Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!gatech!gitpyr!byron
From: byron@pyr.gatech.EDU (Byron A Jeff)
Newsgroups: sci.electronics
Subject: Re: Stepper Motor
Message-ID: <8462@pyr.gatech.EDU>
Date: 7 Jun 89 15:11:15 GMT
References: <7137@cbnews.ATT.COM> <21000026@m.cs.uiuc.edu>
Reply-To: byron@pyr.UUCP (Byron A Jeff)
Organization: Georgia Institute of Technology
Lines: 77

In article <21000026@m.cs.uiuc.edu> irwin@m.cs.uiuc.edu writes:
-
-/* 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:
-[deleted for brevity - BAJ]
-
-	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.
-
-
-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.

If you have access to an eprom programmer a really quick solution
comes to mind. Program the eprom with the step sequence and use
a counter to pick the step. By using a up-down counter it's possible
to get the motor to rotate in both directions (by presenting the sequence 
backward). So something like this:

                                                                         
                                                                         
             |---------|--------|---------|-------|---------|------|-------|
             |         |--------|         |-------|         |------|       |
Step Pulse---| Counter |--------| EPROM   |-------| Drivers |------| Motor |
             |         |--------|         |-------|         |------|       |
             |---------|        |---------|       |---------|      |-------|

Would be a sufficient driver to make it go.

Does anyone know about drivers for these motors?

BAJ
-- 
Another random extraction from the mental bit stream of...
Byron A. Jeff
Georgia Tech, Atlanta GA 30332
Internet:	byron@pyr.gatech.edu  uucp:	...!gatech!pyr!byron