68.6.6.3 Cycle-By-Cycle Duty Mode

Cycle-by-cycle duty mode is selected by programming TRGMODE = 3 in PWM_ETRGx.

In this mode, the PWM frequency is constant and is defined by the CPRD value in the PWM Channel Period Register.

An external trigger event has no effect on the PWM output if it occurs while the internal PWM counter value is above the CDTY value of the PWM Channel Duty Cycle Register.

If the internal PWM counter value is below the value of CDTY of the PWM Channel Duty Cycle Register, an external trigger event makes the PWM output inactive.

The external trigger event can be detected on rising or falling edge according to the TRGEDGE bit in PWM_ETRGx.