nrf52840 low power pwm in nRF Connect SDK

Question

There is a low power pwm in nRF5 SDK. I can not find it in the nRF Connect SDK. Any suggestion how to achieve the same using nRF Connect SDK?

pmochocki · Accepted Answer

Thank you. I will give it a try. What is the maximum frequency? Will I be able to dive a piezo at 4kHz?

Einar Thorsrud · Answer

The RTC is 32.768 kHz and you can get a toggle on every tick, so that should be OK. 
 As a side note, this implementation use PPI and GPIOTE also with the RTC, which is different than the low power PWM library in the nRF5 SDK (where only RTC and SW was used via the app_timer library). That frees up the CPU, but which is more power efficient of this and the low_power PWM library in the nRF5 SDK probably depend on the frequency (as PPI usage will increase the idle current, but you will avoid th e high current consumption of the CPU on every change). So for lower frequencies (probably much lower than 4 kHz though I have not measured this), it might be more efficient to do this with kernel timers and setting and clearing GPIOs yourself. If you would like to do that, you could look at the low-power PWM library implementation for inspiration and implement something like that yourself.

nrf52840 low power pwm in nRF Connect SDK

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