Can't write to flash memory after erase

Question

So I can't write to internal flash memory directly after erasing it. If there's no erase operation before write operation, then I can. Any ideas as to why?

Programming function returns 'successful write' value, but when looking at memory, no data is written. Here's the code:

uint32_t pageAddress = 0x08008000;
uint16_t buffer = 0xAAAA;

HAL_FLASH_Unlock();
FLASH_PageErase(pageAddress);
HAL_FLASH_Program(TYPEPROGRAM_HALFWORD, pageAddress, buffer);
HAL_FLASH_Lock();

I've tried locking the memory between erasing and programming it, creating a delay between these operations, that doesn't help.

Frond

Do the flash erase/write calls not return any status/error information? – Scorper

@MartinJames 'FLASH_PageErase()' doesn't. 'HAL_FLASH_Program()' does, and it's 'HAL_OK' regardless of whether writing was actually successful or not. – Frond

What happens if you just replace HAL_FLASH_Program() by FLASH_Program_HalfWord() ? – Nordgren

Answer 1

The problem was that PER bit in FLASH->CR register which is set when FLASH_PageErase() is called isn't cleared at the end of it. Clearing this bit while flash is still unlocked allows other operations on flash to be run after that.

STM documentation has nothing to say about this.

Frond

You saved my day. Another thing I noticed is, that when you try to perform few consecutive stores (using HAL_FLASH_Program) you have to clear PG bit after each operation (at least that was my case on STM32F072). So I modified my program so it performs CLEAR_BIT (FLASH->CR, (FLASH_CR_PER)) after page clear and CLEAR_BIT (FLASH->CR, (FLASH_CR_PG)) after programming a word. – Revolutionize

i wanted to erase a page and i called FLASH_pageErase (pageaddress) but after erasing I'm not able to burn code into ST.Its showing"internal command Error" and "Flash download failed " what may be the issue? – Shirleeshirleen

Load "abc\\abc.axf" Error: Flash Download failed - Target DLL has been cancelled Flash Load finished at 15:08:10 Load "abc\\abc.axf" Error: Flash Download failed - Target DLL has been cancelled Flash Load finished at 15:08:18 – Shirleeshirleen

OMG. You saved my day, an incorrect AND! My code was |= !PER, instead |= ~PER. Damn! Thanks a bunch. – Eliseelisee

:) this was great help for me. THANK YOU – Camacho

Answer 2

You can use HAL_FLASHEx_Erase instead.

uint32_t pageAddress = 0x0801FC00;
FLASH_EraseInitTypeDef EraseInitStruct;
uint32_t page_err;

EraseInitStruct.TypeErase = FLASH_TYPEERASE_PAGES;
EraseInitStruct.PageAddress = pageAddress;
EraseInitStruct.NbPages = 1;

uint32_t buffer = 0xC0FFEE;
HAL_FLASH_Unlock();
HAL_FLASHEx_Erase(&EraseInitStruct, &page_err);
HAL_FLASH_Program(FLASH_TYPEPROGRAM_WORD, pageAddress, buffer);
HAL_FLASH_Lock();

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