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baudrate generation on stm32f4

Question asked by achterop.sietse on Oct 7, 2014
Latest reply on Oct 8, 2014 by achterop.sietse
Hi list,
page 932 of the reference manual gives a formula to calculate USARTDIV.
But if I check the first entry in table 133 I get completely different values.
With Pclk=8MHz I get 8.10^6/(16*1200)=14.7, while the table says 416.6875.


I also have a working system that uses 115200 as baudrate, and if I do
 printf(" pclk1 %d en BRR %x\r\n", RCC_ClocksStatus.PCLK1_Frequency, USART2->BRR);
I get
Pclk = 42MHz and BRR = 0x1117.
And 42.10^6/(16*273.44) = 1272654.6
Completely different from 115200

What am I doing wrong?
     Sietse

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