I don't actually have to achieve this, it's more of an attempt to see what the best way to do this is. I'm sure the answer also differs depending on what circuitry you're trying to connect.
In this case, I plan on an Arduino (probably a Pro Mini or similar) that will control some RGB LEDs (via the WS2811 chip). If I wanted to add a second Arduino that would drive the LEDs if the first one failed (obviously very unlikely), I was wondering how I would do it. The WS2811 chip takes 5V, GND and data in.
My best attempt at a solution is using 3 relays which are SPDT. Connect the LEDs to the main Arduino via the normally open, which is controlled by that particular Arduino, and connect the LEDs to the backup Arduino via the normally closed, which is held open by the main Arduino. In the event of a failure, the main Arduino would lose connection to the LEDs while the backup would make a connection.
This probably isn't a very safe way of doing it (especially if the relay failed for example). Is there a way to do this?
The two Arduinos will be powered from two separate laptops.