The hardware solution was getting too complicated
and using up too much printed circuit board space.
I never got it to work perfectly either and I was spending
a lot of time doing it. The Teensy is only about 1.4 inches
long and .7 inches wide. One Teensy per coil and one coil
per spark plug for high redundancy and safety. Cost only $20.
I can get 4 Teensy on one printed circuit board with4 voltage
supplies.
The Teensy is way way over kill for this project but
the cost is low. I could probably do it with a BASIC
Stamp but it does not support A to D and hardware interrupts.
Hardware interrupts are the best way to deal with
all sorts of mechanical things. If you don't have 4 or
5 you don't have squat :) It is like having 4 smart cell phones
in your ignition system :)
So I wrote a program in QB64 to see what it
would look like.
The idea here is break the RPM into ranges.
Say every 1000 RPM. For each range the coil would trigger
six times about 5 degrees apart.
This may not be necessary so this prog is not cast
in concrete yet. It took less than an hour to write
as I am a bit rusty :)
Neal, send this to Dominic. I would send it myself but
he does not answer me so I don't know if he is getting it.
Paul Lamar
That' s great work Paul, thanks again for your hard work !
Steve Carlisle
Thanks Steve.
Here is a somewhat simpler and IMHO better version.
No ranges. Continuous calculations based on RPM only
The print statements are for debug purposes only of course.
Also easily possible is to store the history of RPM
in RAM for a short period of time and then dump it through
the USB connector after you land (or crash :)).
Black Black box mode. No hard disk in your ignition
system but it would be possible.
It might also be possible to use a cell phone or a tablet as
an RPM display :) That is kind of ridiculous of course.
To keep the program short, fast and simple I assume a hardware
analog tach feeding voltage data to a Teensy A to D pin.
This has been extensively tested and it works quite well.
Paul Lamar
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