An embedded system is a combination of hardware and software
designed to perform a specific function or a limited set of functions within a
larger electrical, electronic or mechanical system.
The word embedded means that the computing system is built
inside another product. It is generally not visible to the user as a separate
computer, but it controls the working of the complete product.
Examples
Washing machine controller
Microwave oven
Digital camera
Automobile braking system
Printer
Smart television
Medical monitoring system
Industrial robot
Exam Definition: An embedded system is a special-purpose
computer system consisting of processor, memory, input-output devices and
software, designed to perform a dedicated function with specific timing,
cost, power and reliability constraints.
2. Basic Block Diagram of Embedded System 14 Marks
+----------------------+
Inputs -->| Sensors / Input Unit |
+----------+-----------+
|
v
+----------------------+
| Processor / |
| Microcontroller |
+----+------------+----+
| |
v v
+---------+ +---------+
| Memory | | Timers, |
| ROM/RAM | | ADC, I/O|
+---------+ +---------+
|
v
+----------------------+
| Output / Actuator |
+----------------------+
Explanation of Components
Input unit: Receives data from sensors, switches or communication ports.
Processor: Executes the embedded program and controls the system.
Memory: Stores program instructions, constants and temporary data.
Peripheral devices: Timers, counters, ADC, PWM and communication interfaces.
Output unit: Controls displays, motors, alarms, relays and actuators.
Power supply: Provides electrical power to all components.
3. Embedded Systems vs General Computing Systems 14 Marks
Basis
Embedded System
General Computing System
Purpose
Designed for a specific task
Designed for many different tasks
User interface
Limited or application-specific
Rich keyboard, mouse and display interface
Software
Fixed and dedicated software
Many user-installed applications
Resources
Limited memory and processing power
Large memory and high processing power
Power consumption
Usually low
Generally higher
Real-time response
Often required
Not always required
Cost
Optimized for low unit cost
Comparatively expensive
Examples
Washing machine, camera, router
Desktop, laptop, workstation
A smartphone is a complex system containing several embedded subsystems, but
it also provides many general-purpose computing features.
4. History of Embedded Systems 7 Marks
Early Development
Early embedded systems were developed for military, aerospace and industrial
control applications. They used fixed-function electronic circuits.
1960s
Embedded guidance computers were used in spacecraft.
The Apollo Guidance Computer is a famous early embedded computer.
1970s
The invention of microprocessors made embedded systems smaller and cheaper.
Intel 4004 and early microcontrollers supported dedicated control systems.
1980s and 1990s
Microcontrollers became common in consumer products.
Automotive, telecom and industrial applications increased.
Real-time operating systems became widely used.
Modern Era
Embedded systems are connected through the Internet of Things.
ARM processors dominate many mobile and low-power devices.
Artificial intelligence is increasingly deployed at the edge.
Systems are becoming smaller, smarter and more connected.
5. Classification of Embedded Systems 14 Marks
A. Based on Function and Performance
1. Stand-Alone Embedded Systems
They work independently and take input from sensors or users to produce output.
Examples: microwave oven, calculator and digital camera.
2. Real-Time Embedded Systems
They must produce correct output within a specified time limit.
Hard real-time system: Missing a deadline can cause complete failure.
Soft real-time system: Missing a deadline reduces quality but does not cause total failure.
Airbag control is a hard real-time application, while video streaming is a
soft real-time application.
3. Networked Embedded Systems
These systems are connected through wired or wireless networks.
Examples: network printer, router and smart security camera.
4. Mobile Embedded Systems
These are portable, battery-powered systems with limited size and power.
Examples: fitness tracker, digital camera and portable medical device.
B. Based on Complexity
Small-scale: 8-bit or 16-bit controller, simple software and no operating system.
Medium-scale: 16-bit or 32-bit controller, RTOS and multiple peripherals.
Large or sophisticated: Powerful processors, complex software, networking and advanced operating systems.
