31.25 K 38.4 K 46.88 K
1 1 13 4800 9600 12.02 K 14.42 K
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SERIAL COMMUNICATIONS INTERFACE
TECHNICAL DATA 7-9
The prescale bits, SCP[1:0], determine the highest baud rate and the SCR[2:0] bits se-
lect an additional binary submultiple (≥1, ≥2, ≥4, through ≥128) of this highest baud
rate. The result of these two dividers in series is the 16 X receiver baud rate clock. The
SCR[2:0] bits are not affected by reset and can be changed at any time, although they
should not be changed when any SCI transfer is in progress.
Figure 7-3 illustrates the SCI baud rate timing chain. The prescale select bits deter-
mine the highest baud rate. The rate select bits determine additional divide by two
stages to arrive at the receiver timing (RT) clock rate. The baud rate clock is the result
of dividing the RT clock by 16.
Table 7-2 Baud Rate Selects
SCR[2:0] Divide
Prescaler Highest Baud Rate
(Prescaler Output from Previous Table)
By 4800 9600 38.4 K
0 0 0 1 4800 9600 38.4 K
0 0 1 2 2400 4800 19.2 K
0 1 0 4 1200 2400 9600
0 1 1 8 600 1200 4800
1 0 0 16 300 600 2400
1 0 1 32 150 300 1200
1 1 0 64 — 150 600
1 1 1 128 — — 300
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SERIAL COMMUNICATIONS INTERFACE
7-10 TECHNICAL DATA
Figure 7-3 SCI Baud Rate Diagram
7.7 Status Flags and Interrupts
The SCI transmitter has two status flags. These status flags can be read by software
(polled) to tell when the corresponding condition exists. Alternatively, a local interrupt
enable bit can be set to enable each of these status conditions to generate interrupt
requests when the corresponding condition is present. Status flags are automatically
set by hardware logic conditions, but must be cleared by software, which provides an
interlock mechanism that enables logic to know when software has noticed the status
indication. The software clearing sequence for these flags is automatic — functions
that are normally performed in response to the status flags also satisfy the conditions
of the clearing sequence.
SCI BAUD GENERATOR
÷3 ÷4 ÷13
OSCILLATOR
AND
CLOCK GENERATOR
(÷ 4)
XTAL
EXTAL
E
AS
INTERNAL BUS CLOCK (PH2)
1:1
SCP[1:0]
1:00:10:0
÷2
0:0:0
÷2
0:0:1
÷2
0:1:0
÷2
0:1:1
÷2
1:0:0
÷2
1:0:1
÷2
1:1:0
1:1:1
÷16
SCI
RECEIVE
BAUD RATE
(16X)
SCR[2:0]
SCI
TRANSMIT
BAUD RATE
(1X)
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SERIAL COMMUNICATIONS INTERFACE
TECHNICAL DATA 7-11
TDRE and TC flags are normally set when the transmitter is first enabled (TE set to
one). The TDRE flag indicates there is room in the transmit queue to store another
data character in the TDR. The TIE bit is the local interrupt mask for TDRE. When TIE
is zero, TDRE must be polled. When TIE and TDRE are one, an interrupt is requested.
The TC flag indicates the transmitter has completed the queue. The TCIE bit is the lo-
cal interrupt mask for TC. When TCIE is zero, TC must be polled; when TCIE is one
and TC is one, an interrupt is requested.
Writing a zero to TE requests that the transmitter stop when it can. The transmitter
completes any transmission in progress before actually shutting down. Only an MCU
reset can cause the transmitter to stop and shut down immediately. If TE is written to
zero when the transmitter is already idle, the pin reverts to its general-purpose I/O
function (synchronized to the bit-rate clock). If anything is being transmitted when TE
is written to zero, that character is completed before the pin reverts to general-purpose
I/O, but any other characters waiting in the transmit queue are lost. The TC and TDRE
flags are set at the completion of this last character, even though TE has been dis-
abled.
The SCI receiver has five status flags, three of which can generate interrupt requests.
The status flags are set by the SCI logic in response to specific conditions in the re-
ceiver. These flags can be read (polled) at any time by software. Refer to Figure 7-4,
which shows SCI interrupt arbitration.
When an overrun takes place, the new character is lost, and the character that was in
its way in the parallel RDR is undisturbed. RDRF is set when a character has been
received and transferred into the parallel RDR. The OR flag is set instead of RDRF if
overrun occurs. A new character is ready to be transferred into RDR before a previous
character is read from RDR.
The NF and FE flags provide additional information about the character in the RDR,
but do not generate interrupt requests.
The last receiver status flag and interrupt source come from the IDLE flag. The RxD
line is idle if it has constantly been at logic one for a full character time. The IDLE flag
is set only after the RxD line has been busy and becomes idle, which prevents repeat-
ed interrupts for the whole time RxD remains idle.
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SERIAL COMMUNICATIONS INTERFACE
7-12 TECHNICAL DATA
Figure 7-4 Interrupt Source Resolution within SCI
FLAG Y
N
OR = 1? Y
N
Y
N
TDRE = 1?
TC = 1? Y
N
IDLE = 1? Y
N
Y
N
Y
N
Y
N
ILIE = 1?
RIE = 1?
TIE = 1?
BEGIN
RE = 1? Y
N
Y
N
TE = 1?
TCIE = 1? Y
N
RE = 1? Y
N
RDRF = 1?
VALID SCI REQUEST
NO
VALID SCI REQUEST
INT SOURCE RES
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SERIAL PERIPHERAL INTERFACE
TECHNICAL DATA 8-1
SECTION 8
SERIAL PERIPHERAL INTERFACE
The serial peripheral interface (SPI), an independent serial communications sub-
system, allows the MCU to communicate synchronously with peripheral devices, such
as transistor-transistor logic (TTL) shift registers, liquid crystal diode (LCD) display
drivers, analog-to-digital converter subsystems, and other microprocessors. The SPI
is also capable of inter-processor communication in a multiple master system. The SPI
system can be configured as either a master or a slave device with data rates as high
as one half of the E-clock rate when configured as master, and as fast as the E-clock
rate when configured as slave.
8.1 Functional Description
The central element in the SPI system is the block containing the shift register and the
read data buffer. The system is single buffered in the transmit direction and double
buffered in the receive direction. This means that new data for transmission cannot be
written to the shifter until the previous transfer is complete; however, received data is
transferred into a parallel read data buffer so the shifter is free to accept a second se-
rial character. As long as the first character is read out of the read data buffer before
the next serial character is ready to be transferred, no overrun condition occurs. A sin-
gle MCU register address is used for reading data from the read data buffer, and for
writing data to the shifter.
The SPI status block represents the SPI status functions (transfer complete, write col-
lision, and mode fault) performed by the serial peripheral status register (SPSR). The
SPI control block represents those functions that control the SPI system through the
serial peripheral control register (SPCR).
Refer to Figure 8-1, which shows the SPI block diagram.
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SERIAL PERIPHERAL INTERFACE
8-2 TECHNICAL DATA
Figure 8-1 SPI Block Diagram
8.2 SPI Transfer Formats
During an SPI transfer, data is simultaneously transmitted and received. A serial clock
line synchronizes shifting and sampling of the information on the two serial data lines.
A slave select line allows individual selection of a slave SPI device; slave devices that
are not selected do not interfere with SPI bus activities. On a master SPI device, the
select line can optionally be used to indicate a multiple master bus contention. Refer
to Figure 8-2.
11 SPI BLOCK
SPR0
SPR1
CPHA
CPOL
MSTR
DWOM
SPE
SPIE
SPI CONTROL REGISTER
MODF
WCOL
SPIF
SPI STATUS REGISTER
8/16-BIT SHIFT REGISTER
READ DATA BUFFER
MSB LSB
INTERNAL
DATA BUS
SPI INTERRUPT
REQUEST
MSTR
SPE
MSTR
DWOM
SPE
SPR0
SPI CLOCK (MASTER)
SPI CONTROL
SELECT
DIVIDER
INTERNAL
MCU CLOCK
CLOCK
LOGIC
CLOCK
PIN CONTROL LOGIC
S
M
S
M
M
S
MISO
PD2
MOSI
PD3
SCK
PD4
SS
PD5
SPR1
÷2 ÷4 ÷16 ÷32
8 8
8
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SERIAL PERIPHERAL INTERFACE
TECHNICAL DATA 8-3
Figure 8-2 SPI Transfer Format
8.2.1 Clock Phase and Polarity Controls
Software can select one of four combinations of serial clock phase and polarity using
two bits in the SPI control register (SPCR). The clock polarity is specified by the CPOL
control bit, which selects an active high or active low clock, and has no significant ef-
fect on the transfer format. The clock phase (CPHA) control bit selects one of two dif-
ferent transfer formats. The clock phase and polarity should be identical for the master
SPI device and the communicating slave device. In some cases, the phase and polar-
ity are changed between transfers to allow a master device to communicate with pe-
ripheral slaves having different requirements.
When CPHA equals zero, the slave select (SS) line must be negated and reasserted
between each successive serial byte. Also, if the slave writes data to the SPI data reg-
ister (SPDR) while SS is active low, a write collision error results.
When CPHA equals one, the SS line can remain low between successive transfers.
8.3 SPI Signals
The following paragraphs contain descriptions of the four SPI signals: master in slave
out (MISO), master out slave in (MOSI), serial clock (SCK), and SS.
SPI TRANSFER FORMAT 1
23456781
SCK (CPOL = 1)
SCK (CPOL = 0)
SCK CYCLE #
SS (TO SLAVE)
654321 LSBMSB
MSB654321LSB
1
2
3
5
4
SLAVE CPHA=1 TRANSFER IN PROGRESS
MASTER TRANSFER IN PROGRESS
SLAVE CPHA=0 TRANSFER IN PROGRESS
1. SS ASSERTED
2. MASTER WRITES TO SPDR
3. FIRST SCK EDGE
4. SPIF SET
5. SS NEGATED
SAMPLE INPUT
DATA OUT
(CPHA = 0)
SAMPLE INPUT
DATA OUT
(CPHA = 1)
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SERIAL PERIPHERAL INTERFACE
8-4 TECHNICAL DATA
8.3.1 Master In Slave Out
MISO is one of two unidirectional serial data signals. It is an input to a master device
and an output from a slave device. The MISO line of a slave device is placed in the
high impedance state if the slave device is not selected.
