Re: Can I do this with a uProcessor?

On May 20, 8:22 pm, "tempus fugit"
<tocc...@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Hi all;

I currently have a switching system that uses logic like latches and
inverters, along with lots of diodes. I'm thinking about changing some
things in it, and was wondering if I shouldn't just revamp the whole thing
and go to a PIC. Here's what I would like it to do:

I suggest you say "micro" not "PIC" and consider other types. I'll
explain why as we go through the various requirements.


I have 14 switches - when any one of them was switched to ground
(momentary),

You want to have 14 port connections to do this with so we now know
one specification of the micro.

You didn't say how quickly it needs to react. Since a human is
pushing the switch, perhaps 20mS or so should be the required maximum
responce time.

it would cause the PIC to:
1. clear any previous data in the PIC
2. latch a signal to the required output that would ramp up the control
voltage over a few ms.

This sounds like you want a micro with a built in DAC or an external
DAC connected to the micro. How smoothly does it need to ramp and how
linear etc? How many output lines need to be ramped? Does only one
go high at a time?

You can use fairly simple analog circuits to make a ramp. You also
didn't speak about how the signals ever go low again. I assume they
do this also with a ramp.


I have a 15th switch that when switched causes the each switch to activate a

Opps make the 15 port lines.

different set of devices (sort of like having 2 different banks). Could I
use a PIC to have the same function, kind of like having it latch that
switch in one position or another, and telling the PIC to execute the proper
instruction?

This is simple code.


These switches control 6 different relays to switch in different effects or

Ok so now we have a total of 15+6=21 port connections.

effects combinations for my guitar pedalboard. Would I need many PICs to
accomplish this, or would it be possible to set things up with just one?

I suspect these are fairly newb questions, but I don't know what types of
things are possible with the instruction set available with a PIC. I have
downloaded a couple data sheets, but at about 200 or more pages each,
there's a lot to digest, and i don't quite understand it all yet.

Is it possible to do these things with a PIC?

Now I'm going to suggest you reconsider the question of which micro.
You could look at the ones at www.cygnal.com as an example of a very
different one. There are lots and lots of chips that can do what you
want.




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