Flash writing issue

[IK]

Hi I'am using two different boards stm32f411 and stm32h723zg, so I am trying to write one byte data on flash which is 0xFF -> 0x70-> 0x10 -> 0x00 on same address in the sequence without erasing the flash, it’s working for stm32f411 but it doesn’t support for stm32h723zg. In order to write the above sequence on stm32h723zg I have to erase the entire sector.

1. So basically (0xFF -> 0x70-> 0x10 -> 0x00) these are flags which I need to update on same address. How to solve this issue without erasing sector?
2. also need know why it is working for stm32f411 and why it is not wrking for stm32h723

[Uwe Bonnes]

H7 programms flash in 256 bit units and use an ECC on these units. You can only flash some non-null value once after erase but you can also flash a none-null unit to all null . F4 allows even byte programming an can overwrite set bits to zeros in several steps.