CS3691 - EMBEDDED SYSTEMS & IOT

UNIT – 1
2 MARKS
1. What are the flags in 8051?
The 8051 microcontroller has five flags in the Program Status Word (PSW):

1. Carry (CY)
2. Auxiliary Carry (AC)
3. Overflow (OV)
4. Parity (P)
5. User-defined flag (F0)

2. List out the addressing modes of 8051.

The 8051 supports the following addressing modes:

1. Immediate
2. Register
3. Direct
4. Indirect
5. Indexed

3. What is the use of PSW?

The Program Status Word (PSW) holds status bits such as flags and register bank select bits.
It is used to reflect the status of the ALU and to control certain operations in the 8051.

4. Name the interrupts available in 8051.

The 8051 microcontroller has five interrupts:

1. External Interrupt 0 (INT0)

2. Timer 0 Overflow (TF0)
3. External Interrupt 1 (INT1)
4. Timer 1 Overflow (TF1)
5. Serial Communication (RI/TI)

5. Define JUMP and CALL.

JUMP is used to transfer program control to a different address within the program.
CALL is used to invoke a subroutine, storing the return address on the stack for later return
using the RET instruction.
13 MARKS

1.8051 Microcontroller Architecture and Components

1. 8051 Microcontroller – Overview

The 8051 is an 8-bit microcontroller developed by Intel. It contains:

• 4 KB on-chip ROM
• 128 Bytes RAM
• 32 I/O lines
• 2 Timers
• Serial communication port
• 5 interrupt sources

It is widely used in embedded systems due to its simplicity and efficient instruction set.

2. Architecture of 8051 Microcontroller

The 8051 architecture consists of the following main components:

• Central Processing Unit (CPU)

• Internal RAM and ROM
• Input/Output Ports (P0–P3)
• Timers/Counters
• Serial Communication
• Interrupt Control
• Oscillator & Clock Circuit
• Special Function Registers (SFRs)
• Data Bus and Address Bus
3. Central Processing Unit (CPU)

The CPU is the brain of the microcontroller. It fetches, decodes, and executes instructions.
The CPU interacts with internal memory and peripherals using buses.

Key CPU components:

• ALU (Arithmetic Logic Unit)

• Accumulator (A Register)
• B Register
• Program Counter (PC)
• Stack Pointer (SP)
• Flags and PSW
• Data Pointer (DPTR)

4. A and B CPU Registers

• A Register (Accumulator):
o 8-bit register used for arithmetic, logic, and data transfer operations.
o Most operations involve the accumulator.
• B Register:
 o Used with the A register in multiplication and division instructions.
o Also used as a general-purpose register in some instructions.

5. Data Pointer (DPTR)

• DPTR is a 16-bit register used to access external memory.

• It consists of two 8-bit registers:
o DPH (Data Pointer High)
o DPL (Data Pointer Low)
• Used in indirect addressing to point to data or code memory.

6. Program Counter (PC)

• PC is a 16-bit register.
• Holds the address of the next instruction to be executed.
• Automatically increments after each instruction.
• Enables sequential execution of instructions.

7. 8051 Flag Bits and the PSW Register

🔷 Program Status Word (PSW)

• The PSW is an 8-bit register that contains flag bits and register bank select bits.
• PSW Format:

CY AC F0 RS1 RS0 OV — P
7 6 5 4 3 2 1 0

🔷 Flags Description:

• CY (Carry Flag): Set if there is a carry in arithmetic operations.

• AC (Auxiliary Carry): Used in BCD operations.
• F0: User-defined general-purpose flag.
• RS1, RS0: Register bank select bits (00–11 selects banks 0–3).
• OV (Overflow): Set if result exceeds 8 bits.
• P (Parity): Set if number of 1’s in Accumulator is even (even parity).

8. Special Function Registers (SFRs)

 • SFRs are memory-mapped registers used to control the operation of 8051.
• Located from address 80H to 0FFH.

Summary Table

Component Description
CPU Executes instructions
A, B Registers A for main operations, B for MUL/DIV
DPTR 16-bit data address register
PC Holds address of next instruction
PSW Status register with flags
Flags CY, AC, OV, P, etc.
SFRs Special registers to control peripherals
2.8051 Microcontroller – Pin Diagram and Block Diagram
1. Pin Diagram of 8051 Microcontroller

You must draw a 40-pin DIP (Dual Inline Package) layout as shown below:

____________________________

2. Pin Description

• Pins 1-8 (Port 1): General-purpose I/O port.

