braindrizzle

[Phil Hunter]

I thought I'd offer a brain-drizzle (as opposed to
a brain-storm) for the list's consideration, seems
pretty obvious to me:

Imagine an Analog-to-Digital convertor, the output
driving the address lines of an EPROM who's data lines
drive a Digital-to-Analog convertor. In essence, any
input voltage can be mapped to any output voltage
depending what you program into the EPROM. A signal
can be inverted, a sine wave converted to a cosine
wave, and a wide-band O2 sensor output can be mapped
into a narrow-band sensor output.

Now this is generally too simple for real life, things
like settling times, access times and no sample-n-hold
cause glitches in the output. But if we substitute a
microcontroller for the EPROM, better yet a uC with
built in A/D such as in the PIC family, things can
stay fairly simple. I don't know of a PIC uC that has
a D/A output other than Pulse Width Modulation, so we
will still need an external D/A chip.

Assuming this is a good idea, I'd like to see the
group focus on something like this before doing
complete end-to-end projects such a WB-to-LED bargraph
or WB-to-LCD. Get a core of hardware & software that
has a lot of commonality and everyone more-or-less
understands then build from there. I can invision
software modules such as A/D, lookup, PWM output,
serial D/A chip output, parallel D/A chip output,
RS-232 output, etc. Hardware can be a 28 or 40 pin uC
driving a 16 pin D/A for a lot of flexibility, or an
8pin uC driving an 8pin serial D/A for simplicity.
Depending on what the user wants to do, they can
pick-n-choose what they need, then build it. You want
an analog display of A/F, you can probably do it w/
just an 8pin uC and PWM output. You want a digital
display of A/F, you could program the lookup to output
in steps such that 1.125V is 11.25:1 and you mentally
move the decimal point one position on your DVM. I
want to eventually substitute the NB sensor w/
a WB sensor, so I'd use the bigger uC driving a
parallel in D/A chip so I don't have to worry about
the latency of the serial input D/A chip confusing
the ECM.

Perhaps the WB-LED & WB-LCD projects could be
redesigned in a modular fashion, one using the large
PIC and one using the small, then the user could
"stuff" them as needed, only putting in the parts
to accomplish what they want.

Get the picture...Kodak?

phil
(digest mode)

__________________________________________________
Do You Yahoo!?
Listen to your Yahoo! Mail messages from any phone.
http://phone.yahoo.com
----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org