STM32F10xxx Flash Memory Microcontrollers Stm32f1 PM0075 Programming Manual

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August 2012 Doc ID 17863 Rev 2 1/31
PM0075
Programming manual
STM32F10xxx Flash memory microcontrollers
Introduction
This programming manual describes how to program the Flash memory of STM32F101xx,
STM32F102xx, STM32F103xx, STM32F105xx and STM32F107xx microcontrollers. For
convenience, these will be referred to as STM32F10xxx in the rest of this document unless
otherwise specified.
The STM32F10xxx embedded Flash memory can be programmed using in-circuit
programming or in-application programming.
The in-circuit programming (ICP) method is used to update the entire contents of the
Flash memory, using the JTAG, SWD protocol or the boot loader to load the user application
into the microcontroller. ICP offers quick and efficient design iterations and eliminates
unnecessary package handling or socketing of devices.
In contrast to the ICP method, in-application programming (IAP) can use any
communication interface supported by the microcontroller (I/Os, USB, CAN, UART, I2C, SPI,
etc.) to download programming data into memory. IAP allows the user to re-program the
Flash memory while the application is running. Nevertheless, part of the application has to
have been previously programmed in the Flash memory using ICP.
The Flash interface implements instruction access and data access based on the AHB
protocol. It implements a prefetch buffer that speeds up CPU code execution. It also
implements the logic necessary to carry out Flash memory operations (Program/Erase).
Program/Erase operations can be performed over the whole product voltage range.
Read/Write protections and option bytes are also implemented.
Table 1 lists the microcontrollers and evaluation tool concerned by this programming
manual.
Table 1. Applicable products
Type Applicable products
Microcontrollers STM32F101xx, STM32F102xx, STM32F103xx, STM32F105xx and
STM32F107xx microcontrollers
Evaluation tool STM3210C-EVAL evaluation board
www.st.com
Contents PM0075
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Contents
1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2 Flash module organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Reading/programming the embedded Flash memory . . . . . . . . . . . . . 11
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.2 Read operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.2.1 Instruction fetch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.2.2 D-Code interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.2.3 Flash access controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.3 Flash program and erase controller (FPEC) . . . . . . . . . . . . . . . . . . . . . . 12
2.3.1 Key values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.3.2 Unlocking the Flash memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.3.3 Main Flash memory programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.3.4 Flash memory erase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.3.5 Option byte programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.4 Protections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.4.1 Read protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.4.2 Write protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.4.3 Option byte block write protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.5 Option byte description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3 Register descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.1 Flash access control register (FLASH_ACR) . . . . . . . . . . . . . . . . . . . . . . 23
3.2 FPEC key register (FLASH_KEYR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.3 Flash OPTKEY register (FLASH_OPTKEYR) . . . . . . . . . . . . . . . . . . . . . 24
3.4 Flash status register (FLASH_SR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.5 Flash control register (FLASH_CR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.6 Flash address register (FLASH_AR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.7 Option byte register (FLASH_OBR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.8 Write protection register (FLASH_WRPR) . . . . . . . . . . . . . . . . . . . . . . . . 28
3.9 Flash register map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
PM0075 List of tables
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List of tables
Table 1. Applicable products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Table 2. Flash module organization (low-density devices) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Table 3. Flash module organization (medium-density devices) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Table 4. Flash module organization (high-density devices) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Table 5. Flash module organization (connectivity line devices) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Table 6. Flash memory protection status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Table 7. Option byte format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Table 8. Option byte organization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Table 9. Description of the option bytes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Table 10. Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Table 11. Flash interface - register map and reset values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Table 12. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
List of figures PM0075
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List of figures
Figure 1. Programming procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Figure 2. Flash memory Page Erase procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 3. Flash memory Mass Erase procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
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Glossary
This section gives a brief definition of acronyms and abbreviations used in this document:
●Low-density devices are STM32F101xx, STM32F102xx and STM32F103xx
microcontrollers where the Flash memory density ranges between 16 and 32 Kbytes.
●Medium-density devices are STM32F101xx, STM32F102xx and STM32F103xx
microcontrollers where the Flash memory density ranges between 64 and 128 Kbytes.
●High-density devices are STM32F101xx and STM32F103xx microcontrollers where
the Flash memory density ranges between 256 and 512 Kbytes.
●Connectivity line devices are STM32F105xx and STM32F107xx microcontrollers.
●The Cortex-M3 core integrates two debug ports:
– JTAG debug port (JTAG-DP) provides a 5-pin standard interface based on the
Joint Test Action Group (JTAG) protocol.
– SWD debug port (SWD-DP) provides a 2-pin (clock and data) interface based on
the Serial Wire Debug (SWD) protocol.
For both the JTAG and SWD protocols please refer to the Cortex M3 Technical
Reference Manual
●Word: data/instruction of 32-bit length
●Half word: data/instruction of 16-bit length
●Byte: data of 8-bit length
●FPEC (Flash memory program/erase controller): write operations to the main memory
and the information block are managed by an embedded Flash program/erase
controller (FPEC).
●IAP (in-application programming): IAP is the ability to re-program the Flash memory of
a microcontroller while the user program is running.
●ICP (in-circuit programming): ICP is the ability to program the Flash memory of a
microcontroller using the JTAG protocol, the SWD protocol or the boot loader while the
device is mounted on the user application board.
●I-Code: this bus connects the Instruction bus of the Cortex-M3 core to the Flash
instruction interface. Prefetch is performed on this bus.
●D-Code: this bus connects the D-Code bus (literal load and debug access) of the
Cortex-M3 to the Flash Data Interface.
●Option bytes: product configuration bits stored in the Flash memory
●OBL: option byte loader.
●AHB: advanced high-performance bus.
