World Scientific Research Journal (WSRJ) ISSN: Design and Implementation of Stepper Motor Control System Based on 52 MCU

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1 World Scientific Research Journal (WSRJ) ISSN: Design and Implementation of Stepper Motor Control System Based on 52 MCU Xinglan Zhang a, Xianda Zhang b, * and Xin Zhong c School of Mechatronic Engineering, Shandong University of Science and Technology, Qingdao, China. a @qq.com,*, b @qq.com, c zhongxinlulu@163.com Abstract: A method for controlling the angular displacement of a stepper motor by using AT89C52 single chip microcomputer to convert the input signal into a control signal is described, including hardware design and software design. The system controls the rotation of the stepper motor through the AT89C52 single chip microcomputer and has high reliability. The start and stop, speed and direction programs of the motor were written in assembly language. The above functions were achieved through the single-chip microcomputer, the motor drive chip ULN2004 and the corresponding keys, to improve the stepping accuracy of the stepper motor and to control the three-phase stepper motor. The system can be used in most occasions such as electromechanical integration control of stepper motors. Keywords: Microcontroller, AT89C52, Stepper Motor, Control System. 1. INTRODUCTION A stepper motor is an actuator that converts an electric pulse signal into an angular displacement or a linear displacement. Each electric pulse is input, and the electric motor rotates by an angle and goes further. The number of control pulses, the frequency, and the sequence of energization of the motor phases can be used to control the rotation of the stepper motor. Stepper motors have no cumulative error and are widely used in various open-loop systems.this study uses a microcontroller timer TIMER-A (TA) interrupt to generate a pulse signal, realize the accurate count of stepping motor step number and lap number through the interrupt program, and realize the control to the stepping motor rotational speed through PWM. 2. THE WORKING PRINCIPLE OF STEPPING MOTOR The stepper motor is a brushless DC motor, which is an open-loop control system motor that converts electrical pulse signals into angular displacement or linear which is an open-loop control system motor that displacement, and is a main implementing element in modern digital program control systems. The simple definition of a stepper motor is that if a pulse is input to it, 61

2 the stepper motor will automatically rotate an angle and go one step forward. On this basis, stepper motors are basically divided into two categories: unipolar stepper motors and bipolar stepper motors. A unipolar stepper motor generally has five or six wires, four of which are one ends of four stator coils (A, B, C, D) [1]. The other ends of the four coils are connected together to represent the fifth wire. Called the public side. Bipolar stepper motors have no common terminal. On this basis, the single-stage stepper motor work method is divided into subdivided drive mode, full drive mode and half drive mod The response of the stepping motor is only determined by the pulse signal, without accumulation error, high precision, simple structure and low cost[2]. 3. THE OVERALL DESIGN OF THE SYSTEM The stepper motor based on the 52 series single-chip microcomputer mainly consists of the following components: the minimum system of the single-chip microcomputer, the drive circuit module, the key control circuit module, and the stepping motor. The single-chip microcomputer is the core part of the whole system, and it processes and distributes the pulse signal through programming, and transmits the signal to the driving circuit to realize the control of the speed and the steering of the stepping motor. The hardware circuit diagram is shown in Figure CONTROL SYSTEM DESIGN Fig the Hardware circuit diagram According to the overall structure of the stepper motor system, the system design schematic of the stepper motor control system based on the 52 series single-chip microcomputer is designed, as shown in Fig The port of P1 and P2 of the single-chip microcomputer judges whether 62

3 to step into the interrupt service to change the working status of the stepper motor according to the state of the keyboard during the working process of the stepping motor. Key control module SCM minimum system LED display moudle Drive circuit module Stepping motor Fig The system design schematic 4.1 SCM minimum system The minimum system of the microcontroller consists of three parts: the microcontroller, the reset circuit, and the clock circuit. The internal 8KB byte Flash of the ST89C52 microcontroller and the 256 byte RAM satisfy the storage requirements of the control system. The pulse signal sent by the MCU software programming realizes the recording of the number of steps and the number of laps of the stepping motor [3]. The angle of the stepping motor is proportional to the number of pulses sent by the MCU, and the direction of rotation of the stepping motor is related to the output pulse sequence. 4.2 Drive circuit module Because the power of the output signal of the AT89C52 microcontroller is not enough to drive the motor, it is necessary to use an external driving circuit to make the stepper motor work normally. The integrated driver IC ULN2004 is used in the design to form the entire driver circuit. The pulse signals output from the P2.0-P2.3 microcontroller are sent to the 1B-4B input of the ULN2004. The output pulse signal amplified by ULN2004 drives the stepper motor to perform corresponding actions.drive motor module schematic shown in Fig.1.3. Fig.1.3. Drive motor module schematic 63

4 4.3 Key control module The keyboard is mainly used to provide man-machine interface.the circuit diagram is shown in Figure1.4. It adopts a separate button circuit and uses p0 port as its input part. It connects the buttons and the pins of port p0.stepper motor working condition control: press the key switch S1, the motor is rotating; press the key switch S2, the motor reverse; press the key switch S5, the motor stops [4]. 5. SYSTEM SOFTWARE DESIGN Fig1.4. The key driver circuit The software system program consists of a main program, a keyboard program, a forward and reverse program, a time-delay program, and acceleration and deceleration programs. After the control system is powered on, the SCM is initialized and the motor is stopped. When a key is pressed, the interrupt enablers IE and XICON in the CPU judge the value entered by the keyboard to execute the corresponding subroutine and realize the control of the speed and direction of the stepper motor. Stepping motor speed is too large, prone to "out of step" or "overshoot" phenomenon, affecting the positioning accuracy of the stepper motor. Therefore, controlling the speed of the stepping motor is actually controlling the time interval between the stepping pulses. The design uses software programming to delay, that is, to achieve the delay through a set of subroutines. The smaller the delay time constant, the faster the stepper motor rotates. Changing the pulse sequence applied to the winding by the microcontroller can change the direction of rotation of the stepper motor. For the three-phase six-shot working method used in 64

5 this design: A AB B BC C CA when positive rotation; A AC C CB B BA when reversed[5]. 6. CONCLUSION Based on 52 series single-chip microcomputer, the stepper motor is controlled by software programming. The combination of software and hardware improves the precision and flexibility of the stepping motor and reduces the cost. By changing and writing different control programs, it is possible to flexibly control the running state of the stepper motor, enhance the interactivity of the stepper motor, and meet the needs of different users. REFERENCES [1] LI Xi-qin, DING, Ming-jun, WU, Hong-guang, et al. High-voltage pulsed power controlled by TTL digital circuit. High Power Laster and Particle Beams, 2012, 24 (3): [2] Qi Fa-Qun,Jing Xue-Dong,Zhao Shi-qing, Design of stepping motor control system based on AT89C51 microcontroller. Procedia Engineering, Volume 15, 2011, Pages [3] CAI Jing-jing, QIAN Shan-zhu, YAN Shuang-hong. Design of stepping motor servo controller based on single-chip computer [J]. Journal of Inner Mongolia Agricultural university, 2012 (7); [4] ZHANG Zhan-li, KANG Chun-hua, GUO Shi-jun, et al. Control system of step-motor based on microtroller unit [J].Electric Machines & Control Application, 2011 (3): [5] YU Shi-chao, GAO Zhi, SHAO Peng. Design and research of MCU-based control system for stepper motor [J].Coal Mine Machinery, 2010 (5):