• Pin 9 (RST): Reset input; active high.
• Pins 10–17 (Port 3): I/O port with alternate functions:
o RXD, TXD (Serial)
o INT0, INT1 (Interrupts)
o T0, T1 (Timers)
o WR, RD (External memory access)
• Pins 18-19 (XTAL1, XTAL2): Crystal oscillator connections.
• Pin 20 (GND): Ground.
• Pins 21–28 (Port 2): High-order address byte (A8–A15) for external memory.
• Pin 29 (PSEN): Program Store Enable; used to read external program memory.
• Pin 30 (ALE): Address Latch Enable; latches lower byte of address.
• Pin 31 (EA): External Access; tied to GND for external ROM, Vcc for internal.
• Pins 32–39 (Port 0): Multiplexed address/data bus (AD0–AD7).
• Pin 40 (Vcc): Power supply +5V.
3. Block Diagram of 8051 Microcontroller
+---------------------+
| 4 KB ROM |
+---------------------+
| 128 Bytes RAM |
+---------------------+
| Accumulator (A) |
| B Register |
+---------------------+
| Arithmetic Logic Unit|
+---------------------+
| Program Counter |
| Stack Pointer |
+---------------------+
| Timer 0 | Timer 1 |
+---------------------+
| Serial Port (TXD/RXD)|
+---------------------+
| Interrupt Control |
+---------------------+
| I/O Ports (P0–P3) |
+---------------------+
| Oscillator & Clock |
+---------------------+

4. Explanation of Block Diagram

• ROM & RAM: 8051 has 4KB on-chip ROM and 128B RAM.
• ALU: Performs arithmetic and logical operations.
• A & B Registers: Special function registers used in operations.
• Program Counter (PC): Holds address of the next instruction.
• Stack Pointer (SP): Points to top of the stack in internal RAM.
• Timers: Two 16-bit timers/counters for delay or event counting.
• Serial Port: Enables serial communication using TXD and RXD.
• Interrupt Control: Handles five interrupt sources (INT0, INT1, TF0, TF1, Serial).
• Ports P0–P3: Each is 8-bit wide and used for input/output operations.
• Oscillator: Provides system clock, typically using a 12 MHz crystal.

3.Timer Modes and Interrupt Handling in 8051

Microcontroller
Timer Modes of 8051

Introduction to Timers

The 8051 microcontroller has two timers/counters:

• Timer 0
 • Timer 1
Each timer is 16-bit and can be used as a timer (for internal clock-based delays) or a
counter (to count external events).

Registers Used

• TMOD (Timer Mode Register) – Selects timer mode

• TCON (Timer Control Register) – Starts/stops the timers

TMOD Register Format (8-bit)

Bit No. 7 6 5 4 3 2 1 0
Name GATE C/T M1 M0 GATE C/T M1 M0
For T1 T1 T1 T1 T0 T0 T0 T0

🚦 Timer Modes

Mode Description Operation

0 13-bit timer TLx = 5 bits, THx = 8 bits
1 16-bit timer TLx + THx = 16 bits (full range)
2 8-bit auto-reload TLx = 8 bits; reload from THx
3 Split Timer Mode (T0 splits to 2x 8-bit) T0 → TL0 and TH0 act as two timers

Usage Example:
Timer mode 1 (16-bit) is commonly used for generating delays or baud rate timing for serial
communication.

Interrupt Handling in 8051

Introduction

8051 supports five interrupt sources with vector addresses:

Interrupt Source Vector Address

INT0 External 0 0003H
TF0 Timer 0 000BH
INT1 External 1 0013H
TF1 Timer 1 001BH
Serial (RI/TI) UART 0023H

Interrupt Process (Handling Steps)

 1. Interrupt occurs
2. Current program execution is suspended
3. Program jumps to ISR (Interrupt Service Routine)
4. ISR executes
5. RET or RETI returns control to main program

Registers Used

• IE (Interrupt Enable Register) – Enables/disables interrupts

• IP (Interrupt Priority Register) – Sets priority among interrupts

IE Register Format

EA — ET2 ES ET1 EX1 ET0 EX0

7 6 5 4 3 2 1 0

• EA – Global enable/disable
• EX0, ET0, EX1, ET1, ES – Enables respective interrupts

Interrupt Priority (IP Register)

— — PT2 PS PT1 PX1 PT0 PX0

• Priority bits:
o High priority = 1
o Low priority = 0
• Allows nesting of interrupts
 UNIT – 2
2 MARKS
1. What is RTOS?

