Brand new the group and LED control in general, but I’m excited to use FastLED and start developing some stuff. I have a couple newbie questions… I guess we all had to start our learning somewhere.
I just bought a string of 300 LEDs with WS2811 interface chips. I noticed every 3 LEDs is controlled by 1 WS2811 chip. With that in mind do I set the variable NUM_LEDS to 300 or 100? I’m guessing 100.
The power requirements for the LEDs is 12VDC. I intend to control with Arduino. I have a separate 12VDC power supply that is capable of several hundred Watts (so I can control more strings in the future). I understand only 1 data pin is required from Arduino, but is it also the best practice / suggestion to tie the common of the 5V and 12V power supplies together?
Welcome to this wonderful addiction!
Yes, you must tie the common (ground) of the systems together otherwise you’ll get flickering pixels.
I haven’t used those 12V strips with every 3 pixels controlled together, but yes I suspect you’re correct with guessing NUM_LEDS would be 100 in that case. Won’t hurt anything to test either way though.
Thanks for the quick response. Last night I ran one of the demo programs, but the end result was only to prove that flickering lights can’t cause me to have a seizure! It was not behaving correctly. I woke up this morning thinking my data line was probably floating / unreferenced.
I’ll tie the electrical grounds together tonight and hope for better a better start going into the weekend.
It’s also a good idea to put a resistor on the signal line, as close as you can to the strip. I believe I’m using something like a 470k (??). I’m not sure because I’m at work now – feeding my LED addiction by checking posts here.
Yes, good point. A resistor on the end of the Data line can help counteract potential signal interference. Something like this:
A capacitor can also be added across the + / - wires to help smooth out large power fluctuations if lots of LEDs are being quickly turned on/off. For 5V LED strips it’s usually recommended it be 1000 uF 16V or higher rating, but for a 12V strip you might want to start with 20V or higher rating. The capacitor might not be needed though depending on the power supply, wire lengths, and how many LEDs are being lit up.
Thanks for all the tips! So far connecting the 5V and 12V commons has resolved many issues and allowed me to run supplied demo code fairly successfully. I’ll look at adding the resistors and capacitors to ward off future issues.
A new issue popped up. When I issue:
CRGB::Blue – My LEDs actually display Green.
When CRGB::Green – My LEDs display Red.
When CRGB::Red - My LEDs are Blue.
Setting the hex values also results in wrong display.
Chips show WS2811 on them and that’s what I’m using in my initial .addLED call. Anyone have experience with this before?
Hello all, my led strip also behaves the same way.
ie 3 pixels get lit up at a time,
and have the same specification as @Mike_Katchmar 's( 12v, ws2811, grb color)
I was hoping to control each pixel individually.
Am i doing something wrong?
or is the strip built that way. noob alert
Pretty sure your strip is built that way. There are definitely strips out there designed to do that, and sounds like that’s what you have. If that’s the case, you’ll probably see one chip, then three LEDs, one chip, three LEDs, etc.
You’re not doing anything wrong, many of the 12V strips are like that. When buying make sure it says something like “individually addressable pixels” if that’s what you’re looking for.
