18.4.12 Filter (Secondary Accumulator)

The setting channels 17, 18 and 19 with the implemented secondary accumulator ADnCHxACC sums the output of the primary accumulator ADnCHxDATA. The secondary accumulator is enabled when the ACCRO bit (ADnCHxCON[26]) is set. If the ACCRO bit = ‘1’, the ADnCHxDATA and ADnCHxACC accumulator are not cleared; instead, they will roll-over as the data is accumulated over many multi-sample operations. The accumulators function as a Second Order Cascaded-Integrator-Comb filter (CIC). Some of the CIC operations (differentiation functions) need to be performed by the application software as shown in Figure 18-3.