Overview PM0075
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1 Overview
1.1 Features
●up to 512 Kbytes of Flash memory
●Memory organization:
– Main memory block:
4 Kbits × 64 bits for low-density devices
16 Kbits × 64 bits for medium-density devices
64 Kbits × 64 bits for high-density devices
32 Kbits × 64 bits for connectivity line devices
– Information block:
2306 × 64 bits for connectivity line devices
258 × 64 bits for other devices
Flash memory interface (FLITF) features:
●Read interface with prefetch buffer (2 × 64-bit words)
●Option byte Loader
●Flash Program / Erase operation
●Read / Write protection
●Low-power mode
1.2 Flash module organization
The memory organization is based on a main memory block containing 32 pages of 1 Kbyte
(for low-density devices), 128 pages of 1 Kbyte (for medium-density devices), 128 pages of
2 Kbyte (for connectivity line devices) or 256 pages of 2 Kbyte (for high-density devices),
and an information block as shown in Tabl e 3 and Table 4.
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Table 2. Flash module organization (low-density devices)
Block Name Base addresses Size (bytes)
Main memory
Page 0 0x0800 0000 - 0x0800 03FF 1 Kbyte
Page 1 0x0800 0400 - 0x0800 07FF 1 Kbyte
Page 2 0x0800 0800 - 0x0800 0BFF 1 Kbyte
Page 3 0x0800 0C00 - 0x0800 0FFF 1 Kbyte
Page 4 0x0800 1000 - 0x0800 13FF 1 Kbyte
.
.
.
.
.
.
.
.
.
Page 31 0x0800 7C00 - 0x0800 7FFF 1 Kbyte
Information block System memory 0x1FFF F000 - 0x1FFF F7FF 2 Kbytes
Option Bytes 0x1FFF F800 - 0x1FFF F80F 16
Flash memory
interface
registers
FLASH_ACR 0x4002 2000 - 0x4002 2003 4
FLASH_KEYR 0x4002 2004 - 0x4002 2007 4
FLASH_OPTKEYR 0x4002 2008 - 0x4002 200B 4
FLASH_SR 0x4002 200C - 0x4002 200F 4
FLASH_CR 0x4002 2010 - 0x4002 2013 4
FLASH_AR 0x4002 2014 - 0x4002 2017 4
Reserved 0x4002 2018 - 0x4002 201B 4
FLASH_OBR 0x4002 201C - 0x4002 201F 4
FLASH_WRPR 0x4002 2020 - 0x4002 2023 4
Table 3. Flash module organization (medium-density devices)
Block Name Base addresses Size (bytes)
Main memory
Page 0 0x0800 0000 - 0x0800 03FF 1 Kbyte
Page 1 0x0800 0400 - 0x0800 07FF 1 Kbyte
Page 2 0x0800 0800 - 0x0800 0BFF 1 Kbyte
Page 3 0x0800 0C00 - 0x0800 0FFF 1 Kbyte
Page 4 0x0800 1000 - 0x0800 13FF 1 Kbyte
.
.
.
.
.
.
.
.
.
Page 127 0x0801 FC00 - 0x0801 FFFF 1 Kbyte
Information block System memory 0x1FFF F000 - 0x1FFF F7FF 2 Kbytes
Option Bytes 0x1FFF F800 - 0x1FFF F80F 16
Overview PM0075
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Flash memory
interface
registers
FLASH_ACR 0x4002 2000 - 0x4002 2003 4
FLASH_KEYR 0x4002 2004 - 0x4002 2007 4
FLASH_OPTKEYR 0x4002 2008 - 0x4002 200B 4
FLASH_SR 0x4002 200C - 0x4002 200F 4
FLASH_CR 0x4002 2010 - 0x4002 2013 4
FLASH_AR 0x4002 2014 - 0x4002 2017 4
Reserved 0x4002 2018 - 0x4002 201B 4
FLASH_OBR 0x4002 201C - 0x4002 201F 4
FLASH_WRPR 0x4002 2020 - 0x4002 2023 4
Table 4. Flash module organization (high-density devices)
Block Name Base addresses Size (bytes)
Main memory
Page 0 0x0800 0000 - 0x0800 07FF 2 Kbytes
Page 1 0x0800 0800 - 0x0800 0FFF 2 Kbytes
Page 2 0x0800 1000 - 0x0800 17FF 2 Kbytes
Page 3 0x0800 1800 - 0x0800 1FFF 2 Kbytes
.
.
.
.
.
.
.
.
.
Page 255 0x0807 F800 - 0x0807 FFFF 2 Kbytes
Information block System memory 0x1FFF F000 - 0x1FFF F7FF 2 Kbytes
Option Bytes 0x1FFF F800 - 0x1FFF F80F 16
Flash memory
interface
registers
FLASH_ACR 0x4002 2000 - 0x4002 2003 4
FLASH_KEYR 0x4002 2004 - 0x4002 2007 4
FLASH_OPTKEYR 0x4002 2008 - 0x4002 200B 4
FLASH_SR 0x4002 200C - 0x4002 200F 4
FLASH_CR 0x4002 2010 - 0x4002 2013 4
FLASH_AR 0x4002 2014 - 0x4002 2017 4
Reserved 0x4002 2018 - 0x4002 201B 4
FLASH_OBR 0x4002 201C - 0x4002 201F 4
FLASH_WRPR 0x4002 2020 - 0x4002 2023 4
Table 3. Flash module organization (medium-density devices) (continued)
Block Name Base addresses Size (bytes)
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The Flash memory is organized as 32-bit wide memory cells that can be used for storing
both code and data constants. The Flash module is located at a specific base address in the
memory map of each STM32F10xxx microcontroller type. For the base address, please
refer to the related STM32F10xxx reference manual.
