Module :1

What is an Embedded systems ? History of an embedded system? Classification of an Embedded system ?

Applications of Embedded Systems?
Definition :
Embedded Systems is a computational system that is developed based on an integration of both hardware
and software in order to perform a given task. It can be said as a dedicated computer system has been
developed for some particular reason.

Components of Embedded Systems

1. Hardware 2. Software 3. Firmware
History of an Embedded systems:
 1960s - The Beginning: NASA developed the Apollo Guidance Computer (AGC), one of the first
embedded systems used in space missions.
 1970s - Rise of Microprocessors: Intel introduced the 4004 and 8080 microprocessors, leading to the
first engine control units (ECUs) in automobiles.
 1980s - Microcontrollers & Consumer Electronics: The invention of 8051 and other MCUs enabled
embedded systems in home appliances, industrial automation, and medical devices.
 1990s - Networked & Mobile Embedded Systems: Embedded systems became more connected,
powering ATMs, mobile devices, and automotive CAN networks for real-time communication.
 2000s - IoT & Smart Devices: The rise of wireless embedded systems with Wi-Fi, Bluetooth, and
embedded Linux led to smartphones, smart homes, and automotive ADAS.
 2010s-Present - AI & Autonomous Systems: Embedded systems now integrate AI, machine learning,
edge computing, and autonomous technology, transforming robotics, healthcare, and self-driving
vehicles.
Classifications of an Embedded systems:
Classification Type Category Description Examples

Based on Real-Time
Executes tasks within strict Airbag systems, Medical
Performance & Embedded
time constraints. devices, Robots
Functionality Systems

Stand-Alone
Works independently without Calculators, Digital cameras,
Embedded
external control. MP3 players
Systems

Networked
Connected via networks like Smart home devices, ATMs,
Embedded
Wi-Fi, Bluetooth, IoT. Routers
Systems

Mobile
Portable devices designed for Smartphones, Smartwatches,
Embedded
specific tasks. Fitness trackers
Systems

Small-Scale Uses 8-bit or 16-bit

Based on Digital thermometers, Remote
Embedded microcontrollers, minimal
Complexity controls
Systems processing.

Medium-Scale Uses 16-bit or 32-bit

Smart appliances, Industrial
Embedded microcontrollers, moderate
machines
Systems processing.

Large-Scale
Uses multi-core processors, Autonomous vehicles,
Embedded
high-performance systems. Aerospace systems
Systems

Based on Consumer Smart TVs, Washing

Used in daily life electronics.
Application Domain Electronics Machines, Cameras

Automotive Used in vehicle automation &

ECUs, ABS, Airbag Systems
Systems safety.

Medical Used in healthcare and Pacemakers, MRI Scanners,

Devices diagnostics. BP Monitors

Industrial Used in manufacturing and SCADA, Robotics, CNC

Automation process automation. Machines

Aerospace & Used in aircraft, military, and Flight Control Systems,

Defense space tech. Missile Guidance

IoT & Smart Used in interconnected smart Smart Homes, Wearable Tech,
Systems devices. AI Edge Devices
Major Applications of Embedded Systems
1. Consumer Electronics
o Smart TVs, Refrigerators, Washing Machines, Microwave Ovens, Digital Cameras
2. Automotive Industry
o Engine Control Unit (ECU), Anti-lock Braking System (ABS), Airbag Control, Autonomous
Vehicles
3. Healthcare and Medical Devices
o MRI Machines, Pacemakers, Blood Pressure Monitors, Wearable Health Trackers
4. Industrial Automation
o Robotics, CNC Machines, SCADA Systems, IoT Sensors
5. Telecommunication
o Mobile Phones, Routers, Modems, Satellite Communication
6. Aerospace and Defense
o Flight Control Systems, Radar Systems, Missile Guidance
7. IoT & Smart Devices
o Smart Home Systems, Smart Meters, Edge Computing Devices

2. what are characteristics or purpose of an Embedded systems? And explain about Advantages and
Disadvantages?
Characteristics of an Embedded System:
 Performs specific task: Embedded systems perform some specific function or tasks.
 Low Cost: The price of an embedded system is not so expensive.
 Time Specific: It performs the tasks within a certain time frame.
 Low Power: Embedded Systems don’t require much power to operate.
 High Efficiency: The efficiency level of embedded systems is so high.
 Minimal User interface: These systems require less user interface and are easy to use.
 Less Human intervention: Embedded systems require no human intervention or very less human
intervention.
 Highly Stable: Embedded systems do not change frequently mostly fixed maintaining stability.
 High Reliability: Embedded systems are reliable they perform tasks consistently well.
 Use microprocessors or microcontrollers: Embedded systems
use microprocessors or microcontrollers to design and use limited memory.
  Manufacturable: The majority of embedded systems are compact and affordable to manufacture.
They are based on the size and low complexity of the hardware.
1. Advantages of Embedded System
 Small size.
 Enhanced real-time performance.
 Easily customizable for a specific application.
2. Disadvantages of Embedded System
 High development cost.
 Time-consuming design process.
 As it is application-specific less market available.

