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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Fri, 4 Sep 1998 13:29:24 GMT
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Original-From:
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fthompson9@aol.SPAMCAKEcom
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Viewed:
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1210 times
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Phillip:
In the process I was referring to, you do not use the Handy board, driver
or anything to determine the step sequence. You only use the motor and a
battery (after you finish with the Ohm meter). The idea is to learn what the
motor is expecting only. Once you have this down on paper, you can also make
measurements as to what your driver (if any) is doing. If you are using a
driver (chip or board) you should clock this with the handy board. If you use
switches of wires, you will get a random number of pulses on either rising or
falling edges. (For the motor by itself this is not a problem, but a driver
chip/board will count each pulse as a step, not just the switch closure.
(This is called bounce.))
If your motor does not draw too much current, you should not need any
external components. If the motor is bi-polar, each coil plugs into a motor
output; so two motor outputs would be consumed by one stepper motor. In this
case you would need to program the sequence into the handy board. If your two
coils were plugged into motor outputs 1 and 2 your sequence would look like
Motor 1 Motor 2
motor 1 forward +
wait a pulse width
motor 1 off
motor 2 forward +
wait a pulse width
motor 2 off
motor 1 reverse -
wait a pulse width
motor 1 off
motor 2 reverse -
wait a pulse width
repeat the sequency
If your motor is really low current and you need extra resolution you
could:
Motor 1 Motor 2
motor 1 forward +
wait a pulse width
motor 2 forward + +
wait a pulse width
motor 1 off +
wait a pulse width
motor 1 reverse - +
wait a pulse width
motor 2 off -
wait a pulse width
motor 2 reverse - -
wait a pulse width
motor 1 off -
wait a pulse width
motor 1 forward + -
wait a pulse width
motor 2 off +
This is the first state in this list, repeat the sequence
Here there is an overlap between the coils of the sequence given last
time. This is called half stepping and draws just a little less than twice
the current as the first sequence.
But I'm getting a little off topic here. The point is to first find out
what step sequence the motor needs, then wire it to the Handy board/driver
system to insure the sequence it gets.
If you are using a stepper motor driver chip like the Motorola MC3479,
then you only need to provide signals like: Clock, Direction, and maybe Motor
On. These are TTL level signals and do not use the Motor driver ports. But
this chip can only deliver 350mA of current per coil so you might as well use
the motor ports on the handy board (unless you need the 16 volts/coil). If
your are using a drive like this, you do not need to "Program" the step
sequence into the handy board, you need to "wire" the sequence to the motor.
But your handy board program will still need to time the pulses correctly to
drive the motor.
In a message dated 98-09-04 04:47:34 EDT, you write:
<<
Hi ,
Thank for the infor. Does the sequence of the stepper motor which connected
to the driver need to be programmed into the microcontroller 6811 ? In
another word, does the squence of steps need be created out by programming
or just by defalt that the driver and the motor have the sequence step
itself already ?
Is it the driver has to be connected to the microcontroller first to see
the step sequence ?
>>
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