This nice document: https://cache.nxp.com/docs/en/application-note/AN5142.pdf
provides many code examples on how to program K66 chips with FTM. On my Teensy 3.6 (which uses K66), the code for "Phase-shift PWM signal" from section 3.4 works perfectly well. However, the code from "Single-edge capture mode" in section 3.8 doesn't work. Both use FTM0, and both should be using the same ports. For capture mode, I expect to input a signal at FTM0_CH0, and then get the interrupt triggered to modify the value of diff. But I noticed that the interrupt is never called.
What am I missing? Please assist.