One item you mentioned below needs some clarification.
The RX8 coil can not be used in a simple ignition as implied, because of the
2ms dwell time required. The trigger is at the rising edge of a 2ms square
wave, and coil firing is at the falling edge. This will give you a 90deg.
retarded ignition at 7500RPM.
I believe we talked about that already a few years back.

It would be nice, if someone came up with a simple electronic setup, without
a microprocessor, taking care of that.

Richard Sohn
N2071U
www.fairpoint.net/~res12/home.html

Real easy to do that Richard with a 555. It is called
a non-retriggerable one shot.

Paul Lamar

After thinking about this a lot more. It appears the cheapest
and easiest way to do it is use a very small computer by todays
standard the AVR ATtiny13A. One can buy them in an 8 pin dip.
Probably for about a buck :)

It will look just like a 555 as it has an internal clock
so no crystal will be required. This is the kind of computer
one would find in a steam iron or kitchen blender.

Its only job is to take in a bit from the CAS and decide when
to fire the ignition depending on RPM. That will keep the software
simple and easy to understand. The idea of this limited job idea
is computer hardware is cheaper than software if the software
is kept short and simple.

This a sub set of all the instructions but all the instructions one
needs to do this simple job.

I am still looking into what it takes to program them.
I may already have the development system.

Any questions so far?

BTW this is emerging as an essential device if you are using a carburetor.

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When fooling around with this sort of stuff an oscilloscope is essential.

The  Tektronic 2430 storage scope I have cost thousands of dollars when new.

Here is one that is truly amazing and dirt cheap.

http://www.youtube.com/watch?v=U8bXpzppdR0&feature=related

http://OscilloscopeApp.com/

Geek mind blowing! :)

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Not only do they have pad O-scopes. They now have O-scope probes with
audio mini jacks.

http://hmb-tec.de/HMB-TEC/Scope_Cable.html


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One simple strategy for the ignition program.
Determine the time it takes to make one rev.

Increment a 16 bit counter over and over using
a routine that you know how long it takes to execute.

INC – Increment
Description:

Adds one -1- to the contents of register Rd and places the result in the
destination register Rd.
The C (carry) Flag in SREG is not affected by the operation, thus allowing the INC
instruction to be used on a loop counter in mul-tiple-precision
computations.

You can measure the time it takes using an O-scope.  Lets say the routine
takes half a millisecond. If there are 16 counts in the counter
it took the engine 8 msec to make one rev or 7500 RPM.

If there are 32 counts in the counter it took 16 msec
to make one rev or 3750 RPM.

If there are more than 32 counts don't do anything.
Fire the plugs from the hall effect sensor. That means
the engine is running at less than 3750 RPM.

If less than 32 counts fire the plugs 2 msec sooner
on the next rev and measure the time period over
again and keep storing it in a register it so you will know
when to fire the plugs on the next rev.

Thats it. Half a dozen different instructions with
less than 100 total instructions.

Paul Lamar