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The "windowing mode" is enabled by setting CR1[WE]. When set, the comparator output
is sampled only when WINDOW=1. This feature can be used to ignore the comparator
output during time periods in which the input voltages are not valid. This is especially
useful when implementing zero-crossing-detection for certain PWM applications.
The comparator filter and sampling features can be combined as shown in the following
table. Individual modes are discussed below.
Table 35-1. Comparator sample/filter controls
Mode #
CR1[EN]
CR1[WE]
CR1[SE]
CR0[FILTER_C
NT]
FPR[FILT_PER]
Operation
1
0
X
X
X
X
Disabled
2A
1
0
0
0x00
X
Continuous Mode
.
2B
1
0
0
X
0x00
3A
1
0
1
0x01
X
Sampled, Non-Filtered mode
3B
1
0
0
0x01
> 0x00
4A
1
0
1
> 0x01
X
Sampled, Filtered mode
See the
4B
1
0
0
> 0x01
> 0x00
5A
1
1
0
0x00
X
Windowed mode
Comparator output is sampled on
every rising bus clock edge when
SAMPLE=1 to generate COUTA.
See the
.
5B
1
1
0
X
0x00
6
1
1
0
0x01
0x01–0xFF
Windowed/Resampled mode
Comparator output is sampled on
every rising bus clock edge when
SAMPLE=1 to generate COUTA,
which is then resampled on an
interval determined by FILT_PER to
generate COUT.
.
7
1
1
0
> 0x01
0x01–0xFF
Windowed/Filtered mode
Comparator output is sampled on
every rising bus clock edge when
SAMPLE=1 to generate COUTA,
which is then resampled and filtered
to generate COUT.
All other combinations of CR1[EN], CR1[WE], CR1[SE], CR0[FILTER_CNT], and FPR[FILT_PER] are illegal.
Chapter 35 Comparator (CMP)
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
NXP Semiconductors
829
Summary of Contents for K22F series
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