3.Difference between Microcontroller and Microprocessors?

Feature Microcontroller (MCU) Microprocessor (MPU)

A single-chip solution with CPU, A CPU that requires external memory
Definition
memory, and peripherals. and peripherals.

Includes CPU, RAM, ROM, I/O Contains only the CPU; needs external
Architecture
ports, and timers in one chip. RAM, ROM, and I/O controllers.

Used in embedded systems like Used in general-purpose computers,

Applications robotics, appliances, and IoT servers, and high-performance
devices. systems.

Optimized for real-time control, low High processing power, supports

Performance
processing power. multitasking and OS.

Power Low power, suitable for battery- Higher power consumption due to
Consumption operated devices. external components.

Cheaper due to integration of Expensive due to the need for

Cost
components. additional hardware.

MSP430, ATmega328 (Arduino), Intel Core i7, AMD Ryzen, ARM

Examples
PIC16F877A, STM32. Cortex-A series.

Development Easier to program and implement in Requires OS and complex software

Complexity small-scale projects. development.
4.Difference between Von-neumann and Harvard Architecture?

Feature Von Neumann Architecture Harvard Architecture

Memory Single memory for instructions & data Separate memory for instructions & data

Data & Instruction

Sequential (one at a time) Parallel (simultaneous)
Fetching

Speed Slower due to shared bus (bottleneck) Faster due to separate buses

More flexible (can modify program

Flexibility Less flexible (fixed memory division)
memory)

Cost Cheaper, simpler More expensive, complex

Microcontrollers, DSPs (PIC, ARM

Used In General computers, PCs (Intel, AMD)
Cortex-M)

5.Differenebetween RISC and CSIC?

1. RISC (Reduced Instruction Set Computing)
RISC is a CPU design strategy that emphasizes simplified instructions that can be executed in a single
clock cycle. The goal is to enhance performance by optimizing instruction execution speed.
Key Features of RISC:
 Uses a small and fixed set of simple instructions.
 Instructions are executed in one clock cycle (load/store architecture).
 Pipelining is efficient, leading to higher performance.
 Uses more RAM because programs require multiple simple instructions.
 Suitable for embedded systems, smartphones, and IoT devices.
 Examples: ARM Cortex, RISC-V, MIPS, PowerPC.
2. CISC (Complex Instruction Set Computing)
CISC is a CPU design strategy that uses a large set of complex instructions. Some instructions perform
multiple operations, reducing the number of instructions required per program.
Key Features of CISC:
 Uses a large and complex set of instructions.
 Some instructions take multiple clock cycles to execute.
  Pipelining is difficult due to varying instruction lengths.
 Uses less RAM, as complex instructions reduce program size.
 Suitable for general-purpose computing (PCs, laptops, servers).
 Examples: Intel x86, AMD Ryzen, Pentium processors.
Comparison between RISC vs CISC
RISC (Reduced Instruction Set CISC (Complex Instruction Set
Feature
Computing) Computing)

Instruction Set Small and simple Large and complex

Slower (some instructions take multiple

Execution Speed Faster (one instruction per cycle)
cycles)

Instruction Length Fixed (usually 32-bit) Variable (8-bit to 120-bit)

Pipelining Efficient (uniform instructions) Difficult (variable-length instructions)

Memory Usage More RAM required (more instructions) Less RAM required (fewer instructions)

Hardware More complex, requires additional

Simpler, requires fewer transistors
Complexity circuitry

Lower (better for battery-powered

Power Consumption Higher
devices)

Used In Embedded systems, smartphones, IoT PCs, laptops, workstations, servers

Examples ARM Cortex, RISC-V, MIPS, PowerPC Intel x86, AMD Ryzen, Pentium

6.Difference between Big-Endian and Little -Endian processors?