8.3.2 Master Out Slave In
The MOSI line is the second of the two unidirectional serial data signals. It is an output
from a master device and an input to a slave device. The master device places data
on the MOSI line a half-cycle before the clock edge that the slave device uses to latch
the data.
8.3.3 Serial Clock
SCK, an input to a slave device, is generated by the master device and synchronizes
data movement in and out of the device through the MOSI and MISO lines. Master and
slave devices are capable of exchanging a byte of information during a sequence of
eight clock cycles.
There are four possible timing relationships that can be chosen by using control bits
CPOL and CPHA in the serial peripheral control register (SPCR). Both master and
slave devices must operate with the same timing. The SPI clock rate select bits,
SPR[1:0], in the SPCR of the master device, select the clock rate. In a slave device,
SPR[1:0] have no effect on the operation of the SPI.
8.3.4 Slave Select
The SS input of a slave device must be externally asserted before a master device can
exchange data with the slave device. must be low before data transactions and must
stay low for the duration of the transaction.
The SS line of the master must be held high. If it goes low, a mode fault error flag
(MODF) is set in the serial peripheral status register (SPSR). To disable the mode fault
circuit, write a one in bit 5 of the port D data direction register. This sets the SS pin to
act as a general-purpose output. The other three lines are dedicated to the SPI when-
ever the serial peripheral interface is on.
The state of the master and slave CPHA bits affects the operation of SS. CPHA set-
tings should be identical for master and slave. When CPHA = 0, the shift clock is the
OR of SS with SCK. In this clock phase mode, SS must go high between successive
characters in an SPI message. When CPHA = 1, SS can be left low between succes-
sive SPI characters. In cases where there is only one SPI slave MCU, its SS line can
be tied to VSS as long as only CPHA = 1 clock mode is used.
8.4 SPI System Errors
Two system errors can be detected by the SPI system. The first type of error arises in
a multiple-master system when more than one SPI device simultaneously tries to be
a master. This error is called a mode fault. The second type of error, write collision,
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SERIAL PERIPHERAL INTERFACE
TECHNICAL DATA 8-5
indicates that an attempt was made to write data to the SPDR while a transfer was in
progress.
When the SPI system is configured as a master and the SS input line goes to active
low, a mode fault error has occurred — usually because two devices have attempted
to act as master at the same time. In cases where more than one device is concurrent-
ly configured as a master, there is a chance of contention between two pin drivers. For
push-pull CMOS drivers, this contention can cause permanent damage. The mode
fault attempts to protect the device by disabling the drivers. The MSTR control bit in
the SPCR and all four DDRD control bits associated with the SPI are cleared. An in-
terrupt is generated subject to masking by the SPIE control bit and the I bit in the CCR.
Other precautions may need to be taken to prevent driver damage. If two devices are
made masters at the same time, mode fault does not help protect either one unless
one of them selects the other as slave. The amount of damage possible depends on
the length of time both devices attempt to act as master.
A write collision error occurs if the SPDR is written while a transfer is in progress. Be-
cause the SPDR is not double buffered in the transmit direction, writes to SPDR cause
data to be written directly into the SPI shift register. Because this write corrupts any
transfer in progress, a write collision error is generated. The transfer continues undis-
turbed, and the write data that caused the error is not written to the shifter.
A write collision is normally a slave error because a slave has no control over when a
master initiates a transfer. A master knows when a transfer is in progress, so there is
no reason for a master to generate a write-collision error, although the SPI logic can
detect write collisions in both master and slave devices.
The SPI configuration determines the characteristics of a transfer in progress. For a
master, a transfer begins when data is written to SPDR and ends when SPIF is set.
For a slave with CPHA equal to zero, a transfer starts when SS goes low and ends
when SS returns high. In this case, SPIF is set at the middle of the eighth SCK cycle
when data is transferred from the shifter to the parallel data register, but the transfer
is still in progress until SS goes high. For a slave with CPHA equal to one, transfer be-
gins when the SCK line goes to its active level, which is the edge at the beginning of
the first SCK cycle. The transfer ends in a slave in which CPHA equals one when SPIF
is set. For a slave, after a byte transfer, SCK must be in inactive state for at least 2 E-
clock cycles before the next byte transfer begins.
8.5 SPI Registers
The three SPI registers, SPCR, SPSR, and SPDR, provide control, status, and data
storage functions. Refer to the following information for a description of how these reg-
isters are organized.
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SERIAL PERIPHERAL INTERFACE
8-6 TECHNICAL DATA
8.5.1 Serial Peripheral Control
SPIE — Serial Peripheral Interrupt Enable
0 = SPI interrupt disabled
1 = SPI interrupt enabled
SPE — Serial Peripheral System Enable
0 = SPI off
1 = SPI on
DWOM — Port D Wired-OR Mode
DWOM affects all six port D pins.
0 = Normal CMOS outputs
1 = Open-drain outputs
MSTR — Master Mode Select
0 = Slave mode
1 = Master mode
CPOL — Clock Polarity
When the clock polarity bit is cleared and data is not being transferred, the SCK pin of
the master device has a steady state low value. When CPOL is set, SCK idles high.
Refer to Figure 8-2 and 8.2.1 Clock Phase and Polarity Controls.
CPHA — Clock Phase
The clock phase bit, in conjunction with the CPOL bit, controls the clock-data relation-
ship between master and slave. The CPHA bit selects one of two different clocking
protocols. Refer to Figure 8-2 and 8.2.1 Clock Phase and Polarity Controls.
SPR1 and SPR0 — SPI Clock Rate Selects
These two serial peripheral rate bits select one of four baud rates to be used as SCK
if the device is a master; however, they have no effect in the slave mode.
SPCR — Serial Peripheral Control Register $0028
Bit 7654321Bit 0
SPIE SPE DWOM MSTR CPOL CPHA SPR1 SPR0
RESET:000001UU
SPR[1:0] E Clock
Divide By Frequency at
E = 2 MHz (Baud)
0 0 2 1.0 MHz
0 1 4 500 kHz
1 0 16 125 kHz
1 1 32 62.5 kHz
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SERIAL PERIPHERAL INTERFACE
TECHNICAL DATA 8-7
8.5.2 Serial Peripheral Status
SPIF — SPI Transfer Complete Flag
SPIF is set upon completion of data transfer between the processor and the external
device. If SPIF goes high, and if SPIE is set, a serial peripheral interrupt is generated.
To clear the SPIF bit, read the SPSR with SPIF set, then access the SPDR. Unless
SPSR is read (with SPIF set) first, attempts to write SPDR are inhibited.
WCOL — Write Collision
Clearing the WCOL bit is accomplished by reading the SPSR (with WCOL set) fol-
lowed by an access of SPDR. Refer to 8.3.4 Slave Select and 8.4 SPI System Errors.
0 = No write collision
1 = Write collision
Bit 5 — Not implemented
Always reads zero
MODF — Mode Fault
To clear the MODF bit, read the SPSR (with MODF set), then write to the SPCR. Refer
to 8.3.4 Slave Select and 8.4 SPI System Errors.
0 = No mode fault
1 = Mode fault
Bits [3:0] — Not implemented
Always read zero
8.5.3 Serial Peripheral Data I/O
The SPDR is used when transmitting or receiving data on the serial bus. Only a write
to this register initiates transmission or reception of a byte, and this only occurs in the
master device. At the completion of transferring a byte of data, the SPIF status bit is
set in both the master and slave devices.
A read of the SPDR is actually a read of a buffer. To prevent an overrun and the loss
of the byte that caused the overrun, the first SPIF must be cleared by the time a second
transfer of data from the shift register to the read buffer is initiated.
NOTE
SPI is double buffered in and single buffered out.
SPSR — Serial Peripheral Status Register $0029
Bit 7654321Bit 0
SPIFWCOL0MODF0000
RESET:00000000
SPDR — SPI Data Register $002A
Bit 7654321Bit 0
Bit 7654321Bit 0
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SERIAL PERIPHERAL INTERFACE
8-8 TECHNICAL DATA
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TIMING SYSTEM
TECHNICAL DATA 9-1
SECTION 9
TIMING SYSTEM
The M68HC11 timing system is composed of five clock divider chains. The main clock
divider chain includes a 16-bit free-running counter, which is driven by a programma-
ble prescaler. The main timer's programmable prescaler provides one of the four
clocking rates to drive the 16-bit counter. Two prescaler control bits select the prescale
rate.
The prescaler output divides the system clock by 1, 4, 8, or 16. Taps off of this main
clocking chain drive circuitry that generates the slower clocks used by the pulse accu-
mulator, the real-time interrupt (RTI), and the computer operating properly (COP)
watchdog subsystems, also described in this section. Refer to Figure 9-1.
All main timer system activities are referenced to this free-running counter. The
counter begins incrementing from $0000 as the MCU comes out of reset, and contin-
ues to the maximum count, $FFFF. At the maximum count, the counter rolls over to
$0000, sets an overflow flag, and continues to increment. As long as the MCU is run-
ning in a normal operating mode, there is no way to reset, change, or interrupt the
counting. The capture/compare subsystem features three input capture channels, four
output compare channels, and one channel that can be selected to perform either in-
put capture or output compare. Each of the three input capture functions has its own
16-bit input capture register (time capture latch) and each of the output compare func-
tions has its own 16-bit compare register. All timer functions, including the timer over-
flow and RTI have their own interrupt controls and separate interrupt vectors.
The pulse accumulator contains an 8-bit counter and edge select logic. The pulse ac-
cumulator can operate in either event counting or gated time accumulation modes.
During event counting mode, the pulse accumulator's 8-bit counter increments when
a specified edge is detected on an input signal. During gated time accumulation mode,
an internal clock source increments the 8-bit counter while an input signal has a pre-
determined logic level.
RTI is a programmable periodic interrupt circuit that permits pacing the execution of
software routines by selecting one of four interrupt rates.
The COP watchdog clock input (E÷215) is tapped off of the free-running counter chain.
The COP automatically times out unless it is serviced within a specific time by a pro-
gram reset sequence. If the COP is allowed to time out, a reset is generated, which
drives the RESET pin low to reset the MCU and the external system. Refer to Table
9-1 for crystal related frequencies and periods.
