Problem in using flash memory of STM32H745

[hryu.1]

MCU : STM32H745

Boot : booting from user main memory(0x08000000 )of flash memory ( boot0 :low)

compiler: IAR

I am coding to write in address 0x08060000 of flash memory in Cortex M7 .

Cache is enabled, MPU is configured below

After at first writing 44444(0xad9c) , writing same value (44444) in same address , everything works well

But I have problem in writing different value(44443) in same address

this is state of memory after writing 44444(0xad9c)

and this is state of memory after writing 44443 which is different value than before.

Memory is changed strangely .

since this, reading of the value will result in an error.

I don't understand why

[Tesla DeLorean · Accepted solution]

Because the Flash lines are wide, have ECC, and cannot be written multiple times, even if just knocking down bits.

I​f you want to change content expect to Erase first. Consider journalling data over subsequent words.