The Use of PIC Microcontrollers in Multiple DC Motors Control Applications

摘要

This article is an applied engineering example of using microprocessor/microcontroller in various controls of the senior project designs in Electricity, Electronics, and Computer Technology (EECT) concentration in Industrial Technology curricula, but also of interest in industry applications. This project reflects the Industrial Technology curricula as a combination of hands-on and minds-on approach on real-world applications. The design of a microprocessor/ microcontroller control system involves the process of designing application programs starts from the individual module development through extensive testing, verification, and modification. Applying these developed modules in a useful manner requires the links and integrations that lead to the practical project implementation. Frequently, in students’ senior project designs and faculty’s research plans, the microprocessor/microcontroller resources become scarce or cause conflicts during the modules’ integration stage. This development demonstrates the accommodation of the shortfall of the resources and resolves any conflict that may force the designers to: (1) revise the module design, (2) rework most of the design, or (3) add additional circuit to the module otherwise. This use of multiple PICs presents a tested research concept that implements simple serial communication protocols in a multiprocessor environment, which aims to keep the pre-developed modules intact with the least possible modification during project implementation. Introduction The focus of this project is how to expand the role of existing small scale PIC microcontrollers into a multiplemicrocontrollers system to resolve limited resource issues in meeting complex project needs. A project was implemented under a contract between a private company and Old Dominion University, Technology Applications Center in 2004; this project, designed to develop a teaching robot, was used in the boxing training exercises. Its original design relied on a single CPU Motorola 68HC11) to control 8 DC motors, 8 position sensors, and some other peripheral and safety features. After the prototyping and examination of the mechanical functions, it was determined that the control circuits had to be revised. The requirements for this 68HC11 had grown to 9 DC motors and 18 position sensors with the same safety features. Due to the limitation of the 8 bit 68HC11 CPU, the processor’s resources were exhausted (Motorola, 1991). The mechanical designers desired to have a total of 20 or more position sensors to gain adequate controls of the training model, but this list was forced to cut down to accommodate the CPU. The 68HC11 is a microcontroller that has been in the market since 1980 (Cady, 1997) and Motorola has discontinued the manufacture of this product. It became difficult to find the supplier for this chip and its price is higher than expected. After a study of the specifications and potential applications on SPI (Serial UART Tutorial, Dr. Steve Hsiung is an associate professor of electrical engineering technology at Old Dominion University. Prior to his current position, Dr. Hsiung had worked for Maxim Integrated Products, Inc., Seagate Technology, Inc., and Lam Research Corp., all in Silicon Valley, CA. Dr. Hsiung also taught at Utah State University and California University of Pennsylvania. He earned his BS degree from National Kauhsiung Normal University in 1980, MS degrees from University of North Dakota in 1986 and Kansas State University in 1988, and PhD degree from Iowa State University in 1992. Steve can be reached at [email protected].