The information block is divided into two parts:
●System memory is used to boot the device in System memory boot mode. The area is
reserved for use by STMicroelectronics and contains the boot loader which is used to
reprogram the Flash memory using the USART1 serial interface. It is programmed by
ST when the device is manufactured, and protected against spurious write/erase
operations. For further details please refer to AN2606.
In connectivity line devices the boot loader can be activated through one of the
following interfaces: USART1, USART2 (remapped), CAN2 (remapped) or USB OTG
FS in Device mode (DFU: device firmware upgrade). The USART peripheral operates
with the internal 8 MHz oscillator (HSI). The CAN and USB OTG FS, however, can only
function if an external 8 MHz, 14.7456 MHz or 25 MHz clock (HSE) is present. For
further details, please refer to AN2662 (“STM32F105xx and STM32F107xx system
memory boot mode”) available from www.st.com.
●Option bytes
Write operations to the main memory block and the option bytes are managed by an
embedded Flash Program/Erase Controller (FPEC). The high voltage needed for
Program/Erase operations is internally generated.
Table 5. Flash module organization (connectivity line devices)
Block Name Base addresses Size (bytes)
Main memory
Page 0 0x0800 0000 - 0x0800 07FF 2 Kbytes
Page 1 0x0800 0800 - 0x0800 0FFF 2 Kbytes
Page 2 0x0800 1000 - 0x0800 17FF 2 Kbytes
Page 3 0x0800 1800 - 0x0800 1FFF 2 Kbytes
.
.
.
.
.
.
.
.
.
Page 127 0x0803 F800 - 0x0803 FFFF 2 Kbytes
Information block System memory 0x1FFF B000 - 0x1FFF F7FF 18 Kbytes
Option Bytes 0x1FFF F800 - 0x1FFF F80F 16
Flash memory
interface
registers
FLASH_ACR 0x4002 2000 - 0x4002 2003 4
FLASH_KEYR 0x4002 2004 - 0x4002 2007 4
FLASH_OPTKEYR 0x4002 2008 - 0x4002 200B 4
FLASH_SR 0x4002 200C - 0x4002 200F 4
FLASH_CR 0x4002 2010 - 0x4002 2013 4
FLASH_AR 0x4002 2014 - 0x4002 2017 4
Reserved 0x4002 2018 - 0x4002 201B 4
FLASH_OBR 0x4002 201C - 0x4002 201F 4
FLASH_WRPR 0x4002 2020 - 0x4002 2023 4
Overview PM0075
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The main Flash memory can be protected against different types of unwanted access
(read/write/erase). There are two types of protection:
●Page Write Protection
●Read Protection
Refer to Section 2.4 for more details.
During a write operation to the Flash memory, any attempt to read the Flash memory will
stall the bus. The read operation will proceed correctly once the write operation has
completed. This means that code or data fetches cannot be made while a write/erase
operation is ongoing.
For write and erase operations on the Flash memory (write/erase), the internal RC oscillator
(HSI) must be ON.
The Flash memory can be programmed and erased using in-circuit programming and in-
application programming.
Note: In the low-power modes, all Flash memory accesses are aborted. Refer to the
STM32F10xxx reference manual for further information.
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2 Reading/programming the embedded Flash memory
2.1 Introduction
This section describes how to read from or program to the STM32F10xxx embedded Flash
memory.
2.2 Read operation
The embedded Flash module can be addressed directly, as a common memory space. Any
data read operation accesses the content of the Flash module through dedicated read
senses and provides the requested data.
The read interface consists of a read controller on one side to access the Flash memory and
an AHB interface on the other side to interface with the CPU. The main task of the read
interface is to generate the control signals to read from the Flash memory and to prefetch
the blocks required by the CPU. The prefetch block is only used for instruction fetches over
the I-Code bus. The Literal pool is accessed over the D-Code bus. Since these two buses
have the same Flash memory as target, D-code bus accesses have priority over prefetch
accesses.
2.2.1 Instruction fetch
The Cortex-M3 fetches the instruction over the I-Code bus and the literal pool
(constant/data) over the D-code bus. The prefetch block aims at increasing the efficiency of
I-Code bus accesses.
Prefetch buffer
The prefetch buffer is 2 blocks wide where each block consists of 8 bytes. The prefetch
blocks are direct-mapped. A block can be completely replaced on a single read to the Flash
memory as the size of the block matches the bandwidth of the Flash memory.
The implementation of this prefetch buffer makes a faster CPU execution possible as the
CPU fetches one word at a time with the next word readily available in the prefetch buffer.
This implies that the acceleration ratio will be of the order of 2 assuming that the code is
aligned at a 64-bit boundary for the jumps.
Prefetch controller
The prefetch controller decides to access the Flash memory depending on the available
space in the prefetch buffer. The Controller initiates a read request when there is at least
one block free in the prefetch buffer.
After reset, the state of the prefetch buffer is on.
The prefetch buffer should be switched on/off only when SYSCLK is lower than 24 MHz and
no prescaler is applied on the AHB clock (SYSCLK must be equal to HCLK). The prefetch
buffer is usually switched on/off during the initialization routine, while the microcontroller is
running on the internal 8 MHz RC (HSI) oscillator.
Note: The prefetch buffer must be kept on (FLASH_ACR[4]=’1’) when using a prescaler different
from 1 on the AHB clock.
Reading/programming the embedded Flash memory PM0075
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In case of non-availability of a high frequency clock in the system, Flash memory accesses
can be made on a half cycle of HCLK (AHB clock), the frequency of HCLK permitting (half-
cycle access can only be used with a low-frequency clock of less than 8 MHz that can be
obtained with the use of HSI or HSE but not of PLL). This mode can be chosen by setting a
control bit in the Flash access control register.
Note: Half-cycle access cannot be used when there is a prescaler different from 1 on the AHB
clock.
