Any idea what could be causing this weird flashing? It was happening (a lot more) with another PSU earlier so I swapped in the beefier one. Strangely enough by turning down the brightness I can make it happen more.
It may be a grounding problem? Do you have common ground between your PSU and your micocontroller?
Yeah, I do. There’s a direct connection between the ground pin of the panel and the ground on the Teensy (and the level shifter).
But your suggestion made me think, and I unplugged the USB from the computer and it seems to have gotten better. Hmm.
Are they ws2812’s? Are you pushing data too fast to them?
They are WS2812Bs, and I’m only trying to do 60 frames/second.
And, I use my Teesny3.1 without any shifting, just hook the data out to the strips and they work just fine. What happens if you remove the level shifting circuit?
I had that in the last configuration but it kept glitching out. @Mark_Kriegsman recommended to put in a level shifter (I’m using the Sparkfun breakout: https://www.sparkfun.com/products/12009) as that’s what @Paul_Stoffregen (the P in Teensy’s PJRC) recommends in a few threads on the PJRC forums. This was at Burning Man though, so I’m not sure if my glitching problems were due to a short, my battery issues or the fact that I was putting a 3.3V signal into the WS2812Bs.
The only level shifters that I have had work reliable have been 74HCT245’s everything else I sometimes get glitching.
If your voltage levels are low enough you can often get away without needing a level shifter, but it’s a gamble.
What happens if you turn off dithering? setDither(0)
You can also check the power. I had the same effect with a powersupply that gave 5.5V. For me al lower voltage (4.9) worked better. Adding a 74HCT245 level shifter in combination with the 5.5V as well.
I’ve seen lots of people mention the 74HCT245 as the only thing they’d found reliable in this situation. Huge chip though.
It’s not happening right now (no idea why not!) but when it does next I’ll try turning off the dithering and see if that has any effect.
You can get smd versions of that chip.
Then I’d have to solder them 
(Not set up to do SMD, but the Sparkfun level shifting breakout I got was really convenient. But of course, that’s only if it works.)
Have I mentioned that i’m looking forward to the APA102 taking over the world? It appears to have no issues w/3.3v signals 
Oh - here’s another chip - 74HCT125 - only 14 pin instead of 20, so a little bit smaller - only does 4 lines instead of 8, but i suspect that’s fine?
@Robert_Atkins Not be accident this one: https://www.sparkfun.com/products/retired/8745 ? I was using this one at least that unreliable results.
I’ve gotten flashing like that from having too long a cable run where power and signal were near each other. (induced noise?) And also from poor connector seating. Not sure what your specifics are.
AC power will cause noise, not DC, if I’m not mistaken…
Yes. So clearly, “noise” is not the correct technical term. However, I have run into trouble using long power + signal cables. Call it what you will.
For long signal runs I use cat5/6 cables - for locus I had digix-> 74HCT245 -> cat5e cable -> leds.
I make sure that ground/data are on a twisted pair and I ran four lines of data over each cat5e cable.