Bench tests needed...

[Ludis Langens]

Shannen Durphey wrote:
> 
> I'm curious about something.  Anyone who's got a bench ecm set up, I'd
> like to know if you can set up the timing to get more than 90 degrees
> advance.  I've been playing with a 749 and it seems like timing
> passing 90 degrees gets reset to 0.  Anyone else see this?

No need for a bench test.  All the GM ECM code I've looked has computed
the advance in essentially the same way.  They end up with a byte which
represents the angle of advance (or retard) with the value 256 being 90
degrees.  The time for 90 degrees of crank rotation is calculated
elsewhere.  Then they do some math with these values to convert the
angle of advance into the time domain.  This is then programmed into the hardware.

So - once that byte overflows (which happens at 90 degrees), the timing
will wrap around back to 0 degrees.

Is this something to do with the DIS/dizzy conversion?

-- 
Ludis Langens                               ludis (at) cruzers (dot) com
Mac, Fiero, & engine controller goodies:  http://www.cruzers.com/~ludis/
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