This document provides an overview of embedded systems. It defines an embedded system as a special purpose system that has hardware and software designed to perform dedicated functions. Examples provided include watches, washing machines, and microcontrollers. Programming languages for embedded systems are discussed, with C and C++ being the most common. Key features of embedded systems are also summarized such as limited resources, real-time constraints, reliability requirements, and diverse hardware platforms. Embedded systems are classified based on their functionality, with examples given of stand-alone, real-time, mobile, and networked embedded systems. Finally, common applications of embedded systems are listed.

1. D.K.M COLLEGE FOR WOMEN
(autonomous)
DEPARTMENT OF COMPUTER
SCIENCE AND APPLICATIONS

2. EMBEDDED SYSTEM
BY,
R.SIVAGAMI

3. Embedded System
• An Embedded system is one that has hardware with software embedded in it as one of its
important components.
• A Special purpose system which is having at least one programmable device( mp, mc),which is
used for controlling the specific application.
• Its Software embeds in ROM(READ ONLY MEMORY).It does not need secondary memories as
in computers.

4. Some Examples
WATCH
It is a time display system.
Parts: hardware, needles, battery and strap etc
RULES:
1) All needle move clockwise only.
2) A thin needle rotates every second.
3) A long needle rotates every minute.
4) A short needle rotates every hour.
5) All needle returns to the original position after 12 hours.

5. WASHING MACHINE
It is an automatic clothes washing system.
Parts: status display panel, switches & dials, motor,
Control unit, inner water level sensor etc..
RULES:
1)wash by spinning
2)rinse
3)drying
4)each step display the process stage.
5)in case of any interruption, it execute only the remaining.

6. Processor
A processor is the heart of the embedded system.
An embedded processor is a microprocessor that is used in an
embedded system
TWO ESSENTIAL UNITS OPERATIONS
CONTROL UNIT(CU) FETCH
EXECUTION UNIT(EU) EXECUTE

7. Comparison of
Microprocessor and
Microcontroller
Microprocessor Microcontroller
CPU is standalone, RAM, ROM, I/O & Timer are
separate
CPU,RAM,ROM,I/O & Timer all are on single
chip
High Processing Power Low Processing Power
High Power consumption Low Power consumption
Typically 32/64 bit 8/16 bit
General purpose Single purpose(control oriented)
Less reliable High reliable
Eg: 8086,8085 Eg: 8051

8. Overview of
Microprocessor

9. Languages for Programming
Embedded Systems
Assembly language was the pioneer for programming embedded systems till recently.
Now a days there are many more languages to the program these system. Some of the
languages are C,C++, ada, forth and java together with its new enhancement J2ME.
Recent survey indicates that approximately45% of the embedded software is still
being done in c language
C++ is also increasing its presence in embedded systems . as C++ is based on C
language, thus providing programmer the object oriented methodologies to get the
benefits of such an approach
A huge number of high quality compilers and debugging tools are available in the C
language

10. Features of an embedded System
Embedded systems do a very Specific task, they cannot br programmed to do
different things.
• Embedded systems have very limit resources, particularly the memory.
Generally, they do not have secondary storage devices such as the CD-ROM
or the floppy disk.
• Embedded systems have to work against some deadlines. A Specific job
has to be completed within a specific time. In some embedded systems,
called real-time systems, the deadlines are stringent. Missing a dead line
may cause a catastrophe-loos of life or damage to property

11. • Embedded systems are constrained for power, as many embedded
systems operate through a battery, the power consumption has to be
very low.
• Embedded systems need to be highly reliable. Once in a while,
pressing ALT-CTRL-DEL is OK on your desktop, but you cannot
afford to rest your embedded system.
• Some embedded systems have to operate in extreme
environmental conditions such as very high temperature and humidity
• Unlike desktop computers in which the hardware platform is
dominated by intel and the operating system is dominated by
microsoft, there is a wide variety of processors and operating systems
for the embedded systems. So , choosing the right platform is the
most complex task.

12. Classification of Embedded Systems
Based on functionality and performance
requirements, embedded systems are classifies as:
Stand-alone embedded systems.
Real-time embedded systems.
Networked information appliances
Mobile devices

13. Stand –alone embedded systems:
• As the name implies, stand-alone systems work in stand-
alone mode. They take inputs, process them and produced
the desired output.
• The input can be electrical signals or commands from a
human being such as the pressing of a button.
• The output can be electrical signals to drive another system,
an LED display or LCD display for display for displaying of
information to the users.
• Embedded systems usesd in process control, automobiles,
consumers electronic items etc.,fail into this category.

14. Real-time Systems
• Embedded systems in which some specific work has to be done in a
specific time period are called real-time systems.
• For example, consider a system that has to open a valve within 30
milliseconds when the humidity crossed a particular threshold. If the
valve is not opened within 30 milliseconds, a catastrophe may occur.
Such system with strict deadlines are called hard real-time systems.
• In some embedded systems, deadlines are imposed, but not adhering to
them once in a while may not lead to a catastrophe. For example,
consider a DVD player. Suppose, you give a command to the DVD
player from a remote control. And there is a delay of a few milli
seconds in executing that command. But, this delay won’t lead to a
serious implication. Such systems are called soft real-time systems.

15. Mobile devices
Mobile devices such as mobile phones, personal digital assistants(pdas), smart
phones etc., Are a special category of embedded systems. Though the pdas do
many general purpose tasks, they need to be designed just like the ‘conventional’
embedded system.
Just consider the limitation of mobile devices-memory constraints, amall size,
lack of good user interfaces such as full fledged keybord and display etc. Sre same
as those found in the embedded systmes, discussed above. Hence, mobile devices
are considered as embedded systems.

16. Networked Information Appliances
Embedded systems that are provided with network interfaces and
accessed by networks such as local area network or the internet are called
networked information appliances. Such embedded systems are connected
to a network, typically a network running TCP/IP protocol suite, such as
the internet or a company’s intranet.
For example consider a web camera can be connected to the internet.
The web camera can send pictures in real-time to any computer connect to
the internet. In such a case, the web camera has to run the HTTP server
software in addition to the TCP/IP protocol stack.

17. Applications
1)HOUSEHOLD APPLIANCES:
MICROWAVE OVENS, TELEVISION, DVD PLAYERS ETC
2)INTEGRATED SYSTEM IN AIRCRAFTS AND MISSILES
3)CELLULAR TELEPHONES
4)ELECTRIC MOTOR AND ELECTRONIC MOTOR
CONTROLLERS
5)CALCULATORS
6)MEDICAL EQUIPMENT’S
7)VIDEOGAMES
8) DIGITAL MUSICAL INSTRUMENTS, ETC.

18. THANK YOU