DPRG mailing list archives: [DPRG] Handy Board and Encoders

Wed Sep 5 00:29:28 CDT 2001

Hey Ed,
 Think those motors you've got run about 1000 rpm out the
gear shaft, which means the encoder end is twirling at about
6000 rpm. Times 500 is 3 million per minute or 50k per
second, about 1 pulse every 2 microseconds possible (in no
load). A Basic Stamp 2 can pick up a 2 us pulse, but
probably not consecutively, so I'm guessing that a
Handyboard could as well. Storing all those pulses might be
the real problem. Trying to do 4x mode might be a problem
too, and the HCTL chip Tom mentioned could help, but think
it's $18+ (x2) unless it can be sampled. Oh, those encoders
should be HEDS 9100. Other quad encoder chips include the
LS7083 and 84 ($3 x 2) at
http://www.usdigital.com/products/ls7083-84/ which then
interface with a counter logic chip like a 74xx193. Also
there's the LS7166 ($12 x 2) and 266 ($16 x 1) too, more
direct to an MCU. I could be wrong about that price too.
David P

----- Original Message -----
>From: "Ed Okerson" <eokerson at fw.telenic.net>
To: <dprglist at dprg.org>
Sent: Tuesday, September 04, 2001 8:47 PM
Subject: [DPRG] Handy Board and Encoders

> I am working on a robot that has Pittman motors with built
in encoders.  The
> encoders appear to be 500 slots per revolution of the
motor shaft, and the
> gearbox is 5.9:1.  Is it possible for the handyboard to
keep up with that
> pace of pulses?  Or do I need to implement some sort of
divider to reduce
> the pulse count?  So far just playing with Interactive C
and it's encoder
> routines, it seems to loose many pulses if the motor speed
is anywhere above
> the speed of a crippled snail.
>
> Ed Okerson
>
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> DPRGlist at dprg.org
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