iso can be done with a couple transistors, but the obd market is partly about keeping things simple, i.e. avoiding questions like "whats ISO?", and getting all sorts of values on just the one interface. But it is a whole lot of work just to get to universal protocol state from scratch, unless we build upon what Alex the
allpro guy has put together or go with the 327 ($25US after conversion).
I could put a board together with all that (not much worse than the elm all protocols interface) and it might come out cheaper than the elm327. I should give Alex a note and see how much he wants just to use the hex file and relevant circuitry on our own board, just to see if it is worth the effort or not, he claims 327 compatibility. But who knows if the 327 vs the allpro actually works with more cars or not? With a custom circuit, we at least know how to support it and aren't left saying "sorry, this other thing we chose to use is broken". But as I said, it is a lot of work and needs to be coordinated to be of much use.