Newsgroups: comp.robotics
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From: dpalmer@csuohio.edu (Darryl Palmer)
Subject: Re: PWM of Servos
Message-ID: <1994Jul25.181342.10789@news.csuohio.edu>
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References: <brianvm.3.003CF334@halcyon.com> <CtDL7H.Fyw@osuunx.ucc.okstate.edu>
Date: Mon, 25 Jul 1994 18:13:42 GMT
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Gordon Couger (gcouger@olesun.okstate.edu) wrote:
: In article <brianvm.3.003CF334@halcyon.com>,
: Brian Van Mondfrans <brianvm@halcyon.com> wrote:
: >Jeff and I have run into problems with the twelve servos we need to control 
: >for our walking robot.  There is no software solution to creating the PWM for 
: >all the servos with a 6.270 board and still have processor time left over.  
: >The high pulse is just too small for any of my solutions.
: >
: >
: >If anyone has any other suggestions, information on the chips, or information 
: >on networking with the HC11 it would be greatly appreciated.
: Using a PIC micorporcessor from Parralax would be a less expensive choice. The
: programmer comes with sample code for doing both of those things and at $4.00
: a pop for the PIC chips and less than $200  for the assembler, programmer,
: documentation and a proto board you will have a hard time beating the price.
: You can order from Parralx direct or from digi-key. 

: Good luck
: Gordon

:                          Gordon Couger                            
:                          Biosystems & Agricultural Engineering              
:                          Oklahoma State University                         
:                          114 Ag Hall, Stillwater, OK  74074                 
:  gcouger@olesun.agen.okstate.edu 405-744-9763 day 624-2855 evenings 
:     I do not speak for my employer

You might want to check out the Low-Cost serial servo controller article
from ComputerCraft May 1993 issue.  It uses 2 PICs, one for serial 
communication, and the other actually does the servo control.  The controller
from the article can be modified to allow up to 256 servos with a fraction
of 1 degree resolution.  If you don't want serial, you can just send the
appropriate control bits to the servo controller PIC and go from there.
Please be aware of the fact that the magazine is now called MicroComputer
Journal and their number is (516)681-2922.  


Darryl Palmer
