Subject:
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Re: Steppr motor pulse problem
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Thu, 27 Aug 1998 16:09:01 GMT
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Original-From:
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FTHOMPSON9@AOLsaynotospam.COM
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Viewed:
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2121 times
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Phillip
First step is to put a piece of tape on the shaft so that you can clearly
see the shaft turn.
Next determine what kind of motor you have (you have probably already
done this). Get an ohm meter and determine which wires are connected to
which. There are two general styles of steppers. The first has a common wire
which is connected to +Supply and four more wires that are grounded in
sequence. If your motor has five wires it is a good bet that it is this one
and the actual resistance values will tell you the common. Sometimes the
common wire is split between two coil phases giving you a six wire motor. The
two commons are +Supply and the remaining four are grounded in sequence, but
the sequence will alternate between the two separate commons. I have
forgotten the name of the motors but the advantage of them is cheap and easy
drive electronics. The other style of motor is more common and is called
BiPolar as the coils are to be energised in both polarities and the drive
electronics must drive each "signal" wire equally well to both ground and
supply. These motors generally have four wires (and more times than not I
have found them to be Red, Blue, Yellow and White). Once again check which
wires are connected together. You might find for example Red connected to
blue and Yellow connected to white.
Next move the motor by applying voltages by hand with alligator clips.
Use the smallest voltage needed to make the motor move (no point heating the
thing with rated voltage. Next apply the power to the wires in alternating
sequence and make written notes as to which way the shaft moves. Eventually
you will arrive at a sequence that continues to move the shaft in a consistant
direction. Write this pattern down neatly on a sheet of paper that you can
find again. You will be looking at this paper for the rest of your life (as I
am doing now).
Next measure the sequence produced by your computer and make it match the
colors you wrote on that sheet of paper. Then move on to determining the
ramping rates and maximum speeds that you can use with your stepper under load
(lovingly applied by a pair of fingers).
By way of a starting point the sequence that I found to work for that
color set I mention earlier for BiPolars is as follows:
Red Blue Yellow White
+ -
+ -
- +
- +
By the way the Handy Board has four BiPolar outputs from the motor driver
strip. You should be able to just Poke this pattern out and drive two
steppers if the L293s (or a stacked pair of them) will give you enough
current.
Hope this helps,
Pherd
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Message has 1 Reply:
 | | Re: Steppr motor pulse problem
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| Phillip and others, To this excellent exposition I would change only one thing: (...) Change this to : "Write this pattern down neatly IN YOUR ROBOTICS NOTEBOOK." One of my professors at school noted that the most important thing he learned in (...) (27 years ago, 27-Aug-98, to lugnet.robotics.handyboard)
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