RTOS stands for Real-Time Operating System.

It is an operating system designed to process data and respond to inputs within a guaranteed
time, making it suitable for time-critical applications like embedded systems, robotics, and
medical devices.

2. What is Kernel?

A kernel is the core part of an operating system that manages system resources, such as
CPU, memory, and I/O devices.
It handles task scheduling, interrupt handling, and inter-process communication.

3. What is Priority Scheduling?

Priority scheduling is a CPU scheduling algorithm where each process is assigned a

priority.
The CPU is allocated to the process with the highest priority (lowest number or highest
rank), either preemptively or non-preemptively.

4. Differentiate Preemptive and Non-Preemptive Scheduling

Preemptive Scheduling Non-Preemptive Scheduling

CPU can be taken away from a running Once a process starts, it runs to
process completion

More responsive to high-priority tasks Simpler and less overhead

5. What do you mean by LED Interfacing?

LED interfacing refers to the process of connecting and controlling an LED using a
microcontroller or processor.
It typically involves configuring a GPIO pin as output and sending logic high or low
signals to turn the LED ON or OFF.
13 MARKS
1.RTOS (Real-Time Operating System)
1. What is RTOS?

An RTOS (Real-Time Operating System) is a special type of operating system designed to

process and respond to external inputs within a guaranteed time constraint.
It is used in embedded systems, robotics, medical instruments, automotive systems, and
aerospace where timing is critical.

2. Qualities of a Good RTOS

A good RTOS should meet the following requirements:

Quality Description
Determinism Predictable task execution time
Minimal Latency Quick interrupt and context switch
Multitasking Support Run multiple tasks with efficiency
Low Memory Footprint Works with limited memory/resources
Scalability & Portability Works across hardware platforms
Robust Synchronization Semaphores, mutexes, message queues
Reliability & Fault Tolerance Stable under failure conditions

3. Characteristics of RTOS

Characteristic Explanation
Predictable Timing Meets strict deadlines
Priority-Based Scheduling Executes high-priority tasks first
 Fast Context Switching Quickly switches between tasks
Real-Time Clock Support Time-stamped operations
Efficient Interrupt Handling Minimal ISR latency
Task Synchronization Avoids conflicts with shared resources
Minimal Jitter Consistent task execution intervals

4. How to Choose an RTOS?

Criteria to select the right RTOS:

1. Application Requirements:
o Real-time needs (hard or soft?)
o Timing constraints and precision
2. Hardware Compatibility:
o CPU architecture and memory support
3. Performance Metrics:
o Latency, context switching time, throughput
4. Footprint & Scalability:
o Minimal ROM/RAM usage
o Modularity for scaling
5. Toolchain Support:
o IDE, compiler, debugger availability
6. Vendor Support & Licensing:
o Open-source vs commercial
o Technical documentation and community support

5. Difference Between Hard and Soft Real-Time Systems

Feature Hard Real-Time System Soft Real-Time System

Timing Constraint Strict and must be met Desirable but not mandatory
Deadline Miss System failure or hazardous Reduced performance or quality
Impact

Examples Pacemakers, airbags, industrial Audio/video streaming, online

robots gaming

Tolerance to Delay No tolerance Some tolerance allowed

Complexity & Cost Higher Moderate to low
2.Priority-Based Scheduling Algorithm and Scheduling
Problems
1. Introduction to CPU Scheduling

CPU scheduling is the process of determining which process in the ready queue should be
allocated the CPU next. Among various algorithms, Priority Scheduling selects processes
based on assigned priorities.

2. What is Priority-Based Scheduling?

In Priority Scheduling, each process is assigned a priority number. The CPU is allocated
to the process with the highest priority.

• Priorities can be static (fixed at design time) or dynamic (change during execution).
• A lower number often indicates higher priority (conventionally).

3. Types of Priority Scheduling

Type Description
Preemptive If a new process with higher priority arrives, it preempts the running
process.
Non- Once a process starts, it runs to completion—even if a higher priority
Preemptive process enters.

