The Low-Pass Filter mode (
MD =
'b100) acts
similarly to the Average mode in how it handles samples (accumulates samples until the
ADCNT value is greater than or equal to
RPT, then triggers a threshold comparison), but instead of a simple
average, it performs a low-pass filter operation on all of the samples, reducing the
effect of high-frequency noise on the total, then performs a threshold comparison on the
results. In this mode, the
CRS bits determine the cutoff frequency of the low-pass filter (as
demonstrated by
Digital Filter/Average). Refer to the
Computation Operation section for a more detailed description of the
mathematical operation.
For more information about Low-Pass Filter mode, refer to the
following Microchip application note, available in the corporate website (
www.microchip.com):
- AN2749, “PIC18 12-bit ADCC in
Low-Pass Filter Mode”