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MPC8321 1200 Baud Rate Issue

Question asked by Y 1272 on Jul 31, 2017
Latest reply on Aug 1, 2017 by Serguei Podiatchev

Hi ,We have MPC8321 processor in PCI Agent mode with 33 MHz input clock,we are trying to achieve UCC UART communication with baud rate of 1200.Our BRGCLK is set to 83.33 MHz.Although in the BRGCx register the value of Clock divider is coming according to the 1200 baud rate we are not able to get the same baud rate when we measure on scope.So we hardcoded the clock divider value to maximum i.e 4096, we achieve a baud rate of 1250.We are able to achieve  all other baud rates with same clock.

Formula used to calculate Clock Divider:

Async Baud Rate =                                                        BRGCLK or External Clock Source                                                                              -----------------------------------------------------------------------------------------------------------------------------
                                                               ( Prescale Divider ) • ( Clock Divider + 1 ) • ( Sampling Rate )

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