In Compare mode, Timer1 must be running in either Timer mode or
Synchronized Counter mode. The compare operation may not work in Asynchronous Counter
mode.
See the “TMR1 - Timer1 Module with Gate Control” chapter for
more information on configuring Timer1.
Important: Clocking Timer1 from the system clock
(FOSC) should not be used in Compare mode. In order for Compare mode to
recognize the trigger event on the CCPx pin, Timer1 must be clocked from the instruction
clock (FOSC/4) or from an external clock source.