Custom board with nrf9160 and RGB led (WS2812B)

RE: Custom board with nrf9160 and RGB led (WS2812B)

Hieu — Mon, 28 Aug 2023 07:30:41 GMT

Hi ax_shepherd,

It's great to know that everything has worked now. Please feel free to close this thread at your convenience 🙂

RE: Custom board with nrf9160 and RGB led (WS2812B)

ax_shepherd — Mon, 28 Aug 2023 00:42:45 GMT

Hi Hieu,

I manage to make it work by following the tutorial here to create a working template for my nrf9160 based custom board. And I used the MOSI pin of the arduino_spi to drive the WS2812 based on this sample.

nrf9160vs_nrf9160.overlay

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

#include "nrf52-bindings.h"

&arduino_spi { /* MOSI on D11 / P0.23 */
	compatible = "nordic,nrf-spim";
	led_strip: ws2812@0 {
		compatible = "worldsemi,ws2812-spi";

		/* SPI */
		reg = <0>; /* ignored, but necessary for SPI bindings */
		spi-max-frequency = <SPI_FREQ>;

		/* WS2812 */
		chain-length = <1>; /* arbitrary; change at will */
		color-mapping = <LED_COLOR_ID_GREEN
				 LED_COLOR_ID_RED
				 LED_COLOR_ID_BLUE>;
		spi-one-frame = <ONE_FRAME>;
		spi-zero-frame = <ZERO_FRAME>;
	};
};

Thanks

RE: Custom board with nrf9160 and RGB led (WS2812B)

Hieu — Thu, 17 Aug 2023 22:50:49 GMT

Hi ax_shepherd,

Thank you for the detailed information.

I think you might have misunderstood how the WS2812 LED works. It is a chainable/scalable LED that is controlled using a 1-wire interface, not via regular PWM.

I think you can still use the led_ws2812 as a base. It demonstrates the WS2812 Driver usage on two nRF52832 boards, thingy52_nrf52832, and nrf52832dk_nrf52832. The WS2812 Driver implements the 1-wire interface of the LED using the I2S or SPI peripherals of the nRF52832.

The sample shows how to setup the I2S version of the driver with the thingy52 board, and the SPI version with the nrf52dk board. You will need to choose one of the two approaches, and replicate it for the nRF9160.

Secondly, in your design, the nRF9160 logic level is 3.3V, while the WS2812 input is specified at 5V. Some online discussions I found suggests that it might still work, but please pay attention to this.

Thirdly, also in your design, the WS2812 is powered by VCC 3.3V. Just like above, some online discussions suggest that it would still work, but with bad color correctness.

Hieu