4. Example: Priority Scheduling (Non-Preemptive)

Process Arrival Time Burst Time Priority

P1 0 10 2
P2 0 5 1
P3 0 8 3

✅ Execution Order: P2 → P1 → P3
(P2 has the highest priority)

5. Gantt Chart
| P2 | P1 | P3 |
0 5 15 23

6. Advantages of Priority Scheduling

• ✅ Efficient for real-time systems

 • ✅ Quick response for critical tasks
• ✅ Supports differentiated service levels (high-priority tasks handled first)

7. Comparison: Priority vs Other Scheduling Algorithms

Feature Priority Scheduling FCFS Round Robin

Fairness Low (starvation risk) High High
Preemption Optional No Yes
Real-Time Use Yes No Limited

8. Use Cases

• Embedded systems
• Real-time operating systems
• Multimedia applications
• Critical safety applications (e.g., airbags, pacemakers)
 UNIT – 3
2 MARKS
1. What is IoT?

IoT (Internet of Things) refers to a network of physical objects embedded with sensors,
software, and connectivity to exchange data with other devices or systems over the internet.
Example: Smart home devices, smart watches.

2. What is Arduino?

Arduino is an open-source electronics platform based on simple microcontroller boards

and a development environment.
It is used for building digital devices and interactive systems for IoT, automation, and
robotics.

3. What is Arduino Toolchain?

The Arduino toolchain is a set of software tools used for writing, compiling, and
uploading code to an Arduino board.
It includes the Arduino IDE, compiler (AVR-GCC), loader (AVRDUDE), and libraries.

4. What are Sketches?

A sketch is a program written using the Arduino IDE.

It consists of two main functions: setup() (runs once) and loop() (runs continuously), and
is uploaded to the Arduino board.

5. Differentiate Actuators and Sensors

Sensors Actuators
Detect physical changes (input) Cause physical movement (output)
Convert physical signals to electrical Convert electrical signals to physical
Example: Temperature sensor Example: Motor, Relay
13 MARKS
1.Explain the Structure of Arduino Programming
1. Introduction to Arduino Programming

Arduino is an open-source electronics platform used for prototyping embedded systems.

Arduino programs are written in a simplified form of C/C++, using the Arduino IDE. The
structure of an Arduino program is very simple and includes two primary functions:
setup() and loop().

2. Basic Structure of Arduino Sketch

void setup() {
// Code that runs once when the program starts
}

void loop() {
// Code that runs repeatedly in a loop
}

3. Main Components of Arduino Programming

a) Setup Function

• Function: void setup()

• Executes once when the microcontroller starts or resets.
• Used for initializing variables, pin modes, libraries, and serial communication.

void setup() {
Serial.begin(9600); // Start serial communication
pinMode(13, OUTPUT); // Set digital pin 13 as output
}
b) Loop Function

• Function: void loop()

• Runs continuously after setup() is complete.
• It forms the core logic of your program, repeatedly executing the code.

void loop() {
digitalWrite(13, HIGH); // Turn LED on
delay(1000); // Wait 1 second
digitalWrite(13, LOW); // Turn LED off
delay(1000); // Wait 1 second
}

4. Other Elements in Arduino Programming

c) Variable Declarations

Variables can be declared globally (before setup()) or locally (inside functions).

int ledPin = 13; // Global variable

d) Functions

User-defined functions can be created to organize and reuse code.

void blinkLED() {
digitalWrite(13, HIGH);
delay(500);
digitalWrite(13, LOW);
delay(500);
}

e) Libraries

Libraries extend the functionality of Arduino (e.g., sensors, displays).

#include <Servo.h> // Include Servo library

Servo myServo;

f) Comments

Used for documentation and ignored during compilation.

// This is a single-line comment

/* This is a
multi-line comment */

5. Example: Complete Sketch

int ledPin = 13;
void setup() {
pinMode(ledPin, OUTPUT);
}

void loop() {
digitalWrite(ledPin, HIGH);
delay(1000);
digitalWrite(ledPin, LOW);
delay(1000);
}

6. Compilation Process (Toolchain Overview)

1. Preprocessing – The sketch is prepared for compilation.

2. Compilation – Code is converted to machine code using AVR-GCC.
3. Uploading – AVRDUDE uploads the compiled code to the Arduino board.

