What is the recommended way to use nRF52840 advanced PWM sequence and looping functions with nRF Connect SDK v2.9.0?

[Ken58]

Hi,

I am developing an application for an nRF52840 using nRF Connect SDK v2.9.0.  The application currently uses the Zephyr driver for simple PWM functions on several GPIOs. Now, I need to add PWM sequences and looping as supported by the SOC on other GPIOs. Correct me if I am wrong, but I don't think the Zephyr driver can support the Nordic PWM module in this way.

What is the best way to do this? Some questions that come to mind: Can the Zephyr PWM driver and the nrfx PWM driver live together in the same application? Must I chose one driver or the other? How does DeviceTree manage this? I'm sure I'll have more questions once the discussion is opened.

Thank you,

Ken

[Sigurd]

Hi!

The Zephyr driver API does not have the full functionality that is offered in nrfx pwm API.

So one option it to use nrfx directly. I would not recommend trying to mix and use both APIs.

https://github.com/zephyrproject-rtos/hal_nordic/blob/master/nrfx/samples/src/nrfx_pwm/common_mode/main.c

[Ken58]

Hi Sigurd,

Do you have any response to why the sample application you mentioned will not build?

Thanks,

Ken

[Ken58]

Hi Sigurd,

I have modified my application to use the nrfx PWM driver, disabled PWMs in Devicetree, and use Devicetree macros to get my PWM pin configurations per your recommendations. Thank you on all that. However, I am not able to build my application. I have a failure adding the build configuration.  Screen shot is below. How can I get past this?

Thanks,

Ken

[Sigurd]

Instead of 

CONFIG_NRFX_PWM=y

Try e.g.

CONFIG_NRFX_PWM0=y

[Ken58]

Hi Sigurd,

That worked.  I'm currently using 2 PWM modules so I needed CONFIG_NRFX_PWM1=y as well.

Question:  Where in the latest documentation can I find instruction to set these variables if I intend to use the nfrx PWM driver?  (I think it may be missing)

Thanks,

Ken

[Sigurd]

Ken58 said:

Question:  Where in the latest documentation can I find instruction to set these variables if I intend to use the nfrx PWM driver?  (I think it may be missing)

Yes, I don't think there are any explicit docs on these variables and when to set them.

[Ken58]

Hi Sigurd,

Now that I have been through the change from Zephyr PWM driver/API to the nfrx PWM driver/API, I want to offer the following advice:

It would have been very helpful to have 3 sample applications in the nRF Connect SDK. The first would be a simple PWM/LED application using the Zephyr PWM driver/API with development kit overlay. The second would be a modification of the same application to use the nfrx PWM driver/API. Finally, the last version of the application, modified from the second one, would use the nfrx GPIO driver/API. Being able to compare the code in these applications would have made all the difference in the world to me.

Thanks,

Ken