Getting WS2815B LEDs to work

Troubleshooting
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1

Hi! I have a Pixelblaze V3 standard plugged into a strip of WS2815B LEDs, but having trouble getting them to respond to the controller. My understanding is that I should be using the NeoPixel selection from the LED Type dropdown, and that at least gets the lights to shift from all white to some kind of weird, not-quite-random colored pattern that’s unrelated to the selected pattern.

I’m feeding 12v power to both ends of the strip (same power supply) with the Pixelblaze wired to the data and timing wires while drawing 5v power through the USB port. I’ve triple-checked that it’s connected to the input end of the strip, and I’ve tried all the LED Type options, and all the Color Order options for NeoPixel at least.

These are the specific LEDs I’m working with:

I feel like I’m missing something very, very basic, like how I missed setting the # of pixels higher than 100 the first time I worked with a full strip, but damned if I can figure out what it is.

Any suggestions?

2

Hey there! Just to verify, have you traced the wires with a continuity checker, being sure that DAT on Pixelblaze connects to something labeled DI or DI1 on the strip? BI or DI2 can go to CLK or any GND.

Also be sure you have a ground connected between them but nothing to Pixelblaze’s VIN in this configuration. You could damage the board if you connected your +12V for the pixels to the Pixelblaze VIN.

There’s no timing wires on a WS2815 (no clock); just data in and backup data in. The first backup data-in is grounded, but subsequent backup data-in lines will get the data out from two pixels earlier in the strip.

3

Board USB is connected to 5v power, DAT is connected to the strip’s D1, CLK is connected to the strip’s B1. Connections are sound. Power and ground run from power supply to strip without touching the board.

Good to know about no timing circuit. That makes things easier.

I’m able to get into the Pixelblaze UI, connect it to wi-fi, make config changes, and see some sort of response on the strip as a result - just not a response that makes sense, which makes me think it’s a configuration issue rather than a power issue. But it’s my first time working with this type of LED, and first time running 12v, so I don’t want to rule anything out.

4

It sounds like your issue is the ground. Ground needs to be also connected between Pixelblaze and the strip so they have a common reference point.

Check out step 3 on the Getting Started page:

https://electromage.com/docs/quickstart-v3-standard

5

The USB connector and the 12v power supply both plug into the same power outlet (the same outlet has a 110v and a 5v USB connector). I believe that should give them the same ground, right?

6

No, unfortunately not. They will share an AC line and neutral and perhaps a chassis ground, but you need a non-isolated common DC ground.

7

Aha, I’ll give that a shot. Thanks!