Re: OT -> bit twiddling on a parallel port?

It would be reletively straightforward to do with some basic hardware,
especially if you have preset voltages that you know you will be working
with. If you need a range of voltages, you'd have to use a
potentiometer for each pin. If you know what preset voltages you need,
(0 volt, 1 volt, 2 volt, 3 volt, etc) maybe a dip switch or rotary
switch connected to the various resistors and/or variable voltage
regulators for each pin. You could even get extra fancy and indicate
the voltage on each pin with leds or a 7-segment digital display.

Depending on how many pins he wants to control and how many voltages he
wants to work with, this could quickly become unfeasible though - for
instance, if he wants to control all 25 pins with 10 or 20 different
voltages. If he just wants to control the 8 data pins and only has
three different voltages, obviously something like that would be much
simpler.

To do it in hardware, you are looking at a couple days (or longer -
depending on your experience level) of working it out on paper and
constructing it and who knows how much to build it.. I'd say expect at
least $50-$100 if you have to buy all the various components. Probably
more if you want to put it in a nice enclosure and whatnot.

If it has to be controlled via software, you could theoretically control
some sort of chip (don't ask me what - but I know they are out there)
via your serial port, which would basically do what I described above,
instead of physically toggling a switch, the software would send the
signal over the serial cable, which would control the chip which
controls the voltage, but as you can imagine, this adds quite a bit of
complexity and you would not only have to build the hardware, you would
have to write the software.

Maybe try contracting the EE department at UAA in the fall - maybe some
student will want to do it as an extra credit project :)

Justin

Mac Mason wrote:

>So, I got an interesting question the other day. I know a guy who wants to
>programatically set the voltages on individual pins on a parallel port. (IE,
>have a command for "set pin 5 to 2 volts" or "set pin 7 to 1 volt".
>He wants to do this in windows, but I'm having no luck figuring this out on
>any platform...
>
>Ideas?
>
> --Mac
>
>
>

---------
To unsubscribe, send email to <aklug-request@aklug.org>
with 'unsubscribe' in the message body.
Received on Wed Jul 20 00:05:39 2005