Access time tuner
In order to maintain the control signals to read the Flash memory, the ratio of the prefetch
controller clock period to the access time of the Flash memory has to be programmed in the
Flash access control register. This value gives the number of cycles needed to maintain the
control signals of the Flash memory and correctly read the required data. After reset, the
value is zero and only one cycle is required to access the Flash memory.
2.2.2 D-Code interface
The D-Code interface consists of a simple AHB interface on the CPU side and a request
generator to the Arbiter of the Flash access controller. D-code accesses have priority over
prefetch accesses. This interface uses the Access Time Tuner block of the prefetch buffer.
2.2.3 Flash access controller
Mainly, this block is a simple arbiter between the read requests of the prefetch/I-code and D-
Code interfaces.
D-Code interface requests have priority over I-Code requests.
2.3 Flash program and erase controller (FPEC)
The FPEC block handles the program and erase operations of the Flash memory. The
FPEC consists of seven 32-bit registers.
●FPEC key register (FLASH_KEYR)
●Option byte key register (FLASH_OPTKEYR)
●Flash control register (FLASH_CR)
●Flash status register (FLASH_SR)
●Flash address register (FLASH_AR)
●Option byte register (FLASH_OBR)
●Write protection register (FLASH_WRPR)
An ongoing Flash memory operation will not block the CPU as long as the CPU does not
access the Flash memory.
2.3.1 Key values
The key values are as follows:
●RDPRT key = 0x00A5
●KEY1 = 0x45670123
●KEY2 = 0xCDEF89AB
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2.3.2 Unlocking the Flash memory
After reset, the FPEC block is protected. The FLASH_CR register is not accessible in write
mode. An unlocking sequence should be written to the FLASH_KEYR register to open up
the FPEC block. This sequence consists of two write cycles, where two key values (KEY1
and KEY2) are written to the FLASH_KEYR address (refer to Section 2.3.1 for key values).
Any wrong sequence locks up the FPEC block and FLASH_CR register until the next reset.
Also a bus error is returned on a wrong key sequence. This is done after the first write cycle
if KEY1 does not match, or during the second write cycle if KEY1 has been correctly written
but KEY2 does not match. The FPEC block and FLASH_CR register can be locked by the
user’s software by writing the LOCK bit of the FLASH_CR register to 1. In this case, the
FPEC can be unlocked by writing the correct sequence of keys into FLASH_KEYR.
2.3.3 Main Flash memory programming
The main Flash memory can be programmed 16 bits at a time. The program operation is
started when the CPU writes a half-word into a main Flash memory address with the PG bit
of the FLASH_CR register set. Any attempt to write data that are not half-word long will
result in a bus error response from the FPEC. If a read/write operation is initiated during
programming, (BSY bit set), the CPU stalls until the ongoing main Flash memory
programming is over.
Figure 1. Programming procedure
Read FLASH_CR_LOCK
FLASH_CR_LOCK
= 1
Yes
No
Yes
No
Perform unlock sequency
Write FLASH_CR_PG to 1
Perform half-word write at the
desired address
FLASH_SR_BSY
= 1
Check the programmed value
by reading the programmed
address ai14307b
Reading/programming the embedded Flash memory PM0075
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Standard programming
In this mode the CPU programs the main Flash memory by performing standard half-word
write operations. The PG bit in the FLASH_CR register must be set. FPEC preliminarily
reads the value at the addressed main Flash memory location and checks that it has been
erased. If not, the program operation is skipped and a warning is issued by the PGERR bit in
FLASH_SR register (the only exception to this is when 0x0000 is programmed. In this case,
the location is correctly programmed to 0x0000 and the PGERR bit is not set). If the
addressed main Flash memory location is write-protected by the FLASH_WRPR register,
the program operation is skipped and a warning is issued by the WRPRTERR bit in the
FLASH_SR register. The end of the program operation is indicated by the EOP bit in the
FLASH_SR register.
The main Flash memory programming sequence in standard mode is as follows:
●Check that no main Flash memory operation is ongoing by checking the BSY bit in the
FLASH_SR register.
●Set the PG bit in the FLASH_CR register.
●Perform the data write (half-word) at the desired address.
●Wait for the BSY bit to be reset.
●Read the programmed value and verify.
Note: The registers are not accessible in write mode when the BSY bit of the FLASH_SR register
is set.
2.3.4 Flash memory erase
The Flash memory can be erased page by page or completely (Mass Erase).
Page Erase
A page of the Flash memory can be erased using the Page Erase feature of the FPEC. To
erase a page, the procedure below should be followed:
●Check that no Flash memory operation is ongoing by checking the BSY bit in the
FLASH_CR register
●Set the PER bit in the FLASH_CR register
●Program the FLASH_AR register to select a page to erase
●Set the STRT bit in the FLASH_CR register
●Wait for the BSY bit to be reset
●Read the erased page and verify
PM0075 Reading/programming the embedded Flash memory
Doc ID 17863 Rev 2 15/31
Figure 2. Flash memory Page Erase procedure
Mass Erase
The Mass Erase command can be used to completely erase the user pages of the Flash
memory. The information block is unaffected by this procedure. The following sequence is
recommended:
●Check that no Flash memory operation is ongoing by checking the BSY bit in the
FLASH_SR register
●Set the MER bit in the FLASH_CR register
●Set the STRT bit in the FLASH_CR register
●Wait for the BSY bit to be reset
●Read all the pages and verify
Read FLASH_CR_LOCK
FLASH_CR_LOCK
= 1
Yes
No
Yes
No
Perform unlock sequency
Write into FAR an address
within the page to erase
Write FLASH_CR_PER to 1
Write FLASH_CR_STRT to 1
FLASH_SR_BSY
= 1
Check the page is erased by
reading all the addresses in
the page ai14305c
Reading/programming the embedded Flash memory PM0075
16/31 Doc ID 17863 Rev 2
Figure 3. Flash memory Mass Erase procedure
2.3.5 Option byte programming
The option bytes are programmed differently from normal user addresses. The number of
option bytes is limited to 8 (4 for write protection, 1 for read protection, 1 for configuration
and 2 for user data storage). After unlocking the FPEC, the user has to authorize the
programming of the option bytes by writing the same set of KEYS (KEY1 and KEY2) to the
FLASH_OPTKEYR register to set the OPTWRE bit in the FLASH_CR register (refer to
Section 2.3.1 for key values). Then the user has to set the OPTPG bit in the FLASH_CR
register and perform a half-word write operation at the desired Flash address.
