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

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

Ken58 — Wed, 02 Apr 2025 23:18:38 GMT

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

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

Sigurd — Tue, 04 Mar 2025 09:38:19 GMT

[quote user="Ken58"]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)[/quote]

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

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

Ken58 — Mon, 03 Mar 2025 21:01:54 GMT

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

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

Sigurd — Mon, 03 Mar 2025 11:25:28 GMT

Instead of

CONFIG_NRFX_PWM=y

Try e.g.

CONFIG_NRFX_PWM0=y

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

Ken58 — Sun, 02 Mar 2025 19:44:46 GMT

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

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

Sigurd — Tue, 11 Feb 2025 09:59:03 GMT

Hi!

Let's say you have something like this in pinctrl dts

	pwm0_default: pwm0_default {
		group1 {
			psels = <NRF_PSEL(PWM_OUT0, 0, 13)>;
			nordic,invert;
		};
	}

then something like this:

#include <stdio.h>

#include <zephyr/drivers/pwm.h>
#include <zephyr/drivers/gpio.h>
#include <zephyr/pm/device.h>
#include <zephyr/pm/device_runtime.h>
#include <zephyr/drivers/gpio.h>

#ifdef CONFIG_PINCTRL
#include <pinctrl_soc.h>
#endif

#define PWM_PIN(node_id, prop, idx) \
	NRF_GET_PIN(DT_PROP_BY_IDX(node_id, prop, idx)),

	static const uint8_t pwm_pin_nums[] = {
		DT_FOREACH_CHILD_VARGS(
			DT_PINCTRL_BY_NAME(DT_NODELABEL(pwm0), default, 0),
			DT_FOREACH_PROP_ELEM, psels, PWM_PIN
		)
	};


int main(void)
{
	printf("Hello World! %s\n", CONFIG_BOARD_TARGET);

    for (size_t i = 0; (i < ARRAY_SIZE(pwm_pin_nums)); i++) {
        printf("PWM LEDS[%d]: %d\n",i, pwm_pin_nums[i]);
    }

	return 0;
}

Will give you this output:

*** Booting nRF Connect SDK v2.9.0-7787b2649840 ***
*** Using Zephyr OS v3.7.99-1f8f3dc29142 ***
Hello World! nrf52840dk/nrf52840
PWM LEDS[0]: 13

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

Ken58 — Sat, 08 Feb 2025 20:08:02 GMT

Hi Sigurd,

Can you give me an example of what the code using the Devicetree API you referenced above would look like? For for a simple example: using a nRF52840 Dongle, how would I get the pin for the pwm-led0 keeping in mind that pwm0 will have a status = "disabled" in an overlay since the nrfx PWM API will be used?

Thanks,

Ken

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

Sigurd — Mon, 03 Feb 2025 11:30:18 GMT

Hi!

[quote user="Ken58"]how would you recommend getting the correct GPIOs configuration for each of the 3 boards supported without changing the application code in each instance?[/quote]

You could still have the pinctrl pwm devicetree node present, and use the Devicetree API to get the correct pins when using the nrfx API.

https://docs.nordicsemi.com/bundle/zephyr-apis-2.9.0/page/group_devicetree-pinctrl.html

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

Ken58 — Sun, 02 Feb 2025 21:10:29 GMT

Hi Sigurd,

To this point, I have used overlays or custom board definition to allow my application code to be unchanged when driving PWM LEDs on 3 different boards where the GPIOs used have been different. When disabling PWMs in the devicetree and using nrfx driver directly, how would you recommend getting the correct GPIOs configuration for each of the 3 boards supported without changing the application code in each instance?

Ken

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

Ken58 — Fri, 31 Jan 2025 20:26:31 GMT

Thank you Sigurd. I'll let you know if I run into any problems.

Ken

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

Sigurd — Fri, 31 Jan 2025 12:35:48 GMT

Hi!

[quote user="sigurdon"]github.com/.../quote]

Looks like the sample is not been updated for some time. I suggest e.g. starting with the hello_world zephyr sample, and start adding the relevant PWM functionality to that sample.

[quote user="Ken58"]If I use the nrfx driver/API for PWM, can I continue to use the Zephyr GPIO driver/API?[/quote]

Yes.

[quote user="Ken58"]What is the impact I will see in DeviceTree for PWM when using the nrfx driver/API?[/quote]

I suggest disabling PWM in the devicetree when using the nrfx driver directly, to avoid any conflict.

[quote user="Ken58"]As I look into how this can be done, is there an specific documentation section on using Zephyr with nrfx at the same time? Is there a cookbook for this situation? Is there a particular sample showing simultaneous use of Zephyr drivers for some devices and nrfx drivers/APIs for others?[/quote]

There are 2 nrfx sample in the Zephyr repo here: https://github.com/nrfconnect/sdk-zephyr/tree/main/samples/boards/nordic

[/quote]

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

Ken58 — Tue, 28 Jan 2025 19:57:12 GMT

Hi Sigurd,

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

Thanks,

Ken

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

Ken58 — Sun, 19 Jan 2025 16:26:30 GMT

(Hi Sigurd,)**2

I may not have time to figure this out today, and in case you have a look at this on Monday: I created a new application by picking the common_mode PWM sample from the library. Without making any changes to the sample, when I attempt to "Add build configuration", it fails with the following output:

I would have thought this sample would have built without modification but it will not. What do I need to do? Is it documented somewhere?

Thanks again,

Ken

CCMakeError.log contents:

Compiling the C compiler identification source file "CMakeCCompilerId.c" failed.

Compiler: C:/ncs/toolchains/b620d30767/opt/zephyr-sdk/arm-zephyr-eabi/bin/arm-zephyr-eabi-gcc.exe

Build flags:

Id flags:

The output was:

c:/ncs/toolchains/b620d30767/opt/zephyr-sdk/arm-zephyr-eabi/bin/../lib/gcc/arm-zephyr-eabi/12.2.0/../../../../arm-zephyr-eabi/bin/ld.exe: c:/ncs/toolchains/b620d30767/opt/zephyr-sdk/arm-zephyr-eabi/bin/../lib/gcc/arm-zephyr-eabi/12.2.0/../../../../arm-zephyr-eabi/lib\libc.a(lib_a-exit.o): in function `exit':

exit.c:(.text.exit+0x34): undefined reference to `_exit'

collect2.exe: error: ld returned 1 exit status

Compiling the CXX compiler identification source file "CMakeCXXCompilerId.cpp" failed.

Compiler: C:/ncs/toolchains/b620d30767/opt/zephyr-sdk/arm-zephyr-eabi/bin/arm-zephyr-eabi-gcc.exe

Build flags:

Id flags:

The output was:

exit.c:(.text.exit+0x34): undefined reference to `_exit'

collect2.exe: error: ld returned 1 exit status

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

Ken58 — Sat, 18 Jan 2025 17:37:06 GMT

Hi again Sigurd,

As I look into how this can be done, is there an specific documentation section on using Zephyr with nrfx at the same time? Is there a cookbook for this situation? Is there a particular sample showing simultaneous use of Zephyr drivers for some devices and nrfx drivers/APIs for others?

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

Ken58 — Fri, 17 Jan 2025 20:45:48 GMT

Hi Sigurd,

I will check out the sample you mention. For clarification, let me ask:

If I use the nrfx driver/API for PWM, can I continue to use the Zephyr GPIO driver/API?
What is the impact I will see in DeviceTree for PWM when using the nrfx driver/API?

Ken

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

Sigurd — Wed, 15 Jan 2025 09:06:39 GMT

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