Freescale Semiconductor ZU Digital Data ZigBee Device User Manual Part 1

Freescale Semiconductor, Inc. Digital Data ZigBee Device Users Manual Part 1

Contents

Users Manual Part 1

freescale.comWireless Sensing Triple Axis Reference design(ZSTAR) Designer Reference ManualZSTARRMRev. 0.98/2006
Warnings Safety of Radio Frequency Energy The manufacturer has evaluated the transmitter for safe operation for uncontrolled use in the general population. The measured power density at 1 cm is under the threshold established by the FCC and is not required to be tested for specific absorption rate. The manufacturer instructs the user that the transmitter should not be handled or placed near the body continuously for more than 30 minutes while operating. USA: NOTE: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures: -- Reorient or relocate the receiving antenna. -- Increase the separation between the equipment and receiver. -- Connect the equipment into an outlet on a circuit different from that to which the receiver is connected. -- Consult the dealer or an experienced radio/TV technician for help. This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) this device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation. Changes or modifications not expressly approved by the party responsible for compliance could void the user's authority to operate the equipment. The antenna(s) used for this transmitter must not be co-located or operating in conjunction with any other antenna or transmitter. Canada: This Class [*] digital apparatus complies with Canadian ICES-003. Cet appareil numériqué de la classe [*] est conformé à la norme NMB-003 du Canada. Europe: TBD
Wireless Sensing Triple Axis Reference design, Rev. 0.9Freescale Semiconductor 3Wireless Sensing Triple Axis Reference designDesigner Reference Manualby: Pavel Lajšner and Radomír KozubFreescale Czech Systems LaboratoriesRožnov pod RadhoštČm, Czech RepublicTo provide the most up-to-date information, the revision of our documents on the World Wide Web will be the most current. Your printed copy may be an earlier revision. To verify you have the latest information available, refer to:http://www.freescale.comThe following revision history table summarizes changes contained in this document. For your convenience, the page number designators have been linked to the appropriate location.Revision HistoryDate RevisionLevel Description PageNumber(s)May,2006 0.02 First draft N/AJuly2006 0.9 Language correction, minor updates N/A
Revision HistoryWireless Sensing Triple Axis Reference design, Rev. 0.94 Freescale Semiconductor
Wireless Sensing Triple Axis Reference design, Rev. 0.9Freescale Semiconductor 5Table of ContentsChapter 1 Introduction1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91.2 MMA7260Q 3-axis Accelerometer Sensor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Chapter 2 Wireless Sensing Triple Axis Reference design introduction2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112.2 Featured products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.2.1 Triple Axis Accelerometer MMA7260Q . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.2.2 Microcontroller MC9S08QG8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.2.3 MC13191 2.4 GHz ISM Band Low Power Transceiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132.2.4 Microcontroller MCHC908JW32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Chapter 3 Sensor Board description3.1 Board overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153.2 A/D conversion of XYZ levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173.2.1 ADC module init: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173.2.2 ADC measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183.3 Power management. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183.3.1 MC13191 power management features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.4 ZSTAR Sensor Board hardware overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213.4.1 Analog connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213.4.2 g-select connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213.4.3 BDM (Background Debug Mode) connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213.4.4 Sensor Board schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223.4.5 Button connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233.4.6 MC13191 to MC9S08QG8 microcontroller interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233.4.7 MC13191 RF interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233.4.8 Clocking options of MC9S08QG8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243.4.9 LED indicators connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243.4.10 Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253.5 Bill of Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26Chapter 4 USB stick board description4.1 Board overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274.2 ZSTAR USB stick Board hardware overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304.2.1 USB connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304.2.2 Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304.2.2.1 Fixed voltage regulators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table of ContentsWireless Sensing Triple Axis Reference design, Rev. 0.96 Freescale Semiconductor4.2.3 MC13191 to MCHC908JW32 microcontroller interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314.2.4 Oscillator and clocking options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314.2.5 LED indicators connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314.2.6 Button connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324.2.7 MON08 interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324.2.8 Optional serial interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324.2.9 USB stick schematics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334.3 Bill of Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Chapter 5 Software Design5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355.2 SMAC (Simple Media Access Controller) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355.2.1 SMAC Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355.2.2 Modifications of SMAC for ZSTAR demo. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355.2.2.1 MC9S08QG8 SMAC modifications (Sensor Board) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365.2.2.2 MCHC908JW32 SMAC modifications (USB stick) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365.2.2.3 Generic SMAC modifications (USB stick + Sensor Board). . . . . . . . . . . . . . . . . . . . . . . . 