These are chat archives for Makuna/NeoPixelBus

12th
Jun 2018
r1dd1ck
@r1dd1ck
Jun 12 2018 12:55

@kopierschnitte Still having issues with random colours showing up within the first 10 pixels from time to time (making them dirty helps!) and inability to change pixel state for pixels 100+ after the strip is fully lit for a while.

The first pixels misbehaving could be a sign of cross-talk or static build-up where at the beginning of transmission the shape of pulses gets distorted enough to cause corruption until the line stabilizes. But this usually also results in pixel-shift, so I'm not sure it is what happens in your case too. Putting a ferrite core on the data line, or altering the timing a bit (as @Makuna suggested above) might help.

The 100+ pixel issue points to either a bug in your code, or a fault in the strip/leds itself. Could be a bad solder joint on LED # 100/101 D-out/D-in, which after a certain temperature is reached loses contact - so carefully resoldering those two pads might help. Or it could be a cracked/broken trace on the strip. Or even one of the two LEDs being faulty. All other causes are significantly less likely.

kopierschnitte
@kopierschnitte
Jun 12 2018 17:14
@Makuna @r1dd1ck Already tried the NeoWs2813Method … without luck. As I've already tried a different (quite tiny) data cable between my controller and the strip (which didn't help) I'm now trying to replace the whole strip. The code seems to be ok because it also happens with Makuna's example code. Thanks for your suggestions!
Michael Miller
@Makuna
Jun 12 2018 17:15
What was your Arduino device? If its 3.3v, are you using a level shifter?
kopierschnitte
@kopierschnitte
Jun 12 2018 19:52
@Makuna I'm using an ESP8266 and a simple TTL level shifter (grounded). Before adding the shifter, the color channels (RGBW in my case) were totally screwed and strange color combinations occured. My PS is rated 20A (100W) and I measure 4.95V on both ends of my strip.
@Makuna That's the Level shifter I use: 3.3V 5V TTL
Michael Miller
@Makuna
Jun 12 2018 19:54
@kopierschnitte Do you connect the + to both sides? Is it a single strip?
The issue is that each pixel can draw 60ma, doesn't sound like much, but over a 100 pixels that's 6A! Those flex strips have a problem with that much at the ends. but this can be tested by drawing a single pixel, and moving it along the strip, having the others black. If this works fine, then the problem is the wire on the strip is too thin and you need to provide power from the center or both ends.
Your connecting TXI from esp, and TXO to pixels, right?
Michael Miller
@Makuna
Jun 12 2018 20:03
(BTW, I haven't used a level shifter except for early NeoPixels, most of the newer ones work fine with the 3.3v signal as long as they are connected close and the RF noise isn't strong)