STM32WL5MOC Bootloader NACK

[alexemdesgagne]

Hi,

I'm having an issue regarding sending commands to the Bootloader by UART. My commands are followed by a NACK. I'm working with an STM32WL5MOC and my baudrate is set at 9600 (Also tried with 115200). Here's my sequence:

Sending 0x7F twice and receiving an ACK. Then, sending 0x00FF to get the commands and receiving a NACK.

If I'm sending 0x7F once, I'm receiving a NACK after the byte 0x00 of my first command as bellow. It's kind of unsync.

Do you have an idea of why I'm getting NACK after each command I'm trying to send? According to the AN3155, 0x00 is not a protected command and should receive something.

Thanks,

Alexandre

[TDK · Accepted solution]

Looks like you're using 8-N-1. Bootloader expects even parity, 8-E-1. So you should have 9 bits sent for each byte.