375.3 ZSTAR RF protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385.3.1 Zpacket format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385.3.1.1 Network number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395.3.1.2 RX strength. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395.3.1.3 Zcommand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395.3.1.4 Zdata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395.3.2 ZSTAR protocol Zcommand description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405.3.2.1 ZSTAR_BROADCAST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405.3.2.2 ZSTAR_CONNECT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405.3.2.3 ZSTAR_DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405.3.2.4 ZSTAR_ACK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415.3.2.5 ZSTAR_CALIB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415.3.2.6 ZSTAR_STATUS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415.4 STAR protocol and ZSTAR extensions (over USB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425.4.1 Communication handshake ‘R’ (0x52) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425.4.1.1 Extended Communication handshake ‘r’ (0x72). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425.4.2 Accelerometer data transfer ‘V’ (0x56). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425.4.2.1 Extended Accelerometer data transfer ‘v’ (0x76) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435.4.3 Calibration data ‘K’ (0x4B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435.4.4 Calibration process ‘k’ (0x6B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 445.4.4.1 Remaining STAR demo commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 445.4.5 Additional ZSTAR commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 445.4.5.1 g-select reading ‘G’ (0x47) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 445.4.5.2 g-select setting ‘g’ (0x67) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 455.4.5.3 Info ‘I’ (0x49). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 455.4.5.4 Debug on ‘U’ (0x55) and Debug off ‘u’ (0x75) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 455.4.6 Further debug and test commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 465.4.6.1 Forced channel number selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 465.4.6.2 Semiautomatic self-calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 465.5 Bootloader . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Wireless Sensing Triple Axis Reference design, Rev. 0.9Freescale Semiconductor 75.5.1 Bootloading procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 485.5.2 Dualboot guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 515.5.2.1 Dualboot applications switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52Chapter 6 Application Setup6.1 ZSTAR Installation Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 536.1.1 USB stick installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 536.1.2 AN2295 Bootloader Drivers installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Table of ContentsWireless Sensing Triple Axis Reference design, Rev. 0.98 Freescale Semiconductor
Wireless Sensing Triple Axis Reference design, Rev. 0.9Freescale Semiconductor 9Chapter 1 Introduction1.1 IntroductionThis paper describes the design of a Wireless Sensing Triple Axis Reference design (ZSTAR), a demo for wireless demonstration of the 3-axis accelerometer MMA7260Q sensors from Freescale.The reference design will enable you to see how Freescale's accelerometers can add additional functionality to applications in various industries. The accelerometer measurements can be grouped into 6 sensing functions - Fall, Tilt, Motion, Positioning, Shock and Vibration - for multifunctional applications.The RD3152MMA7260Q development tool offers robust wireless communication using the powerful, easy-to-use 2.4GHz frequency MC13191 transceiver. Minor changes can be made with pin to pin compatibility allowing implementation of the MC13192 and MC13193 for ZigBeeTM wireless applications.Figure 1-1 ZSTAR Demo photo (CR2032 batteries for comparison)1.2 MMA7260Q 3-axis Accelerometer SensorThe MMA7260Q low cost capacitive micromachined accelerometer features signal conditioning, a 1-pole low pass filter and temperature compensation, and g-Select, which allows a selection from 4 sensitivities. Zero-g offset full scale span and filter cut-offs are factory set and require no external devices. This device includes a sleep mode making it ideal for handheld battery powered electronics.
IntroductionWireless Sensing Triple Axis Reference design, Rev. 0.910 Freescale Semiconductor
Wireless Sensing Triple Axis Reference design, Rev. 0.9Freescale Semiconductor 11Chapter 2 Wireless Sensing Triple Axis Reference design introduction2.1 IntroductionThe Wireless Sensing Triple Axis Reference design (ZSTAR) has been designed as a wireless complement to the previous STAR (Sensing Triple Axis Reference design) RD3112MMA7260Q demo. A 2.4GHz radio-frequency (RF) link based on the low-cost MC13191 family is used for connection from the sensor to PC, allowing the visualization of key accelerometer applications.Figure 2-1ZSTAR demo overviewThe demo consists of the two boards:• Sensor Board (or remote board) containing the MMA7260Q 3-axis accelerometer, S08 family MC9S08QG8 8-bit microcontroller and the 2.4GHz RF chip MC13191 for wireless communication.• USB stick, again with the MC13191 RF front-end, and the HC08 family MCHC908JW32 for the USB communication.Both sides communicate over the RF medium utilizing the freely available software stack SMAC from Freescale.
Wireless Sensing Triple Axis Reference design introductionWireless Sensing Triple Axis Reference design, Rev. 0.912 Freescale SemiconductorFigure 2-2ZSTAR Block diagram2.2 Featured productsThis demo consist of several Freescale products whose main features are listed below.2.2.1 Triple Axis Accelerometer MMA7260QThe ZSTAR board is a demonstration tool for the MMA7260Q, a 3-Axis Low-g accelerometer. The MMA7260Q has many unique features that make it an ideal solution for many consumer applications, such as freefall protection for laptops and MP3 players, tilt detection for e-compass compensation andmobile phone scrolling, motion detection for handheld games and game controllers, position sensing forg-mice, shock detection for warranty monitors, and vibration for out of balance detection.Features such as low power, low current, and a sleep mode with a quick turn on time, allow the batterylife to be extended in end applications. The 3-axis sensing in a small QFN package requires only a 6mmx 6mm board space, with a profile of 1.45mm, allowing for easy integration into many small handheld electronics.There are several other derivatives of the MMA7260Q:•MMA7261Q with a selectable 2.5g to 10g range•MMA6270Q is an XY dual axis accelerometer•MMA6280Q is an XZ dual axis accelerometerAll members of this sensor family are footprint (QFN package) compatible which simplifies evaluation and design of the target application.2.2.2 Microcontroller MC9S08QG8The MC9S08QG8 is a highly integrated member of Freescale’s 8-bit family of microcontrollers based on the high-performance, low-power consumption HCS08 core. Integrating features normally found in larger,more expensive components, the MC9S08QG8 MCU includes a background debugging system and on-chip in-circuit emulation (ICE) with real-time bus capture, providing a single-wire debugging and S08QG8MC39MMA7260QMC39HC908JW32
