connecting neopixel strips to strips

Hello,
I am looking for someone to describe the most effective and safest way on how to connect a RGB addressable 60led per M strip to another strip ( I have 3 separate 60led Meter neopixel strips) that I would like to connect together into one continuous strip.

Each of these strips I’m currently using on a project of mine that’s on a sweatshirt each with its own adafruit Gemma microcontroller and (3.7v 2700mah battery I believe) is there a way i can incorporate these three batteries together to power the new would be 180 led m strip and be able to program it with one adafruit Gemma? I would really love to incorporate some cool color changes throughout the whole 180 leds instead of the 3 split up strips I have now. Please include the most effective and safest way if possible concerning things like size wire, resistors, and such.

Would I need to change the code or would it read the next starting neopixel of one strip from the previous ending of the last strip correctly without needing any extra code to include to specify?

thanks very much I’m very new to LEDs and only have a semester worth of programming experience in c++ appreciate any feed back

Hi, it sounds straight forward.

Continue to power each stip with its separate battery as now. This is preferable to daisy-chaining the power from one strip to the next, which might overload the conductors on the first strip. Remember to connect the grounds together.

Connect the data out of the first strip to the data in on the second strip and the same between second and third. Then in your sketch, simply initialise the strip as a 180 led strip.

Paul

Would I need to change the code

Yes the bit that says how many LEDs you have.

would it read the next starting neopixel of one strip from the previous ending of the last strip

Yes.

OK, so you connect each battery directly to power and ground of its respective strip. If it happens that the start and end of the strip are close, then connect both power and ground to both ends of that strip. In fact, it does not matter whether you connect the power to one end or the other.

Now whether or not you connect power to both ends you need to connect ground and data from the end of the first strip to the beginning of the next, and so on. Keep the wires closely paired, both for power and signal.

Hey Paul,
thanks for the reply it is much appreciated sir! So I am using a 3.7V 2500mAh battery that has a red and black wire coming out of it with the end being a JST connector. I am able to cut this off and just solder it to ground and power of strip 2 and the same for 3; that way I can get rid of the micro controller for 2 and 3 since that's how it was being powered correct?

I will be connecting a battery to the starting of strip 2 and 3 respectively and won't be connecting these to the ends since they aren't near but as you said it shouldn't matter. To my understanding it will be okay to have the the beginning GND start of strip 2 and 3 share a solder connection with the battery ground and the ground coming from strip 1 and then strip 2 and 3 and then connect a data from 1 to 2 and 2 to 3.

Should I use 22 AWG wire to connect ground and data from strip 1 to 2 and 2 to 3?

thanks,
ricky

Don't recall quite how thick 22 AWG is, but the data connections do not need to be heavy at all - quite thin wire will do, You should of course be using multi-strand flexible wire if this is a wearable and you need to secure the solder connections of the flexible wire to strips or PCB with a blob of silicone or hot melt glue as movement at this point leads to rapid breakage.

I am not sure how you intend to charge the batteries. It would be better not to cut off the JST connectors; you should have obtained the mating connectors when you got the batteries - you probably want to un-plug them for charging (or indeed, to shut down the system as you must not over-discharge Li-Po batteries). If you intend to charge them whilst mounted, you might want the ground wires between strips to be as heavy as the power wiring as you may want to be charging from a common point.

Ah good catch because I didn’t think about how I would charge it if I cut that off. this may seem like a noob question to you but how would I achieve connecting my battery to strip 2 and 3 without the microcontroller and keeping the JST connector on it?

Do I need this mating connector or can I do this by cutting the ground and power from battery to JST, adding/twisting extra wire to the now spliced power and ground coming out of the battery then solder it to the power and ground of the strip. Then add/twist the other power and ground wire of the cut end of the JST connector to the cut end of the battery that is connected to the extra wires connected to the strip so in simplicity it’s battery → JST & extra wire to strip so basically a 3 way connection then solder together and hot glue to minimize breakage. sorry if this doesn’t make sense it’s the best way I thought of explaining it. would this work or can you link me to a mating connector? I can show you a picture of some close ups of my set up to clarify tomorrow when I’m with it but this is the only picture I have of it right now and it doesn’t show how I have it rigged up.

https://instagram.com/p/-YPuFdFcct/

I don’t recall getting anything with my battery except I have, give or take; a foot long JST to JST connector wire but I don’t think that will help me with anything except cut and use for extra wiring at this point.

