dead pixels?

[Pixellated]

Hey guys!

I'm having a blast playing with my neopixel array that I spent all weekend piecing together. It consists of 30 neopixels in a 6x5 layout, made with the bare WS2812B neopixels, and mounted on a sheet of polycarbonate. Looks sleek and just the strandtest blew me away. I do have some questions though, please help!

-Are individual capacitors really necessary? I have a big one on the input, but I don't see why I need a single .1uF capacitor on every led, unless I start to have problems with resets.. I assuming the capacitor is just so the little chip doesn't take small line variations as a signal to reset?? What is the purpose of the capacitors on every led, and if they're all in parallel couldn't I just put a 10uF cap every few leds?

-I had two pixels in the middle of my array die on me. I double checked the wiring, voltage drop, solderjob, etc. Can't find any reason as to how/why they died on me. Any ideas? They were on for maybe 3 hours. If I move the data line past those 2, everything works as normal. Could this really have to do with me omitting single capacitors?

-NeoMatrix.. is it limited to 8x5 or what? No matter how I set the initial parameters, it seems like the scrolling characters are missing the bottom two lines. (my array is 6x5) Anyone know how to fix this, or another library compatible with neopixels and smaller arrays?

-Neopixel library. I'm still new/rusty with the arduino and programming. Where can I find a list of commands/features of the neopixel library, or I just supposed to pick it up after looking at the strandtest code?? How do I open the README file with .md extension?

edit; now 3 pixels are dead. I don't understand, are these leds supposed to have a resistor?? I thought they were current limited internally. I didn't use a cheap power supply, and I do have a capacitor at the input. All wiring is good, supply voltage never went above 5.0 volts, I'm at a loss!? I've ordered more to replace the damaged ones, but I wonder why i'm blowing them up?! I havnt fried an led in ages... If I look close there is some funkiness inside the burnt out leds, maybe I should drop the voltage and stick to batteries?!? I dont want to keep replacing leds, huge pain with the SMT types. Please advise!

[adafruit_support_rick]

Not sure why your pixels are dying. The lack of caps may have something to do with it. Your power supply may be spiky.

NeoMatrix should work for any size matrix. I'll check with the author of the library.
We do have a tutorial on the NeoMatrix library:
https://learn.adafruit.com/adafruit-neo ... ix-library

We don't have a tutorial on the NeoPixel library. Basically, yes, have a look at strandtest.

The readme.md file is just the text that shows up on the github library page.

[pburgess]

The NeoMatrix library uses a 5x7 font (5x8 if you count the descenders on some letters)...that is, 5 pixels wide, 7-8 pixels tall. So yes, the characters will be clipped. Needs a bigger matrix, or you'd have to create a 5x5 font (if that can be done legibly) in the Adafruit_GFX code.

I can't say -for certain- that leaving out caps is causing the pixel-toasting, but there's a good -probability- that this is the issue. Among other things, NeoPixels don't seem to appreciate it when the DIN voltage significantly exceeds VDD...which is what can happen when a pixel has its own mini-brownout, as when switching from a dim to bright state (normally the individual caps cover the difference).

[Pixellated]

Thanks!

-I doubt I'll have any fun modifying the Adafruit_GFX code, so maybe I'll just skip the matrix for now :)

-Hmm, this sounds plausible. I wonder if when DIn>VDD, there are reverse voltage/current issues. Well, since my project is going to be battery powered I will probably stick to recharable NIMH batteries from here on out to avoid any more damage, and next time in the future, I'll check out my supply with a oscilloscope, or add a known good linear regulator with caps in-line with my 5v supply to additionally smoothen out ripples/spikes.

Thanks again!