FPEC preliminarily reads the value of the addressed option byte and checks that it has been
erased. If not, the program operation is skipped and a warning is issued by the PGERR bit in
the FLASH_SR register. The end of the program operation is indicated by the EOP bit in the
FLASH_SR register.
The FPEC takes the LSB and automatically computes the MSB (which is the complement of
the LSB) and starts the programming operation. This guarantees that the option byte and its
complement are always correct.
Read FLASH_CR_LOCK
FLASH_CR_LOCK
= 1
Yes
No
Yes
No
Perform unlock sequency
Write into FLASH_CR_MER
to 1
Write FLASH_CR_STRT to 1
FLASH_SR_BSY
= 1
Check the erase operation by
reading all the addresses in
the user memory ai14306b
PM0075 Reading/programming the embedded Flash memory
Doc ID 17863 Rev 2 17/31
The sequence is as follows:
●Check that no Flash memory operation is ongoing by checking the BSY bit in the
FLASH_SR register.
●Unlock the OPTWRE bit in the FLASH_CR register.
●Set the OPTPG bit in the FLASH_CR register
●Write the data (half-word) to the desired address
●Wait for the BSY bit to be reset.
●Read the programmed value and verify.
When the Flash memory read protection option is changed from protected to unprotected, a
Mass Erase of the main Flash memory is performed before reprogramming the read
protection option. If the user wants to change an option other than the read protection
option, then the mass erase is not performed. The erased state of the read protection option
byte protects the Flash memory.
Erase procedure
The option byte erase sequence (OPTERASE) is as follows:
●Check that no Flash memory operation is ongoing by reading the BSY bit in the
FLASH_SR register
●Unlock the OPTWRE bit in the FLASH_CR register
●Set the OPTER bit in the FLASH_CR register
●Set the STRT bit in the FLASH_CR register
●Wait for BSY to reset
●Read the erased option bytes and verify
2.4 Protections
The user area of the Flash memory can be protected against read by untrusted code. The
pages of the Flash memory can also be protected against unwanted write due to loss of
program counter contexts. The write-protection granularity is then of:
●four pages for low- and medium-density devices
●two pages for high-density and connectivity line devices.
2.4.1 Read protection
The read protection is activated by setting the RDP option byte and then, by applying a
system reset to reload the new RDP option byte.
Note: If the read protection is set while the debugger is still connected through JTAG/SWD, apply a
POR (power-on reset) instead of a system reset (without debugger connection).
Once the protection byte has been programmed:
●Main Flash memory read access is not allowed except for the user code (when booting
from main Flash memory itself with the debug mode not active).
●Pages 0-3 (for low- and medium-density devices), or pages 0-1 (for high-density and
connectivity line devices) are automatically write-protected. The rest of the memory can
be programmed by the code executed from the main Flash memory (for IAP, constant
storage, etc.), but it is protected against write/erase (but not against mass erase) in
debug mode or when booting from the embedded SRAM.
Reading/programming the embedded Flash memory PM0075
18/31 Doc ID 17863 Rev 2
●All features linked to loading code into and executing code from the embedded SRAM
are still active (JTAG/SWD and boot from embedded SRAM) and this can be used to
disable the read protection. When the read protection option byte is altered to a
memory-unprotect value, a mass erase is performed.
●When booting from the embedded SRAM, Flash memory accesses through the code
and through data read using DMA1 and DMA2 are not allowed.
●Flash memory access through data read using JTAG, SWV (serial wire viewer), SWD
(serial wire debug), ETM and boundary scan are not allowed.
The Flash memory is protected when the RDP option byte and its complement contain the
pair of values shown in Table 6.
Note: Erasing the option byte block will not trigger a mass erase as the erased value (0xFF)
corresponds to a protected value.
Unprotection
To disable the read protection from the embedded SRAM:
●Erase the entire option byte area. As a result, the read protection code (RDP) will be
0xFF. At this stage the read protection is still enabled.
●Program the correct RDP code 0x00A5 to unprotect the memory. This operation first
forces a Mass Erase of the main Flash memory.
●Reset the device (POR Reset) to reload the option bytes (and the new RDP code) and,
to disable the read protection.
Note: The read protection can be disabled using the boot loader (in this case only a System Reset
is necessary to reload the option bytes). For more details refer to AN2606.
2.4.2 Write protection
In high-density and connectivity line devices, from page 0 to page 61, write protection is
implemented with a granularity of two pages at a time. The remaining memory block (from
page 62 to page 255 in high-density devices, and from page 62 to page 127 in connectivity
line devices) is write-protected at once.
In low- and medium-density devices, write protection is implemented with a granularity of
four pages at a time.
If a program or an erase operation is performed on a protected page, the Flash memory
returns a protection error flag on the Flash memory Status Register (FLASH_SR).
The write protection is activated by configuring the WRP[3:0] option bytes, and then by
applying a system reset to reload the new WRPx option bytes.
