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Old 08-20-2008, 12:16 PM   #139 (permalink)
Test Tool Engr.
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@Magister: Fair enough. I got one of those off of eBay before I even really looked into it (and realized the real ELM parts are over $30, which would've been a warning siren going off in my head).

At this point though, I'm kinda thinking OBDuino 1.0 should be the Arduino+ELM (mitigates risk), and 2.0 could be the AT90CAN or a more limited version that only does ISO/VPW in software on Arduino.

I'm also a software guy, but I've laid out boards successfully in the past with similar requirements without issue, so I'm sure we can come up with something decent for this. I was planning on laying out an "Altoiduino" board -- an Arduino clone board (probably based off of RBBB) with the components needed for the various protocols, but now I'm wondering if I shouldn't concentrate on the AT90CAN.

@dcb: I should rephrase that -- I wasn't really speaking of full-on reverse engineering, but just getting an idea of the protocol, since I'm not completely familiar with how they work (voltages, pulse shapes, etc.) I wasn't thinking too much about taking the data going across the bus and straight cloning it. But I suppose you're right -- it's a fine line.

To be honest, if ELM has a copyright on their implementation of the protocols in a CPU, the project is kinda doomed to begin with, isn't it?

I'm not condoning anything I perceive to be illegal either. If I open up the case of this thing I got off of eBay and find out it's a clone (and now I am fairly certain it is), I'll be a little disappointed -- mostly in myself for being suckered! But with a protocol, there's typically only one way to skin a cat. If I was talking about ripping the code from an ELM327 and reverse engineering that, that'd definitely be wrong, but seeing the messages it sends out just to get an idea of the protocol's ins and outs in a real-world example seems to be clean.
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