Introduction to Embedded Systems

Introduction to
EMBEDDED SYSTEM
Presented By
SANDEEP REDDY
Application Engineer
Cell: 9000424550
Mail: sandeep.mekas@gmail.com

What is a System?
 A system is a way of working, organizing or doing one or
many tasks according to a fixed plan, program or set of
rules.
 A system is also an arrangement in which all its units
assemble and work together according to the plan or
program.

SYSTEM EXAMPLES
It is a time display SYSTEM
Parts: Hardware, Needles, Battery, Dial, Chassis and Strap
Rules
 All needles move clockwise only
 A thin needle rotates every second
 A long needle rotates every minute
 A short needle rotates every hour
 All needles return to the original position after 12 hours
WATCH

SYSTEM EXAMPLES
It is an automatic clothes washing SYSTEM
Parts: Status display panel, Switches & Dials, Motor, Power
supply & control unit, Inner water level sensor and
solenoid valve.
Rules
 Wash by spinning
 Rinse
 Drying
 Wash over by blinking
 Each step display the process stage
 In case interruption, execute only the remaining
WASHING MACHINE

EMBEDDED SYSTEM
Definition: An Embedded System is one that has computer
hardware with software embedded in it as one of its
important components.
SOFTWARE PROGRAM
#include <16f876a.h>
#use delay (clock=20000000)
#byte PORTB=6
main()
{
set_tris_b(0);
portb=255; //decimal
delay_ms(1000);
portb=0x55; //hexadecimal
delay_ms(1000);
portb=0b10101010; //binary
delay_ms(500);
}
HARDWARE
Its software embeds
in ROM (Read Only
Memory). It does not
need secondary
memories as in a
computer

Other Definitions
 We can define an embedded system as “A microprocessor
based system that does not look like a computer”.
Or
 we can say that it is “A combination of computer hardware
and software, and perhaps additional mechanical or other
parts, designed to perform a dedicated function. In some
cases, embedded systems are part of a larger system or
product, as is the case of an antilock braking system in a
car ”.

 An embedded product uses a microprocessor (or
microcontroller) to do one task and one task only.
 A printer is an example of embedded system since the
processor inside it performs only one task; namely, getting
the data and printing it.

Comparison
Embedded Systems
 Few applications that
are known at design-
time.
 Not programmable by
end user. (?)
 Fixed run-time
requirements
(additional computing
power not useful).
 Criteria:
 cost
 power consumption
 predictability
 …
General Purpose
Computing
 Broad class of
applications.
 Programmable
by end user.
 Faster is
better.
 Criteria:
 cost
 average
speed

Significance
Due to their compact size, low cost and simple design
aspects made embedded systems very popular and
encroached into human lives and have become
indispensable.

History
• In the earliest years of
computers in 1930 – 40s,
computers were sometimes
dedicated to a single purpose
task.
• One of the first recognizably
modern embedded system was
the Apollo Guidance Computer,
developed by Charles Stark
Draper at the MIT
Instrumentation Laboratory.

History
Since these early applications
in the 1960s, embedded systems have
come down in price and there has
been a dramatic rise in processing
power and functionality. The first
microprocessor for example, the Intel
4004 was designed for calculators
and other small systems but still
required many external memory and
support chips.

History
By the mid-1980s, most of the
common previously external system
components had been integrated into
the same chip as the processor and
this modern form of the
microcontroller allowed an even more
widespread use, which by the end of
the decade were the norm rather than
the exception for almost all electronics
devices.

Advantages of ES
 Low cost.
 Small size.
 High reliability.
 Fast operations.
 Easy to manufacture.
 Fewer interconnections.

Applications of ES
• Medical Systems
– pace maker, patient monitoring systems, injection
systems, intensive care units, …
• Office Equipment
– printer, copier, fax, …
• Tools
– multimeter, oscilloscope, line tester, GPS, …
• Banking
– ATMs, statement printers, …
• Transportation
– (Planes/Trains/[Automobiles] and Boats)
• radar, traffic lights, signaling systems, …

Applications of ES
• Automobiles
– engine management, trip computer, cruise control,
immobilizer, car alarm,
– airbag, …
• Building Systems
– elevator, heater, air conditioning, lighting, key card
entries, locks, alarm systems, …
• Agriculture
– feeding systems, milking systems, …
• Space
– satellite systems, …

Applications of ES
Household appliances:
Microwave ovens,
Television,
DVD Players &
Recorders

CLASSIFICATIONS OF EMBEDDED SYSTEM
1. Small Scale Embedded System
2. Medium Scale Embedded System
3. Sophisticated Embedded System

SMALL SCALE EMBEDDED SYSTEM
• Single 8 bit or 16bit Microcontroller.
• Little hardware and software complexity.
• They May even be battery operated.
• Usually “C” is used for developing these system.
• The need to limit power dissipation when system is
running continuously.
Programming tools:
Editor, Assembler and Cross Assembler

MEDIUM SCALE EMBEDDED SYSTEM
• Single or few 16 or 32 bit microcontrollers or Digital Signal
Processors (DSP) or Reduced Instructions Set Computers
(RISC).
• Both hardware and software complexity.
Programming tools:
RTOS, Source code Engineering Tool,
Simulator, Debugger and Integrated Development
Environment (IDE).

SOPHISTICATED EMBEDDED SYSTEM
• Enormous hardware and software complexity
• Which may need scalable processor or configurable processor and
programming logic arrays.
• Constrained by the processing speed available in their
hardware units.
Programming Tools:
For these systems may not be readily available at a
reasonable cost or may not be available at all. A compiler or
retargetable compiler might have to br developed for this.

What is inside an embedded system ?
 Every embedded system consists of custom-built
hardware built around a Central Processing Unit (CPU). This
hardware also contains memory chips onto which the software
is loaded. The software residing on the memory chip is also
called the ‘firmware’.
 The operating system runs above the hardware, and the
application software runs above the operating system. The
same architecture is applicable to any computer including a
desktop computer. However, there are significant differences.
It is not compulsory to have an operating system in every
embedded system.

Layered architecture of an Embedded System

Now let us see the details of the various building blocks of the
hardware of an embedded system.
 Central Processing Unit (CPU)
 Memory (Read only memory and Random access
memory)
 Input Devices
 Output Devices
 Communication interfaces
 Application specific circuitry

Hardware architecture of an embedded system

Features of an embedded system
Embedded systems do a very specific task, they cannot be
programmed to do different things.
 Embedded systems have very limited resources, particularly
the memory. Generally, they do not have secondary storage
devices such as the CDROM 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 – loss of life or damage to property.

• 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 reset your embedded system.
• Some embedded systems have to operate in extreme environmental
conditions such as very high temperatures 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 .

Languages used in ES
Assembly Language:
 Lowest-level human-readable method for programming
 Platform specific
 No need for compilation
 Used by some compilers, such as GCC, to convert high-level
languages (such as C) into platform-dependent assembly
language before assembling into machine language.

Assembly Disadvantages:
 Platform Specific
 Operated by acting on specific instructions
 Can perform no other actions besides those specifically listed
 Instructions are highly atomic: each instruction performs a
single, small instruction
 Too difficult to program large applications

C Language:
 Source files ‘linked’ together
 Ability to program in assembly right inside the C- code
 Easy to write and portable
 Knowledge of C enables freedom

Introduction to Embedded Systems

Introduction to Embedded Systems

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