Embedded Systems

1. EMBEDDED SYSTEMS

2. Module III
Embedded Systems – Definition, Embedded systems vs general computing
systems, Classification of Embedded Systems, Major application areas of
Embedded Systems, Elements of an Embedded System, Core of the
Embedded System, Microprocessor vs Microcontroller, RISC vs CISC,
Harvard vs Von-Neumann. Text 2: 1.1, 1.2, 1.4, 1.5, Fig. 2.1, 2.1, 2.1.1.4,
2.1.1.6, 2.1.1.7.
Sensors and Interfacing – Instrumentation and control systems, Transducers,
Sensors. Text 1: Chapter 15
Actuators, LED, 7-Segment LED Display, Stepper Motor, Relay, Piezo Buzzer,
Push Button Switch, Keyboard. Text 2: 2.3.2, 2.3.3.1 to 2.3.3.8 except 2.3.3.3
Communication Interface, UART, Parallel Interface, USB, Wi-Fi, GPRS. Text 2:
2.4, 2.4.1.3, 2.4.1.5, 2.4.2.2, 2.4.2.6, 2.4.2.8.

3. Applications of Embedded Systems

4. DEFINITION
An Electronic/Electro mechanical system which is
designed to perform a specific function and is a
combination of both hardware and firmware
(Software)

5. Classification of Embedded Systems
Generation
Complex and
Performance
Requirements
Deterministic
Behaviour
Triggering

6. Embedded Systems Vs
General Computing Systems
General Computing System Embedded Systems
combination of generic hardware and General
Purpose Operating System
combination of special purpose hardware and
embedded OS for executing a specific set of
applications
Contain a General Purpose Operating System (GPOS) May or may not contain an operating system for
functioning
Applications are alterable (programmable) by user The firmware of the embedded system is pre-
programmed and it is non-alterable by end-user
Performance is the key deciding factor on the
selection of the system. Always ‘Faster is Better’
Application specific requirements (like performance,
power requirements, memory usage etc) are the key
deciding factors

7. Embedded Systems Vs
General Computing Systems
General Computing System Embedded Systems
Less/not at all tailored towards reduced operating
power requirements, options for different levels of
power management.
Highly tailored to take advantage of the power saving
modes supported by hardware and Operating System
Response requirements are not time critical For certain category of embedded systems like
mission critical systems, the response time
requirement is highly critical
Need not be deterministic in execution behavior Execution behavior is deterministic for certain type of
embedded systems like ‘Hard Real Time’ systems

8. Classification
of Embedded
Systems
This Photo by Unknown Author is licensed under CC BY-SA-NC

9. Classification of
Embedded Systems
Based on Complexity and performance
Small Scale Embedded Systems
Medium Scale Embedded
Systems
Large Scale Embedded Systems
Based on Generation
First Generation Second Generation Third Generation Fourth Generation

10. Classification of Embedded
Systems based on Generation
First Generation
• 8 Bit Microprocessors(8085) and 4 bit Microcontrollers .
Simple in hardware circuits with firmware developed in
assembly code.
Digital Telephone Keypads, Stepper Motor Control units.
Second Generation
• built around 16 bit microprocessors. 8 bit and 16 bit
microcontrollers. More complex and powerful
Data Acquisition systems, SCADA systems

11. Classification of Embedded
Systems based on Generation
Third Generation
• Application and domain specific processors/controllers like
Digital Signal Processors(DSP) and Application Specific
Integrated Circuits(ASICs)
• Instruction set more complex and powerful
• Instruction Pipelining
Fourth Generation
• System on Chip, Reconfigurable processors and multicore
processors
• High performance, tight integration and miniaturization

12. Classification Based on
Complexity and Performance
Small Scale Embedded Systems
Medium Scale Embedded Systems
Large Scale Embedded Systems

13. Classification of Embedded Systems
based on Complexity and
Performance
Small Scale Embedded Systems
• Simple in application needs, performance
requirements are not time critical
• Built on low cost 8 or 16 bit
microprocessors/microcontrollers
• May or may not contain an operating system for
its functioning
Eg: Electronic Toy

14. Classification of Embedded Systems
based on Complexity and
Performance
Medium Scale Embedded Systems
• Slightly complex in hardware and firmware
requirements
• Built around low cost 16 bit/ 32 bit
microprocessors/microcontrollers
• Usually contain an embedded operating
system

15. Classification of Embedded Systems
based on Complexity and
Performance
Large Scale Embedded Systems
• Highly complex hardware and firmware
requirements.
• Mission critical applications demanding high
performance
• May contain multiple processors/controllers
and co units/ hardware accelerators
• Complex embedded systems usually contain a
high performance RTOS