Endianness refers to the order in which bytes are stored in memory. It determines how multi-byte data (like
integers or floating-point numbers) is arranged in a computer's memory.
1. Big-Endian
In a big-endian system, the most significant byte (MSB) is stored at the lowest memory address, while the
least significant byte (LSB) is stored at the highest address.
Example (Big-Endian Order)
Consider the 32-bit hexadecimal number:
0x12345678
Stored in memory (assuming address starts from 1000h):

Address Value

1000h 12
 Address Value

1001h 34

1002h 56

1003h 78

Used In:
 Motorola processors
 PowerPC (older versions)
 Network protocols (TCP/IP, IPv4, Ethernet)

2. Little-Endian
In a little-endian system, the least significant byte (LSB) is stored at the lowest memory address, while the
most significant byte (MSB) is stored at the highest address.
Example (Little-Endian Order)
For the same 32-bit number 0x12345678:

Address Value

1000h 78

1001h 56

1002h 34

1003h 12

Used In:
 Intel x86, x86-64 processors
 AMD processors
 ARM (configurable, but typically little-endian)
Comparison between Big-Endian vs. Little-Endian
Feature Big-Endian Little-Endian

LSB at lowest address, MSB at

Byte Order MSB at lowest address, LSB at highest
highest

Readability Matches human reading order Reverse order (not intuitive)

Motorola, PowerPC, Network protocols (TCP/IP, Intel x86, AMD, ARM (default
Used In
IPv4) mode)
Feature Big-Endian Little-Endian

Faster in some architectures (e.g.,

Performance Slower for some memory operations
x86)

Network Used in networking (big-endian is standard for

Not commonly used in networking
Usage TCP/IP)

7.What are memories in embedded system and classification of memories?

Memory in embedded systems is a crucial component that determines the performance, efficiency, and
capabilities of the system. It is categorized into different types based on functionality and usage:
1. Types of Memory in Embedded Systems
A. Read-Only Memory (ROM)
Used to store firmware (software that is permanently programmed into the device).
 PROM (Programmable ROM) – Can be programmed once.
 EPROM (Erasable Programmable ROM) – Can be erased and reprogrammed using UV light.
 EEPROM (Electrically Erasable Programmable ROM) – Can be erased and reprogrammed
electronically.
 Flash Memory – A type of EEPROM that allows faster erase and write operations. Commonly used
for firmware updates.
B. Random Access Memory (RAM)
Used for temporary data storage while the system is running.
 SRAM (Static RAM) – Faster but consumes more power and is expensive. Used for cache memory.
 DRAM (Dynamic RAM) – Slower but cheaper and requires periodic refreshing. Used for main
memory in larger systems.
C. Non-Volatile Memory (NVM)
Retains data even when power is off.
 FRAM (Ferroelectric RAM) – Combines the speed of SRAM and non-volatility of Flash.
 MRAM (Magnetoresistive RAM) – Uses magnetic storage elements for fast and durable memory.
2. Memory Hierarchy in Embedded Systems
 Registers (Fastest, smallest, inside CPU)
 Cache Memory (Small, stores frequently used data)
 RAM (SRAM/DRAM) (Main memory for executing programs)
 Flash/EEPROM (Stores firmware, configuration data)
 External Storage (SD cards, HDD, SSD) (Used in high-end embedded systems)
3. Memory Management in Embedded Systems
 Memory Mapping – Organizing memory into addressable sections (ROM, RAM, peripherals).
 Memory Protection – Using MMUs (Memory Management Units) to prevent memory corruption.
 DMA (Direct Memory Access) – Allows peripherals to transfer data without CPU involvement.
8.Explain about sensors and actuators?
Sensors and actuators are essential components in automation, robotics, IoT, and embedded systems. They
help machines and electronic devices interact with the physical worl
1. Sensors
A sensor is a device that detects and measures physical changes in the environment and converts them into
electrical signals for processing.
Working Principle of Sensors
Sensors work on the principle of detecting physical properties like temperature, pressure, light, motion, etc.,
and converting them into electrical signals (voltage or current). These signals are processed by a
microcontroller or processor for decision-making.
Types of Sensors and Their Working Principles

Sensor Type Working Principle Example Applications

HVAC systems, Weather

Uses resistance (RTD), voltage (thermocouples), or
Temperature Sensor monitoring, Industrial
capacitance changes to measure temperature.
automation

Converts force applied to a diaphragm into an Automotive (tire pressure

Pressure Sensor electrical signal using piezoelectric or capacitive monitoring), Industrial fluid
technology. control

Detects the presence of objects without physical

Touchless switches, Object
Proximity Sensor contact using infrared (IR), ultrasonic, or
detection in robots
electromagnetic fields.

