I have two LED pixel strips, one is a 4 wire and that works fine because it has a ground wire for the Arduino. I ordered a new LED pixel strip that only has 3 wires. That leaves no wire for the Arduino ground, so I'm getting random behavior and the first LED pixel always lights up even when it's not programmed to do so.
From what I've read that's expected behavior when not having a common ground. I'm just a little confused on how to wire this common ground. Any advice or diagrams would be much appreciated.
I ordered a new LED pixel strip that only has 3 wires.
So you are not going to tell us what type of strip this is then?
Some strips with 3 wires have power ground and data. If you have one of these then there is no problem as there is a ground. Random photos of your glove compartment and a pair of scissors is not going to cut it here.
In the picture, there are two red circles. One of those pins from EACH circle is a gnd too. So you could use jumper wires or something, and use them as grounds. Or use some really excellent bonding method to bond an extra header to the UNO board, and then you can use jumper wires to patch those grounds through to your header board.
Grumpy_Mike:
So you are not going to tell us what type of strip this is then?
Some strips with 3 wires have power ground and data. If you have one of these then there is no problem as there is a ground. Random photos of your glove compartment and a pair of scissors is not going to cut it here.
Sorry about that, it was late when I made this post. The actual image URL is Imgur: The magic of the Internet if you want to zoom in more, not sure if that would help. The new 3wire strip is a DC5v WS2811. It does have a power, ground, and data wire. The ground is for the power supply, but my other WS2811 strip has the extra ground wire for the arduino. See it here: https://amzn.com/B01DZV3PNO
Southpark:
In the picture, there are two red circles. One of those pins from EACH circle is a gnd too. So you could use jumper wires or something, and use them as grounds. Or use some really excellent bonding method to bond an extra header to the UNO board, and then you can use jumper wires to patch those grounds through to your header board.
But where would the other end of the jumper wire go to? The LED strip has a pos/neg for power, and a data wire for arduino. I'm asking how I would add an extra wire to go from the LED strip to the Arduino ground.
vater:
But where would the other end of the jumper wire go to? The LED strip has a pos/neg for power, and a data wire for arduino. I'm asking how I would add an extra wire to go from the LED strip to the Arduino ground.
If that's how you want to do things, literally just take the 1 GND wire, and split it. Since you seem to be having trouble actually showing your strip, it's hard to point out to you that there are tons of GND points and possible this magical "extra" GND wire at the other end.
I feel like the answer is so simple you're kind of missing it.
I can in your picture you've got the strip connected to one of those wall wart adapters where the lead ends with green screw terminals. Connect a wire between the negative screw terminal and any of the free ground pins on your arduino.
GypsumFantastic:
I feel like the answer is so simple you're kind of missing it.
I can in your picture you've got the strip connected to one of those wall wart adapters where the lead ends with green screw terminals. Connect a wire between the negative screw terminal and any of the free ground pins on your arduino.
Agreed, sorry I'm a noob. Thanks for your help. I'll try that.
One end of the new wire goes to a GND terminal on the Arduino, the other goes to the negative terminal on the power connector. There are other ways to do it.
GypsumFantastic:
Don't apologise. We were all new once.
Here's what I meant:
One end of the new wire goes to a GND terminal on the Arduino, the other goes to the negative terminal on the power connector. There are other ways to do it.
Your pic isn't loading, but I have a pretty good idea of what you mean. Thanks again.
vater:
But where would the other end of the jumper wire go to? The LED strip has a pos/neg for power, and a data wire for arduino. I'm asking how I would add an extra wire to go from the LED strip to the Arduino ground.
Oh.... ok! Got what you mean now. Ok....... the usual procedure is to connect NEGATIVE terminal for the LED strip to GND of arduino.
Earlier, I had wrongly assumed that you needed an extra GND pin for the arduino. So I went ahead to show a photo of an UNO, to show that there are other GND pins on the UNO (aside from the usual single gnd slot on the header connector).
