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?
that depends entirely on the ST hardware implementation - it has nothing to do with Keil or ARM.
You need to consult the stm32l073 chip documentation for details of its flash implementation and capabilities.
www.st.com/.../stm32l073rz.html
Note the link there for ST's Support & Community.
OK. thanks for your reply. I will ask the ST for support.
Be sure to study their documentation first!
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.