Embedded Systems
├── Function Based
│ ├── Stand-Alone
│ ├── Real-Time
│ ├── Networked
│ └── Mobile
└── Complexity Based
├── Small Scale
├── Medium Scale
└── Large Scale
6. Major Application Areas 14 Marks
Consumer Electronics
Television
Digital camera
Gaming console
Home appliances
Automotive Systems
Engine control unit
Anti-lock braking system
Airbag controller
Navigation and infotainment
Industrial Automation
Robotic systems
Process controllers
Motor-control systems
Programmable logic controllers
Medical Electronics
Pacemaker
ECG machine
Patient monitoring system
Infusion pump
Communication
Routers
Modems
Mobile base stations
Network switches
Aerospace and Defence
Missile guidance
Aircraft navigation
Radar systems
Satellite control
Banking and Office Automation
ATM
Printer
Scanner
Biometric attendance system
7. Purpose of Embedded Systems 7 Marks
Embedded systems are designed to monitor, control, communicate, compute or
perform a combination of these functions.
Major Purposes
Data collection: Collecting data from sensors.
Data processing: Processing signals and measurements.
Monitoring: Continuously observing system conditions.
Control: Controlling motors, temperature, speed or pressure.
Communication: Exchanging data with other systems.
User interface: Displaying information and accepting commands.
In an air conditioner, the embedded system reads temperature, compares it with
the selected value and controls the compressor accordingly.
8. Characteristics of Embedded Systems 14 Marks
Dedicated function: Designed for a particular application.
Reactive operation: Continuously reacts to external events.
Real-time behaviour: Often responds within a deadline.
Limited resources: Has limited memory, processing capacity and power.
High reliability: Must work correctly for long periods.
Low power consumption: Important for portable systems.
Compact size: Usually integrated inside another product.
Hardware-software integration: Hardware and software are co-designed.
Minimal user interface: May use only switches, LEDs or a small display.
Low cost: Cost is optimized for mass production.
9. Quality Attributes of Embedded Systems 14 Marks
Operational Quality Attributes
Response: Time taken to react to an event.
Throughput: Amount of work completed per unit time.
Reliability: Probability of operating without failure.
Availability: Percentage of time the system remains operational.
Safety: Ability to avoid harm and dangerous failure.
Security: Protection against unauthorized access.
Usability: Ease of operation by the user.
Non-Operational Quality Attributes
Maintainability: Ease of correcting and updating the system.
Testability: Ease of testing system functions.
Portability: Ease of moving software to another platform.
Reusability: Ability to reuse components in another system.
Flexibility: Ease of adapting to new requirements.
Attribute
Meaning
Example
Reliability
Continuous correct operation
Medical monitor
Safety
Avoiding dangerous behaviour
Airbag controller
Security
Preventing unauthorized access
ATM
Maintainability
Easy fault correction
Industrial controller
10. Common Design Metrics 14 Marks
Design metrics are measurable properties used to evaluate and compare embedded-system designs.
1. Unit Cost
Cost of manufacturing one product.
2. Non-Recurring Engineering Cost
One-time cost of design, development, testing and tooling.
3. Performance
Speed at which the system executes its required functions.
4. Power Consumption
Electrical energy consumed during operation.
5. Size
Physical size of the hardware and memory size of software.
6. Flexibility
Ease of changing functionality without redesigning the complete system.
7. Time-to-Market
Time required to develop and launch the product.
8. Maintainability
Ease of repairing, updating or improving the system.
9. Correctness
Ability to satisfy functional specifications.
10. Safety and Reliability
Ability to operate safely and continuously under expected conditions.
Design metrics often conflict. Higher performance may increase power,
development cost and system size.
Design-Metric Trade-Off
Higher Performance
|
+--> More Power
+--> Higher Cost
+--> More Heat
Lower Cost
|
+--> Limited Memory
+--> Lower Performance
Short Time-to-Market
|
+--> Use Existing Processor
+--> Greater Unit Cost
11. Processor Technology 14 Marks
The processor executes the embedded software and controls the entire system.
Processor selection depends on performance, cost, power, flexibility and
production volume.
A general-purpose processor is programmable and can execute many different applications.
Features
Contains a programmable instruction set.
Offers high flexibility.
Can run many applications by changing software.
Development is comparatively easy.
Unit cost may be higher than custom hardware.
Examples
Microprocessor
Microcontroller
ARM processor
x86 processor
Advantages
High flexibility
Short development time
Easy software updates
Low development cost
Limitations
May consume more power.
May be slower than dedicated hardware.
May include unused features.
13. Application-Specific Processor 14 Marks
An application-specific instruction-set processor is programmable but optimized for a particular class of applications.
