I'm having an issue driving 12 volt WS2811 pixels with a teensy 3.2.

(Jared Alexander) #1

I’m having an issue driving 12 volt WS2811 pixels with a teensy 3.2. I am using four output pins. The first three pins have 100 pixels each and the fourth pin has 71 pixels. The first two pins output fine but I am getting a lot of artifacts and incorrect color on the last two pins. If I swap the strands around they all work fine on the first two pins. I am running a simple test pattern. I tested the pixels with an Arduino Due and the same test code and they work fine. Is there some kind of power issue?

(Jason Coon) #2

Possibly. How are you powering them? 371 pixels at a max of 60mA each (full bright, full white) is 22 amps.

A few quick suggestions: Tied all the grounds together (all strips and the Teensy)? Tried running power and ground to both ends of each strip? Measured the voltage at the problematic strands?

(Marc Miller) #3

Other ideas to try:
Add a resistor (inline) to each data line. Put it on the end of the data line at/near the strip. Try something in the range of 200 to 470 ohm. (I’ve always used 470 ohm.)

Maybe run the data lines through a level shifter (74HCT245)?

(Ben Delarre) #4

Try running at 5v. I had a strip of supposedly 12v LEDs that ran a whole load better at 5v.

(Jeremy Spencer) #5

How far are the strips from the controller? I had similar issues another set up, I swapped out the data wires for shielded cat6 network cable and this solved the problem. I also use 100 ohm resistors near to the controller on the data lines.

(Jared Alexander) #6

They are all being powered with a 12V 30A power suppply and all the grounds are tied together. The Teensy is being powered through the computer USB port and a ground line running to the PSU. I tried 180 ohm and 470 ohm resistors and they completely block the data signal. I don’t get anything on the pixels. If I connect them directly to the output pins I get a signal but with the same issues described above. There is about 3 feet of data wire from the controller to the pixels. I will look into a level shifter.