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Chippernut Forums > Shift Light v2.3

Add extra Neopixel

posted Sep 26, 2015 23:06:22 by
This project is great. but i was curious, can you daisy chain Neopixel LED strips? or can it only be the two?

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6 replies
Jonduino said Sep 28, 2015 12:18:37
Yes - you can daisy chain LED strips, it does not need to be just two. You can also use individual Neopixels or the neopixel rings for this project.
Chris Ward said Jan 02, 2016 11:55:33
Building on the previous comment im using a 144 neopixel strand but am running into difficulties using a UNO. The system seems to freekout when i go above the programmed 32 pixels. Any advice?
Jonduino said Jan 03, 2016 19:18:13
Hi Chris,

Neopixels (WS2812b) work best when the number of LED's are specifically addressed digitally. So if you program 32 LEDs and have 50 wired up - the remaining 18 may exhibit unpredictable behavior. To use more than 32, you'll have to modify the source code.

See code on line #929

case 8: // NUMBER OF LEDS
matrix.writeDigitRaw(0,0x54); //n
matrix.writeDigitRaw(1,0x38); //L
matrix.writeDigitRaw(3,0x79); //E
matrix.writeDigitRaw(4,0x5E); //D

while (menu_enter == 1){

int coloradjust1 = rotary_process();
if (coloradjust1 == -128){NUMPIXELS--;}
if (coloradjust1 == 64){NUMPIXELS++;}
NUMPIXELS = constrain(NUMPIXELS, 0, 32);

All you'll have to do is increase the number "32" to whatever number you need.

NUMPIXELS = constrain(NUMPIXELS, 0, 32);

Another important factor that affects the Neopixels is the amount of power readily available. Each Neopixel draws 60ma of current per LED "pixel" when on full-white. Times 32 pixels that's roughly 1.9 AMPS of draw -- if the 5V regulator cannot keep up, data integrity suffers and the system voltage drops. This may also result in erroneous Neopixel behavior. Make sure your 5V source has enough 'oomf' to power the number of pixels you're using.

Hope this helps! :)
- jon
Chris Ward said Jan 03, 2016 23:01:52
Hi jon,
As you've mentioned i have tried modifying the code to extend the numpixels constrain to 144 but it seems to just cause problems. For reference when i say problems i am referring to the 7-segment display either going non responsive or becoming completely unuseable. This seems to happen if the neopixel strand is powered up or not.

With regards to power im currently running the strand and UNO off different power sources (with common ground) (usb to UNO and 9V battery to pixel strand). As such i dont think this would be the problem.

Could i be having a memory shortage issue as im aware the standard setup is nearing the limits of a UNO?
Jonduino said Jan 25, 2016 13:56:48
Hi Chris,
Sorry for the long delay in responding. I think your problems are caused by running out of power. 144 LED's is going to draw a lot of power - more than the UNO can supply. For that many, you'd need a standalone power-supply, or some big 12v - 5v converter that can supply enough amps for the job. Hope this helps.

- jon
Chris Ward said Feb 08, 2016 11:16:09
Thanks Jon,
I agree the power req is way too much for the current setup. Decided to reduce my pixel count back to 32. Will post some picks of the final outcome.
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