16. Major Applications of Embedded Systems
Consumer Electronics:
Camcorders, Cameras etc.
Household Appliances:
Television, DVD players,
Washing machine, Fridge,
Microwave Oven etc.
Home Automation and
Security Systems: Air
conditioners, sprinklers,
Intruder detection
alarms, Closed Circuit
Television Cameras
Automotive Industry:
Anti-lock breaking
systems (ABS), Engine
Control, Ignition Systems,
Automatic Navigation
Systems etc.
Telecom: Cellular
Telephones, Telephone
switches, Handset
Multimedia Applications
etc.
Computer Peripherals:
Printers, Scanners, Fax
machines etc.
Computer Networking
Systems: Network
Routers, Switches, Hubs,
Firewalls etc.
Health Care: Different
Kinds of Scanners, EEG,
ECG Machines etc.
Measurement &
Instrumentation: Digital
multi meters, Digital
CROs, Logic Analyzers PLC
systems etc.
Banking & Retail:
Automatic Teller
Machines (ATM) and
Currency counters, Point
of Sales (POS)
Card Readers: Barcode,
Smart Card Readers,
Hand held Devices etc.

17. Elements of an Embedded Systems
I/p Ports
(Sensors)
O/p Ports
(Actuators)
Communication Interface
System
Core
Memory
FPGA/ASIC/DSP/SoC
Microprocessor/controller
Real World
Embedded System
Embedded
Firmware
Other supporting
Integrated Circuits &
subsystems

18. Core
of
the
Embedded
System
General Purpose and Domain Specific
Processors
• Microprocessors
• Microcontrollers
• Digital Signal Processors
Programmable Logic Devices (PLDs)
Application Specific Integrated
Circuits (ASICs)
Commercial off the shelf
Components (COTS)

19. Microprocessor Vs
Microcontroller

20. Microprocessor
CPU
General-
Purpose
Micro-
processor
RAM ROM I/O
Port
Timer
Serial
COM
Port
Data Bus
Address Bus
Many chips on mother board
CPU for Computers
No RAM, ROM, I/O on CPU chip itself
Example：Intel’s x86, Motorola’s 680x0

21. Microcontroller
A smaller computer
On-chip RAM, ROM, I/O ports...
Example：Motorola’s 6811, Intel’s 8051, Zilog’s Z8 and PIC 16X
RAM ROM
I/O
Port
Timer
Serial
COM
Port
CPU
A single chip

22. Microprocessor Vs Microcontroller
Microprocessor
• Silicon chip representing a CPU, performs
arithmetic and logical operations
• Dependent Unit
• General purpose in design and operation
• Doesn’t contain built in I/O port
• Limited power saving options compared to
microcontrollers
Microcontroller
• Highly integrated chip contains CPU, scratch
pad RAM, on chip ROM/flash memory, I/O
ports
• Self contained unit
• Application oriented and domain specific
• Contains multiple built in I/O ports
• Includes lot of power saving features

23. Microcontroller Architectures

24. Harvard Architecture

25. Von Neumann Architecture

26. Harvard vs Von Neumann Architectures
Separate buses for instruction and data
fetching
Easier to pipeline, so high performance
Comparatively high cost
No memory alignment problems
Since data memory and program memory
are stored physically in different
locations, no chances for accidental
corruption of program memory
Single shared bus for instruction and
data fetching
Low performance Compared to
Harvard Architecture
Cheaper
Allows self modifying codes
Since data memory and program
memory are stored physically in same
chip, chances for accidental
corruption of program memory

27. RISC vs CISC
Processors
Lesser no. of instructions
Instruction Pipelining and
increased execution
speed
Orthogonal Instruction
Set
Operations are performed
on registers only, the only
memory operations are
load and store
Large number of registers
are available
Greater no. of
Instructions
Generally no instruction
pipelining feature
Non Orthogonal
Instruction Set
Operations are
performed on registers
or memory depending
on the instruction
Limited no. of general
purpose registers

28. RISC vs CISC
Processors
Programmer needs to write
more code to execute a task
since the instructions are
simpler ones
Single, Fixed length
Instructions
Less Silicon usage and pin
count
Harvard Architecture
Instructions are like
macros in C language
Variable length
Instructions
More silicon usage since
more additional decoder
logic is required to
implement the complex
instruction decoding
Can be Harvard or Von-
Neumann Architecture

29. THANK YOU