OBDuino questions before ordering
 

I've not actually done anything with Arduino yet, so this will probably be a bit challenging for me, but that's ok. I'd like to build an OBDuino to put on an 05 Scion xA (Toyota Ist outside the US). It has an ISO OBD interface.

It would be nice to keep it as small as possible so I'm looking at the Arduino Pro Mini to do this. Will this work with the Arduino Pro Mini? It looks to me like the only thing the Pro Mini doesn't have is a 9V power. According to the diagram this is used to power the MC33290. It looks like the MC33290 will work with 8V - 18V so I could either run it from a 9V battery or the car's 12V, right? Just to be safe I would still go through a voltage regulator though.

According to the ISO diagrams and pictures I've seen there's always a DB9 connected in there. I understand that this allows the OBDuino to work with both ISO and CAN, but if I only want it to work with ISO can I connect the MC33290 directly to the OBD connector?