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Old 05-21-2008, 11:19 AM   #157 (permalink)
needs more cowbell
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If *I* were to play around with an obd version it will be elm based, and use the less expensive single protocol chips because:
1. they are less expensive
2. they are less complicated to hookup (only care about a couple obd pins, not all of them.
3. I already have a 323

Here are some schematics:

[looking at the 323 elmiso schematic] if it is connected to a duino, you can skip the rs232 stuff on the lower right , just use ttl to the duino tx/rx ports@9600, and all the blinky LEDs in the upper right and the voltage regulator circuit. So you'd be left with 8 resistors, 3 transistors, 1 crystal, 2 capacitors, 1 diode, and of course the elm323 and an obd plug, just for iso protocol.
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