f4 discovery rs232 baud problem

[ian239955]

Posted on July 11, 2013 at 10:29

Hi, 

I have it working but seem to get about 1/3 of the baud rate that I program into 

USART_InitStructure.USART_BaudRate

In other words, I have to set it to 9600*3 to get a baud rate of approximately 9600 baud.

Maybe I have to change something in system_stm32f4xx.c but I'm not sure what?

Thanks

[waclawek.jan]

Posted on July 11, 2013 at 10:52

My crystal ball says, that you attempt to use firmware intended for the STM32-EVAL board (with 25MHz crystal) on an 'F4 DISCOVERY (8MHz crystal). But my crystal ball used to be wrong at times.

From system_stm32f4xx.c:

  * 4. The default value of HSE crystal is set to 25MHz, refer to ''HSE_VALUE'' define

  *    in ''stm32f4xx.h'' file. When HSE is used as system clock source, directly or

  *    through PLL, and you are using different crystal you have to adapt the HSE

  *    value to your own configuration.

JW

[ian239955]

Posted on July 11, 2013 at 16:29

Thanks, your crystal ball was right!

Cheers, Ian

[jj2]

Posted on July 11, 2013 at 18:47

Might that ''xtal ball'' soon provide, Internet Access?

[waclawek.jan]

Posted on July 12, 2013 at 10:18

> Might that ''xtal ball'' soon provide, Internet Access?

:D