Featured productsWireless Sensing Triple Axis Reference design, Rev. 0.9Freescale Semiconductor 13emulation interface. It also features a programmable 16-bit timer/pulse-width modulation (PWM) module (TPM), that is one of the most flexible and cost-effective of its kind.The compact, tightly integrated MC9S08QG8 delivers a versatile combination, from wealth of Freescale peripherals and the advanced features of the HCS08 core, including extended battery life with a maximum performance down to 1.8V, industry-leading Flash and innovative development support. The MC9S08QG8 is an excellent solution for power and size-sensitive applications, such as wireless communications and handheld devices, small appliances, Simple Media Access Controller (SMAC)-based applications and toys.• MC9S08QG8 Features– Up to 20 MHz operating frequencies at >2.1 volts and 16 MHz at <2.1 volts – 8 K Flash and 512 bytes RAM – Support for up to 32 interrupt/reset sources – 8-bit modulo timer module with 8-bit prescaler – Enhanced 8-channel, 10-bit analog-to-digital converter (ADC) – Analog comparator module – Three communication interfaces: SCI, SPI and IIC 2.2.3 MC13191 2.4 GHz ISM Band Low Power TransceiverThe MC13191 is a short range, low power, 2.4 GHz Industrial, Scientific, and Medical (ISM) band transceivers. The MC13191 contains a complete packet data modem which is compliant with the IEEE® 802.15.4 Standard PHY (Physical) layer. This allows the development of proprietary point-to-point and star networks based on the 802.15.4 packet structure and modulation format. For full 802.15.4 compliance, the MC13192 and Freescale 802.15.4 MAC software are required.When combined with an appropriate microcontroller (MCU), the MC13191 provides a cost-effective solution for short-range data links and networks. Interface with the MCU is accomplished using a four wire serial peripheral interface (SPI) connection and an interrupt request output, which allows the use of a variety of processors. The software and processor can be scaled to fit applications ranging from simple point-to-point to star networks.2.2.4 Microcontroller MCHC908JW32The MCHC908JW32 is a member of the low-cost, high-performance M68HC08 Family of 8-bit microcontroller units (MCU’s). All MCU’s in the family use the enhanced M68HC08 central processor unit(CPU08) and are available in a variety of modules, memory sizes and types, and package types.• MCHC908JW32 Features– Maximum internal bus frequency: 8-MHz at 3.5-5V operating voltage – Oscillators:- 4-MHz crystal oscillator clock input with 32MHz internal phase-lock loop- Internal 88-kHz RC oscillator for timebase wakeup– 32,768 bytes user program FLASH memory with security feature – 1,024 bytes of on-chip RAM – 29 general-purpose input/output (I/O) ports:– 8 keyboard interrupt with internal pull-up- 3 pins with direct LED drive- 2 pins with 10mA current drive for PS/2 connection
Wireless Sensing Triple Axis Reference design introductionWireless Sensing Triple Axis Reference design, Rev. 0.914 Freescale Semiconductor– 16-bit, 2-channel timer interface module (TIM) with selectable input capture, output compare, PWM capability on each channel, and external clock input option – Timebase module– PS/2 clock generator module– Serial Peripheral Interface Module (SPI) – Universal Serial Bus (USB) 2.0 Full Speed functions: - 12 Mbps data rate - Endpoint 0 with an 8-byte transmit buffer and an 8-byte receive buffer - 64 bytes endpoint buffer to share amongst endpoints 1–4
Wireless Sensing Triple Axis Reference design, Rev. 0.9Freescale Semiconductor 15Chapter 3 Sensor Board description3.1 Board overviewThe Sensor Board utilizes a small footprint size dual-layer printed circuit board (PCB) containing all the necessary circuitry for MMA7260Q accelerometer sensing and transferring data over a radio frequency (RF). Figure 3-1Sensor Board overviewThe board is powered by a Lithium coin-sized CR2032 battery with provisions also made for the larger capacity CR2477 size. The block diagram of the board is as follows:Lithium battery on the opposite sideMC13191MC9S08QG8MMA7260QBattery SwitchLED indicatorsPCB antennasBDM interfaceButtons
Sensor Board descriptionWireless Sensing Triple Axis Reference design, Rev. 0.916 Freescale SemiconductorFigure 3-2Sensor board block diagramFigure 3-3 shows in more detail, how different software and hardware modules co-operate with each other. The main task of the Sensor board is to:• periodically wake-up from power saving mode• measure all three XYZ acceleration values from the sensor• compose a data frame using simple ZSTAR RF protocol• use SMAC (Simple Media Access Controller) to send this data frame over the RF link• wait for an acknowledgment from the other end (here, the USB stick)• go to sleepThis basic loop repeats roughly 20 times per second providing nearly a real-time response from the sensor.MMA7260QaccelerometerX Y Z sleep g-selectMC9S08QG8MCUMC131912.4GHz RFreceive antennatransmit antennaSPIIRQCR2032 or CR2477Lithium battery
