A microcontroller is a highly integrated circuit that comprises a CPU, I/O port, RAM, timers and some form of ROM – every element necessary for building a general purpose computer. But unlike a general purpose computer, a microcontroller is designed to undertake only a very specific task or to control only a particular system. As a result, the elements forming a microcontroller can be simplified and reduced, cutting down the production cost. This has made the microcontrollers market a hotbed of activity globally. Over the past decade, the market for microcontrollers has been characterized by innovation and breakthroughs.
Microcontrollers are sometimes referred to as embedded microcontrollers as they are commonly a part of an embedded system, which means being part of a larger system or device.
They are commonly used in automatically controlled, stand-alone devices and products such as implantable medical devices, kitchen and household appliances, remote controls, power tools, toys, automobile engine control systems, to name a few. As the complete mechanism needed to undertake any particular operation resides on a single chip in a microcontroller, their use makes it economical to digitalize and remotely control a wide range of devices and products.
Microcontrollers and Microprocessors – The Difference
Microcontrollers are not to be confused with microprocessors – commonly called the heart of a computer as they contain the central processing unit, the CPU as it is commonly known. But microprocessors have only the CPU. Other elementary components of a computer such as the RAM, ROM, I/O ports, timers, etc., are external to the microprocessor.
A microcontroller, on the other hand, has it all in a single chip. The CPU, a fixed amount of RAM, ROM and all other elementary components sit embedded on a single chip to make a microcontroller. Logically, when you hold a microcontroller, you are actually holding a miniature computer, sans an interactive interface.
Unlike microprocessors that are designed to suit a wide array of purposes, microcontrollers are designed to suit only a specific task or a set of tasks. By specific we mean tasks where the relation between the input and the output is defined. Depending on the type of input provided some processing takes place and a specific output is generated. The common examples include vending machines, microwave ovens, mobile phones, washing machines, remote controls, watches, etc. Since the applications of these devices are very specific, they need only a small amount of RAM, ROM and other resources in smaller formats. Hence, these parts can be easily embedded on a single chip.
Microcontrollers have a dedicated input port or device but often have a small LED or LCD display (not always) for output. The microcontroller takes input from the device it is handling and controls the device by sending signals to the various components of the device. The microcontroller in a microwave oven, for instance, takes inputs from a keyboard, displays some output on a LCD screen and controls a communication switch that turns the device on and off.
Microcontrollers are often, but not always, built to work in extreme conditions. The controller in a car engine, for instance, has to face temperatures as less as -340 C and as high as 490 C depending on the place where the car is being used. In the latter case when you add to that number the heat generated by the engine itself, one can expect the temperatures to soar to as high as 65-800 C. Such extremes cannot usually be handled by computers.
The processor used in microcontrollers can widely vary. For instance, the controllers in basic cell phones may be a basic 8-bit processor. Controller in an automated washing machine, on the other hand, may have a 12-bit processor.
There are a countless number of applications for microcontrollers, which can be limited only by one’s imagination. Hundreds of variants of microcontrollers are commonly available for various purposes. Some are programmed once and used for a specific application, such as for controlling a microwave oven. Some are capable of re-programming, making them suitable for different applications.