From: email@example.com (Mike)
Subject: Re: PIC/Microcontroller recommendation?
Date: 16 Dec 2002 20:58:15 -0800
NNTP-Posting-Date: 17 Dec 2002 04:58:15 GMT
Spehro Pefhany wrote in message news:...
> On Mon, 16 Dec 2002 17:18:54 GMT, the renowned Jonathan Kirwan
> >I see three digital inputs:
> > "extend" momentary pushbutton
> > "retract" momentary pushbutton
> > "stop" momentary pushbutton
> >and three analog inputs:
> > "extend limit" potentiometer
> > "retract limit" potentiometer
> > "arm position" potentiometer
> >I assume the four outputs are for the motor control?
> Yes, what's the deal? Are there two motors? If so, are they
> run exactly at the same time? Why are there not just two
> outputs- extend and retract?
My goof... I added a need for additional 2 outputs after posting that.
The actuator does have 2 inputs; extend and retract; it is a 120v ac
motor (2 separate windings) and I intend to drive with triacs. About
.9A max current.
I figured I'd get the extra 2 outputs and add both an extend and
retract LED, to indicate the relative position of the arm with respect
to the limit stop potentiometers; this would allow the user to set the
limit pots without actually initiating movement of the arm (i.e, the
LED would indicate if movement would occur).
> BTW, almost anything you could come up with would be overkill
> for this application.
Yes, but going with discrete logic components would incurr way to many
components; I figured performance of the uP would not be an issue.
> Another possibility would be to use the 18-pin PIC16F628, which
> has no ADC, but it does have two analog comparators, which is all
> you really need if you think about it. It costs $1.92 in 100's,
> but no ICD (ISP, though, so you can do crash and burn
> development if you like)
Without thinking about it too much, how do I get by with my three
inputs by only comparing 2 voltages?