Multiple Expander Boards using standard V3

[Unobtainian]

Hello,
I am new to the forums, thanks for the pixel blaze and all that comes with it, the community and the support so far have been amazing.

I have set up 3 sets of V3 each with its own expander board with 6 24V 5.8m neon flex LED strips, and individually they work great, flawlessly I must say, the colors and patterns are amazing. I have not had time to dive into creating my own patterns, as the ones native to the board are already quite good, for the purposes.

I want to now connect these 3 sets so that they are linked and I can control all 18 strips @ 81 pixels/strip. I have tried to use the new app and it has acted a bit funky, potentially Wi-Fi interference or noise as this installation is in downtown SLC. I was thinking about using a microcomputer to connect but worried it might not work that well with the set up. Tonight I tried to use one V3 and connect the 3 expander boards to it by connecting the expander boards to the data line of the V3. However I seem to be getting some problems. Each expander board and 6 led strips are connected to a different power supply and different outlet outside. They are 8’ from each other. I wonder if the data signal fades as the distance increases? The 1st set runs the patterns great, the next set is glitchy and slow but the expander signal led is solid green and the third set 16’ away shows the colors of the pattern but does not do the pattern really at all. Does the data signal fade as the distance from the source increases? Or am I getting a problem because they are not all connected to the same power source?

Thanks for your help!

[wizard]

Hi @Unobtainian,
Welcome to the forum! Are you part of the The In Theory Art Collective? Amazing stuff!

Wireless:

When you say app, do you mean Firestorm, or the Pixel Lights phone app? How did you set up WiFi for that, do you use another AP/router, or set one Pixelblaze in AP mode, and connect the rest? If that can be figured out, it might be easier, assuming WiFi will reach.

Wired expander:

Yes, fast data signals tend to pick up noise and have transmission issues with very long runs. It uses a serial protocol that works well over shorter distances. The expander has checks to prevent drawing garbage data, which improves the distance capabilities, or otherwise it would probably look very random and glitchy instead of drawing the actual pattern colors.

One way around this issue is to use a converter to a long distance protocol, like RS485, that is designed to ignore noise over long runs. It uses more wires, but can travel very long distances. It needs a receiver on the other end. RS485 can also handle multiple “drops” or connection points as long as there aren’t very long branches.

We’ve talked about this a little on the forum before for pixel data.

I would recommend picking up this cheap 5 pack of rs485 tranceivers (they can transmit and/or receive) https://www.amazon.com/Max485-Chip-RS-485-Module-Raspberry/dp/B00NIOLNAG

On the main set, where your Pixelblaze is located, the connection to the local expander doesn’t change. Install a tranceiver in that node and wire it up like this to have it transmit data:
VCC → Power 5V
A → long wire to second set
B → long wire to second set
GND → Power GND, and long wire to second set

DI → Pixelblaze data (also connected to the local expander)
DE → 5V
RE → 5V
RO → not connected

From there, you would run 3 wires connected to: A, B, and GND to the second set.

On the second set, install a tranceiver and wire it up like this:
VCC → Power 5V
A → input from first set, and continue long wire to second set
B → input from first set, and continue long wire to second set
GND → Power GND, also connect GND first first set, and continue long wire to second set

DI → not connected
DE → GND
RE → GND
RO → expander data input

The 3rd set would be wired much the same as the second set.

It’s better to run the A/B transmission wires as one long path than to create branches. If it would be easier to run 2 sets of transmission wires from the main set (like if it was in the center of the others), then you can use 2 independent transmitters.

The differential transmission wires work best with twisted pair, this is super easy to find as CAT 5 ethernet cabling. For your distances that wouldn’t be critical though.