From: cmcmanis@pepper.Eng.Sun.COM (Chuck McManis)
Newsgroups: gnu.gcc.help,comp.robotics
Subject: Re: gcc cross compiler for the 6811?
Date: 7 Oct 1992 05:25:50 GMT
Organization: Sun Microsystems, Mt. View, Ca.
NNTP-Posting-Host: pepper

In article <BvKGxE.464@acsu.buffalo.edu> (Richard M Wasserman) writes:
>	Actually as I've been thinking about designing such a bus card 
> oriented system based on the intel 80196kb series.  I'd be interested in
> feedback on what to include on the robotics card, best way to go about
> getting them made etc.  If anyone is intersted they can mail direct for more
> info.  This is just a new thought so all input will be taken into account -
> though I have built up 196kb designs that due work :-)
>	Thanks,
>	Rich Wasserman
>
> P.S. Maybe this can become a group thing ala the miniboard since I'm not
> looking to make a profit ( though a good word at your local graduate 
> robotics program for next fall would be much appreciated ;-) )

Sigh, well it is better than nothing. The problem set for building mobile
bases (the most prevalent form of "hobby" robotics) is fairly well known.

You need something to control the motors that move the base. Light weight
mobiles can use steppers, most use some form of gear motor (C & H surplus
used to have a bunch of copier machine motors that were great for this.)
Anyway,  for steppers, being able to sink 750mA - 1000mA is plenty, for
gear motors up to about 2A is fine.

You need to have a very *clean* design in terms of sheilding from EMI
for the parts. One thing hobby roboticists learn about are ground spikes
from switching motors on and off. Doing a 1A PWM wave form into a couple
of motors can put 2 or 3 volts of bounce into a circuit. When the bounce
causes the difference between Vcc and Vss to drop below 3V all sorts of
not so fun stuff can happen. Also this is much more pronounced under
"load" so running test cases with the wheels up doesn't always show these
problems.

Sensors are another area where the input to the microcontroller generally
isn't "clear cut". Using a simple level detect on an IR motion sensor
for instance (feeding it into a digital input) is very unsatisfactory.
If you tune it for sensitivity you get false positives, if you elimnate
the false positives you run into the cat sometimes. Having space for a
general purpose signal conditioner circuit can often be quite an advantage.

Finally, even if you've got the finest microcontroller in the world it
isn't worth beans if there isn't some way to do development for it. I
think there is real potential in getting the GCC compiler set up for
miniboard and GCB11 type systems. Using the resources of the net to
develop and fine tune things like PWM functions, quadrature interpreters
etc, is a real asset. But the 80196kb on the other hand? So who
knows if this won't become another one of those "phantom" Intel products
that gets slowly desupported out of existence ? 

I'm certainly willing to help (most of what I can offer is function
coding, ideas, basic architecture suggestions, etc) The miniboard is
a good test for this. I did receive my boards by the way!


--
--Chuck McManis						    Sun Microsystems
uucp: {anywhere}!sun!cmcmanis   BIX: <none>   Internet: cmcmanis@Eng.Sun.COM
NIS+ Architect
These opinions are my own and no one elses, but you knew that didn't you.