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okelly
okelly
Associate II
March 3, 2015
Question

PGERR writing user data option bytes STM32F103RE

  • March 3, 2015
  • 3 replies
  • 1574 views
Posted on March 03, 2015 at 18:44

Hi all,

I am trying to read and write the STM32F103 user data bytes (Data0 and Data1 in Table 8 of STM32F10xxx PM0075 Programming manual).

I wrote this code to set Data0 to value 0x1B:

  FLASH_UnlockBank1();                                         // step 1

  flashStatus = FLASH_ProgramOptionByteData(0x1FFFF804, 0x1b); // step 2

  FLASH_LockBank1();                                           // step 3

and the result after step 2 is 

  flashStatus == FLASH_ERROR_PG

and the memory at 0x1FFFF804 has not changed.

Is there more that I should be doing to establish the proper context for executing step 2?

When I succeed, will the change to Data0 be immediately readable, or does the CPU need to go through a reset cycle for the updated option bytes to be visible?

At the assignment moment within FLASH_ProgramOptionByteData(), just before *address=data, we have FLASH_CR==OPTWRE|OPTPG and all the other control bits are zero.

Before the assignment, FLASH_SR==EOP; after the assignment, FLASH_SR==PGERR|EOP.

The FLASH_* functions are from stm32f10x_flash.c V3.6.1 .

Thank you for any advice or example code.

Owen

#flash #option-bytes
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3 replies

Tesla DeLorean
Tesla DeLorean
Guru
March 3, 2015
Posted on March 03, 2015 at 19:23 

/* Unlock the Flash Program Erase controller */
FLASH_Unlock();
/* Clear All pending flags */
FLASH_ClearFlag(FLASH_FLAG_BSY | FLASH_FLAG_EOP|FLASH_FLAG_PGERR |FLASH_FLAG_WRPRTERR);
/* Erase all the option Bytes */
FLASHStatus = FLASH_EraseOptionBytes();
FLASHStatus = FLASH_ProgramOptionByteData(0x1FFFF804, 0x1B);
/* Generate System Reset to load the new option byte values */
NVIC_SystemReset();
or
/* Lock the Flash Program Erase controller */
FLASH_Lock();

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okelly
okellyAuthor
Associate II
March 3, 2015
Posted on March 03, 2015 at 19:49

Thank you, that is incredibly helpful.

If I understand correctly then, in order to change Data0 and not affect other things, I must first read out DATA1, USER, RDP, WRP0, WRP1, WRP2, WRP3 and then write them back after the erase. Is that correct?

Owen

Tesla DeLorean
Tesla DeLorean
Guru
March 3, 2015
Posted on March 03, 2015 at 19:53

I haven't used STM32F1 parts actively for several years, but yes I believe you'd have to save whatever content you wish to preserve.

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