Digital Electronics: Principles, Devices and Applications

14MicrocontrollersMicrocontrollers are hidden inside almost every product or device with which its user can interact. Infact, any device that has a remote control or has an LED/LCD screen and a keypad has an embeddedmicrocontroller. Some common products where one is sure to find the use of a microcontroller includeautomobiles, microwave ovens, TVs, VCRs, high-end stereo systems, camcorders, digital cameras,washing machines, laser printers, telephone sets with caller ID facility, mobile phones, refrigeratorsand so on. This chapter focuses on microcontroller fundamentals and the application-related aspects ofit. Beginning with an introductory description of the device, with particular reference to its comparisonwith a microprocessor, the chapter covers the general architecture and the criteria to be followed tochoose the right device for a given application. This is followed by application-relevant information,such as salient features, pin configuration, internal architecture, etc., of popular brands of eight-bit,16-bit, 32-bit and 64-bit microcontrollers from major international manufacturers. Intel’s 8051 familyof microcontrollers is described in more detail.14.1 Introduction to the MicrocontrollerThe microcontroller may be considered as a specialized computer-on-a-chip or a single-chip computer.The word ‘micro’ suggests that the device is small, and the word ‘controller’ suggests that thedevice may be used to control one or more functions of objects, processes or events. It is alsocalled an embedded controller as microcontrollers are often embedded in the device or system thatthey control.The microcontroller contains a simplified processor, some memory (RAM and ROM), I/O portsand peripheral devices such as counters/timers, analogue-to-digital converters, etc., all integrated on asingle chip. It is this feature of the processor and peripheral components available on a single chip thatdistinguishes it from a microprocessor-based system. A microprocessor is nothing but a processingDigital Electronics: Principles, Devices and Applications Anil K. Maini©2007 John Wiley &Sons, Ltd. ISBN: 978-0-470-03214-5