Re: Can I do this with a uProcessor?


If you are using an op-amp, they come 4 to a chip. It makes sense to
go up to the next multiple of 4 lines. BTW: Unless I missed
something, we are only talking of one processor to do lets say 24
lines.

[...]
Thankjs for your help Moose - and i'll check out that other site. I'm
glad
for any other advice as well.

Look up the following parts and look at the datasheets:

LM340
LT1499
LM324
2N2222
1N4004

I'm almost certain the design will have most of those parts in it. I
suggest the LT1499 for a reason I'm about to explain so that others
don't throw too many stones at me.

The LT1499 is the op-amp I could remember had a rail to rail input and
output and also has diodes across the inputs. Here's the circuit I'm
thinking of:

ASCII art:
----!!-----
! !
! V+ !
! ! !
PORT PIN -/\/\----+----!-\ !
! >---+--- RAMP
Vcc/2--------!+/
!
GND

It makes a nice linear ramp up and down.

As for voltages, I have 12, 9 and 5v available to me at present. Hi would be
+5 (to control the relay driver), and lo would be ground I think. If I cant
do it easily in software, I may just go with an RC circuit. The idea is to
rebuild what I currently have with the minimum of parts. What would be ultra
slick would be to use a 13 I/O port device and somehow use it for the 6 ins
and outs, since I only have to control 6 parameters. Some switches, though,
would turn on more than one thing at a time, and I haven't yet figured out a
way to connect the switches so that each switch would only switch what i
wanted it to. For instance, if I have a switch that switches A, and 1 that
switches B, and 1 that switches A and B, I can't figure out a way to wire
that to 3 in pins so that they don't all interact.

Thanks again


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