NUCLEO-H743ZI EEPROM_Emulation Bug

[Gorden1970]

\Projects\NUCLEO-H743ZI\Applications\EEPROM\EEPROM_Emulation\Src\eeprom.c, EE_VerifyPageFullWriteVariable function

SCB_EnableICache() was issued at an inappropriate location

[TOUNSTM]

Hello @Gorden1970,

I tried to run the EEPROM_Emulation example onNUCLEO-H743ZI board using IAR version 9.40.1 and achieved the expected behavior as described in the readme.md file. Could you please give me more details about the issue you're experiencing and how I might be able to reproduce it?

Best regards,

[Gorden1970]

In my test steps, as long as I call EE_VerifyPageFullWriteVariable, I will find that the overall performance is reduced. Finally, I found that the SCB_EnableICache I originally set would be changed to SCB_DisableICache

[TOUNSTM]

Hello @Gorden1970,

After discussing with our experts, they explained that disabling the I-Cache before performing flash program/erase operations is essential to ensure data integrity and proper execution. This is why the SCB_EnableICache() and SCB_DisableICache() functions were added to the EE_VerifyPageFullWriteVariable() API. However, your concern is valid—frequent enabling and disabling of the instruction cache (I-Cache) can lead to performance degradation, as it is indeed a resource-intensive operation. I hope this addresses your concern. Could you let me know if further clarification is needed?

Best regards,

[billybednar]

I believe the issue is that EE_VerifyPageFullWriteVariable only re-enables the cache when it returns a PAGE_FULL error and not on success or flash error. There should be a call to SCB_EnableICache before all of the return statements that come after the disabling. As-is, it appears that the cache will always end up disabled since the caller will handle the page full case by retrying on an empty page.

STM32CubeH7/Projects/NUCLEO-H743ZI/Applications/EEPROM/EEPROM_Emulation/Src/eeprom.c

Lines 617 to 649 in bf1cd36

	SCB_DisableICache();
	/* Check each active page address starting from beginning */
	while (Address < PageEndAddress)
	{
	/* Verify if Address and Address+2 contents are 0xFFFFFFFF */
	if ((*(__IO uint32_t*)Address) == 0xFFFFFFFF)
	{
	/* Set variable data */
	FlashStatus = HAL_FLASH_Program(FLASH_TYPEPROGRAM_FLASHWORD, Address, ((uint32_t)data32));
	/* If program operation was failed, a Flash error code is returned */
	if (FlashStatus != HAL_OK)
	{
	return FlashStatus;
	}
	/* Set variable virtual address */
	FlashStatus = HAL_FLASH_Program(FLASH_TYPEPROGRAM_FLASHWORD, Address + 32, ((uint32_t)VirtAddress1));
	/* Return program operation status */
	return FlashStatus;
	}
	else
	{
	/* Next address location */
	Address = Address + 64;
	}
	}
	SCB_EnableICache();
	/* Return PAGE_FULL in case the valid page is full */
	return PAGE_FULL;
	}

[TOUNSTM]

ST Internal Reference: 219313