35.5.6 Low-Pass Filter Mode
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 Microchip Application Note AN2749, “PIC18 12-bit ADCC in Low-Pass Filter Mode”, available at the corporate website (www.microchip.com).