Connector boards
Modules aren't wired to each other. They're bridged by small boards that snap directly between the connectors of two neighbouring module PCBs, so there's nothing to wire and nothing to crimp. Four modules or forty, the back of the display stays flat.
Three boards do this job. They share an outline, four mounting holes and the same pair of 5-pin JST-XH sockets, so any of them drops into any position in a row. What differs is what each one does to the power rail, and that difference decides the layout of a large display.
The connection board
The default, and the one you'll use most. Completely passive: the serial line (TX of module N to RX of module N+1) and the 12 V rail both run straight across to the next module. You can see it on the board itself, where the traces go from one connector to the other with nothing in the way.
Use one between every pair of neighbours that should share power. One comes included with each controller PCB.
The power break
Same board, same footprint, one deliberate difference: the 12 V trace between the connectors is cut. The silkscreen says POWER BREAK so you can tell the two apart at a glance, which matters when you're behind a forty-module display working out why one section is dark.
Only 12 V is cut. Ground runs straight through, deliberately, because the serial chain needs a common reference plane along its whole length. Break ground along with the supply and the two sides of the board would be talking without agreeing on what zero volts means.
Every boundary between two power groups is a power break. That falls out of how the injector works: it feeds 12 V in both directions, so the module to its left is powered as well as the modules to its right. Without a break at the group boundary, the group before it would be fed too.
The injector board
Power enters the display here. The green screw terminal takes your 12 V supply and feeds the rail in both directions, left and right.
That's deliberate. A one-directional injector would need a second variant for the module at the start of a row, and two nearly identical boards is exactly the kind of thing that gets mixed up on a workbench. One symmetric board covers every position.
It's the only one of the three with components, and they earn their place. The TI eFuse guards its group against overvoltage, undervoltage, shorts on the bus and overcurrent, and it trips fast and locally. MAX 3A is printed next to the terminal because that's the real limit of everything behind it.
Signal passes through as on the other two boards.
Which board goes where
| Connection board | Power break | Injector board | |
|---|---|---|---|
| Signal | Passes through | Passes through | Passes through |
| 12 V rail | Passes through | Cut | Fed from the screw terminal |
| Ground | Passes through | Passes through | Passes through |
| Components | None | None | eFuse, protection circuitry |
| 12 V input | — | — | Screw terminal |
| Marked | — | POWER BREAK | MAX 3A |
| Availability | One with each PCB | Ordered separately | Ordered separately |
Each module draws up to 500 mA and a group is rated at 3 A, so a group holds five modules. Within a group, the injector sits at the junction after the first module, so it feeds that module backwards and the remaining four forwards. The junction where one group meets the next takes a power break. Everything else is a connection board.
A ten-module row therefore looks like this:
[1]─INJ─[2]─C─[3]─C─[4]─C─[5]─BREAK─[6]─INJ─[7]─C─[8]─C─[9]─C─[10]
Two injectors, one power break, six connection boards. The display planner works this out for any size: enter rows and columns and it draws the groups and counts the boards.
Signal ignores all of it. It runs as one continuous chain from the row's WiFi entry module to the end, straight through all three board types. Power and signal are independent systems that happen to share a connector; Wiring & Power shows how that plays out across a whole display, and the calculator gives you the counts for a specific size.
Isolated groups keep a fault local. A short or an overcurrent shuts down five modules and trips their eFuse instead of propagating across the display. On a permanent installation that's the difference between one section going dark and the whole wall going down. Planning an Installation covers the rest of the failure behaviour.
Mounting
All three boards have four mounting holes and sit against the backboard, held between the two modules they connect. Screw them down along with the modules and the row becomes one rigid assembly, which also means a board can be released and swapped without disturbing its neighbours.
Watch the orientation. Every board is silkscreened the same way up, so if the text on the connector boards and the module PCBs all reads in the same direction, the polarity is right. Modules are protected against reverse polarity anyway, but reading the text is faster than checking the wiring.