Newsgroups: comp.robotics
Path: brunix!uunet!zaphod.mps.ohio-state.edu!rpi!usenet.coe.montana.edu!news.u.washington.edu!uw-beaver!micro-heart-of-gold.mit.edu!news.media.mit.edu!fredm
From: fredm@media.mit.edu (Fred G Martin)
Subject: Re: Miniboard comments & questions
Message-ID: <1992Dec2.134059.26600@news.media.mit.edu>
Sender: news@news.media.mit.edu (USENET News System)
Organization: MIT Media Laboratory
References: <1992Dec1.215504.52628@gmuvax.gmu.edu>
Date: Wed, 2 Dec 1992 13:40:59 GMT
Lines: 59

In article <1992Dec1.215504.52628@gmuvax.gmu.edu>
klambrec@gmuvax.gmu.edu writes: 

> Windows and DLM don't appear to mix: When I run DLM in a windows DOS
> shell, the download frequently fails.  DLM either stops completely, or
> reports data errors.  It works just fine if I'm not in Windows.  I
> have heard of other people having similar problems with PROCOMM.
> Windows users, BEWARE!  (If I've missed something basic here,stop
> laughing and tell me what it is.)

Oh well.  DLM does its serial work through BIOS calls, so I blame
Windoze if it can't deal.  I've provided the source to DLM, so it
shouldn't be hard to port to Windoze if anyone is psyched.  


> COP timeout: How do you disable the COP watchdog?  I inserted the
> following code at the beginning of my program, but it didn't
> disable COP.  I'm annoyed that I have to add code to re-arm the COP
> timer because I can't turn it off.

The CONFIG register is EEPROM and must be programmed using a special
sequence to burn EEPROM.  It's described in gory detail in the large
6811 manual.  I'd suggest that you download the MS-DOS executables in
our 6270 directory on cherupakha; the program "dl" has capability to
help you change your config register.


> PWM Frequency - CCCC vs AAAA: Using 2 D.C. motors, one driven by the
> Miniboard, and the other used as a generator, I measured output
> voltage as a function of PWM input.  Vout using AAAA was 6.58V. Vout
> using CCCC was 8.08V.  Both patterns have the same average voltage.
> Why the big difference in speed? I tried this several times. It IS
> repeatable.

I don't know what's going on here.  I'd look at the PWM output with a
'scope if you are worried.  Subjectively, does the power with which
the motors turn *feel* different using the two different patterns?


> Plug compatibility: A cable for a IBM-XT will work as a cable for
> Macintosh with modem cable.

Yes this is true.


> Servo Control: Has anyone written assembly code to control servos?  I
> could probably take the PWM routines for the motor driver and modify
> it, but I don't want to duplicate the effort if someone else has
> already done so.

We've got some servo code written for the 6.270 board.  Retrieve the
library files in the Interactive-C directory (in the 6270 directory on
cher.media.mit.edu).  There's a file "servo.asm" has the code.

Good luck

Fred Martin