A/D conversion of XYZ levelsWireless Sensing Triple Axis Reference design, Rev. 0.9Freescale Semiconductor 17Figure 3-3ZSTAR Sensor board software overviewFor the Sensor board operation, several of the MC9S08QG8’s hardware modules are used: Analog to Digital Converter (ADC), Synchronous Peripheral Interface (SPI), External Interrupt Request module (IRQ) and General Purpose Input/Output (GPIO).3.2 A/D conversion of XYZ levelsThe 3-axis accelerometer sensor MMA7260Q provides three separate analog levels for the X, Y and Z axis. These outputs are ratiometric which means that the output offset voltage and sensitivity will scale linearly with applied supply voltage. This is a key feature when interfacing to a microcontroller with A/D converter reference levels tied to a power supply, because it provides system level cancellation of supply induced errors in the analog to digital conversion process.During the analog-to-digital conversion in the microcontroller, 8-bit resolution is used. MC9S08QG8 A/D channels 0, 1 and 2 are connected to X (channel 1), Y (channel 2) and Z (channel 0) outputs of the MMA7260Q. The microcontroller’s APCTL1 register enables these ADC channels for pin I/O control by the ADC module. The ADCCFG register controls the selected mode of operation, clock source, clock divide, and configuration for low power or long sample time.3.2.1 ADC module init:APCTL1 = 0b00000111; /* 0,1,2 channels are ADC */ADCCFG = 0b01100000; /* set prescale to 8, ADICLK=BUS, 8-bit, high speed */Actual ADC measurements are done in the main software loop. There is a macro (called POWSUM) that allows configuration of measurement to take several measurements of each channel during one loop. E.g.changing POWSUM to 3, 2^3 = 8, each channel will be measured 8 times, with POWSUM 7, each channel Sensor dataAnalog-to-Digital converter(ADC) moduleMC9S08QG8SMACZSTAR RF protocol handlersleepsoftwarecalibration datag-selectSerial Peripheral Interface (SPI) moduleIRQMC39MMA7260QGPIO
Sensor Board descriptionWireless Sensing Triple Axis Reference design, Rev. 0.918 Freescale Semiconductoris measured 128 times. By default, POWSUM is 0, for 1 measurement of each channel. Before result values are provided, the accumulated values are scaled back to the 8-bit range and inverted where necessary (may be required depending on the physical MMA7260Q device orientation relative to the Earth gravity).Raw (i.e. not calibrated) values are actually sent, the calibration and calculation of an exact g value is done internally in the PC software.3.2.2 ADC measurementThe following routine is used for accelerometer measurement:unsigned int xx = 0; unsigned int yy = 0;unsigned int zz = 0;unsigned char xxx, yyy, zzz;#define POWSUM 0for (i = 0; i < (1 << POWSUM); i++) {ADCSC1 = 0x01; //read X channelwhile(!ADCSC1_COCO);xx += ADCR;ADCSC1 = 0x02; //read Y channelwhile(!ADCSC1_COCO);yy += ADCR;ADCSC1 = 0x00; //read Z channelwhile(!ADCSC1_COCO);zz += ADCR;}xxx = ~(unsigned char)(xx >> POWSUM);yyy = ~(unsigned char)(yy >> POWSUM);zzz = (unsigned char)(zz >> POWSUM);3.3 Power managementA CR2032 (or CR2477) Lithium battery provides a fairly limited charge for such a realtime-like demo that demands frequent transmissions. Some sort of power management has to be implemented in order to keep the current consumption at a reasonable level.Typically, current consumptions of Sensor board components are as follows:• 2.4GHz transceiver MC13191 – in Hibernate mode, 2.3µA– in Doze mode, 35µA– in Idle mode, 500µA– in Transmit mode, 30mA– in Receive mode, 37mA
Power managementWireless Sensing Triple Axis Reference design, Rev. 0.9Freescale Semiconductor 19• 8-bit microcontroller MC9S08QG8 – in Stop mode, 750nA– in Wait mode, 1mA– in Run mode, 3.5mA• low-g triaxial sensor MMA7260Q– in Sleep mode, 3µA– in Normal mode, 500µAIt is obvious that in a battery operated application care must be taken to ensure the lowest possible current consumption, especially when the maximum current (provided by the battery) is somehow limited. A CR2032 Lithium battery cannot provide current in the range of 40mA for long periods of time. To alleviate high current surges, an additional large capacitor has been designed - see 3.4.10 Power supply.For transmission and reception using the MC13191, a specific scheme has been used to ensure the battery is not depleted or overloaded. Targeting a 20 samples per second (50ms period) transmission rate, the following scheme for one transmission/sleep cycle is used for the data transfer:Figure 3-4Transmission/sleep cycle detailsAs shown on the previous diagram, all parts of the Sensor board remain most of the time in Sleep/Doze/Stop modes, in which the total current consumption is below 10µA. During each loop, once the data has been acquired from sensor, transmission over the MC13191 transceiver is initiated. The current consumption of the transmitter is ~30mA at that time, but only for a short period of time (typically ~600µs).In order to keep the sensor board informed on the status of connection (for example, if the data-receiving side - USB stick - is out of range, disconnected, etc.), the reception has to be turned on after the data has been transmitted. This is not really required within each loop cycle, and in the actual implementation only on every 8th loop the receive window opens (receiver is enabled to receive the acknowledgment). More in the 5.3 ZSTAR RF protocol description.timeSleepwake-upNormalMMA7260Q:DozeMC13191:StopMC9S08QG8:StopSleepRun StopSensorstabilizes SensorbeingmeasuredTXWaitWaitRXoptionalreceivewindow NOT TO SCALEDozedatatransmitted
Sensor Board descriptionWireless Sensing Triple Axis Reference design, Rev. 0.920 Freescale SemiconductorThe reception window is larger to fit any incoming receive data and the current consumption is also higher during reception, so this portion of current consumption would be one of the largest if the acknowledgment was received in every loop cycle.The “optional receive” feature allows huge power savings, still keeping the reception of acknowledgment data from the data-receiving side.Some further savings might be incorporated by utilizing the timer-triggered transceiver events that are described in the MC13191 Reference Manual.The MC13191, for example, latches a so-called time-stamp of each received frame. The data-receiving side may read this value and trigger the acknowledgment to be sent at exactly specified time after reception (also, a start of data frame transmission can be programmed as timer-triggered). The sensor board might then narrow its own receive window to perfectlymatch the expected time of the acknowledgment frame. For the simplicity of code, this has not been implemented in the current version of ZSTAR firmware.3.3.1 MC13191 power management featuresMC13191 provides several power saving modes. One of them is called Doze mode in which the MC13191 crystal oscillator remains active. An internal timer comparator is functional too, providing apower efficient and accurately timed way of waking-up the application after a specified time.This feature is fully utilized within the Sensor board. The microcontroller calculates the time period for which the application should be in power saving mode, then fills in the timer comparator registers in the MC13191, and the microcontroller goes into Stop mode (MC13191 into Doze mode).Once the timer reaches the pre-programmed time (a timer compare occurs), the MC13191’s IRQ signal is asserted which brings the microcontroller out of the Stop mode. There are various scaling possibilities that allow periods from a few µs up to 1073 seconds (~17 minutes) to be programmed, without intervention of the microcontroller.
