RE: Two individual pwm duty cycle control

Elfving — Mon, 17 Jan 2022 13:03:58 GMT

Hello again!

When it comes to questions one, I don't know if low power PWM is the best option here. It is mainly meant to be used with LEDs. When controlling a motor, you are dependent on a rather high PWM frequency in order to avoid noticeable noise etc. The low power PWM uses a 32 clock, giving you limited frequency and rather bad accuracy.

So I recommend sticking to the regular PWM library. For an example of how multiple channels can be implemented, take a look .zip shared by Torbjørn here in this thread.

Best regards,

Elfving

RE: Two individual pwm duty cycle control

Elfving — Fri, 14 Jan 2022 12:29:52 GMT

Hey Joel! Great, then welcome to the world of Nordic and our products!

Sounds like you have a very interesting project on your hands.

[quote user=""]1. Is it possible to have 2 Low Power PWMs in the same code?[/quote]

Yes I think so. I will have to get back to you on this though.

[quote user=""]2. In order to get my PID controller working is it best to work with the RTC or with the Driver Timers in order to calculate the derivative and the integrals? [/quote]

Well if using low power is important you should consider that RTC is running through the Low frequency clock. The LF isn't using much current, about 1uA.

When using TIMER, SPI/TWI, RADIO etc, the HF clock is used in order to get a better "precision". Though both HFXO and LFXO have an accuracy in the same ball park considering drift in accuracy over time (20-40ppm), you can get a higher resolution using the HF clock. However, the HF uses about 1 mA (a 1000x more than the LF).

So what you you want to use it for would depend on how accurate/precise you want to be with your sampling. In the context of a PID it doesn't sound like you need to be that precise.

Best regards,

Elfving