Acura steering wheel volume control implementation

**jayearl** · 09-14-2005, 07:50 PM

I went through Buybytes FAQ on hacking your steering wheel contols but all the solutions seemed more complex than I wanted to dig into so I designed my own simple circuit. This is an implementation of using the Acura steering wheel volume/mute buttons to control the volume on my laptop carputer using parts from Radio Shack. The circuit is designed to interpret the different resistance values on the two wire steering wheel bus and activate relay switches that are hardwired to the volume control switches in the laptop. Originally I had the mute button going to the mute control on the carputer but later decided a better use was controlling the mute on the radar detector mounted in the back of the car.

**acura cl** · 09-15-2005, 11:10 AM

i was also trying to use my swc to control volume on my carputer.

do you have a pic of the actual circuit?

**jayearl** · 09-15-2005, 11:25 AM

Its not much to look at since it is hand built on a perf board but I will post a picture when I get off work.

**acura cl** · 09-15-2005, 02:10 PM

i was thinking about hacking a usb gamepad. did you try that route before making the circuit?

**jayearl** · 09-15-2005, 02:24 PM

I looked into doing the gampad design but this approach at the time seemed simpler to design/implement. The hard part came when I tried to wire the relays to the volume switches in the laptop. Had to completely disassemble the laptop to get at the switches. Not for the weak of heart!

**jayearl** · 09-15-2005, 07:32 PM

As promised here is the board. It is pretty scary right now but it works. Once I figure out all the other custom circuits I need I plan on making one pcb with everything on it.

**acura cl** · 09-16-2005, 01:28 PM

would i be able to use this circuit but instead of connecting it to a volume control of a laptop like you did, connect it to the buttons of the gamepad? or to a ps/2 port of the pc?

**jayearl** · 09-16-2005, 01:45 PM

You could connect the relays to a game pad. Instead of connecting to the volume buttons of the laptop like it did, connect them to the buttons of the gamepad.

Not sure how the ps-2 port works. If it is looking for logic signals you can connect one end of each relay to 5v power (and a pulldown to gnd) and then it can provide a logic high signal when you press a swc button or gnd level by default.

**acura cl** · 09-16-2005, 02:44 PM

hmm.. how much would charge if i asked for one of those circuits?

**jayearl** · 09-16-2005, 03:17 PM

I am planning on having an actual pcb built (www.expresspcb.com). I would be getting 3 bare boards so I would be willing to eat the cost of the bare board but if you could pay for the parts that would be good. I think the relays and pots altogether were about $20. So how about $20 + shipping.