26.3 PWM Period

The PWM period is specified by the TxPR register. The PWM period can be calculated using the formula of Equation 26-1. It is required to have FOSC/4 as the selected clock input to the timer for correct PWM operation.

Equation 26-1. PWM Period
P W M   P e r i o d = [ ( T 2 P R ) + 1 ] • 4 • T o s c • ( T M R 2     Pr e s c a l e ⁢   V a l u e )
Note: TOSC = 1/FOSC

When TxTMR is equal to TxPR, the following three events occur on the next increment cycle:

  • TxTMR is cleared
  • The PWM output is active (Exception: When the PWM duty cycle = 0%, the PWM output will remain inactive)
  • The PWMxDCH and PWMxDCL register values are latched into the buffers
Important: The Timer2 postscaler has no effect on the PWM operation.