CMPx_MUXCR field descriptions (continued)
Field Description
NOTE:
When an inappropriate operation selects the same input for both muxes, the comparator
automatically shuts down to prevent itself from becoming a noise generator.
000 IN0
001 IN1
010 IN2
011 IN3
100 IN4
101 IN5
110 IN6
111 IN7
35.3 Functional description
The CMP module can be used to compare two analog input voltages applied to INP and
INM.
CMPO is high when the non-inverting input is greater than the inverting input, and is low
when the non-inverting input is less than the inverting input. This signal can be
selectively inverted by setting CR1[INV] = 1.
SCR[IER] and SCR[IEF] are used to select the condition which will cause the CMP
module to assert an interrupt to the processor. SCR[CFF] is set on a falling-edge and
SCR[CFR] is set on rising-edge of the comparator output. The optionally filtered CMPO
can be read directly through SCR[COUT].
35.3.1
CMP functional modes
There are the following main sub-blocks to the CMP module:
• The comparator itself
• The window function
• The filter function
The filter, CR0[FILTER_CNT], can be clocked from an internal or external clock source.
The filter is programmable with respect to the number of samples that must agree before
a change in the output is registered. In the simplest case, only one sample must agree. In
this case, the filter acts as a simple sampler.
The external sample input is enabled using CR1[SE]. When set, the output of the
comparator is sampled only on rising edges of the sample input.
Functional description
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
828 NXP Semiconductors
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