Table 6. Flash memory protection status
RDP byte value RDP complement value Read protection status
0xFF 0xFF Protected
RDPRT Complement of RDP byte Not protected
Any value Not the complement value of RDP Protected
PM0075 Reading/programming the embedded Flash memory
Doc ID 17863 Rev 2 19/31
Unprotection
To disable the write protection, two application cases are provided:
●Case 1: Read protection disabled after the write unprotection:
– Erase the entire option byte area by using the OPTER bit in the Flash memory
control register (FLASH_CR)
– Program the correct RDP code 0x00A5 to unprotect the memory. This operation
first forces a Mass Erase of the main Flash memory.
– Reset the device (system reset) to reload the option bytes (and the new WRP[3:0]
bytes), and to disable the write protection
●Case 2: Read protection maintained active after the write unprotection, useful for in-
application programming with a user boot loader:
– Erase the entire option byte area by using the OPTER bit in the Flash memory
control register (FLASH_CR)
– Reset the device (system reset) to reload the option bytes (and the new WRP[3:0]
bytes), and to disable the write protection.
2.4.3 Option byte block write protection
The option bytes are always read-accessible and write-protected by default. To gain write
access (Program/Erase) to the option bytes, a sequence of keys (same as for lock) has to
be written into the OPTKEYR. A correct sequence of keys gives write access to the option
bytes and this is indicated by OPTWRE in the FLASH_CR register being set. Write access
can be disabled by resetting the bit through software.
2.5 Option byte description
There are eight option bytes. They are configured by the end user depending on the
application requirements. As a configuration example, the watchdog may be selected in
hardware or software mode.
A 32-bit word is split up as follows in the option bytes.
The organization of these bytes inside the information block is as shown in Table 8.
The option bytes can be read from the memory locations listed in Table 8 or from the Option
byte register (FLASH_OBR).
Note: The new programmed option bytes (user, read/write protection) are loaded after a system
reset.
Table 7. Option byte format
31-24 23-16 15 -8 7-0
complemented option
byte1 Option byte 1 complemented option
byte0 Option byte 0
Reading/programming the embedded Flash memory PM0075
20/31 Doc ID 17863 Rev 2
Table 8. Option byte organization
Address [31:24] [23:16] [15:8] [7:0]
0x1FFF F800 nUSER USER nRDP RDP
0x1FFF F804 nData1 Data1 nData0 Data0
0x1FFF F808 nWRP1 WRP1 nWRP0 WRP0
0x1FFF F80C nWRP3 WRP3 nWRP2 WRP2
Table 9. Description of the option bytes
Flash memory
address Option bytes
0x1FFF F800
Bits [31:24] nUSER
Bits [23:16] USER: User option byte (stored in FLASH_OBR[9:2])
This byte is used to configure the following features:
– Select the watchdog event: Hardware or software.
– Reset event when entering Stop mode.
– Reset event when entering Standby mode.
Note: Only bits [16:18] are used, bits [23:19]: 0x1F are not used.
Bit 18: nRST_STDBY
0: Reset generated when entering Standby mode.
1: No reset generated.
Bit 17: nRST_STOP
0: Reset generated when entering Stop mode
1: No reset generated
Bit 16: WDG_SW
0: Hardware watchdog
1: Software watchdog
Bits [15:8]: nRDP
Bits [7:0]: RDP: Read protection option byte
The read protection helps the user protect the software code stored in Flash
memory. It is activated by setting the RDP option byte.
When this option byte is programmed to a correct value (RDPRT key = 0x00A5),
read access to the Flash memory is allowed.
(The result of RDP level enabled/disabled is stored in FLASH_OBR[1].)
0x1FFF F804
Datax: Two bytes for user data storage.
These addresses can be programmed using the option byte programming
procedure.
Bits [31:24]: nData1
Bits [23:16]: Data1 (stored in FLASH_OBR[25:18])
Bits [15:8]: nData0
Bits [7:0]: Data0 (stored in FLASH_OBR[17:10])
0x1FFF F808
WRPx: Flash memory write protection option bytes
Bits [31:24]: nWRP1
Bits [23:16]: WRP1 (stored in FLASH_WRPR[15:8])
Bits [15:8]: nWRP0
Bits [7:0]: WRP0 (stored in FLASH_WRPR[7:0])
PM0075 Reading/programming the embedded Flash memory
Doc ID 17863 Rev 2 21/31
0x1FFF F80C
WRPx: Flash memory write protection option bytes
Bits [31:24]: nWRP3
Bits [23:16]: WRP3 (stored in FLASH_WRPR[31:24])
Bits [15:8]: nWRP2
Bits [7:0]: WRP2 (stored in FLASH_WRPR[23:16])
●For low-density devices, one bit of the user option bytes WRPx is used to
protect 4 pages of 1 Kbyte in main memory block.
– 0: Write protection active
– 1: Write protection not active
In total, one user option byte is used to protect the 32-Kbyte main Flash memory.
WRP0: Write-protects pages 0 to 31
●For medium-density devices, one bit of the user option bytes WRPx is used to
protect 4 pages of 1 Kbyte in main memory block.
– 0: Write protection active
– 1: Write protection not active
In total, four user option bytes are used to protect the 128-Kbyte main Flash
memory.
WRP0: Write-protects pages 0 to 31
WRP1: Write-protects pages 32 to 63
WRP2: Write-protects pages 64 to 95
WRP3: Write-protects pages 96 to 127
●For high-density devices, one bit of the user option bytes WRPx is used to
protect 2 pages of 2 Kbytes in main memory block. However, the bit 7 of
WRP3 write protects pages 62 to 255.
– 0: Write protection active
– 1: Write protection not active
In total, four user option bytes are used to protect the 512-Kbyte main Flash
memory.
WRP0: Write-protects pages 0 to 15.
WRP1: Write-protects pages 16 to 31.
WRP2: Write-protects pages 32 to 47.
