Cmp Functional Modes - NXP Semiconductors MKL27Z128VFM4 Reference Manual

Table of Contents

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].

24.4.1 CMP functional modes

There are the following main sub-blocks to the CMP module:

• The comparator itself

• The filter function

The filter, CR0[FILTER_CNT], can be clocked from an internal clock source only. 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 comparator filter and sampling features can be combined as shown in the following

table. Individual modes are discussed below.

All other combinations of CR1[EN], CR1[WE], CR1[SE], CR0[FILTER_CNT], and FPR[FILT_PER] are illegal.

For cases where a comparator is used to drive a fault input, for example, for a motor-

control module such as FTM, it must be configured to operate in Continuous mode so

that an external fault can immediately pass through the comparator to the target fault

Freescale Semiconductor, Inc.

Table 24-2. Comparator sample/filter controls

CR0[FILTER_C

KL27 Sub-Family Reference Manual , Rev. 5, 01/2016

FPR[FILT_PER]

Chapter 24 Comparator (CMP)

Disabled mode (#

Continuous Mode

Continuous mode (#s 2A &

Sampled, Non-Filtered mode

Sampled, Non-Filtered

Sampled, Filtered mode

Sampled, Filtered mode (#s