NXP Semiconductors K22F series, Reference Manual, Page: 515 / 1407

23.3.5 Clock Prescaler Register (EWM_CLKPRESCALER)
This CLKPRESCALER register is reset to 0x00 after a CPU reset.
NOTE
This register can be written only once after a CPU reset.
Writing this register more than once generates a bus transfer
error.
NOTE
Write the required prescaler value before enabling the EWM.
NOTE
The implementation of this register is chip-specific. See the
Chip Configuration details.
Address: 4006_1000h base + 5h offset = 4006_1005h
Bit 7 6 5 4 3 2 1 0
Read
CLK_DIV
Write
Reset 0 0 0 0 0 0 0 0
EWM_CLKPRESCALER field descriptions
Field Description
CLK_DIV Selected low power clock source for running the EWM counter can be prescaled as below.
• Prescaled clock frequency = low power clock source frequency / ( 1 + CLK_DIV )
23.4 Functional Description
The following sections describe functional details of the EWM module.
NOTE
When the BUS_CLK is lost, then EWM module doesn't
generate the EWM_out signal and no refresh operation is
possible
23.4.1 The EWM_out Signal
The EWM_out is a digital output signal used to gate an external circuit (application
specific) that controls critical safety functions. For example, the EWM_out could be
connected to the high voltage transistors circuits that control an AC motor in a large
appliance.
Chapter 23 External Watchdog Monitor (EWM)
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
NXP Semiconductors 515