The Low-Pass Filter mode (
MD
=
‘b100) acts
similarly to the Average mode in how it handles samples; it accumulates samples until
the
CNT 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”