14
Microcontrollers
Microcontrollers are hidden inside almost every product or device with which its user can interact. In
fact, any device that has a remote control or has an LED/LCD screen and a keypad has an embedded
microcontroller. Some common products where one is sure to find the use of a microcontroller include
automobiles, microwave ovens, TVs, VCRs, high-end stereo systems, camcorders, digital cameras,
washing machines, laser printers, telephone sets with caller ID facility, mobile phones, refrigerators
and so on. This chapter focuses on microcontroller fundamentals and the application-related aspects of
it. Beginning with an introductory description of the device, with particular reference to its comparison
with a microprocessor, the chapter covers the general architecture and the criteria to be followed to
choose 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 family
of microcontrollers is described in more detail.
14.1 Introduction to the Microcontroller
The 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 the
device may be used to control one or more functions of objects, processes or events. It is also
called an embedded controller as microcontrollers are often embedded in the device or system that
they control.
The microcontroller contains a simplified processor, some memory (RAM and ROM), I/O ports
and peripheral devices such as counters/timers, analogue-to-digital converters, etc., all integrated on a
single chip. It is this feature of the processor and peripheral components available on a single chip that
distinguishes it from a microprocessor-based system. A microprocessor is nothing but a processing
Digital Electronics: Principles, Devices and Applications Anil K. Maini
© 2007 John Wiley & Sons, Ltd. ISBN: 978-0-470-03214-5
Microcontrollers
Microcontrollers are hidden inside almost every product or device with which its user can interact. In
fact, any device that has a remote control or has an LED/LCD screen and a keypad has an embedded
microcontroller. Some common products where one is sure to find the use of a microcontroller include
automobiles, microwave ovens, TVs, VCRs, high-end stereo systems, camcorders, digital cameras,
washing machines, laser printers, telephone sets with caller ID facility, mobile phones, refrigerators
and so on. This chapter focuses on microcontroller fundamentals and the application-related aspects of
it. Beginning with an introductory description of the device, with particular reference to its comparison
with a microprocessor, the chapter covers the general architecture and the criteria to be followed to
choose 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 family
of microcontrollers is described in more detail.
14.1 Introduction to the Microcontroller
The 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 the
device may be used to control one or more functions of objects, processes or events. It is also
called an embedded controller as microcontrollers are often embedded in the device or system that
they control.
The microcontroller contains a simplified processor, some memory (RAM and ROM), I/O ports
and peripheral devices such as counters/timers, analogue-to-digital converters, etc., all integrated on a
single chip. It is this feature of the processor and peripheral components available on a single chip that
distinguishes it from a microprocessor-based system. A microprocessor is nothing but a processing
Digital Electronics: Principles, Devices and Applications Anil K. Maini
© 2007 John Wiley & Sons, Ltd. ISBN: 978-0-470-03214-5