ST STM32F0
The ST STM32F0 devices are Cortex-M0 based MCUs with low-power functionality.
Contents
Internal Flash
The internal flash is divided into 3 different regions:
Region name | Range | Programmable | Supported by J-Link |
---|---|---|---|
Main flash memory | 0x0800_0000 - 0x0800_7FFF | ||
Option bytes | 0x1FFF_F800 - 0x1FFF_F80F |
Reset
For the STM32F0 devices, the Cortex-M default reset strategy is used.
Debug specific
- If no connection can be established the J-Link will try to connect to the device via a connect under reset.
- On connect, some DBGMCU registers will be written to
- freeze the watchdogs during halt to prevent unintended resets.
- prevent the connection from breaking after the CPU enters deepsleep.
- When closing the J-Link connection, the DBGMCU registers are reset.
Option Byte Programming in J-Flash
J-Flash supports programming of the option bytes for STM32F0 devices. In order to program the option bytes simply choose the appropriate Device, which allows option byte programming, in the CPU settings tab (e.g. STM32F030CC (allow opt. bytes)). J-Flash will allow programming a virtual 16-byte sector at address 0x06000000 which represents the 8 option bytes and their complements. You do not have to care about the option bytes complements since they are calculated automatically. The following table describes the structure of the option bytes sector:
Address | [31:24] | [23:16] | [15:08] | [07:00] |
---|---|---|---|---|
0x06000000 | complement | Option byte 1 | complement | Option byte 0 |
0x06000004 | complement | Option byte 3 | complement | Option byte 2 |
0x06000008 | complement | Option byte 5 | complement | Option byte 4 |
0x0600000C | complement | Option byte 7 | complement | Option byte 6 |
- Writing a value of 0xFF inside option byte 0 will read-protect the STM32F0. In order to keep the device unprotected you have to write the key value 0xAA into option byte 0.
- The address 0x06000000 is a virtual address only. The option bytes are originally located at address 0x1FFFF800. The remap from 0x06000000 to 0x1FFFF800 is done automatically by J-Flash.
Example
To program the option bytes 2 and 3 with the values 0xAA and 0xBB, but leave the device unprotected your option byte sector (at addr 0x06000000) should look like as follows:
Address | [31:24] | [23:16] | [15:08] | [07:00] |
---|---|---|---|---|
0x06000000 | 0x00 | 0xFF | 0x55 | 0xAA |
0x06000004 | 0x44 | 0xBB | 0x55 | 0xAA |
0x06000008 | 0x00 | 0xFF | 0x00 | 0xFF |
0x0600000C | 0x00 | 0xFF | 0x00 | 0xFF |
For a detailed description of each option byte, please refer to ST reference manual RM0091, section "Option bytes".
Securing/unsecuring the device
Please refer to the generic wiki-article: STM32#MCU_Security