I was asked how I know what all the wires are when I’m working on, or are looking at an old robot.

Here’s the big secret, I don’t!

I rely on a few important things to help me figure out or remember what the wires are for:

1. Diagrams - I’ll make sketches, they could be biro scribbles, schematics in CAD or quick drawings in any drawing tool. These can then serve as a map of the wiring to look at later, or wire by. I put pin names or numbers by them.
2. Labels or pin names on the robot - I’ve stuck sticky labels on, if the PCB’s don’t have pins labelled on them to help myself.
3. Datasheets, guides and references for the parts. I’ll look up, collect and keep datasheets for the parts I’m using. These often have pinouts and wiring diagrams.

Sometimes, I’ll use the multimeter to check that the wiring I’m looking at matches my maps. But to make it clear, I rarely memorise it all. Sometimes through familiarity with a particular robot I can roughly ese what the wiring is for, but I’d still need to check if the pins are right (and not say shifted left).

I hope that helps!

Specific connectors

Some robots have specific connectors, polarised, that make power wires, motor wires and sensors wires very clear. They are much easier to work on from know where wires go, but trickier sometimes in having the right connectors to hand or between devices.

This type still usually requires a block diagram to know what parts are connected to what, but the wiring is much easier to follow.