Hi,
I try to update the firmware of an STM32L431 with another microcontroller. I use a UART interface to do that. As described in AN3155 §1, I send the 0x7F after managing the Boot0 and reset pins, and I wait for the 0x79 (Ack). But the STM32 answer: 0x28 0x40 0x00 0x01 0x00 0x14 0x74 0x29.
My questions are:
1- Why is this bytes sequence and not the 0x79 as defined in AN3155?
2- Why does it answer without even parity as defined in AN3155?
3- I do not find the real timing sequence for managing the Boot0 pin, but after several tries, the STM32 answers only if I set to 0 the Boot0 pin and after sents the 0x7F. Is it the right sequence?
4- Is even parity mandatory for all commands or not?
5- In AN2606 page 337, USART3 connectes to PC11 and PC10, but we use the LQFP48 package and those pin are not available. Is the update with USART3 possible?
Thanks for your answer and your help
Best regards.
