Oh, something interesting. A friend of mine went and got himself a Skyline GT-R32, and I've been doing some testing with it. While pondering an interface for his car, I went researching CONSULT and stumbled onto this post on a Nissan Q45 forum. Ah, blast from the past.
Quote:
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Originally Posted by Q45 Forum
The output of the ECU is open collector, which requires an external pull-up resistor(provided by the board). On some of the DIY boards, you'll see this signal going straight into the RS232 converter. The MAX232's can be picky about their voltage hi/low signal thresholds, so this is where you run into problems. The problem is the 'low' signal is too high, and the MAX232 registers it as a 'hi'. My boards don't use a MAX232, because it isn't serial, but the same applies to the CP2102 also... there are hi/low thresholds you have to look out for.
I attempt to circumvent this by running the ECU signal into an op-amp comparator. Anything above a set threshold is output as a 'hi', otherwise it's a nice clean 'low'. FWIW, the comparator has an inherently very high input impedance. The only thing that could possibly be done is tweak the pull-up resistor value, but that may keep it from working on other ECUs.
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Sounds kinda familiar, doesn't it?