2.Integration of Sensors and Actuators with Arduino

1. Introduction

Arduino is a microcontroller platform widely used in embedded systems and IoT projects.
One of its core applications is the interfacing of sensors and actuators to collect data from
the environment and control physical devices.

2. What are Sensors and Actuators?

Component Description
Sensor A device that detects physical input from the environment (e.g., temperature,
light, motion) and converts it into electrical signals.

Actuator A device that converts electrical signals into physical action (e.g., motors,
LEDs, buzzers).

3. Types of Sensors and Actuators Commonly Used with Arduino

🔹 Sensors:
 • Temperature Sensor (e.g., LM35, DHT11)
• Light Sensor (LDR)
• Ultrasonic Sensor (HC-SR04)
• IR Sensor
• Gas Sensor (MQ2)

🔹 Actuators:

• LED
• DC Motor
• Servo Motor
• Buzzer
• Relay

4. Interfacing Sensors with Arduino

Example: LM35 Temperature Sensor

int tempPin = A0; // Analog input pin

void setup() {
Serial.begin(9600);
}

void loop() {
int value = analogRead(tempPin);
float voltage = value * (5.0 / 1023.0);
float temperature = voltage * 100;
Serial.println(temperature);
delay(1000);
}

• Analog signal from sensor is read using analogRead().

• Processed and displayed using Serial Monitor.

5. Interfacing Actuators with Arduino

Example: Controlling LED

int ledPin = 13;

void setup() {
pinMode(ledPin, OUTPUT);
}

void loop() {
digitalWrite(ledPin, HIGH); // Turn ON
delay(1000);
digitalWrite(ledPin, LOW); // Turn OFF
delay(1000);
}

• Uses digitalWrite() to control actuator state.

6. Combined Example: Sensor-Controlled Actuator

Automatic Fan Control using Temperature Sensor + DC Motor

int tempPin = A0;

int motorPin = 9;

void setup() {
pinMode(motorPin, OUTPUT);
}

void loop() {
int temp = analogRead(tempPin);
float voltage = temp * 5.0 / 1023.0;
float temperature = voltage * 100;

if (temperature > 30) {

digitalWrite(motorPin, HIGH); // Fan ON
} else {
digitalWrite(motorPin, LOW); // Fan OFF
}
}

• Sensor input is used to control an actuator dynamically.

7. Communication Methods

Method Use Function

Digital I/O LEDs, switches digitalRead(), digitalWrite()
Analog Input Sensors like LM35 analogRead()
PWM Output Motors, dim LEDs analogWrite()
I2C/SPI Advanced sensors/modules Wire.h, SPI.h

8. Applications

• Smart Homes (motion sensors + light control)

• Weather Stations (temperature, humidity)
• Smart Agriculture (moisture sensors + water pumps)
• Industrial Automation
• Health Monitoring Devices
 UNIT – 4
2 MARKS
1. Write the use of Raspberry Pi in IoT

Raspberry Pi is a low-cost, credit-card-sized computer used in IoT for data processing,

device control, cloud connectivity, and edge computing. It supports multiple sensors,
cameras, and communication protocols for building smart and autonomous systems.

2. What is ZigBee?

ZigBee is a low-power, wireless communication protocol based on the IEEE 802.15.4

standard. It is used for short-range communication in IoT applications such as home
automation, industrial control, and smart lighting.

3. What are IoT Communication Protocols?

IoT communication protocols enable data exchange between devices. Examples include:

• MQTT (Message Queuing Telemetry Transport)

• CoAP (Constrained Application Protocol)
• HTTP/HTTPS
• AMQP (Advanced Message Queuing Protocol)
These protocols help devices communicate efficiently and securely over networks.

4. List out the GSM Modules

Common GSM modules used in IoT are:

• SIM800
• SIM900
• SIM808
• Quectel M95
These modules support SMS, voice, and GPRS for remote communication in IoT
applications.

5. What are the states of Bluetooth devices and WiFi?

🔹 Bluetooth States

• Idle
• Inquiry
• Page
• Connected
• Sniff/Hold/Park (low-power modes)
🔹 Wi-Fi States

• Disconnected
• Connecting
• Connected
• Obtaining IP address
• Roaming
• Idle

13 MARKS
1.How to Access, Send, and Receive Signals Using GPIO
Pins?
1. Introduction to GPIO

GPIO stands for General Purpose Input/Output. These are programmable pins available
on microcontrollers (like Arduino, Raspberry Pi, ESP32) used for reading input signals
from sensors or sending output signals to actuators.

