How to reassign LED pin values in NRF Connect SDK

RE: How to reassign LED pin values in NRF Connect SDK

Naeem Maroof — Tue, 01 Nov 2022 17:48:39 GMT

Hi Joe,

Good to know that you have found a solution. There can be other solutions as well like enabling PWM1 and connecting to LED1. However, the solution of changing PWM0 pin to LED1 through overlay is also suitable for your problem. On nRF52840, LEDS are connected to 13-16 pins on port-0.

&pwm0_default {
    phandle = < 0xd >;
    group1 {
        psels = < NRF_PSEL(PWM_OUT0, 0, 0xe) >;
        nordic,invert;
    };
};

Using NRF52840, the led#2 of the board (actually led1) will be connected to the PWM through this overlay.

Thanks,

Naeem

RE: How to reassign LED pin values in NRF Connect SDK

nordicator_prim3 — Mon, 31 Oct 2022 17:19:43 GMT

No problem, it was a fun problem! Im hoping there's a better way to do this -- it feels a bit hacky.

RE: How to reassign LED pin values in NRF Connect SDK

nordicator_prim3 — Mon, 31 Oct 2022 17:19:09 GMT

Just found a slightly friendlier way using the NRF_PSEL() function. Now my overlay looks like this to use led2:

&pwm0_default {
    phandle = < 0xd >;
    group1 {
        psels = < NRF_PSEL(PWM_OUT0, 0, 0xf) >;
        nordic,invert;
    };
};

RE: How to reassign LED pin values in NRF Connect SDK

jrmorris — Mon, 31 Oct 2022 17:18:35 GMT

Changing the psel to the new pin value worked for me, Thank you very much!

RE: How to reassign LED pin values in NRF Connect SDK

nordicator_prim3 — Mon, 31 Oct 2022 17:07:23 GMT

So I hadn't messed with PWMs before, but I think I figured something out. Also, I only have an nrf52840dk, so I'll show you what my devicetree looks like and you can relate it to your board.

First is where the devicetree defines "pwmleds" and "pwm_led0":

pwmleds {
	compatible = "pwm-leds";
	pwm_led0: pwm_led_0 {
		pwms = < &pwm0 0x0 0x1312d00 0x1 >;
	};
};

So that shows it pointing to "pwm0" node:

pwm0: pwm@4001c000 {
	compatible = "nordic,nrf-pwm";
	reg = < 0x4001c000 0x1000 >;
	interrupts = < 0x1c 0x1 >;
	status = "okay";
	label = "PWM_0";
	#pwm-cells = < 0x3 >;
	pinctrl-0 = < &pwm0_default >;
	pinctrl-1 = < &pwm0_sleep >;
	pinctrl-names = "default", "sleep";
	phandle = < 0x19 >;
};

And then, "pinctrl-0" pointing to "pwm0_default" sounded enticing, so I looked at it:

pwm0_default: pwm0_default {
	phandle = < 0xd >;
	group1 {
		psels = < 0x16000e >;
		nordic,invert;
	};
};

Which looked strange. The psels point to "0x16000d". I made a devicetree overlay that redefined the psels in "pwm0_default" to 0x16000e and that started using the second LED. On my devkit, "led0" is pin 0xd and "led1" is 0xe. so it seems like you just need to add 0x160000 to whatever pin you want in the "psels" for "pwm0_default".

RE: How to reassign LED pin values in NRF Connect SDK

jrmorris — Mon, 31 Oct 2022 15:44:00 GMT

NRF52832

RE: How to reassign LED pin values in NRF Connect SDK

nordicator_prim3 — Mon, 31 Oct 2022 15:41:45 GMT

Which DK board are you using? NRF52840?