Is it possible to make 5 PWM outputs on NRF51422 (or NRF51822)?

RE: Is it possible to make 5 PWM outputs on NRF51422 (or NRF51822)?

Brandon A — Wed, 05 Aug 2015 13:36:56 GMT

Ok, I see. I don't think I will try to add a 5th pwm output then. Thanks for helping!

RE: Is it possible to make 5 PWM outputs on NRF51422 (or NRF51822)?

Øyvind Karlsen — Wed, 05 Aug 2015 06:05:07 GMT

Bit bang is not reliable, GPIOTE helps make the big bang implementation more reliable. For the 5th PWM you would not have a GPIOTE available, that makes things even harder.

RE: Is it possible to make 5 PWM outputs on NRF51422 (or NRF51822)?

Brandon A — Tue, 04 Aug 2015 13:20:13 GMT

Hi Øyvind,

Thanks for your answer. When you say that I will not be able to get reliable PWM output on a 5th pin, do you mean that bit bang pwm won't give reliable output, or is there a way to send a 5th PWM output to a non-GPIOTE pin that is unreliable?

RE: Is it possible to make 5 PWM outputs on NRF51422 (or NRF51822)?

Øyvind Karlsen — Mon, 03 Aug 2015 06:23:24 GMT

Hi,

We have 4 compare events per timer instance, for each of these 4 one will be used as a reset. That means that we're left with three possible outputs per timer. In operation alongside the SoftDevice we will have access to two timers, this gives us a total of 6 outputs.

The problem is that we only have 4 GPIOTE slots, which means that you will not get reliable PWM output, this might be fine if you want to control a LED or simple motor.

For help on implementation search google for "bit bang pwm", and there should be some useful results.

Best regards,

Øyvind