I tried to load the application code from my stm32f407 board to stm32f100 by rs232 and the bootloader inside the stm32f100. I set the baudrate as 19200, 8bit, parity-even, one-stop bit per the application note. However, I can only receive 0x79 from the stm32f100 by luck. Sometime, the acknowledge is 0x72 or something else. Once I got 0x79, I send two bytes such as 0x00, 0xff and I got 0x79 and no more. What is wrong with my procedure?