STM32H730VBT6 write user settings in FLASH

[Baxtouxe]

I couldn’t figure out how to write a simple code to write some bytes at the end of the Flash on my STM32H7. I don’t need much bytes, only one uint32_t.

I tried using HAL_FLASH_Program by unlocking the flash first but couldn’t make it work..

Any help?

 

[Tesla DeLorean]

Problems here are there's only one flash sector (128KB), you can only write once per erase cycle, the flash line is 256-bits wide (32-bytes), so you're probably going to want a section toward the end, and journal your writes such that you can write sequential words, and recover the settings from the last set.

The HAL H7 libraries should have examples of writing to FLASH, use those as the basis for your code.

[Baxtouxe]

Thanks for your quick reply.

Any idea where I can find a HAL H7 example to write in the Flash? 

[TDK]

> Any idea where I can find a HAL H7 example to write in the Flash? 

Use the Example Selector in CubeMX to find and run relevant examples.

 

[Tesla DeLorean]

Might I suggest looking through the repositories locally with a file browser or manager, or on GitHub directly?

https://github.com/STMicroelectronics/STM32CubeH7/tree/master/Projects/NUCLEO-H723ZG/Examples/FLASH/FLASH_EraseProgram

[MM..1]

You choice MCU not optimized for this. You dont specify where is your code flashing placed ? External QSPI?

Optimal simple way is use external I2C EEPROM, but if you strict require write, your flash is with CRC and can write only once into 32 bounded bytes area. And when is flash full of additional flashing , you need reflash full sw.

 

[Baxtouxe]

I'm trying to add this small data at the very end of the program FLASH, as far as possible from the code.

[Baxtouxe]

I'm not sure which STM32 would be closest to my STM32H730VBT6 to take an example from. STM32H74x? Or STM32H735x?

[MM..1]

If your write is only once and ontime programming , why not use stmCubeprogrammer cmdline?

[Baxtouxe]

I'd like to write when a specific command comes through the UART

[Pavel A.]

> Would Option Bytes by a solution to my problem?

Option Bytes - not at all. A similar topic was here recently, about some other STM32. A short summary: unless the firmware install procedure has filled the whole flash page, you can find properly aligned empty space past the firmware image and write your data there. Properly aligned here means on 32 bytes boundary.  Write also in multiples of 32 bytes (256 bits). 

Also, as Tesla DeLorean noted, "value line" STM32H7 can actually have more than one flash page, but its up to you to find them and verify they are working. YMMV.

[Baxtouxe]

Writing at the end of the firmware sounds like a great idea.

Do I need to erase the bytes first? Or is it a simple as :

uint32_t data[8] = { 0x123456778,
0x123456778,
0x123456778,
0x123456778,
0x123456778,
0x123456778,
0x123456778,
0x123456778,
};
void writeUserSettings(uint32_t* data, uint32_t address)
{
HAL_FLASH_Unlock();
HAL_FLASH_Program(FLASH_TYPEPROGRAM_FLASHWORD, address, data);
HAL_FLASH_Lock();
}

[Pavel A.]

As simple as. Locate an empty place and write.

[Baxtouxe]

Can you be more specific? I know the address where I want to write but don’t know how to

[Pavel A.]

Yes. Unlock, then write. Then lock (optionally). 

[Tesla DeLorean]

The memory must be in an erased state, and then you get one-shot writing it. Perhaps check content first?

When you write/download your test app in the debugger it's going to erase the memory within the whole 128KB sector. You don't need to erase it again, as this will also erase your application, but you'll get one chance to write each block of 32-bytes. You can walk forward, or backward, within memory and write those slots.

https://github.com/STMicroelectronics/STM32CubeH7/blob/master/Projects/NUCLEO-H723ZG/Examples/FLASH/FLASH_EraseProgram/Src/main.c#L131