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TIMING SYSTEM
9-2 TECHNICAL DATA
Figure 9-1 Timer Clock Divider Chains
TIMER DIV CHAIN
OSCILLATOR AND
CLOCK GENERATOR AS
E CLOCK
SPI
SCI RECEIVER CLOCK
SCI TRANSMIT CLOCK
E÷26PULSE ACCUMULATOR
TCNT
TOF
REAL-TIME INTERRUPTE÷213
÷4
E÷215
RQ
Q
S
RQ
Q
SFORCE
COP
RESET
SYSTEM
RESET
CLEAR COP
TIMER
FF2
FF1
(DIVIDE BY FOUR)
INTERNAL BUS CLOCK (PH2)
IC/OC
÷16
CR[1:0]
PRESCALER
(÷1, 4, 16, 64)
PRESCALER
(÷ 2, 4, 16, 32)
SPR[1:0]
PRESCALER
(÷ 1, 3, 4, 13)
SCP[1:0]
PRESCALER
(÷ 1, 2, 4, 8)
RTR[1:0]
PRESCALER
(÷ 1, 2, 4,....128)
SCR[2:0]
PRESCALER
(÷ 1, 4, 8, 16)
PR[1:0]
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TIMING SYSTEM
TECHNICAL DATA 9-3
9.1 Timer Structure
Figure 9-1 shows the capture/compare system block diagram. The port A pin control
block includes logic for timer functions and for general-purpose I/O. For pins PA2,
PA1, and PA0, this block contains both the edge-detection logic and the control logic
that enables the selection of which edge triggers an input capture. The digital level on
PA[2:0] can be read at any time (read PORTA register), even if the pin is being used
for the input capture function. Pins PA[6:4] are used for either general-purpose output,
or as output compare pins. Pin PA3 can be used for general-purpose I/O, input capture
4, output compare 5, or output compare 1. When one of these pins is being used for
an output compare function, it cannot be written directly as if it were a general-purpose
output. Each of the output compare functions (OC5–OC2) is related to one of the port
A output pins. Output compare one (OC1) has extra control logic, allowing it optional
control of any combination of the PA[7:3] pins. The PA7 pin can be used as a general-
purpose I/O pin, as an input to the pulse accumulator, or as an OC1 output pin.
Table 9-1 Timer Summary
XTAL Frequencies
4.0 MHz 8.0 MHz 12.0 MHz Other Rates
Control 1.0 MHz 2.0 MHz 3.0 MHz (E)
Bits 1000 ns 500 ns 333 ns (1/E)
PR[1:0] Main Timer Count Rates
0 0
1 count —
overflow — 1.0 µs
65.536 ms 500 ns
32.768 ms 333 ns
21.845 ms (E/1)
(E/216)
0 1
1 count —
overflow — 4.0 µs
262.14 ms 2.0 µs
131.07 ms 1.333 µs
87.381 ms (E/4)
(E/218)
1 0
1 count —
overflow — 8.0 µs
524.29 ms 4.0 µs
262.14 ms 2.667 µs
174.76 ms (E/8)
(E/219)
1 1
1 count —
overflow — 16.0 µs
1.049 s 8.0 µs
524.29 ms 5.333 µs
349.52 ms (E/16)
(E/220)
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TIMING SYSTEM
9-4 TECHNICAL DATA
Figure 9-2 Capture/Compare Block Diagram
9.2 Input Capture
The input capture function records the time an external event occurs by latching the
value of the free-running counter when a selected edge is detected at the associated
timer input pin. Software can store latched values and use them to compute the peri-
odicity and duration of events. For example, by storing the times of successive edges
of an incoming signal, software can determine the period and pulse width of a signal.
To measure period, two successive edges of the same polarity are captured. To mea-
sure pulse width, two alternate polarity edges are captured.
11 CC BLOCK
SYSTEM
16-BIT LATCH CLK
4
5
6
7
8
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
PARALLEL PORT
PIN CONTROL
OC1I
OC2I
OC3I
OC4I
I4/O5I
TFLG 1
STATUS
FLAGS
FOC1
FOC2
FOC3
FOC4
FOC5
OC1F
OC2F
OC3F
OC4F
I4/O5F
PA3
PA4
PA5
PA6
PA7
I4/O5
16-BIT COMPARATOR =
TOC1 (HI) TOC1 (LO)
16-BIT COMPARATOR =
TOC2 (HI) TOC2 (LO)
16-BIT COMPARATOR =
TOC3 (HI) TOC3 (LO)
16-BIT COMPARATOR =
TOC4 (HI) TOC4 (LO)
16-BIT COMPARATOR =
TI4/O5 (HI) TI4/O5 (LO)
16-BIT FREE RUNNING
COUNTER
TCNT (HI) TCNT (LO) 9
TOI
TOF
INTERRUPT REQUESTS
PRESCALER — DIVIDE BY
1, 4, 8, 16
PR1
16-BIT TIMER BUS
OC5
IC4
TMSK 1
INTERRUPT
ENABLES
CFORC
FORCE OUTPUT
PIN
FUNCTIONS
PA0
3
2
1
BIT 2
BIT 1
BIT 3
IC1I
IC2I
IC3I
IC1F
IC2F
IC3F
PA1
PA2
16-BIT LATCH
TIC1 (HI) TIC1 (LO)
CLK
16-BIT LATCH
TIC2 (HI) TIC2 (LO)
CLK
16-BIT LATCH
TIC3 (HI) TIC3 (LO)
CLK IC3
IC2
IC1
PR0
CLOCK
OC1
OC2/OC1
OC3/OC1
OC4/OC1
IC4/OC5
OC1
COMPARE
TMSK 1
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TIMING SYSTEM
TECHNICAL DATA 9-5
In most cases, input capture edges are asynchronous to the internal timer counter,
which is clocked relative to the PH2 clock. These asynchronous capture requests are
synchronized to PH2 so that the latching occurs on the opposite half cycle of PH2 from
when the timer counter is being incremented. This synchronization process introduces
a delay from when the edge occurs to when the counter value is detected. Because
these delays offset each other when the time between two edges is being measured,
the delay can be ignored. When an input capture is being used with an output com-
pare, there is a similar delay between the actual compare point and when the output
pin changes state.
The control and status bits that implement the input capture functions are contained in
the PACTL, TCTL2, TMSK1, and TFLG1 registers.
To configure port A bit 3 as an input capture, clear the DDRA3 bit of the PACTL reg-
ister. Note that this bit is cleared out of reset. To enable PA3 as the fourth input cap-
ture, set the I4/O5 bit in the PACTL register. Otherwise, PA3 is configured as a fifth
output compare out of reset, with bit I4/O5 being cleared. If the DDRA3 bit is set (con-
figuring PA3 as an output), and IC4 is enabled, then writes to PA3 cause edges on the
pin to result in input captures. Writing to TI4/O5 has no effect when the TI4/O5 register
is acting as IC4.
9.2.1 Timer Control 2 Register
Use the control bits of this register to program input capture functions to detect a par-
ticular edge polarity on the corresponding timer input pin. Each of the input capture
functions can be independently configured to detect rising edges only, falling edges
only, any edge (rising or falling), or to disable the input capture function. The input cap-
ture functions operate independently of each other and can capture the same TCNT
value if the input edges are detected within the same timer count cycle.
EDGxB and EDGxA — Input Capture Edge Control
There are four pairs of these bits. Each pair is cleared to zero by reset and must be
encoded to configure the corresponding input capture edge detector circuit. IC4 func-
tions only if the I4/O5 bit in the PACTL register is set. Refer to Table 9-2 for timer con-
trol configuration.
TCTL2 — Timer Control 2 $0021
Bit 7654321Bit 0
EDG4B EDG4A EDG1B EDG1A EDG2B EDG2A EDG3B EDG3A
RESET:00000000
Table 9-2 Timer Control Configuration
EDGxB EDGxA Configuration
0 0 Capture disabled
0 1 Capture on rising edges only
1 0 Capture on falling edges only
1 1 Capture on any edge
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TIMING SYSTEM
9-6 TECHNICAL DATA
9.2.2 Timer Input Capture Registers
When an edge has been detected and synchronized, the 16-bit free-running counter
value is transferred into the input capture register pair as a single 16-bit parallel trans-
fer. Timer counter value captures and timer counter incrementing occur on opposite
half-cycles of the phase two clock so that the count value is stable whenever a capture
occurs. The TICx registers are not affected by reset. Input capture values can be read
from a pair of 8-bit read-only registers. A read of the high-order byte of an input capture
register pair inhibits a new capture transfer for one bus cycle. If a double-byte read in-
struction, such as LDD, is used to read the captured value, coherency is assured.
When a new input capture occurs immediately after a high-order byte read, transfer is
delayed for an additional cycle but the value is not lost.
9.2.3 Timer Input Capture 4/Output Compare 5 Register
Use TI4/O5 as either an input capture register or an output compare register, depend-
ing on the function chosen for the I4/O5 pin. To enable it as an input capture pin, set
the I4/O5 bit in the pulse accumulator control register (PACTL) to logic level one. To
use it as an output compare register, set the I4/O5 bit to a logic level zero. Refer to 9.6
Pulse Accumulator.
9.3 Output Compare
Use the output compare (OC) function to program an action to occur at a specific time
— when the 16-bit counter reaches a specified value. For each of the five output com-
pare functions, there is a separate 16-bit compare register and a dedicated 16-bit com-
parator. The value in the compare register is compared to the value of the free-running
counter on every bus cycle. When the compare register matches the counter value, an
output compare status flag is set. The flag can be used to initiate the automatic actions
for that output compare function.
To produce a pulse of a specific duration, write to the output compare register a value
representing the time the leading edge of the pulse is to occur. The output compare
circuit is configured to set the appropriate output either high or low, depending on the
TIC1–TIC3 — Timer Input Capture $0010–$0015
$0010 Bit 15 14 13 12 11 10 9 Bit 8 TIC1 (High)
$0011Bit 7654321Bit 0TIC1 (Low)
$0012 Bit 15 14 13 12 11 10 9 Bit 8 TIC2 (High)
$0013Bit 7654321Bit 0TIC2 (Low)
$0014 Bit 15 14 13 12 11 10 9 Bit 8 TIC3 (High)
$0015Bit 7654321Bit 0TIC3 (Low)
RESET: Input capture registers not affected by reset.
