Real Time Embedded Systems This document discusses real time embedded systems. It defines embedded systems as computer systems with specific functions within larger mechanical or electrical systems. Real time embedded systems are found everywhere and must provide responses in guaranteed time frames, like flight control and medical systems. They have limited operating systems and no user interface. The document discusses the history of embedded systems, how they interact with inputs and outputs, their uses in daily life, advantages like low cost and reliability, and disadvantages like difficult upgrades. It provides examples of embedded system applications in various fields like vehicles, traffic control, manufacturing, and multimedia.

1. Real Time Embedded
Systems
A Complete Assignment
This assignment is discuss the majors of embedded systems.
2018
Gentle_Xhaizi
CIIT Vehari
2/21/2018

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What is real time embedded system?
Definition:
An embedded system is computer system having various functions within a large
mechanical or electrical system. These systems have many of functions which are so critical. Its
include software and hardware devices which are connected to a system.
Introduction:
Real time embedded system are most popular computer nowadays. These devices are
found everywhere like microwave ovens, car engines, robots etc. these computers are used for
specific purposes. Embedded systems are primary and the operating system used for this purpose
provides limited features. Usually they have no user interface. Mostly these systems are used to
monitor and manage the devices like robotics, computerized weapons etc. and also they are used
by armed forces. This system is to be designed within some larger system.
These system are very different from normal system which we are use. Some of these use
as general purpose computer and sometimes they are used to implement a special purpose
activity like embedded systems providing just the functionality desired by user. Some of these
hardware devices with special IC’s that perform their tasks without an operating system. Real
time doesn’t mean real fast computer may be they will be slow. It means that you can calculate
the performance accurately when a program will execute. These systems are used in the industry
of consumer, medical, industrial, technology and military applications. These systems are most
widely used in our routine life.
For the developing of real time systems, it may involve many of activities like
requirements, architectural design, timing analysis, testing, implementation and debugging.
Actually these systems are the combination of computer software and hardware. Sometimes
these systems are using mechanical components. Embedded systems are used sensor, signal and
buttons to input information from these devices.
There are two types of real time.
1. Hard real time
Hard real time means that the systems that give response in required time.
This system is providing guaranteed services.
The examples of this system are Flight Controlling System, antimissile
system, cardiac pacemaker etc.
2. Soft real time
Soft real time means that the system that doesn’t give response in required
time. But it doesn’t means that they give not output. They missed the
deadline but not completely failure.
The examples of this system are global positioning system, digital camera,
robot soccer player, and wireless router system.
History:
Real time embedded systems are developed in 1961.the first embedded system was
developed by Charles Stark Draper in 1961 named Apollo Guidance Computer. He developed
this system in MIT instrumentation Lab. This system was considered the riskiest computer in
Apollo project.

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After this Apollo Guidance Computer another embedded system was developed named
Autonetics D-17 guidance computer for the Minuteman Missile. After the production of
minuteman II the D-17 was replaced with a new computer in which high volume integrated
circuits are used.
Why it’s needed?
Why we need an embedded system? We use an embedded system for interaction with I/O
devices. There are two approaches to interact with I/O devices such as Polling and interrupts. We
needed embedded system to improve the quality of computing. These systems are providing
reliability, power consumption and real time performance etc.
1. Polling
2. Interrupts
1. Polling:
It is a simplest approaches used in the embedded system to handle I/O activities.
In polling the continuous check is required for data arrival.
2. Interrupts:
Interrupts can be categorized into three main parts such that external interrupts,
software interrupts and internal interrupts.
2.1 External interrupts:
These interrupts are called hardware interrupts. These interrupts are
asynchronous events generated by external hardware devices to get the
microprocessor’s attention.
2.12 Software interrupts:
These interrupts are also called traps. These are unconditional in the sense
that the execution of the special instruction will always generate a software
interrupts.
2.13 Internal interrupts:
These interrupts are also called exception. Internal interrupts are
conditional in the sense that the execution of some valid instruction.
Where we use embedded system in routine life?
Mostly we used embedded to improve the routine life computing. These are often used in our
daily life which includes:
1. ATMs
2. Thermostats
3. Digital calculator
4. Mobile Phones
5. Photocopiers
6. Video games
7. Handheld computers

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8. PDAs (personal digital assistants)
9. Households (like microwave ovens)
Advantages and disadvantages of embedded systems:
Everything has its own advantages and disadvantages. We do not make a perfect machine
to solve our problems. Embedded systems have major advantages and disadvantages. The
advantages and disadvantages are given below:
Advantages of the embedded system:
i. These systems are small.
ii. These systems are faster to load.
iii. Managing these systems is easy
iv. Have a low cost
v. Use fewer resources during calculation
vi. Performance is better than other systems
vii. These systems are easy for mass production
viii. Very reliable systems
ix. Have interconnections
x. Improve the quality of the product
Disadvantages of embedded systems:
i. Up gradation of these systems are very difficult instead of other systems
ii. If we have a problem, we have to reset all the settings
iii. Limitation of the material
iv. Difficult to troubleshoot
v. Sharing data is difficult than other systems
vi. These systems are not scalable
vii. The interview is very hard
viii. Take backups of files is very difficult
ix. Technological improvements are not done in these systems
Applications and examples of real-time systems
Embedded systems are mostly used in our daily life in the form of commerce, military,
government, educational, cultural infrastructure and medical. Included are
i. Vehicle systems for automobiles, subways, aircraft, railways and ships
ii. Traffic control for motorways, airspace, railways and shipping lanes
iii. Process control for power plants, chemical plants and consumer products such as
soft drinks and beer
iv. Medical systems for radiotherapy, patient monitoring and defibrillation
v. Military uses such as firing weapons, tracking, and command and control
vi. Manufacturing systems with robots
vii. Telephone, radio, and satellite communications
viii. Computer games

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ix. Multimedia systems that provide text, graphic, audio, and video interfaces
x. Household systems for monitoring and controlling appliances
xi. Building managers that control such entities as heat, lights, doors, and elevators