NeoPixel on nRF5340

[PasVegan]

Hi,

Is it possible to use the Adafruit_NeoPixel library with the nRF5340 DK? I tried controlling an 8-pixel module using Zephyr’s led_strip example, but it didn’t work. I believe the pixels use the WS2812 protocol.

Has anyone successfully controlled NeoPixels with this board?

Thanks!

[jacks60806]

From my experience you won't be able to use the ws2812 gpio driver. I don't know about the ws2812_i2s or ws2812_spi implementations. The WS2812 timing is tight enough you won't be able to use the zephyr ws2812_gpio library and will need to create your own driver.

https://wp.josh.com/2014/05/13/ws2812-neopixels-are-not-so-finicky-once-you-get-to-know-them/

The "TOH 0 code", high voltage time maximum of 500ns is the problem.

As a warning if you attempt to control using gpio, you won't even be able to use the zephyr gpio_pin_set calls because minimum time to set and clear the pin exceeds 500ns. You'll need to call the nRF gpio pin set/clear functions directly.

[PasVegan]

Thank you for your response. I am a beginner in the embedded world. Do you have any code to share that would accomplish this or something similar? If not, where should I start? Could you describe the steps to achieve this? Thank you very much.

[jacks60806]

For controlling the nRF pins directly I would look at the zephyr driver source code that is used.
ncs\v2.9.0\zephyr\drivers\gpio\gpio_nrfx.c

For an example of the driver using gpio I would look at
ncs\v2.9.0\zephyr\drivers\led_strip\ws2812_gpio.c

I also could be wrong and the gpio driver implementation might work.

config WS2812_STRIP_GPIO
     bool "WS2812 LED strip GPIO driver"
     # Only an Cortex-M inline assembly implementation for the nRF91, nRF51,
    # nRF52 and nRF53 is supported currently.

I would suggest looking at v2.9.0\zephyr\dts\bindings\led_strip\worldsemi,ws2812-gpio.yaml for the driver binding