[geeks] Looking for a simple user-interface device

[Jonathan C. Patschke]

On Wed, 24 Apr 2002, Dave Kimmel wrote:

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

That is -precisely- what I wanted to build.  Thanks!

> 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.

Far better-looking than anything I'd come up with, I'm sure.  My artistic
talents cap out somewhere around signing my name with all the letters in 
the right order.

> 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.

SMBus is almost always I2C.  I didn't think of that, and I'm completely
ignorant about it, but that sounds like a decent use for it.

> As for running it, I'd opt for writing a daemon to handle the user
> interface and executing the commands.

Yeah, that's what I was thinking.

> 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,

I was thinking probably OpenBSD.  FreeBSD's certainly not out of the
picture, though.  I really like OpenBSD's new firewall code, but I don't
know what the state of the I2C code is.

> 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.

Yeah, or connect it to the internal half of the port via a wire harness,
and then cap the outside of the port.  That'd be messy, but effective.

> 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.

Yeah, that's what I was afraid of, but prepared to deal with.  I didn't
know that cool stuff like this was already preassembled.

> 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.

That'd be nice and easy, just wire the two leads of the keyswitch the the
keyboard grid.

> 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.

That's an interesting idea.  I'll have to keep that in mind.

--Jonathan