22.3.3.1.4 Input Capture Frequency Measurement Mode

In the Input Capture Frequency Measurement mode, the TCB captures the counter value and restarts on either a positive or negative edge of the event input signal.

The CAPT Interrupt flag is automatically cleared after the low byte of the Compare/Capture (TCBn.CCMP) register has been read.

The figure below illustrates this mode when configured to act on rising edge.