TI4/O5 — Timer Input Capture 4/Output Compare 5 $001E, $001F
$001E Bit 15 14 13 12 11 10 9 Bit 8 TI4/O5 (High)
$001F Bit 7 6 5 4 3 2 1 Bit 0 TI4/O5 (Low)
RESET: All I4/O5 register pairs reset to ones ($FFFF).
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TIMING SYSTEM
TECHNICAL DATA 9-7
polarity of the pulse being produced. After a match occurs, the output compare register
is reprogrammed to change the output pin back to its inactive level at the next match.
A value representing the width of the pulse is added to the original value, and then writ-
ten to the output compare register. Because the pin state changes occur at specific
values of the free-running counter, the pulse width can be controlled accurately at the
resolution of the free-running counter, independent of software latencies. To generate
an output signal of a specific frequency and duty cycle, repeat this pulse-generating
procedure.
There are four 16-bit read/write output compare registers: TOC1, TOC2, TOC3, and
TOC4, and the TI4/O5 register, which functions under software control as either IC4
or OC5. Each of the OC registers is set to $FFFF on reset. A value written to an OC
register is compared to the free-running counter value during each E-clock cycle. If a
match is found, the particular output compare flag is set in timer interrupt flag register
1 (TFLG1). If that particular interrupt is enabled in the timer interrupt mask register 1
(TMSK1), an interrupt is generated. In addition to an interrupt, a specified action can
be initiated at one or more timer output pins. For OC5–OC2, the pin action is controlled
by pairs of bits (OMx and OLx) in the TCTL1 register. The output action is taken on
each successful compare, regardless of whether or not the OCxF flag in the TFLG1
register was previously cleared.
OC1 is different from the other output compares in that a successful OC1 compare can
affect any or all five of the OC pins. The OC1 output action taken when a match is
found is controlled by two 8-bit registers with three bits unimplemented: the output
compare 1 mask register, OC1M, and the output compare 1 data register, OC1D.
OC1M specifies which port A outputs are to be used, and OC1D specifies what data
is placed on these port pins.
9.3.1 Timer Output Compare Registers
All output compare registers are 16-bit read-write. Each is initialized to $FFFF at reset.
If an output compare register is not used for an output compare function, it can be used
as a storage location. A write to the high-order byte of an output compare register pair
inhibits the output compare function for one bus cycle. This inhibition prevents inap-
propriate subsequent comparisons. Coherency requires a complete 16-bit read or
write. However, if coherency is not needed, byte accesses can be used.
For output compare functions, write a comparison value to output compare registers
TOC1–TOC4 and TI4/O5. When TCNT value matches the comparison value, speci-
fied pin actions occur.
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TIMING SYSTEM
9-8 TECHNICAL DATA
All TOCx register pairs reset to ones ($FFFF)
TI4/O5 — Timer Input Capture 4/Output Compare 5 $001E, $001F
Refer to 9.2.3 Timer Input Capture 4/Output Compare 5 Register.
9.3.2 Timer Compare Force Register
The CFORC register allows forced early compares. FOC[1:5] correspond to the five
output compares. These bits are set for each output compare that is to be forced. The
action taken as a result of a forced compare is the same as if there were a match be-
tween the OCx register and the free-running counter, except that the corresponding
interrupt status flag bits are not set. The forced channels trigger their programmed pin
actions to occur at the next timer count transition after the write to CFORC.
The CFORC bits should not be used on an output compare function that is pro-
grammed to toggle its output on a successful compare because a normal compare that
occurs immediately before or after the force can result in an undesirable operation.
FOC1–FOC5 — Write Ones to Force Compare(s)
0 = Not affected
1 = Output x action occurs
Bits [2:0] — Not implemented, always read zero
9.3.3 Output Compare Mask Registers
Use OC1M with OC1 to specify the bits of port A that are affected by a successful OC1
compare. The bits of the OC1M register correspond to PA[7:3].
TOC1–TOC4 — Timer Output Compare $0016–$001D
$0016 Bit 15 14 13 12 11 10 9 Bit 8 TOC1 (High)
$0017Bit 7654321Bit 0TOC1 (Low)
$0018 Bit 15 14 13 12 11 10 9 Bit 8 TOC2 (High)
$0019Bit 7654321Bit 0TOC2 (Low)
$001A Bit 15 14 13 12 11 10 9 Bit 8 TOC3 (High)
$001BBit 7654321Bit 0TOC3 (Low)
$001C Bit 15 14 13 12 11 10 9 Bit 8 TOC4 (High)
$001DBit 7654321Bit 0TOC4 (Low)
CFORC — Timer Compare Force $000B
Bit 7654321Bit 0
FOC1 FOC2 FOC3 FOC4 FOC5 0 0 0
RESET:00000000
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TIMING SYSTEM
TECHNICAL DATA 9-9
OC1M7–OC1M3 — Output Compare Masks
0 = OC1 is disabled
1 = OC1 is enabled to control the corresponding pin of port A
Bits [2:0] — Not implemented; always read zero
Set bit(s) to enable OC1 to control corresponding pin(s) of port A.
9.3.4 Output Compare 1 Data Register
Use this register with OC1 to specify the data that is to be stored on the affected pin
of port A after a successful OC1 compare. When a successful OC1 compare occurs,
a data bit in OC1D is stored in the corresponding bit of port A for each bit that is set in
OC1M.
If OC1Mx is set, data in OC1Dx is output to port A bit x on successful OC1 compares.
Bits [2:0] — Not implemented; always read zero
9.3.5 Timer Counter Register
The 16-bit read-only TCNT register contains the prescaled value of the 16-bit timer. A
full counter read addresses the most significant byte (MSB) first. A read of this address
causes the least significant byte (LSB) to be latched into a buffer for the next CPU cy-
cle so that a double-byte read returns the full 16-bit state of the counter at the time of
the MSB read cycle.
TCNT resets to $0000.
In normal modes, TCNT is read-only.
9.3.6 Timer Control 1 Register
The bits of this register specify the action taken as a result of a successful OCx com-
pare.
OC1M — Output Compare 1 Mask $000C
Bit 7654321Bit 0
OC1M7 OC1M6 OC1M5 OC1M4 OC1M3 0 0 0
RESET:00000000
OC1D — Output Compare 1 Data $000D
Bit 7654321Bit 0
OC1D7 OC1D6 OC1D5 OC1D4 OC1D3 0 0 0
RESET:00000000
TCNT — Timer Counter $000E, $000F
$000E Bit 15 14 13 12 11 10 9 Bit 8 TCNT (High)
$000FBit 765432 1 Bit 0 TCNT (Low)
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TIMING SYSTEM
9-10 TECHNICAL DATA
OM[2:5] — Output Mode
OL[2:5] — Output Level
These control bit pairs are encoded to specify the action taken after a successful OCx
compare. OC5 functions only if the I4/O5 bit in the PACTL register is clear. Refer to
the following table for the coding.
9.3.7 Timer Interrupt Mask 1 Register
Use this 8-bit register to enable or inhibit the timer input capture and output compare
interrupts.
OC1I–OC4I — Output Compare x Interrupt Enable
If the OCxI enable bit is set when the OCxF flag bit is set, a hardware interrupt se-
quence is requested.
I4/O5I — Input Capture 4 or Output Compare 5 Interrupt Enable
When I4/O5 in PACTL is one, I4/O5I is the input capture 4 interrupt enable bit. When
I4/O5 in PACTL is zero, I4/O5I is the output compare 5 interrupt enable bit.
IC1I–IC3I — Input Capture x Interrupt Enable
If the ICxI enable bit is set when the ICxF flag bit is set, a hardware interrupt sequence
is requested.
NOTE
Bits in TMSK1 correspond bit for bit with flag bits in TFLG1. Ones in
TMSK1 enable the corresponding interrupt sources.
9.3.8 Timer Interrupt Flag 1 Register
Bits in this register indicate when timer system events have occurred. Coupled with the
bits of TMSK1, the bits of TFLG1 allow the timer subsystem to operate in either a
TCTL1 — Timer Control 1 $0020
Bit 7654321Bit 0
OM2 OL2 OM3 OL3 OM4 OL4 OM5 OL5
RESET:00000000
OMx OLx Action Taken on Successful Compare
0 0 Timer disconnected from output pin logic
0 1 Toggle OCx output line
1 0 Clear OCx output line to 0
1 1 Set OCx output line to 1
TMSK1 — Timer Interrupt Mask 1 $0022
Bit 7654321Bit 0
OC1I OC2I OC3I OC4I I4/O5I IC1I IC2I IC3I
RESET:00000000
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TIMING SYSTEM
TECHNICAL DATA 9-11
polled or interrupt driven system. Each bit of TFLG1 corresponds to a bit in TMSK1 in
the same position.
Clear flags by writing a one to the corresponding bit position(s).
OC1F–OC5F — Output Compare x Flag
Set each time the counter matches output compare x value
I4/O5F — Input Capture 4/Output Compare 5 Flag
Set by IC4 or OC5, depending on the function enabled by I4/O5 bit in PACTL
IC1F–IC3F — Input Capture x Flag
Set each time a selected active edge is detected on the ICx input line
9.3.9 Timer Interrupt Mask 2 Register
Use this 8-bit register to enable or inhibit timer overflow and real-time interrupts. The
timer prescaler control bits are included in this register.
TOI — Timer Overflow Interrupt Enable
0 = TOF interrupts disabled
1 = Interrupt requested when TOF is set to one
RTII — Real-time Interrupt Enable
Refer to 9.4 Real-Time Interrupt.
PAOVI — Pulse Accumulator Overflow Interrupt Enable
Refer to 9.6 Pulse Accumulator.
PAII — Pulse Accumulator Input Edge Interrupt Enable
Refer to 9.6 Pulse Accumulator.
NOTE
Bits in TMSK2 correspond bit for bit with flag bits in TFLG2. Ones in
TMSK2 enable the corresponding interrupt sources.
TFLG1 — Timer Interrupt Flag 1 $0023
Bit 7654321Bit 0
OC1F OC2F OC3F OC4F I4/O5F IC1F IC2F IC3F
RESET:00000000
TMSK2 — Timer Interrupt Mask 2 $0024
Bit 7654321Bit 0
TOI RTII PAOVI PAII 0 0 PR1 PR0
RESET:00000000
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TIMING SYSTEM
9-12 TECHNICAL DATA
PR[1:0] — Timer Prescaler Select
These bits are used to select the prescaler divide-by ratio. In normal modes, PR[1:0]
can only be written once, and the write must be within 64 cycles after reset. Refer to
Table 9-1 for specific timing values.
