I'm designing a controller for the front panel of a SBC type product.  It
is PC based and so has the KB and parallel connectors.  We have an LCD and
6 pillow buttons as well as one LED indicator on the front.

The LCD is using the parallel port,  and I plan to interface the keypad to
the keyboard connector on the PC using a PIC (its a fairly simple
synchronous serial type routine).

Simple enough so far.

The other tasks I must complete are to control the the front panel LED and
the LCD contrast.  The keyboard interface is bi-directional, but it seems
that the only commands going back to the keyboard are to turn on and off
the three indicator lights.  I plan on using one of these (CAPS lock say)
to toggle the LED indicator, and the other two (NUM lock and SCROLL lock)
to control the up/down of the LCD contrast with some kind of R2R ladder.

I suppose my questions to the list are as follows :

Does this sound like a reasonable approach?

How many steps of control should I have for the contrast?  I'm thinking 8
should be plenty.

What do you guys think?

-Erik Reikes