21.3.3.1.5 Input Capture Pulse-Width Measurement Mode

In the Input Capture Pulse-Width Measurement mode, the input capture pulse-width measurement will restart the counter on a positive edge, and capture on the next falling edge before an interrupt request is generated. The CAPT Interrupt flag is automatically cleared after the low byte of the Compare/Capture (TCBn.CCMP) register has been read. The timer will automatically switch between rising and falling edge detection, but a minimum edge separation of two clock cycles is required for correct behavior.