Automatic street lights,

Light Sensor (LDR, Changes resistance or generates a voltage based on
Smartphone brightness
Photodiode) light intensity.
adjustment

Motion Sensor (PIR, Detects movement by sensing changes in infrared Security systems, Smart home
Ultrasonic, Radar) radiation or sound waves. automation

Detects gases like CO2, CO, or methane based on

Air quality monitoring,
Gas Sensor chemical reactions that alter resistance or current
Industrial safety
flow.

Measures acceleration and tilt using MEMS Smartphone screen rotation,

Accelerometer
technology (micro-electromechanical systems). Vehicle crash detection
2. Actuators
An actuator is a device that converts electrical signals into mechanical motion or action.
Working Principle of Actuators
Actuators operate based on the input electrical signals and convert them into physical movements using
electromagnetic, hydraulic, or pneumatic forces.
Types of Actuators and Their Working Principles

Actuator Type Working Principle Example Applications

Converts electrical energy into rotational motion using

DC Motor Robotics, Conveyor belts
electromagnetic induction.

Uses a feedback system and PWM (Pulse Width Robotic arms, Drone camera
Servo Motor
Modulation) for precise angle control. stabilization

Moves in discrete steps by controlling the current in

Stepper Motor CNC machines, 3D printers
stator windings.

Hydraulic Heavy machinery, Aircraft

Uses pressurized fluid to create motion.
Actuator landing gear

Pneumatic Industrial automation, Pneumatic

Uses compressed air to generate movement.
Actuator grippers

Solenoid Converts electrical energy into linear motion using a Electric door locks, Valves in
Actuator coil and magnetic field. washing machines

Piezoelectric Uses piezoelectric materials that expand or contract Ultrasonic transducers, Micro-
Actuator when an electric field is applied. positioning devices

3. Difference Between Sensors and Actuators

Feature Sensor Actuator

Function Detects and measures physical parameters. Performs physical actions based on control signals.

Input Physical quantity (e.g., temperature, light). Electrical signal.

Output Electrical signal. Mechanical motion (rotational or linear).

Example Temperature sensor, Motion sensor. Motor, Solenoid, Hydraulic piston.

9.Explain about opto-coupler , Relay, Push-button switch?
Opto-Coupler
An Opto-Coupler (also known as an Opto-Isolator) is an electronic component that allows signal
transmission between two isolated circuits using light. It consists of an LED (Light Emitting Diode) and
a Photodetector (like a phototransistor, photodiode, or photothyristor) enclosed in a single package.
Working Principle:
1. When a voltage is applied to the LED side, it emits light.
2. This light is detected by the photodetector, which then conducts current or changes state.
3. There is no direct electrical connection between the input and output, providing isolation between
circuits.
Applications:
 Microcontroller interfacing with high-power devices (e.g., motor drivers).
 Switching circuits without direct electrical contact.
 Isolation in communication systems (e.g., RS-232, RS-485).
 Noise reduction in signal processing.

Example Component:
 PC817 (Commonly used opto-coupler for low-
power applications)
 MOC3021 (Used for TRIAC control in AC circuits)

Relay
A Relay is an electromechanical switch that uses a small control signal to operate a larger electrical load.
It consists of a coil (electromagnet), a movable armature, and a set of contacts.

Working Principle:
1. When a small voltage is applied to the coil, it creates a
magnetic field.
2. This magnetic field pulls the armature, changing the state of the contacts (Normally Open (NO) →
Closed, or Normally Closed (NC) → Open).
3. When the coil is de-energized, a spring returns the contacts to their default position.
Types of Relays:
 Electromechanical Relay (EMR) – Uses physical movement of contacts.
 Solid-State Relay (SSR) – Uses semiconductor switching (no moving parts).
 Latching Relay – Maintains state even after power is removed.
 Reed Relay – Uses a small, fast-acting magnetic switch.
Applications:
 Isolating microcontrollers from high-power circuits.
 Controlling motors, heaters, and lights.
 Automotive applications (horns, headlights, etc.).
 Industrial automation systems.
Example Component:
 SPDT Relay (Single Pole Double Throw)
 DPDT Relay (Double Pole Double Throw)

Push-Button Switch
A Push-Button Switch is a simple mechanical switch that completes or interrupts an electrical circuit
when pressed.
Working Principle:
1. When the button is pressed, it connects or disconnects the circuit.
2. It can be momentary (returns to the default position when released) or latching (stays in the new
position after being pressed).
Types of Push-Button Switches:
 Normally Open (NO) – Circuit remains open until the button is pressed.
 Normally Closed (NC) – Circuit remains closed until the button is pressed.
 Latching – Maintains its position until pressed again.
Applications:
 Power on/off switches in electronic devices.
 Reset buttons in microcontroller circuits.
 Emergency stop switches in industrial applications.
 User input buttons in consumer electronics.
Example Components:
 Tactile switches (used in keyboards, remotes, etc.).
 Panel-mount push buttons (used in industrial control panels).
Comparison Table for optocoupler, Relay, Push button Switch,
 Mechanical
Component Function Isolation Application
Parts