2. GPIO Pin Modes

Each GPIO pin can be configured in two modes:

• Input Mode – To receive data from external devices (e.g., switches, sensors)
• Output Mode – To send data to external devices (e.g., LEDs, motors)

3. Accessing GPIO Pins

GPIO access involves:

• Pin number identification (e.g., D0, GPIO17)

• Pin configuration (input or output mode)
• Data reading or writing

4. Using GPIO in Arduino (Example)

a) Configure GPIO Pin

pinMode(7, OUTPUT); // Configure pin 7 as output

pinMode(2, INPUT); // Configure pin 2 as input

b) Send Signal (Output)

digitalWrite(7, HIGH); // Set pin 7 to HIGH (5V)
digitalWrite(7, LOW); // Set pin 7 to LOW (0V)

c) Receive Signal (Input)

int value = digitalRead(2); // Read input from pin 2 (HIGH or LOW)

5. Using GPIO in Raspberry Pi (Python Example)

Required Library:

import RPi.GPIO as GPIO

import time

a) Setup

GPIO.setmode(GPIO.BCM) # Use BCM pin numbering

GPIO.setup(17, GPIO.OUT) # Set GPIO17 as output
GPIO.setup(18, GPIO.IN) # Set GPIO18 as input

b) Sending Signal

GPIO.output(17, GPIO.HIGH) # Send HIGH signal

GPIO.output(17, GPIO.LOW) # Send LOW signal

c) Receiving Signal

if GPIO.input(18) == GPIO.HIGH:
print("Input is HIGH")

d) Cleanup

GPIO.cleanup() # Releases all GPIO pins

6. GPIO-Based Applications

Sensor/Input GPIO Input

Push Button Detect HIGH/LOW
PIR Motion Sensor Detect motion
Actuator/Output GPIO Output
LED Turn ON/OFF
Relay/Motor Drive control

7. Precautions When Using GPIO

 • Avoid Overvoltage (Exceeding 3.3V or 5V can damage pins)
• Use resistors with LEDs to limit current
• Debouncing may be needed for mechanical switches
• Don't connect input pins to power without grounding

8. Real-Time Example

IoT Door Monitoring System

• Sensor (Magnetic Switch) connected to GPIO input

• LED/Buzzer connected to GPIO output
• When door opens (switch opens), buzzer is triggered.

2.Architecture of Raspberry Pi, Board Overview, Linux

OS, and Comparison with Desktop Computer

1. Introduction to Raspberry Pi

Raspberry Pi is a low-cost, credit card-sized single-board computer (SBC) developed by

the Raspberry Pi Foundation. It is widely used in IoT, robotics, embedded systems, and
educational projects.

2. Architecture of Raspberry Pi

Raspberry Pi is based on the ARM architecture. Its major architectural components include:

a) System-on-Chip (SoC)

• Contains the ARM CPU, GPU, and other components integrated in a single chip
(e.g., Broadcom BCM2711 in Raspberry Pi 4).

b) Central Processing Unit (CPU)

• Typically a Quad-Core ARM Cortex-A72 @ 1.5 GHz in Raspberry Pi 4.

• Executes instructions and controls system operation.

c) Graphics Processing Unit (GPU)

• VideoCore IV GPU (in most models).

• Handles graphics rendering, especially for HDMI output and video processing.
d) Memory (RAM)

• Varies by model: 1 GB to 8 GB LPDDR4 RAM (in Raspberry Pi 4).

e) Storage

• Uses microSD card as primary storage.

• Can also boot from USB drives (on newer models).

f) Power Supply

• 5V DC via USB Type-C or micro-USB depending on model.

3. Raspberry Pi Board Components

Component Function
GPIO Pins 40 pins for input/output with sensors, actuators
USB Ports Connect mouse, keyboard, and USB drives
HDMI Port Display interface for monitor/TV
CSI Camera Port Interface for Pi Camera Module
DSI Display Port For official Pi touchscreen
Ethernet Port Wired network access
Wi-Fi/Bluetooth Wireless communication
 Audio Jack Audio output
MicroSD Slot Operating system and file storage

4. Linux on Raspberry Pi

a) Raspberry Pi OS (formerly Raspbian)

• Official Linux distribution based on Debian.

