Automotive Shield

Before I even try to make this happen, I wanted to make sure there wasn't something that is already out there that would work without having to re-create the wheel.

I have several accessories that I have added to my off-road vehicle, (lights, compressor, radios, etc.). I'm wiring them all up to automotive relays and switches, but I realized how much more granularity I could have with how each functions if I introduced an arduino. With an arduino, I could change the behavior of each switch without having to rewire everything.

For example, I have additional forward facing lights. I am wiring them to an ignition controlled source, meaning they will only come on when the ignition is on. I may want to only have them come on when the headlights are on and the ignition is on. If there was an arduino, inputs pins could monitor both the ignition and headlight lines for voltage and build a state machine in the arduino to control the output (to a higher powered relay, of course).

The problem is the input and output voltages are all 12v. Is there a simple shield that would do the 12v IO without having to build something from scratch? It seems like there could be a huge application for this, but either I'm not searching for the right thing or there isn't.

Look at a Ruggeduino. That will take 12V on the input pins.

It's a good idea. I think there will be a market for that. Make sure the analog pins will work with common automotive sensors like resistive fuel gauges.

Thanks for that info - that is interesting. From first glance, it looks like it will take 12V on the input pins (won't burn up), but it still operates on the 3.3/5V logic for both input and output. It's nice that it can be powered by up to 24V, but it looks like it would still need some type of shield to be capable of 12V I/O logic. Am I reading that correctly?

Yes, you would need a relay shield or a motor driver shield to get 12V outputs. Personally, I'd use a motor driver as it will be more reliable than relays and it can fade lights on and off rather than hard-switching them.