[geeks] Looking for a simple user-interface device

[Dave Kimmel]

On Wed, 24 Apr 2002, Jonathan C. Patschke wrote:

> Can anyone recommend a good starting point?  There are plugins for the
> BASIC stamp that do serial I/O and LCD interfacing, so that looks like a
> good/easy place to start.  I know that at least one microcontroller kit
> (whose name I have forgotten) abstracts over USB, so that might be an
> option, too, especially in the case that all the serial ports are already
> exposed through the ATX port cluster.

The easiest way, IMHO, would be to start with something like this:
http://www.hvwtech.com/lcd_pc_drive_bay.htm

It doesn't have a full keypad, but with 4 arrows and a few buttons it
might be usable enough for what you want.  Plus its somewhat professional
looking.

If hooking it to the external serial port and running the cable right into
the case isn't an option, it might be worth looking at hooking the I2C
pins into the motherboard's SMBus, which is just I2C.  Of course, this is
just from reading FreeBSD manpages (iic, iicbus, iicsmb, smbus) for a
couple minutes, so I could be completely wrong.

As for running it, I'd opt for writing a daemon to handle the user
interface and executing the commands.  In FreeBSD, there are I2C drivers
and access is done through a device in /dev.  I don't know if FreeBSD is
your operating system of choice or not, and I don't know what other OSs
will let you do with the SMBus.  If I2C isn't an option, you'll probably
have to run a serial cable to one of the ports and (optionally) glue it in
place or something.

I'd avoid a microcontroller simply because, based on my understanding of
what you want, you don't really need it and it will add a lot of
complexity.  I'm playing with one of the LCD displays and think that you
might be able to do the keylock by making the lock a key on the keyboard
grid.  I'm pretty sure that when using I2C you get keyup and keydown data
from the display module.  I know that with the RS232 interface you can
choose either keyup/keydown or keypress with auto repeat.  If you can do
keyup/keydown with whatever communication method you choose, you could
even do fun stuff like make it auto-lock after a certain time so that they
have to re-lock it and unlock it before they can do anything.

Hope that helps
-- Dave Kimmel
   crisco_kid at shaw.ca