I had a question about power/ground and multiple ws2811 strips.
Let’s say that I want to connect an arduino to three led strips (totaling 150-200 lights) and I want the minimal number of wires (because this is a wearable), but I also want all of the lights to get at much power as possible.
The dress has three hoops of ws2811’s. So I was thinking of virtually having a power and ground trunk with each light strip branching off and dead ending.
Then I was going to snake a data line from the arduino to the beginning of the first strip out the end of the first strip and to the second trip, then from the end of the second strip to the third strip.
My question is: do I need to also ‘loop’ a ground from the end of the first strip to the trunk or the beginning of the second strip?
I’ve noticed that Wu’s strips seem to be setup to have two grounds and one power and one data, but i’m not sure why that is.
Assuming each strip is, lets say, 60 LEDs long. Totalling 180. I would feed power into both ends, from your diagram, just repeat the black and red wires from the left to the right. If the ends touch, even better, then it is much easier to wire up. Basically, you will need to re-inject the power about every meter. Otherwise the strip voltage drops and the LEDs do weird things. Just ‘tee’ the power as you have done. If the strips are longer than 1m, then you will need to feed in power at additional points down the strip.
Your battery battery is going to be quite large or the life or the LEDs will be quite short. 180 LEDs with 3 LEDs per chip at 20mA per LED is going to drink about 10A on full white. That means for an hours operational life, you will need about 15Ah battery - that is a lot of weight - have you thought about that?
Your display patterns will need to be carefully chosen to maximise battery life. Displaying a single LED chip colour will triple the battery life. And halving the intensity will double that. Keeping the whole thing at only 10% (pretty dim in daylight) will give you 10 times the battery life, but a boring display. You might need to use a light sensor to dynamically adjust the intensity and extend life. But in daylight (or a bright room), life of the system will be down to how big the battery is…
Sounds fun though, post some video when you have something.
I have a few different led pixel strips that use the ws2811/12 ICs and all seven strips have an extra ground. The extra ground wire makes it easier to test but I don’t see any purpose or reason to connect both ground wires. Just make sure to connect each ground to the Arduino too.
