Can we implment PWM Analyzer on SDK 11?

[Ron]

I need to implement a PWM analyzer. I looked at the example in SDK 6 and it's fairly easy to follow. When I tried it, it doesn't look like GPIOTE handler gets called frequently enough. Is there a better recommendation to calculate duty cycle other than using GPIOTE that will do a good job sensing the rise and drop?

[Einar Thorsrud]

The peripherals use a 16 MHz clock, which is a limiting factor when measurements are performed using PPI. Using GPIOTE and a timer connected via PPI as the pwm_analyzer example in SDK 6 is a sensible way of doing the measurements. You can also use a comparator instead of GPIOTE.

If the frequency of the PWM signal you are analyzing is too high compared to what you are measuring with, you could consider low pass filtering the PWM signal and using the ADC. This will have a few disadvantages, though. It will require an external RC filter and will have lower accuracy.

A few questions:

• What is the maximum frequency of the PWM signal you need to analyze?
• Are you using nRF52 or nRF51?

[Ron]

Thanks for the last tidbit. I will be needing to add bluetooth events at some point. Just to be clear, when you say measuring with gpiote using PPI, there should also be a timer, right? You were saying that the two consecutive transitions could give problems. Are there other ways to do it other than that?