Paul,
I would gleefully welcome a kit of parts (reasonably priced) with
instructions, that I could assemble at home.  It would hopefully include a
printed circuit board, PIC's, multiplexer, LCD, etc.  ...and a some basic
software to get it up and running.  Anyone else interested?
Mark Steitle

I am working on Finn. Unfortunately Finn does not need or like to work.
I know he can do it if we can talk him into getting off the beach.
Tracy is working up something as well. We will just have to wait.
Paul Lamar

Let me see if I can answer all the points you brought up in recent postings:
1) I'm now back on a fulltime job plus other obligations, so time is scarce. Paul, on
the other hand...

Sounds like you are in love. That will eat your lunch and then some.
 

2) You could expand the 8 channel PIC to 16 channels by using 2 CD4066 (Quad bilateral
switch), but since you want 10 bit resolution, the on-resistance becomes an issue
unless you add front end op-amps. Chip count is beginning to rise!

There are better parts than the CD4066 out there now. I just uploaded a partial data
sheet on a 16 channel analog switch with much better specs.

3) What schematic? Never got around to making a full schematic.

4) I don't mind sending you my source code, so you have something to laugh about.

My design philosophy had these points:

1) Cheap as possible (definitely had to be cheaper than analog gauges).

2) Minimum panel space

3) 1. lead to using components I had lying about (except for the display and the
AD817).

I'm quite happy with 8 bit accuracy (1% or so). Do you really need more for engine
monitoring? I haven't even bothered with calibrating my sensors (mostly because I don't
have the proper equipment) and use the nominal offsets and factors listed in the
pressure sensor datasheets.

Please realize that my set-up is very specialized. These are the parameters I display:
Oil pressure
Water pressure
Fuel pressure 1
Fuel pressure 2
Water temp
Oil temp before cooler
Oil temp after cooler
EGT 1
EGT 2
RPM (5 RPM resolution, from 12 pulses/rotation crank angle sensor coil)
MAP
Mixture (using an oxygen sensor)
Voltage
Left tank level (gallons) (home brewed capacitive sensors).
Right tank level (gallons)
Fuel flow
Fuel used

It's also so primitive that I have to burn a new EPROM if I want to change limits,
offsets or factors.

But you know: it works for me. Thus I have very little incentive to develop something
for production unless I have a guaranteed market.

Finn

Sounds good to me Finn. It would make a good article. Send me all the stuff 
in crude form and I will work something up and submit it to EAA under
your name. I promise not to laugh at your code. I don't care how good
a programmer someone is. Code can ALWAYS be improved. 

The article would be a good start for someone.

BTW do you know of a single chip that will do this?
It needs to be designed to take 4 bit wide LCD data and store it in an 8 bit wide flash
memory chip. This, as shown, would take two quad AND gates and an inverter.

I forgot. Is your LCD a four bit interface or an eight bit interface?

Paul Lamar
 
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