9.3.10 Timer Interrupt Flag 2 Register
Bits in this register indicate when certain timer system events have occurred. Coupled
with the four high-order bits of TMSK2, the bits of TFLG2 allow the timer subsystem to
operate in either a polled or interrupt driven system. Each bit of TFLG2 corresponds
to a bit in TMSK2 in the same position.
Clear flags by writing a one to the corresponding bit position(s).
TOF — Timer Overflow Interrupt Flag
Set when TCNT changes from $FFFF to $0000
RTIF — Real-Time (Periodic) Interrupt Flag
Refer to 9.4 Real-Time Interrupt.
PAOVF — Pulse Accumulator Overflow Interrupt Flag
Refer to 9.6 Pulse Accumulator.
PAIF — Pulse Accumulator Input Edge Interrupt Flag
Refer to 9.6 Pulse Accumulator.
Bits [3:0]— Not implemented
Always read zero
9.4 Real-Time Interrupt
The real-time interrupt feature, used to generate hardware interrupts at a fixed periodic
rate, is controlled and configured by two bits (RTR1 and RTR0) in the pulse accumu-
lator control (PACTL) register. The RTII bit in the TMSK2 register enables the interrupt
capability. The four different rates available are a product of the MCU oscillator fre-
quency and the value of bits RTR[1:0]. Refer to the following table, which shows the
periodic real-time interrupt rates.
PR[1:0] Prescaler
0 0 1
0 1 4
1 0 8
1 1 16
TFLG2 — Timer Interrupt Flag 2 $0025
Bit 7654321Bit 0
TOF RTIF PAOVF PAIF 0 0 0 0
RESET:00000000
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TIMING SYSTEM
TECHNICAL DATA 9-13
The clock source for the RTI function is a free-running clock that cannot be stopped or
interrupted except by reset. This clock causes the time between successive RTI time-
outs to be a constant that is independent of the software latencies associated with flag
clearing and service. For this reason, an RTI period starts from the previous time-out,
not from when RTIF is cleared.
Every time-out causes the RTIF bit in TFLG2 to be set, and if RTII is set, an interrupt
request is generated. After reset, one entire real-time interrupt period elapses before
the RTIF flag is set for the first time. Refer to the TMSK2, TFLG2, and PACTL regis-
ters.
9.4.1 Timer Interrupt Mask 2 Register
This register contains the real-time interrupt enable bits.
TOI — Timer Overflow Interrupt Enable
Refer to 9.3 Output Compare.
RTII — Real-time Interrupt Enable
0 = RTIF interrupts disabled
1 = Interrupt requested when RTIF is set to one
PAOVI — Pulse Accumulator Overflow Interrupt Enable
Refer to 9.6 Pulse Accumulator.
PAII — Pulse Accumulator Input Edge
Refer to 9.6 Pulse Accumulator.
NOTE
Bits in TMSK2 correspond bit for bit with flag bits in TFLG2. Ones in
TMSK2 enable the corresponding interrupt sources.
9.4.1 Timer Interrupt Flag 2 Register
Bits of this register indicate the occurrence of timer system events. Coupled with the
four high-order bits of TMSK2, the bits of TFLG2 allow the timer subsystem to operate
in either a polled or interrupt driven system. Each bit of TFLG2 corresponds to a bit in
TMSK2 in the same position.
RTR[1:0] E = 1 MHz E = 2 MHz E = 3 MHz E = X MHz
0 0
0 1
1 0
1 1
2.731 ms
5.461 ms
10.923 ms
21.845 ms
4.096 ms
8.192 ms
16.384 ms
32.768 ms
8.192 ms
16.384 ms
32.768 ms
65.536 ms
(E/213)
(E/214)
(E/215)
(E/216)
TMSK2 — Timer Interrupt Mask 2 $0024
Bit 7654321Bit 0
TOI RTII PAOVI PAII 0 0 PR1 PR0
RESET:00000000
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TIMING SYSTEM
9-14 TECHNICAL DATA
Clear flags by writing a one to the corresponding bit position(s).
TOF — Timer Overflow Interrupt Flag
Set when TCNT changes from $FFFF to $0000
RTIF — Real-Time Interrupt Flag
The RTIF status bit is automatically set to one at the end of every RTI period. To clear
RTIF, write a byte to TFLG2 with bit 6 set.
PAOVF — Pulse Accumulator Overflow Interrupt Flag
Refer to 9.6 Pulse Accumulator.
PAIF — Pulse Accumulator Input Edge Interrupt Flag
Refer to 9.6 Pulse Accumulator.
Bits [3:0] — Not implemented
Always read zero
9.4.2 Pulse Accumulator Control Register
Bits RTR[1:0] of this register select the rate for the real-time interrupt system. Bit
DDRA3 determines whether Port A bit three is an input or an output when used for
general-purpose I/O. The remaining bits control the pulse accumulator.
DDRA7 — Data Direction Control for Port A Bit 7
Refer to 9.6 Pulse Accumulator.
PAEN — Pulse Accumulator System Enable
Refer to 9.6 Pulse Accumulator.
PAMOD — Pulse Accumulator Mode
Refer to 9.6 Pulse Accumulator.
PEDGE — Pulse Accumulator Edge Control
Refer to 9.6 Pulse Accumulator.
DDRA3 — Data Direction Register for Port A Bit 3
Refer to SECTION 6 PARALLEL I/O.
I4/O5 — Input Capture 4/Output Compare 5
Refer to 9.2 Input Capture.
TFLG2 — Timer Interrupt Flag 2 $0025
Bit 7654321Bit 0
TOF RTIF PAOVF PAIF 0 0 0 0
RESET:00000000
PACTL — Pulse Accumulator Control $0026
Bit 7654321Bit 0
DDRA7 PAEN PAMOD PEDGE DDRA3 I4/O5 RTR1 RTR0
RESET:00000000
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TIMING SYSTEM
TECHNICAL DATA 9-15
RTR[1:0] — RTI Interrupt Rate Select
These two bits determine the rate at which the RTI system requests interrupts. The
RTI system is driven by an E divided by 213 rate clock that is compensated so it is in-
dependent of the timer prescaler. These two control bits select an additional division
factor.
9.5 Computer Operating Properly Watchdog Function
The clocking chain for the COP function, tapped off of the main timer divider chain, is
only superficially related to the main timer system. The CR[1:0] bits in the OPTION
register and the NOCOP bit in the CONFIG register determine the status of the COP
function. Refer to SECTION 5 RESETS AND INTERRUPTS for a more detailed dis-
cussion of the COP function.
9.6 Pulse Accumulator
The MC68HC11D3 has an 8-bit counter that can be configured to operate either as a
simple event counter, or for gated time accumulation, depending on the state of the
PAMOD bit in the PACTL register. Refer to the pulse accumulator block diagram, Fig-
ure 9-3.
In the event counting mode, the 8-bit counter is clocked to increasing values by an ex-
ternal pin. The maximum clocking rate for the external event counting mode is the E
clock divided by two. In gated time accumulation mode, a free-running E-clock ÷ 64
signal drives the 8-bit counter, but only while the external PAI pin is activated. Refer to
Table 9-3. The pulse accumulator counter can be read or written at any time.
RTR[1:0] E = 1 MHz E = 2 MHz E = 3 MHz E = X MHz
0 0
0 1
1 0
1 1
2.731 ms
5.461 ms
10.923 ms
21.845 ms
4.096 ms
8.192 ms
16.384 ms
32.768 ms
8.192 ms
16.384 ms
32.768 ms
65.536 ms
(E/213)
(E/214)
(E/215)
(E/216)
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TIMING SYSTEM
9-16 TECHNICAL DATA
Figure 9-3 Pulse Accumulator
Pulse accumulator control bits are also located within two timer registers, TMSK2 and
TFLG2, as described in the following paragraphs.
Table 9-3 Pulse Accumulator Timing
Common XTAL Frequencies
Selected Crystal 4.0 MHz 8.0 MHz 12.0 MHz
CPU Clock (E) 1.0 MHz 2.0 MHz 3.0 MHz
Cycle Time (1/E) 1000 ns 500 ns 333 ns
Pulse Accumulator (in Gated Mode)
(E/26)
(E/214)
1 count -
overflow - 64.0 µs
16.384 ms 32.0 µs
8.192 ms 21.33 µs
5.461 ms
PACNT
8-BIT COUNTER
2:1
MUX
PA7/
ENABLE
OVERFLOW
1
2
INTERRUPT
REQUESTS
INTERNAL
DATA BUS
INPUT BUFFER
&
EDGE DETECTION
PACTL
TFLG2TMSK2
PAOVI
PAII
DDRA7
PAEN
PAMOD
PEDGE
PAOVF
PAIF
11 PULSE ACC BLOCK
OUTPUT
BUFFER
PAI EDGE
PAEN
E ÷ 64 CLOCK
(FROM MAIN TIMER)
PAI/OC1
FROM
MAIN TIMER
OC1
DISABLE
FLAG SETTING
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TIMING SYSTEM
TECHNICAL DATA 9-17
9.6.1 Pulse Accumulator Control Register
Four of this register's bits control an 8-bit pulse accumulator system. Another bit en-
ables either the OC5 function or the IC4 function, while two other bits select the rate
for the real-time interrupt system.
DDRA7 — Data Direction Control for Port A Bit 7
The pulse accumulator uses port A bit 7 as the PAI input, but the pin can also be used
as general-purpose I/O or as an output compare. Note that even when port A bit 7 is
configured as an output, the pin still drives the input to the pulse accumulator. Refer to
SECTION 6 PARALLEL I/O for more information.
PAEN — Pulse Accumulator System Enable
0 = Pulse accumulator disabled
1 = Pulse accumulator enabled
PAMOD — Pulse Accumulator Mode
0 = Event counter
1 = Gated time accumulation
PEDGE — Pulse Accumulator Edge Control
This bit has different meanings depending on the state of the PAMOD bit, as shown in
the following table:
DDRA3 — Data Direction Register for Port A Bit 3
Refer to SECTION 6 PARALLEL I/O.
