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Old 03-18-2008, 01:06 PM   #33 (permalink)
Bearleener
Efficiency freak
 
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Join Date: Mar 2008
Location: Berlin, Germany
Posts: 58

Frugolf - '96 VW Golf wagon
90 day: 40.36 mpg (US)
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Every new feature is just a few lines of code away!
I nearly implemented an Atmel ATMega 32 as an FE gauge, but also to auto-shut-off the engine whenever coasting. The latter feature didn't work too well so I mothballed the project but now I'm dying for an FE gauge so I'm glad that you guys are interested, too!
Most of the FE code (which can be programmed in C or Basic) I basically had running. The ATMega 32 is nice (has floating point arithmetic, lots of counters etc.), but is rather expensive when bought with a development board.

One issue was measuring low-frequency signals such as vehicle speed (about 1 Hz per km/h) and engine speed (which I measured at the Hall sensor on the distributor, running at 1/2 the engine speed = 15 Hz at idle). The processor had built-in frequency counters but at any decent refresh rate you just don't get enough pulses in the sampling period to be accurate. I instead did it with event counters.

So I'd be glad to contribute some coding ideas and info about which signals to tap and how to interpret them (at least on my Volkswagen).

Some other nice-to-have features would be not only measurement but also control features, such as auto-stop-start, engine preheat, etc.
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