[geeks] Looking for a simple user-interface device

[Dave Kimmel]

On Wed, 24 Apr 2002, Dave Kimmel wrote:

> > That'd be nice and easy, just wire the two leads of the keyswitch the the
> > keyboard grid.
>
> Hopefully it will work.  The display will send keyup/keydown, but I don't
> know if it will let you have multiple keys pressed.  I'll play around a
> little with my LK204-25 and see how all that works.

Unfortunately, this won't work, but it may still be doable.  I put some
wirewrap on the keypad connector on my display and wrote some code to get
it to show me the key events.  It does keydown and keyup just fine, but it
does not let you have two keys pressed at once.

It might still be doable because turning the lock will effectively lock
out the keypad.  And since you get the keydown/keyup for it you can even
display a locked icon or react to the locking/unlocking.  The inability to
do anything with the keypad while its locked is a nifty bonus, but may
limit what you can do (ie, unlocked can do anything, locked can only do
certain things).

ObSidenote:  The Matrix-Orbital documentation is wrong on many, many
counts.  Generally speaking, if it contradicts itself, you have to try
both ways to see if it works.  Large digits was where this first bit me.
Relying on always getting keydown/keyup signals from the I2C interface
without telling it to do so (the docs seem to say that the mode that
controls this is ignored if you use I2C) was the second time.

But other than that relatively minor complaint, these are damn nifty
displays.  There are visions of sonar range finders on the back of my car
dancing in my head.  ;-)

-- Dave Kimmel
   crisco_kid at shaw.ca