Effectiveness of RAM induction? (AFM replacement)

[Diehl, Jeffrey]

Ok, you give me a choice:

1. Initial complexity and improved versitility in the fomr of the PIC-driven
circuit.

2. Simple circuit and lots of trial and error.

That's a tough call.

I am a programmer by trade.  I do mostly perl, but I can do BASIC, C, 68K
and i386 code.  I could probably learn to program a PIC.  <grin>  

Stamp Basic...  Sounds almost turn-key.  Is it really that easy?  I have
built simple descrete logic circuits.  Which would be easier, PIC or Stamp?

Thanx,
Mike Diehl.

-----Original Message-----
From: Brian Dessent
To: diy_efi at diy-efi.org
Sent: 10/13/2001 1:55 AM
Subject: Re: Effectiveness of RAM induction? (AFM replacement)


> signal, I'll convert it to voltage.  Then I'll adjust the scale with
an
> op-amp.  Then I'll have to plot volt v. rpm to see what kind of
> (non)linearity I have.  I believe chips exist which will do log and
exponent
> functions on analog signals.  I'll bet they can be tuned to produce
> different functions.  When the MAP looks like the AFM, the AFM is
GONE!
> 
> Hey, talk is cheep, but this is what I'm thinking anyway.
> 
> Comments?

You can certainly do nonlinear stuff directly in analog (there exist
chips to do exponential, log, 4 quadrant divide, multiply) but if *I*
were doing it I would definitely use a PIC or some other
microcontroller.  The PIC is perfect for this job, they are designed to
be cheap, complete, and powerful.  You could probably do the whole thing
with a single chip.  It could probably do the freq->voltage (or a/d if
you want to do f->v externally), loopup table conversion, and d/a (via
PWM), as well as storing your program code in flash or eprom, clock
generation, and automatic power-on reset, all on the one chip.  They can
be programmed with cheap (or build-it-yourself) hardware -- if you
choose a flash variety you don't need a UV source to erase and you can
make a programmer with your computer's serial or parallel port for about
$20.  Look at the 16F87X family for a start:

http://www.microchip.com/14010/lit/pline/picmicro/families/16f87x/index.
htm

If assembly language isn't your thing then look at the Basic Stamp.  It
really doesn't get much easier than these -- you write your program on
your PC in a BASIC-like language, hit the download button, take the chip
out to the car, and drive away.  (the stamp usues the PIC as its guts so
that's why I mention them together.)

This would surely seem easier than cobbling something together with
various analog chips.

Brian
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