nRF52840 DK updating WS2812B led strip?

RE: nRF52840 DK updating WS2812B led strip?

Joonho Jang — Fri, 15 Aug 2025 15:46:27 GMT

Hi mtrobregado,

From the led_ws2812 sample I'm trying to use the I2S interface with the nRF52840DK however I'm running into the following build error. Did you run into this error as well by any chance?

/Users/joonhojang/Local_Drive/Workspace/KEYBOARD/Firmware_Modules/nRF52840/led_ws2812/build/led_ws2812/zephyr/include/generated/zephyr/devicetree_generated.h:1337:42: error: 'DT_N_S_ws2812_P_chain_length' undeclared here (not in a function); did you mean 'DT_N_S_ws2812_P_compatible'?
 1337 | #define DT_N_ALIAS_led_strip             DT_N_S_ws2812

This is my nrf52840dk_nrf52840.overlay file

#include <zephyr/dt-bindings/led/led.h>

/* Wiring:
 * - M1.S connected to GND
 * - SDOUT connected to M1.D
 * - ~300 ohm resistor between M1.D and TP5 (5V / Vbus)
 */

&pinctrl {
	i2s0_default_alt: i2s0_default_alt {
		group1 {
			psels = <NRF_PSEL(I2S_SCK_M, 1, 15)>,
			        <NRF_PSEL(I2S_LRCK_M, 1, 12)>,
			        <NRF_PSEL(I2S_SDOUT, 1, 13)>,
			        <NRF_PSEL(I2S_SDIN, 1, 14)>;
		};
	};
};

i2s_led: &i2s0 {
	status = "okay";
	pinctrl-0 = <&i2s0_default_alt>;
	pinctrl-names = "default";
};

/ {
	led_strip: ws2812 {
		compatible = "worldsemi,ws2812-i2s";

		i2s-dev = <&i2s_led>;
		chain-length = <10>; /* arbitrary; change at will */
		color-mapping = <LED_COLOR_ID_GREEN
		LED_COLOR_ID_RED
		LED_COLOR_ID_BLUE>;
		out-active-low;
		reset-delay = <120>;
	};

	aliases {
		led-strip = &led_strip;
	};
};

RE: nRF52840 DK updating WS2812B led strip?

mtrobregado — Wed, 26 Jun 2024 10:25:03 GMT

Hi,

The led strip using I2S interface works for nRF52840 DK. I have already solved my problem.

Markel

RE: nRF52840 DK updating WS2812B led strip?

mtrobregado — Sun, 23 Jun 2024 03:57:03 GMT

Hi,

Just want to update the issue. Using nrF52850 DK led strip SPI P1.13, the code does not turn on the first WS2812B led. Also, as mentioned you need to turn on the WS2812B one by one and it is not efficient.

Anyway, I will try I2S and see if it works better.

Markel

RE: nRF52840 DK updating WS2812B led strip?

mtrobregado — Wed, 19 Jun 2024 09:21:43 GMT

I just tested this at my 88 WS2812B LEDs project and it does not work properly. I am using SPI MOSI P1.13

Markel

RE: nRF52840 DK updating WS2812B led strip?

runsiv — Thu, 13 Jun 2024 13:07:45 GMT

Ah sorry my bad. I don't think there should be any issue as far as I can see.

Regards

Runar

RE: nRF52840 DK updating WS2812B led strip?

mtrobregado — Wed, 12 Jun 2024 07:54:59 GMT

Hi Runar,

That is what I am using.

Markel

RE: nRF52840 DK updating WS2812B led strip?

runsiv — Wed, 12 Jun 2024 07:50:59 GMT

Hi Markel

Personally I would just use the sample you can already find in Zephyr, which you can find here

Regards

Runar