28.3.2.5 Edge Detector
Use the edge detector to generate a pulse when detecting a rising edge on its input. Program the truth table to provide an inverted output to detect a falling edge.
The edge detector is enabled by writing a ‘1’
            to the Edge Selection (EDGEDET) bit in the CCL.LUTnCTRLA register. To avoid
            unpredictable behavior, a valid filter option must be enabled as well.
The edge detection is disabled by writing
            a ‘0’ to the EDGEDET bit in the CCL.LUTnCTRLA register. After disabling
            an LUT, the corresponding internal edge detector logic is cleared one clock cycle
            later.
