NeoPixel on nRF5340

RE: NeoPixel on nRF5340

Elfving — Mon, 17 Mar 2025 13:06:19 GMT

I see. I guess one could then go through a lot of debugging with a logic analyzer, but trying out the tips mentioned by Jack here sounds like a plan.

Regards,

Elfving

RE: NeoPixel on nRF5340

PasVegan — Fri, 14 Mar 2025 12:28:15 GMT

Hi,

Sometimes, they did react by glitching and displaying the same color with different brightness on only one LED, while the others remained unaffected. It looks a lot like a communication error.

RE: NeoPixel on nRF5340

Elfving — Fri, 14 Mar 2025 12:20:25 GMT

Hi guys, glad to see that the helping is already started.

I am not so sure about the Adafruit_NeoPixel library, though in Zephyr we do have the led strip sample which should support the WS2812 protocol, which you both seems aware of.

Though I am not as experienced with these led strips as it seems that Jack here is so taking his advice here sounds like a plan.

[quote user=""] I tried controlling an 8-pixel module using Zephyr’s led_strip example, but it didn’t work.[/quote]

Did they simply not react? Or how did it not work?

[quote user="PasVegan"]I am a beginner in the embedded world. [/quote]

It feels a bit obligatory then to plug our DevAcademy, which have a course for showing you the essentials for Zephyr and nRF Connect SDK. We also have courses on BLE etc.

Regards,

Elfving

RE: NeoPixel on nRF5340

jacks60806 — Thu, 13 Mar 2025 21:00:41 GMT

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

RE: NeoPixel on nRF5340

PasVegan — Thu, 13 Mar 2025 20:02:57 GMT

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.

RE: NeoPixel on nRF5340

jacks60806 — Thu, 13 Mar 2025 17:46:52 GMT

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.