I4/O5 — Input Capture 4/Output Compare 5
Refer to 9.2 Input Capture.
RTR[1:0] — RTI Interrupt Rate Selects
Refer to 9.4 Real-Time Interrupt.
9.6.2 Pulse Accumulator Count Register
This 8-bit read/write register contains the count of external input events at the PAI in-
put, or the accumulated count. The counter is not affected by reset and can be read or
written at any time. Counting is synchronized to the internal PH2 clock so that incre-
menting and reading occur during opposite half cycles.
PACTL — Pulse Accumulator Control $0026
Bit 7654321Bit 0
DDRA7 PAEN PAMOD PEDGE DDRA3 I4/O5 RTR1 RTR0
RESET:00000000
PAMOD PEDGE Action on Clock
0 0 PAI Falling Edge Increments the Counter.
0 1 PAI Rising Edge Increments the Counter.
1 0 A Zero on PAI Inhibits Counting.
1 1 A One on PAI Inhibits Counting.
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TIMING SYSTEM
9-18 TECHNICAL DATA
9.6.3 Pulse Accumulator Status and Interrupt Bits
The pulse accumulator control bits, PAOVI and PAII, PAOVF, and PAIF are located
within timer registers TMSK2 and TFLG2.
PAOVI and PAOVF — Pulse Accumulator Interrupt Enable and Overflow Flag
The PAOVF status bit is set each time the pulse accumulator count rolls over from $FF
to $00. To clear this status bit, write a one in the corresponding data bit position (bit 5)
of the TFLG2 register. The PAOVI control bit allows configuring the pulse accumulator
overflow for polled or interrupt-driven operation and does not affect the state of
PAOVF. When PAOVI is zero, pulse accumulator overflow interrupts are inhibited, and
the system operates in a polled mode, which requires PAOVF to be polled by user soft-
ware to determine when an overflow has occurred. When the PAOVI control bit is set,
a hardware interrupt request is generated each time PAOVF is set. Before leaving the
interrupt service routine, software must clear PAOVF by writing to the TFLG2 register.
PAII and PAIF — Pulse Accumulator Input Edge Interrupt Enable and Flag
The PAIF status bit is automatically set each time a selected edge is detected at the
PA7/PAI/OC1 pin. To clear this status bit, write to the TFLG2 register with a one in the
corresponding data bit position (bit 4). The PAII control bit allows configuring the pulse
accumulator input edge detect for polled or interrupt-driven operation but does not af-
fect setting or clearing the PAIF bit. When PAII is zero, pulse accumulator input inter-
rupts are inhibited, and the system operates in a polled mode. In this mode, the PAIF
bit must be polled by user software to determine when an edge has occurred. When
the PAII control bit is set, a hardware interrupt request is generated each time PAIF is
set. Before leaving the interrupt service routine, software must clear PAIF by writing to
the TFLG register.
PACNT — Pulse Accumulator Count $0027
Bit 7654321Bit 0
Bit 7654321Bit 0
TMSK2 — Timer Interrupt Mask 2 $0024
Bit 7654321Bit 0
TOI RTII PAOVI PAII 0 0 PR1 PR0
RESET:00000000
TFLG2 — Timer Interrupt Flag 2 $0025
Bit 7654321Bit 0
TOF RTIF PAOVF PAIF 0 0 0 0
RESET:00000000
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ELECTRICAL CHARACTERISTICS
TECHNICAL DATA A-1
APPENDIX A
ELECTRICAL CHARACTERISTICS
*One pin at a time, observing maximum power dissipation limits.
Internal circuitry protects the inputs against damage caused by high static voltages or
electric fields; however, normal precautions are necessary to avoid application of any
voltage higher than maximum-rated voltages to this high-impedance circuit. Extended
operation at the maximum ratings can adversely affect device reliability. Tying unused
inputs to an appropriate logic voltage level (either GND or VDD) enhances reliability of
operation.
NOTES:
1. This is an approximate value, neglecting PI/O.
2. For most applications PI/O « PINT and can be neglected.
3. K is a constant pertaining to the device. Solve for K with a known TA and a measured PD (at equilibrium). Use
this value of K to solve for PD and TJ iteratively for any value of TA.
Table A-1 Maximum Ratings
Rating Symbol Value Unit
Supply Voltage VDD – 0.3 to + 7.0 V
Input Voltage Vin – 0.3 to + 7.0 V
Operating Temperature Range
MC6811D3
MC6811D3C
MC6811D3V
MC6811D3M
TATL to TH
0 to + 70
– 40 to + 85
– 40 to + 105
– 40 to + 125
°C
Storage Temperature Range Tstg – 55 to + 150 °C
Current Drain per Pin*
Excluding VDD and VSS
ID25 mA
Table A-2 Thermal Characteristics
Characteristic Symbol Value Unit
Average Junction Temperature TJTA + (PD x ΘJA)°C
Ambient Temperature TAUser-determined °C
Package Thermal Resistance (Junction-to-Ambient)
44-Pin Plastic Leaded Chip Carrier (PLCC)
44-Pin Plastic Quad Flat Pack (QFP)
52-Pin Plastic Dip (P)
ΘJA 50
50
50
°C/W
Total Power Dissipation (Note 1) PDPINT + PI/O
K / (TJ + 273°C) W
Device Internal Power Dissipation PINT IDD x VDD W
I/O Pin Power Dissipation (Note 2) PI/O User-determined W
A Constant (Note 3) K PD x (TA + 273°C) +
ΘJA x PD2 W < °C
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ELECTRICAL CHARACTERISTICS
A-2 TECHNICAL DATA
NOTES:
1. VOH specification for RESET and MODA is not applicable because they are open-drain pins. VOH specification
not applicable to ports C and D in wired-OR mode.
2. EXTAL is driven with a square wave, and
tcyc = 1000 ns for 1 MHz rating;
tcyc = 500 ns for 2 MHz rating;
tcyc = 333 ns for 3 MHz rating;
VIL ≤ 0.2 V;VIH ≥ VDD - 0.2 V;
No dc loads.
Table A-3 DC Electrical Characteristics
Characteristic Symbol Min Max Unit
Output Voltage (Note 1) All Outputs except XTAL
All Outputs Except XTAL, RESET,
ILOAD = ± 10.0 µA and MODA
VOL
VOH
—
VDD – 0.1 0.1
— V
V
Output High Voltage (Note 1) All Outputs Except XTAL,
RESET, and MODA
ILOAD = – 0.8 mA, VDD = 4.5 V
VOH VDD – 0.8 — V
Output Low Voltage All Outputs Except XTAL
ILOAD = 1.6 mA, VDD = 5.0 V VOL — 0.4 V
Input High Voltage All Inputs Except RESET
RESET VIH 0.7 x VDD
0.8 x VDD
VDD + 0.3
VDD + 0.3 V
V
Input Low Voltage All Inputs VIL VSS – 0.3 0.2 x VDD V
I/O Ports, Three-State Leakage PA7, PA3, PB[7:0], PC[7:0], PD[7:0],
Vin = VIH or VIL MODA/LIR, RESET IOZ — ±10 µA
Input Leakage Current
Vin = VDD or VSS PA[2:0], IRQ, XIRQ
Vin = VDD or VSS MODB/VSTBY
Iin —
— ±1
±10 µA
µA
RAM Standby Voltage Power down VSB 4.0 VDD V
RAM Standby Current Power down ISB — 10 µA
Input Capacitance PA[2:0], IRQ, XIRQ, EXTAL
PA7, PA3, PB[7:0], PC[7:0], PD[7:0], MODA/LIR, RESET Cin —
— 8
12 pF
pF
Output Load Capacitance
All Outputs Except PD[4:1] PD[4:1] CL—
— 90
100 pF
pF
Characteristic Symbol 1 MHz 2 MHz Unit
Maximum Total Supply Current (Note 2)
RUN:
Single-Chip Mode VDD = 5.5 V
Expanded Multiplexed Mode VDD = 5.5 V
WAIT: (All Peripheral Functions Shut Down)
Single-Chip Mode VDD = 5.5 V
Expanded Multiplexed Mode VDD = 5.5 V
STOP:
Single-Chip Mode, No Clocks VDD = 5.5 V
IDD
WIDD
SIDD
8
14
3
5
50
15
27
6
10
50
mA
mA
mA
mA
µA
Maximum Power Dissipation
Single-Chip Mode VDD = 5.5 V
Expanded Multiplexed Mode VDD = 5.5 V
PD44
77 85
150 mW
mW
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ELECTRICAL CHARACTERISTICS
TECHNICAL DATA A-3
Figure A-1 Test Methods
NOTES:
1. Full test loads are applied during all DC electrical tests and AC timing measurements.
2. During AC timing measurements, inputs are driven to 0.4 volts and VDD – 0.8 volts while timing
CLOCKS,
STROBES
INPUTS
VDD
– 0.8 Volts
0.4 Volts
VDD
~
NOMINAL TIMING
NOM.
20% of V
DD
70% of V
DD
VDD
– 0.8 Volts
0.4 Volts
VSS
~
VDD~
NOM.
OUTPUTS
0.4 Volts
DC TESTING
CLOCKS,
STROBES
INPUTS
20% of VDD
70% of VDD
VDD~
SPEC TIMING
VDD
– 0.8 Volts
20% of VDD
70% of VDD
0.4 Volts
VSS~
VDD
~
SPEC
OUTPUTS
AC TESTING
(NOTE 2)
20% of VDD
70% of VDD
20% of VDD
VSS
~
SPEC
measurements are taken at the 20% and 70% of VDD points. TEST METHODS
VSS~
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ELECTRICAL CHARACTERISTICS
A-4 TECHNICAL DATA
NOTES:
1. RESET is recognized during the first clock cycle it is held low. Internal circuitry then drives the pin low for four
clock cycles, releases the pin, and samples the pin level two cycles later to determine the source of the interrupt.
Refer to SECTION 5 RESETS AND INTERRUPTS for further detail.
