In-depth Explanation of How Microcontrollers Work
In-depth Explanation of How Microcontrollers Work
Microcontrollers are hidden inside a surprising number of products these days. If your microwave oven has an LED or LCD screen and a keypad, it contains a microcontroller. All modern automobiles contain at least one microcontroller, and can have as many as six or seven: The engine is controlled by a microcontroller, as are the anti-lock brakes, the cruise control and so on. Any device that has a remote control almost certainly contains a microcontroller: TVs, VCRs and high-end stereo systems all fall into this category. Nice SLR and digital cameras, cell phones, camcorders, answering machines, laser printers, telephones (the ones with caller ID, 20-number memory, etc.), pagers, and feature-laden refrigerators, dishwashers, washers and dryers (the ones with displays and keypads)... You get the idea. Basically, any product or device that interacts with its user has a microcontroller buried inside.
In this edition of HowStuffWorks, we will look at microcontrollers so that you can understand what they are and how they work. Then we will go one step further and discuss how you can start working with microcontrollers yourself -- we will create a digital clock with a microcontroller! We will also build a digital thermometer. In the process, you will learn an awful lot about how microcontrollers are used in commercial products.
What is a Microcontroller?
A microcontroller is a computer. All computers -- whether we are talking about a personal desktop computer or a large mainframe computer or a microcontroller -- have several things in common:
All computers have a CPU (central processing unit) that "executes programs." If you are sitting at a desktop computer right now reading this article, the CPU in that machine is executing a program that implements the Web browser that is displaying this page.
The CPU loads the program from somewhere. On your desktop machine, the browser program is loaded from the hard disk.
The computer has some RAM (random-access memory) where it can store "variables."
And the computer has some input and output devices so it can talk to people. On your desktop machine, the keyboard and mouse are input devices and the monitor and printer are output devices. A hard disk is an I/O device -- it handles both input and output.
The desktop computer you are using is a "general purpose computer" that can run any of thousands of programs. Microcontrollers are "special purpose computers." Microcontrollers...