03-09-2012, 12:22 PM
Microcontrollers
[attachment=33180]
INTRODUCTION
Microcontrollers have only been with us for a few decades but their impact (direct or
indirect) on our lives is profound. Usually these are supposed to be just data processors
performing exhaustive numeric operations. But their presence is unnoticed at most of the
places like
• At supermarkets in Cash Registers, Weighing Scales, etc.
• At home in Ovens, Washing Machines, Alarm Clocks, etc.
• At play in Toys, VCRs, Stereo Equipment, etc.
• At office in Typewriters, Photocopiers, Elevators, etc.
• In industry in Industrial Automation, safety systems, etc.
• On roads in Cars, Traffic Signals, etc.
What inside them makes these machines smart? The answer is microcontroller.
Creating applications for the microcontrollers is different than any other development
job in electronics and computing. Before selecting a particular device for an application,
it is important to understand what the different options and features are and what they
can mean with regard to developing the application.
The purpose of this chapter is to introduce the concept of a microcontrollers, how it
differ from microprocessors, different type of commercial microcontrollers available as
well as their applications. The reminder of the book will go through and present different
types of microcontrollers and also programming and interfacing techniques of
microcontroller, mainly 8051, in detail.
EMBEDDED CONTROLLER
Simply an embedded controller is a controller that is embedded in a greater system. One
can define an embedded controller as a controller (or computer) that is embedded into
some device for some purpose other than to provide general purpose computing.
Is an embedded controller is the same as a microcontroller? The answer is definitely
no. One can state devices such as 68000, 32032, x86, Z80, and so on that are used as
embedded controllers but they aren’t microcontrollers.
MICROCONTROLLERS AND MICROPROCESSORS
A controller is used to control some process. At one time, controllers were built exclusively
from logic components, and were usually large, heavy boxes. Later on, microprocessors
were used and the entire controller could fit on a small circuit board. This is still common–
one can find many controllers powered by one of the many common microprocessors
(including Zilog Z80, Intel 8088, Motorola 6809, and others).
As the process of miniaturization continued, all of the components needed for a controller
were built right onto one chip. A one chip computer, or microcontroller was born.
A CPU built into a single VLSI chip is called microprocessor. The simplified block
diagram of the CPU is shown in the Fig. 1.1. It contains arithmetic and logic unit (ALU),
Instruction decode and control unit, Instruction register, Program counter (PC), clock
circuit (internal or external), reset circuit (internal or external) and registers. For example,
Intel 8085 is 8-bit microprocessor and Intel 8086/8088 is 16-bit microprocessor.
Microprocessor is general-purpose digital computer central processing unit (CPU).
The microprocessor is general-purpose device and additional external circuitry are added
to make it microcomputer.
MICROCONTROLLER APPLICATIONS
In addition to control applications such as the home monitoring system, microcontrollers
are frequently found in embedded applications. Among the many uses that you can find
one or more microcontrollers: automotive applications, appliances (microwave oven,
refrigerators, television and VCRs, stereos), automobiles (engine control, diagnostics, climate
control), environmental control (greenhouse, factory, home), instrumentation, aerospace,
and thousands of other uses.
Microcontrollers are used extensively in robotics. In this application, many specific
tasks might be distributed among a large number of microcontrollers in one system.
Communications between each microcontroller and a central, more powerful
microcontroller (or microcomputer, or even large computer) would enable information
to be processed by the central computer, or to be passed around to other microcontrollers
in the system.
[attachment=33180]
INTRODUCTION
Microcontrollers have only been with us for a few decades but their impact (direct or
indirect) on our lives is profound. Usually these are supposed to be just data processors
performing exhaustive numeric operations. But their presence is unnoticed at most of the
places like
• At supermarkets in Cash Registers, Weighing Scales, etc.
• At home in Ovens, Washing Machines, Alarm Clocks, etc.
• At play in Toys, VCRs, Stereo Equipment, etc.
• At office in Typewriters, Photocopiers, Elevators, etc.
• In industry in Industrial Automation, safety systems, etc.
• On roads in Cars, Traffic Signals, etc.
What inside them makes these machines smart? The answer is microcontroller.
Creating applications for the microcontrollers is different than any other development
job in electronics and computing. Before selecting a particular device for an application,
it is important to understand what the different options and features are and what they
can mean with regard to developing the application.
The purpose of this chapter is to introduce the concept of a microcontrollers, how it
differ from microprocessors, different type of commercial microcontrollers available as
well as their applications. The reminder of the book will go through and present different
types of microcontrollers and also programming and interfacing techniques of
microcontroller, mainly 8051, in detail.
EMBEDDED CONTROLLER
Simply an embedded controller is a controller that is embedded in a greater system. One
can define an embedded controller as a controller (or computer) that is embedded into
some device for some purpose other than to provide general purpose computing.
Is an embedded controller is the same as a microcontroller? The answer is definitely
no. One can state devices such as 68000, 32032, x86, Z80, and so on that are used as
embedded controllers but they aren’t microcontrollers.
MICROCONTROLLERS AND MICROPROCESSORS
A controller is used to control some process. At one time, controllers were built exclusively
from logic components, and were usually large, heavy boxes. Later on, microprocessors
were used and the entire controller could fit on a small circuit board. This is still common–
one can find many controllers powered by one of the many common microprocessors
(including Zilog Z80, Intel 8088, Motorola 6809, and others).
As the process of miniaturization continued, all of the components needed for a controller
were built right onto one chip. A one chip computer, or microcontroller was born.
A CPU built into a single VLSI chip is called microprocessor. The simplified block
diagram of the CPU is shown in the Fig. 1.1. It contains arithmetic and logic unit (ALU),
Instruction decode and control unit, Instruction register, Program counter (PC), clock
circuit (internal or external), reset circuit (internal or external) and registers. For example,
Intel 8085 is 8-bit microprocessor and Intel 8086/8088 is 16-bit microprocessor.
Microprocessor is general-purpose digital computer central processing unit (CPU).
The microprocessor is general-purpose device and additional external circuitry are added
to make it microcomputer.
MICROCONTROLLER APPLICATIONS
In addition to control applications such as the home monitoring system, microcontrollers
are frequently found in embedded applications. Among the many uses that you can find
one or more microcontrollers: automotive applications, appliances (microwave oven,
refrigerators, television and VCRs, stereos), automobiles (engine control, diagnostics, climate
control), environmental control (greenhouse, factory, home), instrumentation, aerospace,
and thousands of other uses.
Microcontrollers are used extensively in robotics. In this application, many specific
tasks might be distributed among a large number of microcontrollers in one system.
Communications between each microcontroller and a central, more powerful
microcontroller (or microcomputer, or even large computer) would enable information
to be processed by the central computer, or to be passed around to other microcontrollers
in the system.