Here's something I'm trying to work on now.
I'm finishing a carputer install and want to integrate steering wheel controls with my linux box.
I've already got most of the idea laid out, but I'm not sure if theory will go with practicality or reason.
I bought myself a cheapo 10-key off amazon for 5 bucks or something. What I plan to do is to pull the wire off the back of the steering wheel and tap into it. My hope is that I can attach it to a simple relay that will be wired to the keyboard. When i send a "change song" command on the steering wheel, it will activate the relay for a split second, connecting the two terminals on the keyboard to send a key command, for this example the "+" symbol. I'll also do the same for the "change track back" command.
Two ways i can do this:
1. I can use the relay itself to actually PRESS the two terminals together.
I'll have to open the relay up, since it's a "disconnected at rest" type relay, the two points will be away from each other. Once the relay sees the voltage, it will connect once i depress the button on the steering wheel and disconnect once I release the button. This seems to be about the easiest way to do this, but it then leaves it very open. Possible i may have to build a small, but bulky ABS box to enclose the setup and attach it up in the dash somewhere hidden from view.
2. Wire leads from the keyboard circuitry to the relays so it basically achieves the same thing as above, without having any open relays. Can possibly do without the printed flex board and wire directly into the chip.. lot more complicated but way less bulky. easier to hide and less chance of ruining the printed flexboard for the keyboard..
if you've come across an issue like this, you may be thinking of buying a carpc joycon or whatever it's called... I thought of using that but it's very expensive at about 20-30 bucks and i can't tap into the wires, i basically have to replace them. I don't want to do that. I'm hoping this method to be as non-intrusive as possible. Also, i think it's for only one command at a time, so i'd probably need to buy two. too expensive.
Thanks for any help, encouragement or ideas.