• Optimized for Raspberry Pi hardware.

b) Other Supported OS

• Ubuntu Server
• Kali Linux
• LibreELEC (for media)
• Windows 10 IoT Core (for IoT apps)

c) Linux Features on Raspberry Pi

• Command Line & GUI (LXDE desktop)

• Python & C/C++ programming
• Package Manager (APT)
• Multitasking and network capabilities

5. Differences Between Raspberry Pi and Desktop Computer

Feature Raspberry Pi Desktop Computer

Processor ARM-based (mobile class) x86/x64-based (Intel/AMD)
Size Credit card-sized Large tower or laptop
Power Consumption Low power (5V, ~3W) High power (>150W)
Performance Limited performance High-performance CPU & GPU
Expandable GPIO, camera, HATs PCIe, SATA, RAM slots, GPUs
Operating System Linux-based (Raspberry Pi OS) Windows/macOS/Linux
Storage MicroSD or USB HDDs/SSDs
Price Low-cost (~₹3500–₹6000) Expensive (₹30,000+)

6. Applications of Raspberry Pi

• Home automation
• Weather monitoring
• Media center
• IoT gateway
• Robotics
• Educational coding kits
 UNIT – 5
2 MARKS
1. What is Smart City?

A Smart City uses IoT, sensors, and data analytics to improve urban services such as
traffic management, waste disposal, water supply, and public safety, aiming to enhance
the quality of life for citizens.

2. What is Smart Healthcare?

Smart Healthcare involves the use of IoT-enabled medical devices, wearables, and health
monitoring systems to provide real-time patient data, remote diagnosis, and automated
alerts for better medical care and treatment.

3. What is Smart Agriculture?

Smart Agriculture uses IoT technologies like soil sensors, weather stations, and
automated irrigation systems to monitor crop conditions, optimize farming practices, and
increase productivity and sustainability.

4. What is the use of developing IoT applications in Home Automation

System?

IoT in home automation allows for remote control and monitoring of appliances, lighting,
security, and climate. It improves energy efficiency, convenience, and safety in smart
homes.

5. List the Design Metrics of Embedded System.

Key design metrics of an embedded system include:

• Performance
• Power consumption
• Cost
• Size
• Reliability
• Time-to-market
13 MARKS
1.Smart Agriculture, Smart Irrigation, Greenhouse
Control, Smart Healthcare, and Health & Fitness
Monitoring
1. Introduction

The Internet of Things (IoT) enables automation, monitoring, and control of various real-
world applications. Smart agriculture and smart healthcare are two major domains using
IoT for improving productivity and quality of life.

SMART AGRICULTURE SYSTEMS

2. Smart Agriculture

Smart Agriculture uses sensors and IoT devices to monitor crop health, soil conditions, and
environmental factors in real time.

Technologies Involved:

• Soil moisture and pH sensors

• Weather monitoring systems
• Drones for crop surveillance
• GPS and data analytics

Benefits:

• Higher crop yields

• Reduced manual labor
• Efficient resource use

3. Smart Irrigation

Smart irrigation automates water supply using soil data and environmental inputs.

Working:

• Sensors monitor soil moisture

• Microcontroller (like Arduino or Raspberry Pi) decides when to water
• Water pump is turned on/off automatically
• Data can be monitored via cloud/mobile apps

Advantages:

• Water conservation
 • Reduced human intervention
• Improves crop health

4. Greenhouse Monitoring and Control

Greenhouse systems maintain controlled conditions for plant growth.

Monitored Parameters:

• Temperature
• Humidity
• Light
• CO₂ levels

IoT Actions:

• Fans, misters, and lights are automatically controlled

• Alerts for abnormal conditions via SMS or app
• Data stored and analyzed over time

Benefits:

• Improved plant growth

• Year-round farming
• Reduced labor cost

SMART HEALTHCARE SYSTEMS

5. Smart Healthcare

Smart Healthcare uses IoT for patient monitoring, diagnostics, and emergency alerts.

Key Features:

• Real-time tracking of heart rate, BP, oxygen levels

• Remote diagnosis by doctors
• Emergency alerts in case of anomalies

Devices Used:

• Wearable health trackers (smartwatches, patches)

• Smart beds and monitoring systems in hospitals
• Cloud platforms for health records

Advantages:

• Early detection of illness

• Remote care for elderly or chronically ill
• Improved hospital efficiency
6. Health and Fitness Monitoring

Wearables and smart fitness devices track body parameters for wellness.

