Microcontrollers In Education: Embedded Control – Everywhere And Everyday

Microcontrollers (MCUs) are used for embedded control in virtually every field of science and engineering. The smallest MCUs have only six pins and are used in toys, appliances, and for tasks as simple as interfacing a few switches in a car door. More sophisticated MCUs have processing horsepower rivaling that of the most powerful desktop computers and are used to perform complex real-time fuel and spark timing computations in modern automobile engines. Everywhere and everyday, hundreds of MCUs drive the many appliances that simplify our daily tasks. To the consumer, MCUs typically go unnoticed, but in industry they are very important. This paper stresses the importance of establishing a strong curriculum surrounding MCUs at various levels of engineering education. Most importantly, we must spark the student’s interest in MCUs in introductory engineering courses by introducing the subject in a very simple form. Students can be easily discouraged by the subject if they are initially drowned by complex MCU architectures and robust programming languages. Though these two topics are necessary to have a full understanding of MCUs, students gain more interest in MCUs if they were first given a glimpse of an end application. This gives students a better sense of what they can achieve by learning more about MCUs. This paper introduces one of the smallest and least expensive 8-bit MCUs. This MCU is in the MC68HC08 Family of MCUs and is available in both 8and 16-pin DIP packages. The specific MCU used in this paper is the MC68HC908QY4 1 in a 16-pin DIP package, which features: • 4K bytes of Flash and 128 bytes of RAM memory • 2-channel 16-bit timer with selectable input capture, output compare, and PWM • 4-channel 8-bit analog-to-digital converter • Flexible high-current I/O and keyboard interrupts This MCU is ideal to ease students with little or no previous knowledge of MCU architecture into the world of MCUs. I will cover all the fundamentals to get started with this device, allowing the student to focus on the end application. Specific topics to be covered include: • Microcontroller Student Learning Kit (MCUSLK) 2 • Monitor modes for serial communication • Metrowerks’ CodeWarrior development tools 3 In conclusion, a simple application will incorporate all the elements discussed in the paper. P ge 10938.1 “Proceedings of the 2005 American Society for Engineering Education Annual Conference & Exposition Copyright © 2005, American Society for Engineering Education” Microcontrollers in Industry Have you ever stopped and retraced your daily routine to count the total number of electronic components that play a part of your life? You will be amazed to know how much we rely on electronics to get through our daily routine and be even more surprised that the majority of those components have a MCU embedded inside. MCUs have been heavily used in the automotive, industrial, and commercial business space. To give you an idea, I have listed several applications that use MCUs in the automotive, industrial, and commercial industry in Table 1. Automotive Industrial Commercial Safety equipment Window lift Chassis Body electronics Transmission control Airbags Radar detector Anti-lock brakes Fuse relay replacement Sunroof systems Climate control Tire Pressure Monitor System Trip computer Seat systems Engine control Lighting Instrument cluster Remote keyless entry Thermostat Fire detection Alarm system Gas pump Traffic signals Credit card validation Automatic toll collection Vehicle tracking Tank level monitor Fast food equipment GPS Medical equipment Barcode scanner Cash register Security camera ATM machine Power over Ethernet HVAC Computer keyboard Computer mouse Inspection robot Warehouse management Cellular base station Safety automation Electronic window Sleep number bed Alarm clock Digital television Entertainment system Remote controls Refrigerator Stovetop Dishwasher Toaster Coffee maker Microwave Electric razor Cordless curling iron Light dimmer Weight scale Exercise equipment Electric toothbrush Cellular phone Pager PDA Garage opener Washer / Dryer Exterior lighting Keyless entry Locks Sprinkler system Bicycle speedometer Table 1: Applications with MCUs This list reinforces the importance of making sure that all engineering students receive a basic understanding of MCUs. The task of introducing MCUs to students will be easier if the student can focus on an end application familiar to them. Also, with some MCU experience the engineering student is much more prepared and marketable to employment opportunities in the automotive, industrial, and commercial industries. P ge 10938.2 “Proceedings of the 2005 American Society for Engineering Education Annual Conference & Exposition Copyright © 2005, American Society for Engineering Education” Microcontrollers in Curriculum From my experience in an electrical engineering program, I recall that the first reference to MCUs was not until I registered for a required sophomore level course titled, Introduction to Microcontrollers. In this course we spent the majority of the semester learning the Motorola MC68HC12 instruction set and how to write software algorithms in assembly programming language. The course did spend some time explaining the MCU architecture, but did not fully illustrate how an MCU is involved in a completed application. Therefore, most students in our program only associated MCUs with complex assembly programming and did not see an MCU as a crucial hardware component in a larger system. Since this was the only required MCU course in our curriculum, many of my peers justifiably did not see the importance of MCU technology in comparison to other digital logic. I know that my MCU experience does not apply to all engineering programs, but through talking to various professors the majority of introductory courses seem to focus on teaching students assembly programming. Strangely, there must have been something about assembly programming that was intriguing to me since I did register to take an elective course titled, Microcontroller Applications. This course along with the next upper division elective titled, Microcontroller Interfacing, led me to a job in the semiconductor industry. It was the hands-on experience and application specific labs in these upper division courses that allowed me to visualize how a tiny chip can process and control various factors. These courses taught me that MCUs went beyond programming. Specifically, they taught me more about selection process of other digital components to interface to the MCU. Also, because MCUs are so flexible in comparison to other digital logic components that are not programmable, the courses taught me the various ways of implementing an application. Learning how to write software and knowing the MCU fundamentals are very important. However, this paper stresses bringing a glimpse of the MCU end application into an introductory engineering course. For example, when a student is tasked with performing a digital logic function with the minimum number of components (NOR gates, NAND gates, INVERTERS, etc.) they should be introduced to using an MCU as an alternative solution. With an MCU, a student could reduce the total number of components necessary for performing a digital logic function to a single chip. Unlike digital logic components, which perform a set task, MCUs have internal memory that can be programmed to perform much more complex functions without additional components. Adding complexity to a function requires only more software in a single MCU. By configuring the software, an MCU can be used to sense inputs, decode data, and generate outputs. In addition, an MCU like the MC68HC908QY4 contains various peripherals like a timer, pulse-width modulator, analog-to-digital converter, and keyboard interrupts. These peripherals provide configurable functions without excess software algorithms. MCUs are becoming smaller and less expensive. The MC68HC908QY4, available in an 8or 16-pin package and costing less than a dollar is a good fit be combined with digital logic courses at an introductory engineering level.