Neopixels on MDBT42Q: are R and G switched?

Posted on Tue 26th, October 2021

• #1

Andreas_Rozek
I just tried to test a recently bought Neopixel RGB LED matrix. Since first experiments with an obniz board could test up to 85 LEDs only (but they were working fine), I though it might be a good idea to reactivate a MDBT42Q (after a firmware update to 2v10).

A very first attempt
```
let Neopixel = require("neopixel")
Neopixel.write(D22, [255,0,0])
```
showed a green(!) pixel - and
```
let Neopixel = require("neopixel")
Neopixel.write(D22, [0,255,0])
```
turned it red(!) - blue seems to be fine.

Are "R" and "G" just switched? That would sound strange...
• #2

Gordon

It depends on the type of LED chip used - it seems there are a bunch of different arrangements of RGS :(
• #3

Andreas_Rozek in reply to @Gordon

strange...everything worked as intended with the obniz board.

Nevertheless, I still prefer the MDBT42Q - because it handles the full matrix! Great!
• #4

Robin

Tue 2021.10.26

You may find this resource of great use @Andreas_Rozek for RGB ordering:

REFERENCE table of RGB Led datasheets

Group discussion around source code

RGBW neopixel leds
• #5

Andreas_Rozek in reply to @Robin

Hello Robin,

thank you very much - meanwhile I indeed found that RGB ordering is far from being "standardized"

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