Common Features:

• Step counter (pedometer)

• Heartbeat sensor
• Calorie tracker
• Sleep monitoring

IoT Integration:

• Data synced to mobile or cloud

• Personalized fitness recommendations
• Goal tracking with visual dashboards

Benefits:

• Promotes healthy lifestyle

• Real-time feedback on fitness
• Easy to share reports with healthcare providers

2.Three Levels of Home Automation System with

Applications
1. Introduction

Home Automation refers to the use of IoT and smart devices to automate and control home
functions like lighting, security, and appliances. It enhances comfort, energy efficiency,
safety, and convenience.

Home automation can be classified into three levels:

2. Levels of Home Automation

Level 1: Monitoring

• The system monitors the state of devices or the environment.

• User is notified but cannot take direct control automatically.

Examples:

• Temperature sensor shows room temperature on a mobile app.

• Security camera sends live feed to the user.
Level 2: Control

• The user can remotely control the devices via mobile apps or voice assistants.

Examples:

• Turn ON/OFF lights using a smartphone.

• Adjust AC temperature remotely.

Level 3: Automation / Intelligence

• Devices act automatically based on conditions or schedules.

• Uses AI, timers, sensors, and rules.

Examples:

• Light turns ON when motion is detected.

• Water heater turns ON at 6 AM daily.

3. Applications of Home Automation

A. Smart Lighting System

• Uses motion sensors, LDRs (Light Dependent Resistors), and Wi-Fi modules.
• Lights turn ON when someone enters the room.
• Brightness is adjusted based on ambient light.

Benefits:

• Energy-saving
• Remote operation
• Mood lighting and scheduling

B. Smart Appliances

Appliances like TVs, ACs, refrigerators, washing machines can be connected to the
internet.

Features:

• Controlled via smartphone or voice assistants (Alexa, Google Home)

• Scheduled operation (e.g., coffee machine at 7 AM)
• Alerts for maintenance or errors

Benefits:

• Convenience
 • Remote access
• Efficient energy use

C. Intrusion Detection System

Used for home security. Devices include:

• PIR sensors – detect human movement

• Door/window sensors – trigger when unauthorized access happens
• CCTV/IP cameras – real-time monitoring
• Alarms and SMS/email alerts

Benefits:

• 24/7 home protection

• Real-time intrusion alerts
• Remote surveillance

D. Smoke and Gas Detection

Ensures fire and gas leak safety.

Components:

• Smoke sensors (e.g., MQ-2, MQ-135)

• Gas sensors for detecting LPG, methane, CO
• Buzzers, LEDs, and SMS alerts

Working:

• If gas concentration crosses safe threshold, alarm sounds, and message is sent.

Benefits:

• Prevents accidents
• Real-time alerting
• Ensures home safety
15 MARKS
1.What is Arduino? Explain its Types
1. Introduction to Arduino

Arduino is an open-source electronics platform based on easy-to-use hardware and

software. It consists of a microcontroller (e.g., ATmega328P) and the Arduino IDE for
programming.

Arduino is used in:

• Embedded systems
• IoT projects
• Robotics
• Home automation
• Sensor-based applications

2. Features of Arduino

• Open-source hardware and software

• USB interface for programming
• Multiple digital and analog I/O pins
• Supports C/C++ language
• Compatible with sensors, motors, and modules
• Easily programmable using Arduino IDE

3. Block Diagram of Arduino UNO

4. Types of Arduino Boards

1. Arduino UNO

• Most popular and beginner-friendly

• Uses ATmega328P
• 14 digital I/O pins, 6 analog inputs
• USB and DC power supply

Used in: Basic electronics, sensor interfacing, robotics

2. Arduino Mega 2560

• Advanced board with more I/O

• ATmega2560 microcontroller
• 54 digital I/O, 16 analog inputs
• Suitable for large projects

Used in: 3D printers, complex automation

3. Arduino Nano

• Small and compact

• ATmega328P or ATmega168
• Same features as UNO in mini form

Used in: Wearable tech, mini IoT devices

4. Arduino Leonardo

• Uses ATmega32u4
• