Quote:
Originally Posted by Freyguy
Well, the fuel gauge works with a variable voltage input which we fake out using PWM of +12V. The tach input expects to see a variable frequency from 0 to 600hz. Slowest freq I can output on the PWM pin is 488hz (using PWM block). Unless the pin is used as standard digital I/O and it is toggled based on another timer under interrupt. A bit of code involved...
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I've just had a quick look at the toothed wheel that drives the magnetic sensor. Its hard to get at as it is fitted to the car and buried under lots of stuff, but best guess is about 60 teeth on a disc of about 20 cms dia. so tooth width is about .5 cm (with a .5 cm gap). This means the frequency at an idle of say 600 rpm is going to be about 600 Hz rising to say 6 KHz at 6000 rpm.
I'll hook my square wave generator to it and measure it that way, it'll be easier than fiddling about with the magnetic sensor etc.
So we need a square wave ouput that runs from - ideally 0, but in practice maybe your 488 Hz - up to 6 KHz and proportional to the current.
That would mean the minimum current reading would be 81A. Might not be so good. Any thoughts?