

Kenny Bauman <kennybauman@yahoo.com> writes:
The ford EDIS is a standalone
microprosessor based ignition. It handles all timing
calculations and trigger wheel processing internally.
MS AVR only has to deal with a SAW and PIP signal to
make the EDIS setup work.

What happens is the EDIS sends out a PIP signal that
will tell MS AVR it needs a SAW in return. The length
of this SAW signal tells EDIS what timing is desired.

If EDIS looses the SAW signal it defaults to 10 deg
timing as a base value. Nice as a built in limp home
mode.

Makes a nice setup as it is proven and hardened for
the underhood environment.

Regarding the 36-1 trigger wheel. This has to be a
Crank trigger not a cam trigger. You can use a cam
trigger, but it needs to be 36-1 and 36-1 on the same
wheel for a total of 72-2 teeth. The missing teeth
would be 180 degs apart. This is for EDIS.

So what I "think" is needed is a interrupt (or event
que) every time EDIS sends the PIP signal. Go to the
lookup table get the timing value stored, do the math
and then send a timed pulse back to EDIS as the SAW
signal. That's it. EDIS takes care of all the hard
stuff.
SAW (microseconds) = 1536 - (25.6 * Commanded_degrees) 

You can go to:

http://www.bgsoflex.com/mjl/mjl_edis_summary.html

to see more about the relationship of PIP and SAW.
Should be very simple to implement in MS AVR.


-----------------
Here are some AC Delco part numbers for the EDIS-4 module and the coil. The 
US model vehicle is: '93 Escort LX w/1.9L 116CID L4 MFI (J) engine.

EDIS Module - AC Delco F1945
Coil AC - Delco F510

NAPA  ONLINE lists:
Echlin Ignition Ignition Control Module ECHTP500

I haven't found a part number for the VR pickup and then there is the 
toothed wheel.
---------------

Another good intro:
http://www.dainst.com/info/edis/edis.html

