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stm32f4discovery bootloader

Question asked by wolke.matthias on Aug 31, 2012
Latest reply on Sep 26, 2012 by wolke.matthias

I have a porblem with the stm32f4 bootloader!

The initialisation of the bootloader via USART1 (PA9/PA10) works so far.

I am using a stm32f4discovery-board. The problem ist that it only works with very low baudrates. I connected PB5, PC11 and PB11 to GND so that none of them  toggles. Furthermore I connected BOOT1 to GND and BOOT0 to 3,3 V before entering the bootloader-mode by pulling the NRST-PIN to GND for a short time.



If I send 0x7F with a baudrate of 2400 I recive an ACK (0x79) so there is no problem with flashing.

With a higher baudrate of 4800 it doesn’t send 0x79 as an answer  but 0xFE.


Baud 9600:  0xFF

Baud 14400: no response


I supposed there is a problem with the autobaudrateadaption!


Using the bootloader demonstrator:

Baud 2400: recognized device

Until Baud 9600: unrecognized device

From Baud 14400: no response from target


First I used usb-ttl-converter. Using a rs232-ttl-converter didn´t help although I measured the boudrate and it is exact !

So is there a way to increse the possible baudrate? What might be the problem? Thanks for your help!