27.4.3.4 Input Capture Operation with Synchronization and Triggering

By default, the CCP module in Input Capture mode operates with a free-running timer. The CCPxPR register is not available to set a different timer period in Input Capture mode. It is recommended to keep SYNC[4:0] configured as ‘11111’ to maintain the free-running timer.

The timer will be held at 0000h under either of these conditions:

Triggered operation is enabled (TRIGEN = 1) and a trigger event has not occurred (CCPTRIG = 0).
An external Sync source has been selected (SYNC[4:0] has a value other than ‘11111’), which has not been enabled.

In either case, Input Capture input events will occur; however, a value of 0000h will always be captured in the FIFO. For these reasons, triggered operation and externally synchronized operation are not recommended.