I am about to rewrite CPU internal flash ROM with HAL function. There is something I do not understand so please let me ask a question.
The CPU used is STM32F4.
I'm writing by the uint16_t unit. HAL_ERASEx...function are being used.
1. Before writing, is it necessary to "read two bytes anywhere on the flash and write the same data to the same place"?
2. Is delay necessary behind ERASE? If necessary, how much is its delay time?
3. Uint16_t Is delay required after writing unit? If so, what is the delay time?
4. Writing in of a flash, interrupt disabled status, ( __disable_irq()), I think it should be done and carried out. 1) Is interrupt disabled processing necessary? 2)Does the HAL_flash-function normally move by interrupt disabled status?
dummyFlash(); by carrying out. I wrote and it became OK.
When I don't act, all everything's writing in related functions of after HAL-Function are an error. (I write and don't stick to the address.) Is there any previous setting?
dummyFlash(); → In 0x08000000* (0x08000000) is written in before flash rewriting of internal organs after a microcomputer reset now.
--Source code-- void test() { dummyFlash(); uint16_t dt[] = { 0x0123, 0x4567 }; internalFlashWrite(1, 0x08004000, dt, 2); }
//-------------------------------------------------------------------------- // internal Flash sector erase // in // uint32_t eraseSector : erase sector no.(0~11) //-------------------------------------------------------------------------- HAL_StatusTypeDef internalFlashErase(uint32_t eraseSector, uint32_t *SectorError) { FLASH_EraseInitTypeDef FEITdef;
FEITdef.TypeErase = FLASH_TYPEERASE_SECTORS; FEITdef.Banks = FLASH_BANK_1; FEITdef.Sector = eraseSector; FEITdef.NbSectors = 1; FEITdef.VoltageRange = FLASH_VOLTAGE_RANGE_3;
HAL_StatusTypeDef r = HAL_FLASHEx_Erase(&FEITdef, SectorError);
return r; }
//-------------------------------------------------------------------------- // dummy flash //-------------------------------------------------------------------------- void dummyFlash() { uint16_t dt = *(uint16_t *)0x08000000; HAL_FLASH_Program(TYPEPROGRAM_HALFWORD, 0x08000000, dt); }
//-------------------------------------------------------------------------- // internal Flash sector write // in // uint32_t eraseSector : 0~11 // uint32_t addr : write flash $ // uint16_t *dt : write data // uint32_t halfWordSize : half word size //-------------------------------------------------------------------------- void internalFlashWrite(uint32_t eraseSector, uint32_t addr, uint16_t *dt,uint32_t halfWordSize) { uint32_t SectorError = 0; HAL_StatusTypeDef r;
r = HAL_FLASH_Unlock(); if( r != HAL_OK ) return;
r = internalFlashErase(eraseSector, &SectorError); if (r != HAL_OK) return;
for (uint32_t i = 0; i < halfWordSize; i++) { r = HAL_FLASH_Program(TYPEPROGRAM_HALFWORD, addr + (i * 2), *(dt + i)); if(r != HAL_OK) return; } r = HAL_FLASH_Lock(); if( r != HAL_OK ) return; }
>>Before writing, is it necessary to "read two bytes anywhere on the flash and write the same data to the same place"?
No, this seems to be a totally unnecessary step. You think this why? Writing to 0x08000000 is something you'd want to avoid. You'd want to clear any pending errors. Erasing blocks you are currently executing from will likely crash the system. Both Erase and Write are self timing, functions return when complete or on failure, check the status returned. The CPU will block if you execute code from the same flash bank you are erasing or writing. This will also limit realtime responsiveness of interrupts, etc. If this is important run code from RAM, with vector table there too. To speed things up you might want to read the memory words to a) ensure they are blank, b) already contain the data you plan on writing.
Read the manual, and review IAP/FLASH examples provided in the libraries.
There are posting instructions for source code, read them.
thank you for your answer.
I want to rewrite the built-in flash to update the program by itself.
Rewriting is not performed on the part where the program to be rewritten exists.
I'd like to ask if the above contents are necessary while updating that program.
You would have to be really sure that the meaning of "the part where" is exactly the same to you on one hand, and the flash programming unit on the other. Odds are they're not.
Just because you're not literally erasing the very branch of the code you're currently executing from under youreself, that doesn't mean that particular region is available for code to run in while an erase is in progress.