I'm using stm32l073 board, and doing delta update for OTA, that need write single byte to flash, but I check the example there write to flash by using double word(4 bytes). Can write single byte to flash? or can't?
It is not designed to write bytes, the flash line has a 64-bit width plus some error-correction bits. For configuration parameters I use larger structures and write as a block as a multiple of 8-bytes. You can also journal in this fashion so as not to burn through erase-write cycles, and to wear level.