2. All timing is shown with respect to 20% VDD and 70% VDD, unless otherwise noted.
Figure A-2 Timer Inputs
Table A-4 Control Timing
Characteristic Symbol 1.0 MHz 2.0 MHz 3.0 MHz Unit
Min Max Min Max Min Max
Frequency of Operation fodc 1.0 dc 2.0 dc 3.0 MHz
E-Clock Period tcyc 1000 — 500 — 333 — ns
Crystal Frequency fXTAL —4.0—8.0—12.0MHz
External Oscillator Frequency 4 fodc 4.0 dc 8.0 dc 12.0 MHz
Processor Control SetupTime
tPCSU = 1/4 tcyc + 50 ns tPCSU 300 — 175 — 133 — ns
Reset Input Pulse Width
To Guarantee External Reset Vector
Minimum Input Time
(Can Be Preempted by Internal Reset)
PWRSTL 8
1—
—8
1—
—8
1—
—tcyc
tcyc
Mode Programming Setup Time tMPS 2—2—2—t
cyc
Mode Programming Hold Time tMPH 10 — 10 — 10 — ns
Interrupt Pulse Width,
IRQ Edge-Sensitive Mode
PWIRQ = tcyc + 20 ns
PWIRQ 1020 — 520 — 353 — ns
Wait Recovery Startup Time tWRS —4—4—4t
cyc
Timer Pulse Width,
Input Capture Pulse
Accumulator Input
PWTIM = tcyc + 20 ns
PWTIM 1020 — 520 — 353 — ns
NOTES:
1. Rising edge sensitive input
2. Falling edge sensitive input
3. Maximum pulse accumulator clocking rate is E-clock frequency divided by 2.
PA7 2,3
PA7 1,3
PA[2:0] 2
PA[2:0] 1
PWTIM
TIMER INPUTS TIM
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ELECTRICAL CHARACTERISTICS
TECHNICAL DATA A-5
Figure A-3 POR and External Reset Timing Diagram
tPCSU
ADDRESS
MODA, MODB
E
EXTAL
VDD
RESET
4064 tCYC
FFFE
FFFE
FFFE NEW
PC
FFFE FFFF FFFE
FFFE
FFFE NEW
PC
FFFE FFFF
FFFE
tMPH
PWRSTL
tMPS
POR EXT RESET TIM
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ELECTRICAL CHARACTERISTICS
A-6 TECHNICAL DATA
Figure A-4 STOP Recovery Timing Diagram
PWIRQ
tSTOPDELAY3
IRQ1
IRQ
or XIRQ
E
SP – 8
SP – 8 FFF2
(FFF4) NEW
PC
STOP
ADDR STOP
ADDR + 1
ADDRESS4STOP
ADDR STOP
ADDR + 1
STOP
ADDR + 1
STOP
ADDR + 1
STOP
ADDR + 2 SP…SP–7 FFF3
(FFF5)
OPCODE
Resume program with instruction which follows the STOP instruction.
NOTES:
1. Edge Sensitive IRQ pin (IRQE bit = 1)
2. Level sensitive IRQ pin (IRQE bit = 0)
3. tSTOPDELAY = 4064 tCYC if DLY bit = 1 or 4 tCYC if DLY = 0.
4. XIRQ with X bit in CCR = 1.
5. IRQ or (XIRQ with X bit in CCR = 0).
INTERNAL
ADDRESS5
STOP RECOVERY TIM
CLOCKS
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ELECTRICAL CHARACTERISTICS
TECHNICAL DATA A-7
Figure A-5 WAIT Recovery Timing Diagram
WAIT RECOVERY TIM
tPCSU
PCL PCH, YL, YH, XL, XH, A, B, CCR
STACK REGISTERS
E
R/W
ADDRESS WAIT
ADDR WAIT
ADDR + 1
IRQ, XIRQ,
OR INTERNAL
INTERRUPTS
NOTE: RESET also causes recovery from WAIT.
SP SP – 1 SP – 2…SP – 8 SP – 8 SP – 8…SP – 8 SP – 8 SP – 8 SP – 8 VECTOR
ADDR VECTOR
ADDR + 1 NEW
PC
tWRS
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ELECTRICAL CHARACTERISTICS
A-8 TECHNICAL DATA
NOTES:
1. Port C and D timing is valid for active drive (CWOM and DWOM bits not set in PIOC and SPCR registers respec-
tively).
2. All timing is shown with respect to 20% VDD and 70% VDD, unless otherwise noted.
Figure A-6 Port Write Timing Diagram
Figure A-7 Port Read Timing Diagram
Table A-5 Peripheral Port Timing
Characteristic Symbol 1.0 MHz 2.0 MHz 3.0 MHz Unit
Min Max Min Max Min Max
Frequency of Operation (E-Clock Frequency) fodc 1.0 dc 2.0 dc 3.0 MHz
E-Clock Period tcyc 1000 — 500 — 333 — ns
Peripheral Data Setup Time
MCU Read of Ports A, B, C, and D tPDSU 100 — 100 — 100 — ns
Peripheral Data Hold Time
MCU Read of Ports A, B, C, and D tPDH 50 — 50 — 50 — ns
Delay Time, Peripheral Data Write
MCU Write to Port A
MCU Writes to Ports B, C, and D
tPWD = 1/4 tcyc + 150 ns
tPWD
—
—200
350 —
—200
225 —
—200
183 ns
ns
D3 PORT WRITE TIM
tPWD
E
MCU WRITE TO PORT
PREVIOUS PORT DATA
PREVIOUS PORT DATA
NEW DATA VALID
NEW DATA VALID
PORTS
B, C, D
PORT A
tPWD
tPDH
E
MCU READ OF PORT
tPDSU
PORTS
A, B, C, D
D3 PORT READ TIM
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ELECTRICAL CHARACTERISTICS
TECHNICAL DATA A-9
NOTES:
1. Input clocks with duty cycles other than 50% affect bus performance. Timing parameters affected by input clock
duty cycle are identified by (a) and (b). To recalculate the approximate bus timing values, substitute the following
expressions in place of 1/8 tcyc in the above formulas, where applicable:
(a) (1-DC) × 1/4 tcyc
(b) DC × 1/4 tcyc
Where:
DC is the decimal value of duty cycle percentage (high time).
2. All timing is shown with respect to 20% VDD and 70% VDD, unless otherwise noted.
Table A-6 Expansion Bus Timing
Num Characteristic Symbol 1.0 MHz 2.0 MHz 3.0 MHz Unit
Min Max Min Max Min Max
Frequency of Operation (E-Clock
Frequency) fodc 1.0 dc 2.0 dc 3.0 MHz
1 Cycle Time tcyc 1000 — 500 — 333 — ns
2 Pulse Width, E Low
PWEL = 1/2 tcyc - 23ns PWEL 477 — 227 — 146 — ns
3 Pulse Width, E High
PWEH = 1/2 tcyc - 28 ns PWEH 472 — 222 — 141 — ns
4A
4B E and AS Rise Time
E and AS Fall Time
tr
tf
—
—20
20 —
—20
20 —
—20
15 ns
ns
9 Address Hold Time
tAH = 1/8 tcyc - 29.5 ns (Note 1a) tAH 95.5 — 33 — 26 — ns
12 Non-Muxed Address Valid Time to E Rise
tAV = PWEL - (tASD + 80 ns) (Note 1a) tAV 281.5 — 94 — 54 — ns
17 Read Data Setup Time tDSR 30 — 30 — 30 — ns
18 Read Data Hold Time (Max = tMAD)t
DHR 0 145.5 0 83 0 51 ns
19 Write Data Delay Time
tDDW = 1/8 tcyc + 65.5 ns (Note 1a) tDDW — 190.5 — 128 — 71 ns
21 Write Data Hold Time
tDHW = 1/8 tcyc - 30 ns (Note 1a) tDHW 95.5 — 33 — 26 — ns
22 Muxed Address Valid Time to E Rise
tAVM = PWEL - (tASD + 90 ns) (Note 1a) tAVM 271.5 — 84 — 54 — ns
24 Muxed Address Valid Time to AS Fall
tASL = PWASH - 70 ns tASL 151 — 26 — 13 — ns
25 Muxed Address Hold Time
tAHL = 1/8 tcyc - 30 ns (Note 1b) tAHL 95.5 — 33 — 31 — ns
26 Delay Time, E to AS Rise
tASD = 1/8 tcyc - 5 ns (Note 1a) tASD 115.5 — 53 — 31 — ns
27 Pulse Width, AS High
PWASH = 1/4 tcyc - 30 ns PWASH 221 — 96 — 63 — ns
28 Delay Time, AS to E Rise
tASED = 1/8 tcyc - 5 ns (Note 1b) tASED 115.5 — 53 — 31 — ns
29 MPU Address Access Time (Note 1a)
tACCA = tcyc – (PWEL– tAVM) – tDSR–tf
tACCA 744.5 — 307 — 196 — ns
35 MPU Access Time
tACCE = PWEH - tDSR
tACCE — 442 — 192 — 111 ns
36 Muxed Address Delay
(Previous Cycle MPU Read)
tMAD = tASD + 30 ns(Note 1a)
tMAD 145.5 — 83 — 51 — ns
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ELECTRICAL CHARACTERISTICS
A-10 TECHNICAL DATA
Figure A-8 Multiplexed Expansion Bus Timing Diagram
MUX BUS TIM
E
AS
1
4a
9
ADDRESS/DATA
(MULTIPLEXED)
READ
WRITE
12
2 3
4b
4a 4b
29
35 17
18
19 21
25
24
27
36 22
26 28
ADDRESS
ADDRESS
DATA
DATA
R/W, ADDRESS
(NON-MUX)
NOTE: Measurement points shown are 20% and 70% of VDD.
