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 Robotics / Handy Board / 7841
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Subject: 
Re: how many servos on handyboard?
Newsgroups: 
lugnet.robotics.handyboard
Date: 
Wed, 17 May 2000 21:55:36 GMT
Original-From: 
Charles Hacker <C.HACKER@MAILBOX.GU.EDUsaynotospam.AU>
Viewed: 
794 times
  
Ray,

Whoops, just read my message again, and realised I had stated STEPPER
motor, and not the intended SERVO motor.

I have used the HB to control 4 SERVO motors.  The SERVO's had an
external 5V power.  The GND of the SERVO supply was attached to the
GND of the HB.  The Motor outputs were then capable of driving the
SERVO motor inputs (with a square wave).
With a bit of programming (machine code) I was able to continually
send a PWM signal (Square wave) to each of the motor outputs and keep
all SERVO's under control.

By the way, it is also possible to use the HB motor outputs to
control 4 STEPPER motors (yes I mean STEPPER this time).
However, you will need to use STEPPER motor driver chips.
I am currently developing a robot vehicle that has 4 stepper motors.
The motors are actually controlled by a chip, the MC3479, stepper
motor controller chip.
The HB outputs only need to supply a clock input to the chip, to get
the STEPPER to turn.
(The chip also needs a direction signal, which I am setting 2 by
Hard wiring and 2 others by the digital output lines).


Really?  One can drive four stepper motors using the four DC motor output
ports?  How are the wirings done in this case?  Are you suggesting a
unipolar stepper motor (because I am trying to make bipolar stepper motors
to work on my board)?  I would really like to have your suggestions.

                                                            Ray
----- Original Message -----
From: Charles Hacker <handyboard@media.mit.edu>
Newsgroups: lugnet.robotics.handyboard
Sent: 17 May 2000 00:28
Subject: Re: how many servos on handyboard?


The base Handy Board is designed to control 4 DC motors.

The DC motor output ports CAN be used to control 4 (four) stepper
motors.  Remember that a stepper motor needs a square wave pulse
continually sent to the motor for operation, and the mark / space
(time high / time low) pulse determines the position.
So by writing code for the motor outputs, you can control 4 (four)
stepper motors, (but YOU need to entire the code to do this).

The expansion board has outputs to control servo's directly, but not
having the expansion, I do not know about it.



I'd like to know how many servos the handy board can control. On the FAQ • it
says 2, in the documentation it says 4 DC motors. what's the deal? (am I
stupid? I'm new at this)

also, when you plug an expansion board, do you get 6 EXTRA servos? or • those
are the only ones you can still use? How about the rest? do all imputs
remain free on the handyboard and everything on the expansion board is
extra? than you.


Charles Hacker
Lecturer in Electronics, Computing and Physics
School of Engineering
Griffith University - Gold Coast
PMB 50 Gold Coast Mail Centre
Southport Queensland 9726
Australia.
Email - C.Hacker@mailbox.gu.edu.au
Ph. (07) 5594 8670
Fax.(07) 5594 8065




Charles Hacker
Lecturer in Electronics, Computing and Physics
School of Engineering
Griffith University - Gold Coast
PMB 50 Gold Coast Mail Centre
Southport Queensland 9726
Australia.
Email - C.Hacker@mailbox.gu.edu.au
Ph. (07) 5594 8670
Fax.(07) 5594 8065



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