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From: irwin@m.cs.uiuc.edu
Newsgroups: sci.electronics
Subject: Re: Stepper Motor
Message-ID: <21000026@m.cs.uiuc.edu>
Date: 6 Jun 89 14:40:00 GMT
References: <7137@cbnews.ATT.COM>
Lines: 67
Nf-ID: #R:cbnews.ATT.COM:7137:m.cs.uiuc.edu:21000026:000:2099
Nf-From: m.cs.uiuc.edu!irwin    Jun  6 09:40:00 1989


/* Written  7:53 am  Jun  5, 1989 by knt@cbnews.ATT.COM in m.cs.uiuc.edu:sci.electronics */
/* ---------- "Stepper Motor" ---------- */

Does anyone know the basics for stepper motor operation.  I've got
a stepper motor with the following data sheet:


           ----------- SW1 -------
           |                      |
          ---------               |
          |       |--- SW2 -------|
     -----| motor |               |------O  +5v
     |    |       |--- SW3 -------|
     |    ---------               |
   __|__   |                      |
    ___    ----------- SW4 -------
     _


	Four-Step Input Sequence
	------------------------

	Step	SW1	SW2	SW3	SW4
	----	---	---	---	---

	1	on	off	on	off
	2	on	off	off	on
	3	off	on	off	on
	4	off	on	on	off
	1	on	off	on	off


What is the meaning of this 'four-step input sequence'?
The data sheet also has an 'eight-step input sequence'.
Is there an easy way to get the motor to step using a single
TTL pulse?  Why all the different wires?


Thanks,


Kirk ...
/* End of text from m.cs.uiuc.edu:sci.electronics */

A stepping motor, as its name implies, advances a given number of
degrees of rotation and will stop there until the next step is
requested. The numerious wires activate given poles within the
motor, to move it from one position to the next. What is lacking
here is a count decoder and step encoder, with motor drivers at
the output.

Some motors will require possibly 24 volts, and driver transistors
at the output of the "stepping motor drive logic". You indicate
yours runs on 5 volts, so drivers would not be subject to quite
as high voltage spikes.

A "motor controller" is needed, to convert the 5 volt logic pulse
that you referred to, to a "step control sequence". The control
logic would decode the logic input pulses into a count and set up
the wires of the motor to be energized for a 4 step full rotation,
or a 8 step rotation, as desired. The sequence given that you
mentioned, tells you what is required to achieve that number of
steps.

To use this, you will have to find, or design and build, a controller
for it.