[Diy_efi] Spark timing above 1 bar

[Perry Harrington]

Judson,

Wire the existing trigger to an IRQ pin on your micro.  Then wire the existing
trigger to a compare match output.  The compare match should stay in the non
triggered state for the delay period, then change state to the triggered
state.

Basically:

irq handler()
delay = tablex[rpm] * tabley[MAP];
timer.compare_high = delay;
timer.state = low;
starttimer();

Pretty simple algorithm.

You could easily do it with a Hitachi H8 3664BP (42pin sdip).

Eval/development kit costs $49-99 (PS and serial cable is added).

--Perry

On Wed, Feb 12, 2003 at 12:06:26AM -0500, pr asdf wrote:
> I am currently looking at finding a way to delay the timing, basicly I need 
> a circut that waits for a change in input state and changes its output to 
> match, almost instantaniously while under normal conditions, (less than 1 
> bar), but delay the state change by as much as .0016 sec (10 degress at 1000 
> rpm) or as little as .000025 sec (1 degree at 6500 rpm). I plan on 
> programing and adjusting the tune with a laptop, so calculating the time it 
> takes to retard X number of degrees at Y rpm can be done beforehand and then 
> to keep it simple, just load the delay time into a look up table for the 
> microcontler to apply. The main part is how to create the delay, without a 
> delay under normal circumstances.
> The lt1 engine is also still a single coil, direcly controled through the 
> computer, and is split to each plug by a normal distributer (if you can call 
> an optispark a normal distibuter).
> 
> Judson Hartley
> 
> 
> 
> 
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-- 
Perry Harrington			Data Acquisition & Instrumentation, Inc	
perry at dainst dot com					 http://www.dainst.com/

Those who would give up essential liberty to purchase a little temporary safety
deserve neither liberty or safety. Nor, are they likely to end up with either.
                             -- Benjamin Franklin

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