Noise Filter - Renesas RX100 Series User Manual

RX13T Group
28.3.2

Noise Filter

Comparator C contains a noise filter. The sampling clock can be selected by the CMPCTL.CDFS[1:0] bits.
The comparator output signal is sampled every sampling clock, and if the same value is sampled three times, that value is
determined as the noise filter output at the next sampling clock.
Figure 28.3 shows the configuration of the noise filter and edge detector and Figure 28.4 shows an example of the
comparator noise filter and interrupt operation.
Sampling clock
Comparator output
n = 0 to 2
Figure 28.3 Noise Filter and Edge Detector Configuration
Sampling timing
Noise filter input
Interrupt status flag
(IR)
Note: The above operation example applies when the CMPCTL.CDFS[1:0] bits are 01b, 10b, or 11b (noise filter used).
The noise canceling width can be changed by setting the value of the CMPCTL.CDFS[1:0] bits to select the sampling
timing.
Figure 28.4 Noise Filter and Interrupt Operation Example
R01UH0822EJ0100 Rev.1.00
Jul 31, 2019
CMPMON0
0 Noise filter
(same value
1 sampled 3 times)
CINV CDFS[1:0]
Unless the same value is sampled 3
consecutive times, it is assumed to be
noise and IR flag does not become 1
CPOE
Edge
detector
CEG[1:0]
Since the same value is sampled
3 times, it is recognized as a signal
change and IR flag becomes to 1
28. Comparator C (CMPC)
COMPn
CMPCn interrupt request
COMPn level detection signal
Set to 0 by program
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