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SIMULTANEO TWO STEPPER MOTORS WITH ONE MICROPROCESSOR

IP.com Disclosure Number: IPCOM000026141D
Original Publication Date: 1990-Aug-31
Included in the Prior Art Database: 2004-Apr-05
Document File: 2 page(s) / 139K

Publishing Venue

Xerox Disclosure Journal

Abstract

In a reprographic machine automatic document handler, or any similar system utilizing stepper motors, it is desirable to minimize the electrical circuitry and number of control microprocessors to reduce the overall complexity and cost of such systems. For example, it is possible to control the operation of dual stepper motors within an automatic document handler with a single microprocessor, such as an INTEL 8031 (8031) microprocessor. Control of two stepper motors in this manner eliminates the need for additional electrical circuitry, and/or additional microprocessors.

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XEROX DISCLOSURE JOURNAL

SIMULTANEOUS CONTROL OF Proposed Classification TWO STEPPER MOTORS WITH ONE
MICROPROCESSOR
Int. C1. G05b 1/02 Mark F. Brotzman
Michael A. Wiegand

U.S. C1.318/606

Phase A I I

Phase B 1

Phase C I

Phase D I I

In a reprographic machine automatic document handler, or any similar system utilizing stepper motors, it is desirable to minimize the electrical circuitry and number of control microprocessors to reduce the overall complexity and cost of such systems. For example, it is possible to control the operation of dual stepper motors within an automatic document handler with a single microprocessor, such as an INTEL 8031 (8031) microprocessor. Control of two stepper motors in this manner eliminates the need for additional electrical circuitry, and/or additional microprocessors.

A potential drawback of using an 8031 microcontroller, for such an application is manifested in the lack of real-time processing capability inherent tothe 803 1, wherein the microprocessor must continually interrupt itself, via a timer interrupt, to output the hase changes required to control the dual stepper

the alteration of interrupt priorities during operation, thereby resulting in one motor always having update priority over the other motor.

motors. The problem is

P urther exacerbated by the 8031's inability to enable

The figure illustrates the sequencing of the phase control for motor X (Phases A, B) and motor Y (Phases C,D). At times tl-t4, phase changes for the motors

XEROX DISCLOSURE JOURNAL - VoI. 15, No. 4 July/August 1990 205

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SIMULTANEOUS CONTROL OF TWO STEPPER MOTORS WITH ONE MICROPROCESSOR(Cont'd)

must occur to maintain synchronization. A problem arises in actual operation whereby the time between phase changes ti and t3 is not of sufficient duration to enable the processing of phase changes for motor X at time t2. This real- time conflict results in delayed processing of the t2 interrupt, due to the locking out of the t2 interrupt until completion of the ti interrupt, thereby causing the loss of synchronization and stalling of stepper motor X. The time required to service the interrupt of each stepper motor includes the time required to update the phases (A,B or C,D) for the motor and additional time to determine when the subsequent interrupt should occur and to re-program the timer to cau...