WRP3: bits 0-6 write-protect pages 48 to 61
bit 7 write-protects pages 62 to 255.
●For connectivity line devices, one bit of the user option bytes WRPx is used to
protect 2 pages of 2 Kbytes in main memory block. However, the bit 7 of
WRP3 write-protects pages 62 to 127.
– 0: Write protection active
– 1: Write protection not active
In total, four user option bytes are used to protect the 256-Kbyte main Flash
memory.
WRP0: Write-protects pages 0 to 15.
WRP1: Write-protects pages 16 to 31.
WRP2: Write-protects pages 32 to 47.
WRP3: bits 0-6 write-protect pages 48 to 61
bit 7 write-protects pages 62 to 127.
Table 9. Description of the option bytes (continued)
Flash memory
address Option bytes
Reading/programming the embedded Flash memory PM0075
22/31 Doc ID 17863 Rev 2
On every system reset, the option byte loader (OBL) reads the information block and stores
the data into the Option byte register (FLASH_OBR) and the Write protection register
(FLASH_WRPR). Each option byte also has its complement in the information block. During
option loading, by verifying the option bit and its complement, it is possible to check that the
loading has correctly taken place. If this is not the case, an option byte error (OPTERR) is
generated. When a comparison error occurs the corresponding option byte is forced to
0xFF. The comparator is disabled when the option byte and its complement are both equal
to 0xFF (Electrical Erase state).
All option bytes (but not their complements) are available to configure the product. The
option registers are accessible in read mode by the CPU. See Section 3: Register
descriptions for more details.
PM0075 Register descriptions
Doc ID 17863 Rev 2 23/31
3 Register descriptions
In this section, the following abbreviations are used:
Note: The Flash memory registers have to be accessed by 32-bit words (half-word and byte
accesses are not allowed).
3.1 Flash access control register (FLASH_ACR)
Address offset: 0x00
Reset value: 0x0000 0030
Table 10. Abbreviations
Abbreviation Meaning
read/write (rw) Software can read from and write to these bits.
read-only (r) Software can only read these bits.
write-only (w) Software can only write to this bit. Reading the bit returns the reset
value.
read/clear (rc_w0) Software can read as well as clear this bit by writing ‘0’. Writing ‘1’ has
no effect on the bit value.
read/set (rs) Software can read as well as set this bit. Writing ‘0’ has no effect on
the bit value.
Reserved (Res.) Reserved bit, must be kept at reset value.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
Reserved
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Reserved
PRFT
BS PRFT
BE HLF
CYA LATENCY
rrwrwrwrwrw
Bits 31:6 Reserved, must be kept cleared.
Bit 5 PRFTBS: Prefetch buffer status
This bit provides the status of the prefetch buffer.
0: Prefetch buffer is disabled
1: Prefetch buffer is enabled
Bit 4 PRFTBE: Prefetch buffer enable
0: Prefetch is disabled
1: Prefetch is enabled
Bit 3 HLFCYA: Flash half cycle access enable
0: Half cycle is disabled
1: Half cycle is enabled
Register descriptions PM0075
24/31 Doc ID 17863 Rev 2
3.2 FPEC key register (FLASH_KEYR)
Address offset: 0x04
Reset value: xxxx xxxx
Note: These bits are all write-only and will return a 0 when read.
3.3 Flash OPTKEY register (FLASH_OPTKEYR)
Address offset: 0x08
Reset value: xxxx xxxx
Note: These bits are all write-only and will return a 0 when read.
Bits 2:0 LATENCY: Latency
These bits represent the ratio of the SYSCLK (system clock) period to the Flash access
time.
000 Zero wait state, if 0 < SYSCLK≤ 24 MHz
001 One wait state, if 24 MHz < SYSCLK ≤ 48 MHz
010 Two wait states, if 48 MHz < SYSCLK ≤ 72 MHz
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
FKEYR[31:16]
wwwwwww wwwwwwwww
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
FKEYR[15:0]
wwwwwww wwwwwwwww
Bits 31:0 FKEYR: FPEC key
These bits represent the keys to unlock the FPEC.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
OPTKEYR[31:16]
wwwwwww wwwwwwwww
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
OPTKEYR[15:0]
wwwwwww wwwwwwwww
Bits 31:0 OPTKEYR: Option byte key
These bits represent the keys to unlock the OPTWRE.
PM0075 Register descriptions
Doc ID 17863 Rev 2 25/31
3.4 Flash status register (FLASH_SR)
Address offset: 0x0C
Reset value: 0x0000 0000
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
Reserved
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Reserved EOP WRPRT
ERR Res.
PG
ERR Res. BSY
rw rw rw r
Bits 31:6 Reserved, must be kept cleared.
Bit 5 EOP: End of operation
Set by hardware when a Flash operation (programming / erase) is completed. Reset by
writing a 1
Note: EOP is asserted at the end of each successful program or erase operation
Bit 4 WRPRTERR: Write protection error
Set by hardware when programming a write-protected address of the Flash memory.
Reset by writing 1.
Bit 3 Reserved, must be kept cleared.
Bit 2 PGERR: Programming error
Set by hardware when an address to be programmed contains a value different from
'0xFFFF' before programming.
Reset by writing 1.
Note: The STRT bit in the FLASH_CR register should be reset before starting a programming
operation.
Bit 1 Reserved, must be kept cleared
Bit 0 BSY: Busy
This indicates that a Flash operation is in progress. This is set on the beginning of a Flash
operation and reset when the operation finishes or when an error occurs.
Register descriptions PM0075
26/31 Doc ID 17863 Rev 2
3.5 Flash control register (FLASH_CR)
Address offset: 0x10
Reset value: 0x0000 0080
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
Reserved
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Reserved EOPIE Res. ERRIE OPTWR
ERes. LOCK STRT OPTER OPT
PG Res. MER PER PG
rw rw rw rw rw rw rw rw rw rw
Bits 31:13 Reserved, must be kept cleared.
