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[DPRG] DPRG ORG 08 Photos
Subject: [DPRG] DPRG ORG 08 Photos
From: David
dpa at io.isem.smu.edu
Date: Thu May 15 10:12:54 CDT 2008
Howdy,
Kenneth, Excellent! Excellent! Excellent!
This is exactly the sort of thing we need and your great experience and
amazingly beautiful work is always inspiring.
I also use the Mini Robominds 68332 board to control jBot, using the
built-in Four Quadrant Decode which uses the TPU FQD function. This
essentially runs the decode in hardware (micro-code, really) and
presents the encoder counts in a memory block shared between the
CPU32 core and the TPU co-processor. Once it is initialized,
reading and resetting the encoder is just a matter of reading and
zeroing a memory location.
One problem with this function is that the encoders on jBot's Pittman
motors generate 2000 counts per revolution for each motor, and that
rate is too high for the FQD function when jBot is running at top
speed.
The solution I've used is to switch to two quadrant mode when the
rpm rises above a certain threshold. That means that it still
returns accurate encoder counts /4, but loses the direction
information. However, at high speed the direction is not
going to change anyway, so that works out ok.
I'll try to get some code snippets online today to illustrate this.
Kenneth wrote:
<snip>
> In writing this I have drug up all those memories about how much I really
> miss working on the robots and not slaving away for "the man" :)
Also reminds us of how much we really missed having you in town last
weekend!
best regards,
dpa
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