ZSTAR Sensor Board hardware overviewWireless Sensing Triple Axis Reference design, Rev. 0.9Freescale Semiconductor 213.4 ZSTAR Sensor Board hardware overviewThis section describes the Sensor board in terms of the hardware design. The MC9S08QG8 microcontroller drives both the MMA7260Q sensor and the MC13191 RF transceiver.3.4.1 Analog connectionsThe MMA7260Q sensor is connected to AD0, AD1, and AD2 inputs to analog-to-digital converter via RC filters formed by R3, C3, R4, C2, R5, C1. These are recommended to minimize clock noise from the switched capacitor filter circuit inside the sensor. Once the software filtering (also described in 3.2 A/D conversion of XYZ levels) is employed, these RC filters may be completely omitted.3.4.2 g-select connectionsR1, R2, R6 and R7 components are made on the PCB. R1 and R2 are just footprints with no components assembled, while R6 and R7 are connected with copper trace allowing the user to disconnect (cut) theselines. By default, g-sel1 and g-sel2 MMA7260Q sensor input pins (used to select the acceleration range) are connected to pins PTB0 and PTB1 of the microcontroller. The range can be controlled by software.If user does not want to use this feature, the g-range can be selected by placing 0R resistors in the R1 and/or R2 positions. If no resistors are assembled, MMA7260Q internal pull-down resistors will automatically select the 1.5g range (both g-sel inputs low).Once R6 and R7 are cut, PTB0 and PTB1 (or their alternate SCI functionality of RxD1 and TxD1, or KBI or AD inputs) may be used. These signals are also routed to BDM connector, pins 3 and 5.3.4.3 BDM (Background Debug Mode) connectionsA J2 connector is a non-standard footprint primarily intended for in-factory programming and testing via “spring-needle” type of connections. The J2 connector carries all standard signals for Background Debug Mode communication so if required, one may solder wires and a standard 2x3 pins 2.54mm (100mil) pitch header for regular BDM re-programming. The pin numbering is shown on Figure 3-5.Figure 3-5BDM connector layout123456
Wireless Sensing Triple Axis Reference design, Rev. 0.922 Freescale SemiconductorSensor Board description3.4.4 Sensor Board schematicsFigure 3-6Sensor board schematicsG_SEL2/TxDG_SEL1/RxDVDDVDDVDDVDDVDDVDDAGND GNDGNDGND GNDGNDGNDGNDGNDGND GND GND GNDGNDGNDGNDVDDVDDGND GNDGNDGNDMOSISPICLKMOSIG_SEL1/RxDG_SEL2/TxDLED1LED2LED1 LED2SPICLKTitleSizeDesign Name:RevModify Date: Sheet ofSchematic Name:Copyright FreescalePOPI Status:Author:1.0Low-cost 2.4GHz Triax BoardFreescale Semiconductor RCSC1. maje 1009756 61 Roznov p.R., Czech Republic, EuropeA41 1Monday, January 30, 2006SCHEMATIC1General Business InformationRadomir Kozub & Pavel Lajsner2005X:\ICONN\IC108 - LOW-COST 2.4GHZ AND XYZ ACCELEROMETER DEMO\HW\00239\00239.DSNTitleSizeDesign Name:RevModify Date: Sheet ofSchematic Name:Copyright FreescalePOPI Status:Author:1.0Low-cost 2.4GHz Triax BoardFreescale Semiconductor RCSC1. maje 1009756 61 Roznov p.R., Czech Republic, EuropeA41 1Monday, January 30, 2006SCHEMATIC1General Business InformationRadomir Kozub & Pavel Lajsner2005X:\ICONN\IC108 - LOW-COST 2.4GHZ AND XYZ ACCELEROMETER DEMO\HW\00239\00239.DSNTitleSizeDesign Name:RevModify Date: Sheet ofSchematic Name:Copyright FreescalePOPI Status:Author:1.0Low-cost 2.4GHz Triax BoardFreescale Semiconductor RCSC1. maje 1009756 61 Roznov p.R., Czech Republic, EuropeA41 1Monday, January 30, 2006SCHEMATIC1General Business InformationRadomir Kozub & Pavel Lajsner2005X:\ICONN\IC108 - LOW-COST 2.4GHZ AND XYZ ACCELEROMETER DEMO\HW\00239\00239.DSN12Q116MHz NX2520SAQ116MHz NX2520SAR2INFR2INF1SSSSR3 10kR3 10kC1110nFC1110nFC1210nFC1210nFR1INFR1INFR5 10kR5 10kBATT1Battery/Renata CR2032BATT1Battery/Renata CR20321 23 465J2BDMJ2BDMRFIN- 1RFIN+ 2PAO+ 5PAO- 6GPIO48GPIO39GPIO210 GPIO111RST12RXTXEN13ATTN14CLKO15SPICLK16MOSI17MISO18CE19IRQ20VDDD 21VDDINT 22GPIO523GPIO624GPIO725CRYSTAL126CRYSTAL227VDDLO2 28VDDLO1 29VDDVCO 30VBATT 31VDDA 32EPGND36 EPGND37 EPGND38 EPGND39 EPGND40 EPGND41EPGND35EPGND34EPGND33U3 MC13191FCU3 MC13191FCC610nFC610nFC710nFC710nFD2LEDD2LEDL222nHL222nH1SPICLKSPICLKg-Sel11g-Sel22VDD 3VSS4SLEEP12 Z13Y14X15U1 MMA7260QU1 MMA7260QL35.6nHL35.6nHC1100nFC1100nFC5 10nFC5 10nFL122nHL122nHD1LEDD1LEDBATT2Battery/Renata CR2477BATT2Battery/Renata CR24771IRQIRQ1 342S1Alps SKRPS1Alps SKRPL44.7nHL44.7nH1MOSIMOSIR70RR70R1MISOMISO+C14470uF/4V+C14470uF/4VR90RR90RC1310nFC1310nFR60RR60RC96.8pFC96.8pFC3100nFC3100nF134 2S2Alps SKRPS2Alps SKRPR80RR80RPTB4/MISO1 8PTB3/KBI7/AD7/MOSI19PTA4/BKGD/MS/ACMP1O 2Vdd 3PTA0/KBI0/AD0/TPM1CH0/ACMP1+16PTA1/KBI1/AD1/ACMP1-15PTA2/KBI2/AD2/SDA114PTA5/RESET/IRQ/TCLK 1Vss 4PTB7/SCL1/EXTAL 5PTB6/SDA1/XTAL 6PTB5/TPM1CH1/SS1 7PTB1/KBI5/AD5/TxD111 PTB0/KBI4/AD4/RxD112 PTA3/KBI3/AD3/SCL113PTB2/KBI6/AD6/SPSCK110U2MC9S08QG8CDTEU2MC9S08QG8CDTEC86.8pFC86.8pFC2100nFC2100nFC1010nFC1010nFSW1Alps/SSSS811101SW1Alps/SSSS811101R4 10kR4 10kC4 100pFC4 100pF