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ELECTRICAL CHARACTERISTICS
TECHNICAL DATA A-11
NOTES:
1. All timing is shown with respect to 20% VDD and 70% VDD, unless otherwise noted.
2. Signal production depends on software.
3. Assumes 100 pF load on all SPI pins.
Table A-7 Serial Peripheral Interface Timing
Num Characteristic Symbol 2.0 MHz 3.0 MHz Unit
Min Max Min Max
Operating Frequency
Master
Slave fop(m)
fop(s)
dc
dc 0.5
2.0 dc
dc 0.5
3.0 fop
MHz
1 Cycle Time
Master
Slave tcyc(m)
tcyc(s)
2.0
500 —
—2.0
333 —
—tcyc
ns
2 Enable Lead Time
Master (Note 2)
Slave tlead(m)
tlead(s)
—
250 —
——
240 —
—ns
ns
3 Enable Lag Time
Master (Note 2)
Slave tlag(m)
tlag(s)
—
250 —
——
240 —
—ns
ns
4 Clock (SCK) High Time
Master
Slave tw(SCKH)m
tw(SCKH)s
340
190 —
—340
190 —
—ns
ns
5 Clock (SCK) Low Time
Master
Slave tw(SCKL)m
tw(SCKL)s
340
190 —
—340
190 —
—ns
ns
6 Data Setup Time (Inputs)
Master
Slave tsu(m)
tsu(s)
100
100 —
—100
100 —
—ns
ns
7 Data Hold Time (Inputs)
Master
Slave th(m)
th(s)
100
100 —
—100
100 —
—ns
ns
8 Access Time
(Time to Data Active from High-Imp. State)
Slave ta0 120 0 120 ns
9 Disable Time
(Hold Time to High-Impedance State)
Slave tdis — 240 — 167 ns
10 Data Valid (After Enable Edge) (Note 3) tv(s) — 240 — 167 ns
11 Data Hold Time (Outputs) (After Enable Edge) tho 0—0— ns
12 Rise Time (20% VDD to 70% VDD, CL = 200 pF)
SPI Outputs (SCK, MOSI, and MISO)
SPI Inputs (SCK, MOSI, MISO, and SS)trm
trs
—
—100
2.0 —
—100
2.0 ns
µs
13 Fall Time (70% VDD to 20% VDD, CL = 200 pF)
SPI Outputs (SCK, MOSI, and MISO)
SPI Inputs (SCK, MOSI, MISO, and SS)tfm
tfs
—
—100
2.0 —
—100
2.0 ns
µs
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ELECTRICAL CHARACTERISTICS
A-12 TECHNICAL DATA
Figure A-9 SPI Master Timing (CPHA = 0)
Figure A-10 SPI Master Timing (CPHA = 1)
SPI MASTER CPHA0 TIM
SEE
NOTE
NOTE: This first clock edge is generated internally but is not seen at the SCK pin.
SCK (CPOL = 0)
(OUTPUT)
SCK (CPOL = 1)
(OUTPUT)
MISO
(INPUT)
MOSI
(OUTPUT)
SS
(INPUT)
1
SEE
NOTE
11
6 7
MSB IN
BIT 6 - - - -1
LSB IN
MASTER MSB OUT MASTER LSB OUT
BIT 6 - - - -1
10
12
13
SS is held high on master.
5
4
13
12
11 (ref)10 (ref)
13
4
512
SPI MASTER CPHA1 TIM
NOTE: This last clock edge is generated internally but is not seen at the SCK pin.
4
5
5
4
1
SEE
NOTE
11
67
MSB IN LSB IN
MASTER MSB OUT MASTER LSB OUTBIT 6 - - - -1
10
13
12
13
12
SCK (CPOL = 0)
(OUTPUT)
SCK (CPOL = 1)
(OUTPUT)
MISO
(INPUT)
MOSI
(OUTPUT)
SS
(INPUT) SS is held high on master.
SEE
NOTE
12
13
BIT 6 - - - -1
11 (ref)10 (ref)
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ELECTRICAL CHARACTERISTICS
TECHNICAL DATA A-13
Figure A-11 SPI Slave Timing (CPHA = 0)
Figure A-12 SPI Slave Timing (CPHA = 1)
SPI SLAVE CPHA0 TIM
NOTE: Not defined but normally MSB of character just received.
4
25
5
4
1
8
SEE
NOTE
MSB OUT
SLAVE SLAVE LSB OUT
6 7
MSB IN
10
BIT 6 - - - -1 LSB IN
11
1213 3
9
SCK (CPOL = 0)
(INPUT)
SCK (CPOL = 1)
(INPUT)
MISO
(OUTPUT)
MOSI
(INPUT)
SS
(INPUT)
11
12 13
BIT 6 - - - -1
SPI SLAVE CPHA1 TIM
NOTE: Not defined but normally LSB of character previously transmitted.
4
2
10
6 7
5
5
4
1
8
MSB IN
SEE
NOTE MSB OUT
10
SLAVE
BIT 6 - - - -1 LSB IN
SLAVE LSB OUT
11
13 12
12 13
3
9
SCK (CPOL = 0)
(INPUT)
SCK (CPOL = 1)
(INPUT)
MISO
(OUTPUT)
MOSI
(INPUT)
SS
(INPUT)
BIT 6 - - - -1
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ELECTRICAL CHARACTERISTICS
A-14 TECHNICAL DATA
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MECHANICAL DATA AND ORDERING INFORMATION
TECHNICAL DATA B-1
APPENDIX B
MECHANICAL DATA AND ORDERING INFORMATION
B.1 Pin Assignments
The MC68HC11D3 is available in the 40-pin DIP, shown in Figure B-1, the 44-pin
PLCC, shown in Figure B-2, or the 44-pin quad flat pack (QFP), as shown in Figure
B-3. Refer to Table B-1 for ordering information.
Figure B-1 40-Pin DIP
PC7/ADDR7
XIRQ/VPP
PD7/R/W
PD6/AS
RESET
IRQ
PD0/RxD
PD1/TxD
PD2/MISO
PD3/MOSI
9
10
11
12
13
14
15
16
17
18
PD4/SCK 19
PD5/SS 20
PC6/ADDR6 8
PC5/ADDR5 7
PC4/ADDR4 6
PC3/ADDR3 5
PC2/ADDR2 4
PC1/ADDR1 3
PC0/ADDR0 2
VSS 1
PB5/ADDR13
PB6/ADDR14
PB7/ADDR15
PA0/IC3
PA1/IC2
PA2/IC1
PA3/IC4/OC5/OC1
PA5/OC3/OC1
PA7/PAI/OC1
VDD
30
29
28
27
26
25
24
23
22
21
PB4/ADDR1231
PB3/ADDR1132
PB2/ADDR1033
PB1/ADDR934
PB0/ADDR835
MODB/VSTBY
36
MODA/LIR37
E38
EXTAL39
XTAL40
MC68HC(7)11D3
D3 40-PIN DIP
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MC68HC11D3
B-2 TECHNICAL DATA
Figure B-2 44-Pin PLCC
PC4/ADDR4
PC5/ADDR5
PC6/ADDR6
PC7/ADDR7
XIRQ/VPP
PD7/R/W
PD6/AS
RESET
IRQ
PD0/RxD
PD1/TxD
PB2/ADDR10
PB3/ADDR11
PB4/ADDR12
PB5/ADDR13
PB6/ADDR14
PB7/ADDR15
NC
PA0/IC3
PA1/IC2
PC3/ADDR3
PC2/ADDR2
PC1/ADDR1
PC0/ADDR0
VSS
EVSS
XTAL
EXTAL
E
MODA/LIR
MODB/VSTBY
PD2/MISO
PD3/MOSI
PD4/SCK
PD5/SS
VDD
PA7/PAI/OC1
PA6/OC2/OC1
PA5/OC3/OC1
PA4/OC4/OC1
PA3/IC4/OC5/OC1
PA2/IC1
7
8
9
10
11
12
13
14
15
16
37
36
35
34
33
32
31
30
29
18
19
20
21
22
23
24
25
26
27
28
6
5
4
3
2
1
44
43
42
41
40
17
PB1/ADDR9
38
PB0/ADDR8
39
MC68HC(7)11D3
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TECHNICAL DATA B-3
Figure B-3 44-Pin QFP
B.2 Package Dimensions
For case outline information check our web site at http://www.motsps.com.
B.3 Ordering Information
Add the proper suffix, from Table B-1, to the M68HC11- (or 711-) MCU number to
specify the appropriate device when placing an order. Figure B-4 identifies the codes
used to identify specific MCU options.
Table B-1 Ordering Information
MCU Package Temperature Description Suffix
40-Pin DIP – 40 to +85°C BUFFALO ROM CP1
D3 44-Pin PLCC – 40 to +85°C BUFFALO ROM CFN1
44-Pin Quad Flat Pack – 40 to +85°C BUFFALO ROM CFBL
40-Pin DIP – 40 to +85°CNo ROM CP
D0 44-Pin PLCC – 40 to +85°CNo ROM CFN
44-Pin Quad Flat Pack – 40 to +85°CNo ROM CFB
PC4/ADDR4
PC5/ADDR5
PC6/ADDR6
PC7/ADDR7
XIRQ/VPP
PD7/R/W
PD6/AS
RESET
IRQ
PD0/RxD
PD1/TxD
PB2/ADDR10
PB3/ADDR11
PB4/ADDR12
PB5/ADDR13
PB6/ADDR14
PB7/ADDR15
NC
PA0/IC3
PA1/IC2
PC3/ADDR3
PC2/ADDR2
PC1/ADDR1
PC0/ADDR0
VSS
EVSS
XTAL
EXTAL
E
MODA/LIR
MODB/VSTBY
PD2/MISO
PD3/MOSI
PD4/SCK
PD5/SS
VDD
PA7/PAI/OC1
PA6/OC2/OC1
PA5/OC3/OC1
PA4/OC4/OC1
PA3/IC4/OC5/OC1
PA2/IC1
2
3
4
5
6
7
8
9
10
31
30
29
28
27
26
25
24
23
12
13
14
15
16
17
18
19
20
21
43
42
41
40
39
38
37
36
35
34
PB1/ADDR9
32
PB0/ADDR8
MC68HC(7)11D3
1
44
33
22
11
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MECHANICAL DATA AND ORDERING INFORMATION
B-4 TECHNICAL DATA
Figure B-4 M68HC11 Part Number Options
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DEVELOPMENT SUPPORT
TECHNICAL DATA C-1
APPENDIX C
DEVELOPMENT SUPPORT
C.1 Development System Tools
Motorola has developed tools for use in debugging and evaluating M68HC11 equip-
ment. Refer to the following list for those development tools that are available for use
with the MC68HC11D3. For information about Motorola and third party development
system hardware and software, contact your Motorola sales representative.
C.2 MC68HC11D3 Development Tools
• M68HC11D3EVS Evaluation System
• M68HC711D3PGMR Programmer Board
• M68HC711D3EVB Evaluation Board
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DEVELOPMENT SUPPORT
C-2 TECHNICAL DATA
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For information on Freescale.s Environmental Products program, go to
http://www.freescale.com/epp.

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