Hi,
Look at Figure 25-26 and description in the “E-Capture” chapter within a Reference Manual.
When INPSELX=0 then the PWMX input signal goes directly to both Capture circuits. By the EDGX1/EDGX0 bits you can select at which signal edge the internal counter value will be captured.
When INPSELX=1 then the input signal comes to an 8 bit counter which counts both the rising and falling edges. The output of this counter is compared to an 8 bit value that is specified by the user (EDGCMPx) and when the two values are equal, the comparator generates a pulse that also resets the 8bit counter. This output pulse is then used to trigger capture logic. Note: EDGX1/EDGX0 bits must be set still to enable capture logic.
BR, Petr