Date: Tue, 22 Oct 91 15:38:09 CDT
From: menelli@sunje.tellabs.com (Ron Menelli)
Message-Id: <9110222038.AA02225@sunJe.TELLABS.COM>
To: glove-list@karazm.math.uh.edu
Subject: More info on 68HC11 controller
Some notes on the 68HC11 power glove controller:

The interface is working better thanks to the addition of Dave Stampe's
hysterisis code (the other deglitching code will be coming soon). I also
have a program similar to the VGA/PG test code that works on the Amiga
with the 68HC11 board interface.

Lance Norskog sent me a number of suggestions, which I plan to incorporate
in one way or another into the design:

    - Add a parallel port interface for added speed. - This should be no
      problem at all if I make sure that only internal processor memory
      is required. (Adding external memory uses up all of the useful
      ports that do handshaking). The only issue here is what type of
      handshaking should be used (I don't know what the IBM parallel port
      is capable of).

    - Don't do deglitching on the microcontroller. - I think since it seems
      to work so well, and it really doesn't take *that* long, I'll keep it
      in and include an option to turn it off.

    - Include a timestamp based on the start of the sample cycle. This
      would be used for synchronization on the receiving side.  - This
      shouldn't be much of a problem, except for potential hardware counter 
      limitations, which I'll look into.

Another plus to the 68HC11 approach is that it has a number of A/D converters
on board which could potentially be used to read the fingers, so we can
disconnect them from the CPU for a faster sample rate. From a quick look at
the HC11 reference manual, it says it can continuously cycle through 4 A/D
inputs and store the digitized values into four registers. The amount of
time it takes to read all four inputs is 64us from start to finish. The
process will run automatically with no software assistance - pretty ideal,
if you ask me. Now we just need to figure out an easy to interface to the
sensors...

Last but not least, if anyone has a 68HC11 evaluation board handy, I could
send you the current version of the code - the more people that use this,
the better we can make it due to all of the suggestions that will be
generated. I should be able to get a schematic made up soon so more people
can try putting it together.

Any more suggestions?
-Ron Menelli
menelli@tellabs.com