ZSTAR Sensor Board hardware overviewWireless Sensing Triple Axis Reference design, Rev. 0.9Freescale Semiconductor 233.4.5 Button connectionsTwo buttons (S1 and S2) are connected directly to pins PTB6 and PTB7. Both have internal pull-up resistors, but are not part of the Keyboard interrupt module, therefore don’t allow a direct microcontroller wake-up from the Stop modes.3.4.6 MC13191 to MC9S08QG8 microcontroller interfaceIn order to fit all the necessary circuitry onto a 16-pin microcontroller, the full recommended MC13191 interface has had to be reduced. The full interface includes the following connections:• 4-wire Synchronous Peripheral Interface (SPI) connection (MISO, MOSI, SPICLK, CE)• Interrupt Request signal (IRQ)• Attention (ATTN) wake-up signal• Receive/Transmit Enable (RXTXEN) signal• External Reset (RST) signalSPI and IRQ are vital for the communication and configuration ofthe MC13191. SPI is connected to the MC9S08QG8 SPI module (pins PTB4/MISO1, PTB3/MOSI1, PTB2/SPSCK1, and GPIO pin PTB5 for CE). Interrupt Request (IRQ) is connected to the microcontroller IRQ pin sharing its alternate RESET function when BDM communication is active.Attention (ATTN)signal is intended to externally wake-up the MC13191 from Doze and Hibernate modes. Since this feature is not used and exit from the Doze mode is done using a timer compare event,The ATTN pin is not routed to the microcontroller and needs to be connected to Vdd.Receive/Transmit Enable (RXTXEN) signal is used to control transitions to/from receive and transmit modes. Since this can be accomplished just by software programming and/or timer compare events, this connection to the microcontroller may also be omitted, saving an additional pin. RXTXEN is connected to Vdd.External Reset (RST) signal places the transceiver in a complete reset condition (Off mode and power down). Alternative Software reset is also possible and since Off mode (the one with the lowest possible power consumption) is not required too, RST is connected to Vdd too.3.4.7 MC13191 RF interfaceThe RF interface (antennas) were designed with the cost and board size in mind. Among several designs,the PCB layout antennas were in the main consideration (cost). Of several PCB antenna designs available for the 2.4GHz band (F-antenna, dipole, loop), the loop antenna has been selected mainly because of the size required on the PCB.The MC13191 transceiver is designed with separated RF IN (receive) and PA OUT (transmit) paths. To avoid the need for an antenna switch, two separate antennas need to be used. Both ZSTAR boards (USB stick and Sensor Board) use the same antenna layout, there are two antennas on the PCB, just on the opposite sides of the PCB.The antenna is designed as a rectangle, 20x24mm (780x940mils), made of 1.25mm (50mils) wide trace of copper. The corners are rounded with a 3.8mm (150mils) radius.
Sensor Board descriptionWireless Sensing Triple Axis Reference design, Rev. 0.924 Freescale SemiconductorFigure 3-7ZSTAR antenna layoutThe matching is provided by L3 (transmit antenna) and L4 (receive antenna) coils. L1 and L2 coils biasthe transmitter output transistors to the VDDA level.The inductors used in this design are from TDK:L3 (5.6nH) MLG1608B5N6DTL4 (4.7nH) MLG1608B4N7STand L1, L2 (22nH) MLG1608B22NJT.3.4.8 Clocking options of MC9S08QG8Due to the availability of accurate timing provided by the MC13191 transceiver, an internal oscillator (ICG) in the MC9S08QG8 is used as the main clock source for the microcontroller. The protocol related timingis derived from MC13191 timers, the microcontroller itself is clocked from an internal oscillator, leaving the oscillator pins as GPIO. This is highly beneficial to the limited pin count microcontroller.3.4.9 LED indicators connectionsThe MC13191 allows extension to the number of general I/O pins by 7 additional GPIO connections. Two of these (GPIO1 and GPIO2) are used for LED indicators. R8 and R9 are their current limiting resistors, and in the actual design orange LED’s are used, with a threshold voltage around 2.0-2.5V.The remaining unused GPIO3-GPIO7 signals are connected to ground, improving the physical PCB layout of the MC13191.
ZSTAR Sensor Board hardware overviewWireless Sensing Triple Axis Reference design, Rev. 0.9Freescale Semiconductor 253.4.10 Power supplyThe Sensor board is powered by a Lithium coin-sized battery. The primary choice was the popular CR2032, with a PCB layout provision made for the CR2477 size. This bigger battery holds roughly 4 times more charge (~1000mAh), but it is not as popular as CR2032 size.A surface mounted SMTU series battery holder from RenataTM is placed on the underside of the PCB. The SMTU series holders provide (by mechanical construction) battery reverse protection, so no additional circuitry is required. Slide switch SW1 disconnects the battery from the application when not in use.A large tantalum capacitor (C14, 470µF/4V) improves the response of the power supply to current peaks caused by reception or transmission. Coin-sized Lithium CR2032 batteries are targetted at a maximum continuous discharge current in the range of 3mA. Such a large capacitor helps to supply enough current to the MC13191 during a receive/transmit without significant Vdd voltage drops.
