How do you set the clock frequency without exceeding the Baud Rate Error?

In MPLAB® Code Configurator (MCC), the Error for the Baud Rate is calculated based on FCY = FOSC/2. The calculation is made by default with BRGH = 1, so it generates four clocks per bit period. BRGH value can be changed, in order to increase the baud rate, in MCC > UARTx > Registers > Register: UxMODE.

For example PIC24F16KA301, without exceeding the Baud Rate Error value '2', the Baud Rate can be set at a maximum of:

  • 38400 for FRC Oscillator, FRC Postscaler 1:2 resulting in a clock frequency of 4 MHz (the default setting in MCC)
  • 115200 for FRC Oscillator, FRC Postscaler 1:1 and enabling the PLL resulting in a clock frequency of 32 MHz.
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