Custom PWM base clock frequency

[Henrik]

Heyho!

Is it possible to set the PWM base clock frequency to 40kHz? If so, how? I see that the predefined base clock frequencies don't go any lower than 125kHz.

I'm using an nRF52 DK with the PWM-hardware driver. (nrf_drv_pwm)

EDIT: I might add that what I want here is to set the switching frequency of the pwm signal to be 40kHz. Is the switching frequency and the base clock frequency the same?

[Stefan Birnir Sverrisson]

Hi Henrik

As I understand it, the PWM switching frequency is actually the multiplication of the base frequency and the COUNTERTOP when in up-counting mode. The formula is also given in the PWM peripheral documentation in the PS below figure 2. So if you want to set PWM frequency of 40kHz, you could for example set mode=count_up, base frequency as 1MHz and COUNTERTOP=25 because 1MHz/25=40kHz.

[Henrik]

Thank you so much!