Sensor Board descriptionWireless Sensing Triple Axis Reference design, Rev. 0.926 Freescale Semiconductor3.5 Bill of MaterialsTable 3-1. Sensor board bill of materialsItem Quantity Reference Part Manufacturer Manufacturer order code1 1 BATT1 battery holder CR2032 Renata SMTU 2032-12 3 C1,C2,C3 100nF TDK C1608JB1H104K3 1 C4 100pF TDK C1608CH1H101J4 7 C5,C6,C7,C10,C11,C12,C13 10nF TDK C1608CH1E103J5 2 C8,C9 6.8pF TDK C1608CH1H070D6 1 L3 5.6nH TDK MLG1608B5N6DT7 1 L4 4.7nH TDK MLG1608B4N7ST8 2 D1,D2 Kingbright KP-1608SEC Kingbright KP-1608SEC 9 1 J2 BDM + serial N/A10 2 L1,L2 22nH TDK MLG1608B22NJT11 1 Q1 16MHz NX2520SA NDK NX2520SA 16MHz EXS00A-02940Specification n° EXS10B-0722812 2 R1,R2 N/A N/A13 3 R3,R4,R5 10k resistor 0603 package14 2 R6,R7 N/A N/A15 2 R8,R9 0R resistor 0603 package16 1 SW1 slide switch Alps/SSSS811101 Alps SSSS811101(or SKRPACE010 or SKRPABE010)17 2 S1,S2 switch SKRP Alps SKRPADE010(or SKRPACE010 or SKRPABE010)18 1 U1 MMA7260Q Freescale MMA7260Q (MMA7260QR2 for tape and reel)19 1 U2 MC9S08QG8CDTE Freescale MC9S08QG8CDTE20 1 U3 MC13191FC Freescale MC13191FC(MC13191FCR2 for tape and reel)21 1 C14 470uF/4V Vishay 594D477X9004C2T
Wireless Sensing Triple Axis Reference design, Rev. 0.9Freescale Semiconductor 27Chapter 4 USB stick board description4.1 Board overviewThe USB stick board utilizes the same small footprint as Sensor Board is also a dual-layer printed circuit board (PCB). It contains the minimalistic design of the MC13191 RF transceiver connected through an 8-bit MCHC908JW32 microcontroller to the USB. It’s main task is to receive data from the Sensor Board and transfer it to the PC over the USB link.Figure 4-1USB stick board overviewThe USB stick board is powered from the USB. The block diagram of the board is as follows:MC13191MCHC908JW32LED indicatorsPCB antennasUSB “A” type plugButton
USB stick board descriptionWireless Sensing Triple Axis Reference design, Rev. 0.928 Freescale SemiconductorFigure 4-2USB stick board block diagramFigure 4-3 shows, in more detail, how different software and hardware modules co-operate with each other. There are two main tasks of the USB stick board:• receive the data from the MC13191 transceiver and store it in RAM buffer• handle the USB module communication, decode and provide the data from the RAM bufferThese two are somewhat independent and the only common point between them is the accelerometer and button data buffer in RAM. The RF software communicates with the Sensor Board and retrieves the latest accelerometer data. This is stored in RAM and can be independently read by the PC application via the USB link. The protocol employed on the PC side is just a subset of the simple STAR protocol used in the original RD3112MMA7260Q demo. The protocol is described in chapter 5.4 STAR protocol and ZSTAR extensions (over USB).MCHC908JW32MCUMC131912.4GHz RFreceive antennatransmit antennaSPIIRQATTNRSTRXTXENUSB+5V USB voltageregulators+5V USB
Board overviewWireless Sensing Triple Axis Reference design, Rev. 0.9Freescale Semiconductor 29Figure 4-3ZSTAR USB stick board software overviewFor the USB stick board operation, several MCHC908JW32 hardware modules are used: USB 2.0 Full-speed module (USB), Synchronous Peripheral Interface (SPI), Keyboard Interrupt module (KBI) and a General Purpose Input/Output (GPIO).SMAClow-level USBSensor & Button dataUSB connection to PCUSB protocolZSTAR RF protocol handlerMCHC908JW32USB 2.0 “virtual serial port” softwareSerial Peripheral Interface (SPI) module KBI GPIO Full Speed moduleMC39protocol driveror mousehandlersimple STARprotocol handler
USB stick board descriptionWireless Sensing Triple Axis Reference design, Rev. 0.930 Freescale Semiconductor4.2 ZSTAR USB stick Board hardware overviewThis section describes the USB stick board in terms of the hardware design. The MCHC908JW32 microcontroller drives the MC13191 RF transceiver and communicates over USB with PC.4.2.1 USB connectionsTwo USB communication lines are connected directly via R1 to PTE2/D+ and R2 to PTE3/D- microcontroller pins. There, the R1 and R2 resistors define the output impedance of both drivers (ZDRVas per chapter 7 of the USB 2.0 specifications).Terminating the D+ line with a 1.5kΩ pull-up resistor (required for Full-speed signalling) is internal in the MCHC908JW32.A USB “A” type SMT Plug is designed at the edge of the USB stick board allowing the stick to be connected directly into a USB hub without the need for a cable.4.2.2 Power supplyThe USB stick board is a Low-power Bus-powered Function (as defined in chapter 7.2.1.3 of USB 2.0 specifications). This means that a maximum of one unit load (100mA) may be drawn by the USB Stick board. Ferrite beads are included on the VBUS and GND USB connections to minimize EMI. The recommended type is a GLF1608T100M or similar from TDK.VBUS voltage is defined as a minimum 4.4V and a maximum 5.25V on a Low-power Bus-powered Function. The MC13191 RF transceiver requires a maximum power supply voltage of 3.4V and the MCHC908JW32 microcontroller could not guarantee an internal 3.3V regulator working at such a low power supply. Therefore, two separate voltage regulators need to be implemented, and in addition, the voltage levelshave to be close enough to avoid the need for level shifters (for the MC13191 to MCHC908JW32 microcontroller interface).4.2.2.1 Fixed voltage regulatorsTwo voltage levels (3.3V for MC13191 and 3.6V for MCHC908JW32) were selected. For these levels, a low-cost, small footprint fixed regulator exists. The NCP502/A series regulators from ON SemiconductorTM were successfully implemented. The NCP502/A series voltage regulator is an 80mA CMOS fixed linear regulator designed primarily for handheld communication equipment and portable battery powered applications which require a low quiescent current.Each device contains a voltage reference unit, an error amplifier, a PMOS power transistor, resistors for setting the output voltage, current limit, and temperature limit protection circuits. The NCP502/A has been designed to be used with low cost ceramic capacitors. The device is housed in a micro-miniature SC70-5surface mount package. Standard voltage versions are 1.5 V, 1.8 V, 2.5 V, 2.7 V, 2.8 V, 3.0 V, 3.3 V, 3.5 V, 3.6 V and 5.0 V. Other voltages are available in 100 mV steps.Typically, a low-cost 1µF ceramic capacitor is recommended for input and output decoupling. 0603-sized SMD TDK capacitor C1608X5R1A105K was used.