Microcontroller
Opto- Electrical signal
Yes (using light) No interfacing, signal
Coupler isolation
isolation

Motors, home
Controls high- Yes (using
Relay Yes automation, industrial
power circuits electromagnet)
control

Push- User control Power switches, reset

No Yes
Button input buttons

10. Explain about Piezo -Buzzer and Communication Interfaces?

Piezo Buzzer
A Piezo Buzzer is a simple electronic component that produces sound using the piezoelectric effect. It
consists of a piezoelectric material that deforms when an AC voltage is applied, causing vibrations that
generate sound waves.
Working Principle:
1. A piezoelectric disc deforms when an electric signal is applied.
2. This deformation causes mechanical vibrations.
3. The frequency of the applied voltage determines the tone of the sound.
Types of Piezo Buzzers:
1. Active Piezo Buzzer – Has an internal oscillator and produces sound when connected to a DC
voltage.
2. Passive Piezo Buzzer – Requires an external signal (PWM from a microcontroller) to generate
sound.
Applications:
 Alarms and notifications (security systems, timers, reminders)
 Feedback sounds (button presses, keypads)
 Medical devices (patient alerts)
 Industrial alerts (fault indication)
Communication Interfaces in Embedded Systems
Communication interfaces in embedded systems enable data exchange between various components, such as
microcontrollers, sensors, actuators, and other peripherals. These interfaces can be broadly classified into
two main categories:
1. Serial Communication Interfaces
 2. Parallel Communication Interfaces
1. Serial Communication Interfaces
In serial communication, data is transmitted one bit at a time over a single data line, making it suitable for
long-distance communication with fewer wires.
Types of Serial Communication:
a) Synchronous Serial Communication
 Data is transmitted in synchronization with a clock signal.
 The sender and receiver use a common clock to coordinate data transfer.
Examples:
1. SPI (Serial Peripheral Interface)
o Uses four wires: MOSI (Master Out Slave In), MISO (Master In Slave Out), SCK (Clock),
and SS (Slave Select).
o High-speed communication between microcontrollers, sensors, and displays.
o Used in SD cards, EEPROMs, and ADCs.
2. I²C (Inter-Integrated Circuit)
o Uses two wires: SDA (Serial Data) and SCL (Serial Clock).
o Supports multiple masters and multiple slaves.
o Used in EEPROMs, temperature sensors, and real-time clocks.
b) Asynchronous Serial Communication
 Data transmission occurs without a shared clock signal.
 Start and stop bits are used for synchronization.
Examples:
1. UART (Universal Asynchronous Receiver-Transmitter)
o Uses two lines: TX (Transmit) and RX (Receive).
o Commonly used in debugging, GPS modules, and Bluetooth communication.
2. RS-232, RS-485, and RS-422
o RS-232: Used in PC serial ports, supports point-to-point communication.
o RS-485: Supports multiple devices on a single bus, used in industrial automation.
o RS-422: Similar to RS-485 but supports only one driver and multiple receivers.
3. CAN (Controller Area Network)
o Used in automotive and industrial applications.
o Supports multiple nodes with robust error handling.
 4. USB (Universal Serial Bus)
o High-speed data transfer between embedded devices and computers.
o Used in external storage devices, mice, keyboards, etc.
2. Parallel Communication Interfaces
In parallel communication, multiple bits are transmitted simultaneously over multiple wires, increasing
speed but requiring more physical connections.
Examples:
1. GPIO (General Purpose Input/Output)
o Used for simple on/off control in embedded systems.
o Common in microcontrollers for controlling LEDs, switches, and sensors.
2. PCI (Peripheral Component Interconnect)
o Used in high-speed computer buses for connecting GPUs, network cards, etc.
3. Parallel ATA (PATA)
o Used in older hard drives and CD-ROM drives.
4. Memory Bus
o Connects microprocessors to RAM and flash memory.

Comparison of Serial and Parallel Communication

Feature Serial Communication Parallel Communication

Speed Slower but efficient Faster but more complex

Wiring Fewer wires (cost-effective) More wires (increases cost)

Distance Suitable for long distances Short distances only

Example I²C, SPI, UART, CAN GPIO, PCI, Memory Bus