Each of the two-phase inputs have digital debounce filters.
When enabled through the DBFEN register, the filter inputs are sampled at a fixed 1 MHz frequency during the entire sample period (which is specified in the SAMPLEPER register). The filters require all of the samples within this sample period to equal before the input signal is accepted and transferred to the output of the filter.
As a result, only input signal with a steady state longer than twice the period specified in SAMPLEPER are guaranteed to pass through the filter. Any signal with a steady state shorter than SAMPLEPER will always be suppressed by the filter. It is assumed that the frequency during the debounce period never exceeds 500 kHz (as required by the Nyquist theorem when using a 1 MHz sample frequency).
The LED will always be ON when the debounce filters are enabled, as the inputs in this case will be sampled continuously.
When the debounce filters are enabled, displacements reported by the QDEC peripheral are delayed by one SAMPLEPER period.