Bit 12 EOPIE: End of operation interrupt enable
This bit enables the interrupt generation when the EOP bit in the FLASH_SR register goes
to 1.
0: Interrupt generation disabled
1: Interrupt generation enabled
Bit 11 Reserved, must be kept cleared
Bit 10 ERRIE: Error interrupt enable
This bit enables the interrupt generation on an FPEC error (when PGERR / WRPRTERR are
set in the FLASH_SR register).
0: Interrupt generation disabled
1: Interrupt generation enabled
Bit 9 OPTWRE: Option bytes write enable
When set, the option bytes can be programmed. This bit is set on writing the correct key
sequence to the FLASH_OPTKEYR register.
This bit can be reset by software
Bit 8 Reserved, must be kept cleared.
Bit 7 LOCK: Lock
Write to 1 only. When it is set, it indicates that the FPEC and FLASH_CR are locked. This bit
is reset by hardware after detecting the unlock sequence.
In the event of unsuccessful unlock operation, this bit remains set until the next reset.
Bit 6 STRT: Start
This bit triggers an ERASE operation when set. This bit is set only by software and reset
when the BSY bit is reset.
Bit 5 OPTER: Option byte erase
Option byte erase chosen.
Bit 4 OPTPG: Option byte programming
Option byte programming chosen.
Bit 3 Reserved, must be kept cleared.
Bit 2 MER: Mass erase
Erase of all user pages chosen.
Bit 1 PER: Page erase
Page Erase chosen.
Bit 0 PG: Programming
Flash programming chosen.
PM0075 Register descriptions
Doc ID 17863 Rev 2 27/31
3.6 Flash address register (FLASH_AR)
Address offset: 0x14
Reset value: 0x0000 0000
Updated by hardware with the currently/last used address. For Page Erase operations, this
should be updated by software to indicate the chosen page.
3.7 Option byte register (FLASH_OBR)
Address offset 0x1C
Reset value: 0x03FF FFFC
Note: The reset value of this register depends on the value programmed in the option byte and the
OPTERR bit reset value depends on the comparison of the option byte and its complement
during the option byte loading phase.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
FAR[31:16]
wwwwwww wwwwwwww w
1514131211109 87654321 0
FAR[15:0]
wwwwwww wwwwwwww w
Bits 31:0 FAR: Flash Address
Chooses the address to program when programming is selected, or a page to erase when
Page Erase is selected.
Note: Write access to this register is blocked when the BSY bit in the FLASH_SR register is
set.
313029282726252423222120191817161514131211109876543210
Reserved Data1 Data0 Not used
nRST_STDBY
nRST_STOP
WDG_SW
RDPRT
OPTERR
rrrrrrrrrrrrrrrrrrrrrrrrrr
Bits 31:26 Reserved, must be kept cleared.
Bits 25:18 Data1
Bits 17:10 Data0
Bits 9:2 USER: User option bytes
This contains the user option byte loaded by the OBL.
Bits [9:5]: Not used (if these bits are written in the Flash option byte, they will be read in this
register with no effect on the device.)
Bit 4: nRST_STDBY
Bit 3: nRST_STOP
Bit 2: WDG_SW
Register descriptions PM0075
28/31 Doc ID 17863 Rev 2
3.8 Write protection register (FLASH_WRPR)
Address offset: 0x20
Reset value: 0xFFFF FFFF
Bit 1 RDPRT: Read protection
When set, this indicates that the Flash memory is read-protected.
Note: This bit is read-only.
Bit 0 OPTERR: Option byte error
When set, this indicates that the loaded option byte and its complement do not match. The
corresponding byte and its complement are read as 0xFF in the FLASH_OBR or
FLASH_WRPR register.
Note: This bit is read-only.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
WRP[31:16]
rrrrrrr rrrrrrrr r
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
WRP[15:0]
rrrrrrr rrrrrrrr r
Bits 31:0 WRP: Write protect
This register contains the write-protection option bytes loaded by the OBL.
0: Write protection active
1: Write protection not active
Note: These bits are read-only.
PM0075 Register descriptions
Doc ID 17863 Rev 2 29/31
3.9 Flash register map
Table 11. Flash interface - register map and reset values
Offset Register
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
0x000 FLASH_ACR Reserved
PRFTBS
PRFTBE
HLFCYA
LATENCY
[2:0]
Reset value 110000
0x004 FLASH_KEYR FKEYR[31:0]
Reset value xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
0x008 FLASH_OPTKEYR OPTKEYR[31:0]
Reset Value xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
0x00C FLASH_SR Reserved
EOP
WRPRTERR
Reserved
PGERR
ERLYBSY
BSY
Reset value 00 000
0x010 FLASH_CR Reserved
EOPIE
Reserved
ERRIE
OPTWRE
Reserved
LOCK
STRT
OPTER
OPTPG
Reserved
MER
PER
PG
Reset value 0000 1000 000
0x014 FLASH_AR FAR[31:0]
Reset value 00000000000000000000000000000000
0x018 Reserved
0x01C FLASH_OBR Reserved Data1 Data0 Not used
nRST_STDBY
nRST_STOP
WDG_SW
RDPRT
OPTERR
Reset value 11111111111111111111111100
0x020 FLASH_WRPR WRP[31:0]
Reset value 11111111111111111111111111111111
Revision history PM0075
30/31 Doc ID 17863 Rev 2
4 Revision history
Table 12. Document revision history
Date Revision Changes
30-Aug-2010 1 Initial release. Same content as PM0042 revision 8.
27-Aug-2012 2 Updated Section 2.3.5: Option byte programming on page 16.
PM0075
Doc ID 17863 Rev 2 31/31
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