Features
Instruction set is designed for a specific domain.
Offers a balance of performance and flexibility.
Consumes less power than many general-purpose processors.
Software can still be modified.
Examples
Digital signal processor
Network processor
Graphics processor
Audio and video processor
Advantages
Better performance for target applications
Good energy efficiency
More flexible than fixed hardware
Limitations
Less flexible than a general-purpose processor
Higher design complexity
Specialized programming tools may be required
14. Single-Purpose Processor 14 Marks
A single-purpose processor is a digital circuit designed to execute one specific function.
Features
Hardware is optimized for one task.
Provides very high performance.
Consumes low power.
Has little or no programmability.
Development cost may be high.
Examples
Hardware timer
JPEG encoder circuit
Digital filter circuit
Application-specific integrated circuit
Advantages
Very high speed
Low power consumption
Small size in mass production
Low unit cost at high volume
Limitations
Very low flexibility
High initial design cost
Long development time
Difficult to modify after manufacture
15. Comparison of Processor Technologies 14 Marks
Feature
General-Purpose Processor
Application-Specific Processor
Single-Purpose Processor
Flexibility
High
Medium
Very low
Performance
Medium
High
Very high
Power consumption
Higher
Medium
Low
Development cost
Low
Medium
High
Time-to-market
Short
Medium
Long
Programmability
Fully programmable
Domain-specific programming
Normally fixed function
Example
Microcontroller
DSP
ASIC hardware block
Processor selection is a trade-off. A general-purpose processor is selected
when flexibility and fast development are important, while a single-purpose
processor is selected when maximum speed and minimum power are required.
16. Embedded System Development Process 7 Marks
Requirement analysis
System specification
Hardware-software partitioning
Processor and component selection
Hardware design
Software development
Integration
Testing and debugging
Deployment and maintenance
Requirements
|
Specification
|
Architecture Design
|
Hardware / Software Development
|
Integration
|
Testing
|
Final Product
17. Advantages and Limitations of Embedded Systems 7 Marks
Advantages
Compact size
Low power consumption
Fast and reliable operation
Low cost in mass production
Dedicated and efficient performance
Can work automatically
Limitations
Limited processing and memory resources
Difficult hardware modification
Application-specific design
Debugging can be complex
Failure may require replacement of the complete unit
Unit 1 Quick Revision
An embedded system performs a dedicated function.
It combines processor, memory, peripherals and software.
Embedded systems may be stand-alone, real-time, networked or mobile.
Hard real-time deadlines cannot be missed.
Embedded systems are used in consumer, automotive, medical and industrial areas.
Important characteristics include reliability, low power and compact size.
Quality attributes include safety, security, maintainability and portability.
Design metrics include cost, performance, power, size and time-to-market.
General-purpose processors provide maximum flexibility.
Application-specific processors balance flexibility and performance.
Single-purpose processors provide maximum efficiency for one function.
Important RGPV Exam Questions
Long Answer Questions
Define an embedded system and explain its basic block diagram.
Compare embedded systems with general-purpose computing systems.
Explain the history and evolution of embedded systems.
Classify embedded systems with suitable examples.
Explain major application areas of embedded systems.
Discuss the characteristics of embedded systems.
Explain operational and non-operational quality attributes.
What are embedded-system design metrics? Explain their trade-offs.
Explain general-purpose, application-specific and single-purpose processors.
Compare the three major processor technologies.
Short Answer Questions
Define an embedded system.
Give four examples of embedded systems.
What is a hard real-time system?
Define a networked embedded system.
What is time-to-market?
Define NRE cost.
What is reliability?
What is an ASIP?
Give two examples of single-purpose processors.
What is hardware-software co-design?
Exam Tip: In long answers, draw the basic embedded-system block
diagram, classification tree and processor comparison table. These improve
presentation and help secure better marks.
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Frequently Asked Questions
It is a small dedicated computer built inside a product to perform a specific task.
An embedded system performs a dedicated task with limited resources, while a general computer performs many different tasks.
A hard real-time system must complete its operation before a strict deadline. Missing the deadline is considered a system failure.
Cost, performance, power, size, reliability and time-to-market are all important. Their priority depends on the application.
GPP is highly programmable, ASIP is optimized for a class of applications, and SPP is fixed for one dedicated task.