How about explaining what pieces have what connectors, and what you have? Perhaps with a photo (perfectly focussed and in daylight, if you please)? The LED strips generally come with JST connectors in order to plug one to the next; you would only have to break out the power wires for the separate batteries. Are the ends of the strips covered to prevent you unsoldering wires?

I didn’t think I needed the JST connectors for the strips so I ripped them off and soldered the connection to my microcontroller. With the information you told me, I was going to power strip 1 to 2 and 2 to 3 with a data wire to data wire and ground to ground while keeping them close. Then I would have to share those same solder points with a ground and power from my battery correct? I have JST connectors on my batteries I tried to include the best pictures I could.

Looks like a dragon tail!

I'm not so keen on the twisted wire and tape connection for the LiPo batteries - you really need to make absolutely sure they can never short out.

the interconnects look OK, but you really need to cover the end of the wire together with the board, with hot melt glue to prevent the wires bending at the point of connection.

Correct lol :stuck_out_tongue:
Yeah Im gonna wait until I put the strips together to melt glue and finalize the connections I suppose.

That isn't tape. It's some kind of material my mom gave me I ironed onto it and when it gets ironed; it sticks well and holds a solid connection wayyyy better than tape ever could but the only thing I'm worried about is will the battery potentially become hot enough to melt through it?

Cover the wire together with the board? Can I see an example because my boards pretty small

also should I be adding any resistors or capacitors anywhere?

Thanks

ricky

The battery had better not get hot! That would be very dangerous.

The strips have capacitors on them. There is some suggestion that a 150 Ohm resistor should go between the Arduino and the first data input, but most people do not bother.

It's some kind of material my mom gave me I ironed onto it and when it gets ironed; it sticks well and holds a solid connection wayyyy better than tape ever could

Bias binding?

http://stitchwitch.biz/fusible-bias/

Hello, sorry for the very late response, couldn’t do anything because I didn’t have a soldering iron but now I do :slight_smile: I am going to upload this crappy picture I made on my mac to verify how I should have the new connection since I still dont feel like we’re on the same page sorry for the hassle and thanks for the help

4a4019f4f8272bfcad56c0603e27075d07e2a220.png
You forgot to connect the grounds. Otherwise ok.

It depends on how many LEDs there are in each strip?
If the strips are long then this is the way to do it, however you can get away with about 4 Meters of strip ( 240 LEDs ) without splitting up the battery supply.

The other thing is you need to carry on the negative connection from strip to strip.

Grumpy_Mike:
The other thing is you need to carry on the negative connection from strip to strip.

I modified OP’s dwg to show that (attached).
[Doesn’t ‘Paint-X’ have text, like Paint?]

I wondered about sourcing the +V for the first strip from that Gemma pad, so I show the battery going to the strip and the Gemma JST.

With Neopixels I had the aforementioned resistor (I used 1k) between the microcontroller and the first strip and everything was OK. In my final build I forgot it and the display would flop (seeming dead) till I cycled power. Looking into the matter, I realized my hasty omission.

I modified OP's dwg to show that (attached).

I would have thought you could use the negative out from the previous strip.

. In my final build I forgot it and the display would flop (seeming dead) till I cycled power.

I think that resistor helps to absorb reflected waves and stop a standing wave building up. Never missed it out myself, good to know it is essential.

Grumpy_Mike:
I would have thought you could use the negative out from the previous strip.

When I made my neopixel glasses, I routed +5 and Gnd wires out to the “far” unit ring.
Jumping to the vias or pads as you suggest is probably OK, too. (see _v3 attached.)