ZSTAR USB stick Board hardware overviewWireless Sensing Triple Axis Reference design, Rev. 0.9Freescale Semiconductor 31Enable Operation - Enable pin of 3.3V regulator (for MC13191) is connected to PTC3 pin of the microcontroller. This way, the microcontroller may completely turn off the RF part of the application to minimize power consumption in USB suspend modes.Alternatively, power down of the MC13191 RF transceiver may be done by forcing it into Off mode by pulling the RST pin low.4.2.3 MC13191 to MCHC908JW32 microcontroller interfaceOn the USB stick board the full recommended MC13191 interface has been used. This includes the following connections:• 4-wire Synchronous Peripheral Interface (SPI) connection (MISO, MOSI, SPICLK, CE)• Interrupt Request signal (IRQ)• Attention (ATTN) wake-up signal• Receive/Transmit Enable (RXTXEN) signal• External Reset (RST) signalThe SPI connection is connected to the MCHC908JW32 SPI module signals (MISO, MOSI, SPCLK, SS). The IRQ signal is routed to the PTA3/KBA3 Keyboard interrupt module pin instead of the MCHC908JW32 IRQ pin, which is left for the MON08 interface and the Button connection. The reason for re-routing this signal is that VTST (1.5xVDD, up to 8V) is applied to the microcontroller’s IRQ during programming, therefore some additional jumper configuration would be required to disconnect this voltage fromthe MC13191. Here, the IRQ‘s MON08 function is only shared with the button under the condition that the button is not pressed during programming.The remaining three signals (ATTN, RXTXEN and RST) are connected to GPIO signals of port D (PTD0, PTD2 and PTD1).4.2.4 Oscillator and clocking optionsThe MCHC908JW32 microcontroller requires a stable clock, mainly for the Full-speed USB module operations. USB specifications define an overall 2500ppm (0.25%) accuracy. Basically, any generic 4MHz crystal is sufficient for such accuracy. The main issue with 4MHz crystals are their physical size. Due to the nature of crystal resonating elements, the 4MHz crystals are simply far too big for the USBstick in the ZSTAR demo.Another option is a SAW resonator (e.g. CERALOCKTM series from Murata). These are usually sorted and selected by the manufacturer to fit the USB 2.0 Full-speed accuracy required. Today, only 6, 12, 24 and 48MHz versions are available from Murata. A 6MHz version (manufacturer order code CSTCR6M00G15) has been used in the USB stick design, although the 6MHz frequency is outside the MCHC908JW32 microcontroller specifications.Provision is also made on the PCB (Q3 component) for an Epson SG-310 series (or compatible) Crystal Oscillator (active output). Here, a 4MHz version oscillator is contained in a small 3.2x2.5mm package.4.2.5 LED indicators connectionsThe MCHC908JW32 microcontroller allows a direct drive of LED’s on its three pins. PTB0, PTB1 and PTB5 are high-current open-drain outputs, so the LED’s D1, D2 and D3 are connected to these high-current outputs.
USB stick board descriptionWireless Sensing Triple Axis Reference design, Rev. 0.932 Freescale Semiconductor4.2.6 Button connectionOne button is implemented on the USB stick board. It is connected to the IRQ microcontroller pin that has internal pull-up and allows an easy software interrupt.4.2.7 MON08 interfaceFor MCHC908JW32 in-circuit programming, a MON08 interface is required. Several pins must be connected to specific voltage levels in order for the MCHC908JW32 to enter the Monitor mode. The details are described in the MCHC908JW32 datasheet, Chapter 7 Monitor ROM (MON).To minimize the number of MON08 connections, several pins are hardwired to specific voltage levels directly on the USB stick board. Namely, PTA1 to Vdd, PTA2 and PTC1 to GND. Pins PTA0, RST, IRQ and OSC1, together with the power supply lines, are routed to PCB pads MON08 connector (J3).There is no standard physical connector to be soldered onto the J3 footprint. The J3 connector pads are used during manufacturing for the initial in-circuit programming. Further re-programming of the USB stick maybe done using an AN2295 Bootloader as described in chapter 5.5.4.2.8 Optional serial interfaceFor the purpose of evaluating the USB functions of the MCHC908JW32 microcontroller, a few other pins were routed to an additional PCB pads connector (J2). The two TIM timer pins are connected to J2 allowing emulation of SCI, IIC or such like serial interfaces in software. A simple example of a USB to UART converter software is a part of the AN3153 Application note - Using the Full-Speed USB Module on the MCHC908JW32.

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