Hello Perry Jagger,
I strongly recommend you first check the input capture demo under MCUXpresso SDK.
Download from https://mcuxpresso.nxp.com/en/select ,

it support MCUXpresso IDE, IAR and KEIL.
There is a demo named "ftm_input_capture" under "driver_examles" folder:

Hope it helps,
Have a great day,
TIC
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