NXP Semiconductors K22F series, Reference Manual, Page: 518 / 1407

Table 23-2. EWM Refresh Mechanisms
Condition Mechanism
An EWM refresh action completes when:
CMPL < Counter < CMPH.
The software behaves as expected and the EWM counter is reset to zero. The
EWM_out output signal remains in the deasserted state if, during the EWM
refresh action, the EWM_in input has been in deasserted state..
An EWM refresh action completes when
Counter < CMPL The software refreshes the EWM before the windowed time frame, the counter is
reset to zero and the EWM_out output signal is asserted irrespective of the input
EWM_in.
Counter value reaches CMPH prior to
completion of EWM refresh action. Software has not refreshed the EWM. The EWM counter is reset to zero and the
EWM_out output signal is asserted irrespective of the input EWM_in.
23.4.6 EWM Interrupt
When EWM_out is asserted, an interrupt request is generated to indicate the assertion of
the EWM reset out signal. This interrupt is enabled when CTRL[INTEN] is set. Clearing
this bit clears the interrupt request but does not affect EWM_out. The EWM_out signal
can be deasserted only by forcing a system reset.
23.4.7 Counter clock prescaler
The EWM counter clock source can be prescaled by a clock divider, by programming
CLKPRESCALER[CLK_DIV]. This divided clock is used to run the EWM counter.
NOTE
The divided clock used to run the EWM counter must be no
more than half the frequency of the bus clock.
Functional Description
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
518 NXP Semiconductors