-
8/3/2019 An Embedded System is a Computer System Designed to Do
One or a Few Dedicated And
1/4
2011
Assignment no 1
MICRO CONTROLLER
-
8/3/2019 An Embedded System is a Computer System Designed to Do
One or a Few Dedicated And
2/4
Embedded system
An embedded system is a computer system designed to do one or a
few dedicated and/or
specific functions often with real-time computing constraints.
It is embeddedas part of a
complete device often including hardware and mechanical parts.
By contrast, a general-purpose
computer, such as a personal computer (PC), is designed to be
flexible and to meet a wide
range of end-user needs. Embedded systems control many devices
in common use today. Since
the embedded system is dedicated to specific tasks, design
engineers can optimize it to reduce
the size and cost of the product and increase the reliability
and performance. Some embedded
systems are mass-produced, benefiting from economies of
scale
Physically, embedded systems range from portable devices such as
digital watches and
MP3players, to large stationary installations like traffic
lights, factory controllers, or the systems
controlling nuclear power plants. Complexity varies from low,
with a single microcontroller
chip, to very high with multiple units, peripherals and networks
mounted inside a large chassis
or enclosure. the embedded systems can be self-sufficient and be
able to deal with cutelectrical and communication systems.
Computer system
Typically a computer system is defined as a physical computer
and the components connected
to it to make it usable, not counting the network or peripherals
like a printer. So that would be
the monitor, computer case, keyboard, and mouse.
Micro processor
Microprocessors such as the Pentium inside a personal computer
have only the Central
Processing Unit and Math Co-processing unit. These
microprocessors do not have built in
memory, input or output functions such as parallel ports or
serial ports etc. They are optimized
to provide only the raw arithmetic and logic functions required
by the operating system at the
highest speed. All other components required to make the
computer such as memory,
input/output ports, serial, parallel, and mass storage are
provided by external chips and
devices. The Pentium is designed to meet a broad range of
general computing needs that are
provided with a personal computer.
-
8/3/2019 An Embedded System is a Computer System Designed to Do
One or a Few Dedicated And
3/4
A microprocessor such as the Pentium inside a personal computer
normally has a very large
instruction set. In the case of the Pentium it is several
hundred instructions. The instructions
cover a very broad range of tasks and functions. Some of these
instructions can be complex and
take many internal steps to execute within the processor. In
computer jargon we categorize this
type of instruction set as CISC or Complex Instruction Set
Computer. CISC has its advantages in
the area that it is used in such as high level languages and
operating systems.
Micro controller
a typical microcontroller one of the first things we notice is
that the microcontroller contains its
own memory, parallel ports, clock and very often a good number
of peripheral functions not
found on a microprocessor. In the case of PIC microcontrollers
we will find both flash program
memory where instructions are stored and a separate ram memory
space where only data is
stored. Computers that have separate memory spaces for data and
program instructions are
classified as the Harvard Architecture. One particular advantage
of the Harvard Architecture is
that data access operations can be taking place simultaneously
with program instruction
execution. Each memory area has its own data bus to the CPU so
operations can go on during
the same time frame. Many different manufacturers use the
Harvard Architecture for designs
of microcontrollers because this design is very efficient for
designing specific purpose
controllers that go into other systems. Microcontrollers usually
get embedded into other
products such as microwave ovens, automobile engine controllers,
power tools, appliances,
industrial instruments, hand held devices, cell phones and many
other areas. The design and
-
8/3/2019 An Embedded System is a Computer System Designed to Do
One or a Few Dedicated And
4/4
programming for these types of products and applications has
become so specialized that it has
taken on its own identity as embedded design.
The PIC microcontroller also has a very different type of
instruction set. The particular PIC
microcontroller located on the trainer board we will be using is
the PIC16F877A. This is in the
midrange family but its capabilities are at the top end of the
midrange family. This unit only
uses 35 instructions! This is the same for all microcontrollers
in the midrange family. The
strategy that is used in the design of this type of
microcontroller is to make a few very simple
instructions that execute very fast. Using this strategy a
complex task can be accomplished with
the combination of many very fast simple instructions in a
relatively short time. Computers that
use just a small number of very simple instructions that execute
very fast are classified as RISC
or Reduced Instruction Set Computers. Since PIC microcontrollers
use only 35 very simple
instructions they fit neatly into this category.
