DIS, and 68HC12

[Jurgen Hartwig]

Hi all, this is my first post to this mailing list.  I've been hiding
for some time enjoying the great wealth of information spread forth by
the likes of Greg Hermann and others.


I am working on a distributorless ignition system, and while it is not
purely FI related, I am hoping that the information I pick up from this
project will help me immensely with later FI projects.

Basically, my friend and I are designing a system around the Motorola
68HC12 series microcontroller.  It is similar to the system that Tim
Drury has outlined on his website.  Now, I'd like to interface with some
of you that have had experience with the 68HC12 or 68HC11.  We need to
find some development boards or similar, and I have found two at around
$100.  Is it easy to build my own board?  The HC12 has 110+ pins, so it
sounds like it would be tough.

We are planning on using the Motorola chip to permit fully adjustable
timing curves, and thanks to the archives, I've found a large amount of
data pertaining to adjusting the curves.  The system will be waste
spark, with junkyard variety coil packs and wires.  Does anyone have a
source or list of vehicles that came with coil packs?  I am heading down
to a U-Pull-It yard here in Atlanta this Friday, and I'd like to know
what to keep my eyes open for.  Any ideas on cost for wires and coil
packs (need two minimum for first project)?

Also, the first car we are trying this system on will be a '92 Ford
Probe.  Does anyone know where we can get timing curves for the
distributor?  I suppose I should call the dealer, but I wonder if there
is anything online or printed that I could consult.

Lastly, the final version of the distributorless ignition system will be
crank fired, but for simplicity I am going to use the distributor to
trigger the MCU.  I was thinking of grabbing an old distributor from a
junked Ford Probe and super gluing the centrifugal advance, and
disconnecting the vacuum advance.  Then we can use the existing hall
effect sensor as the trigger, but I don't know if the four lobes will
provide enough timing resolution.  Any thoughts or ideas?

We are using a GM MAP sensor as load input for the MCU.  The MCU will
calculate timing vs. RPM vs. load.  The timing curve will be adjustable
from a laptop computer through the serial interface.  Anything I'm
missing here?

I apologize for the great length, but I value your opinions greatly and
would appreciate any guidance on our first project.


Take care
Jay
-- 
When you were born you cried
And the world rejoiced.
Live your life so in death you rejoice
And the world cries.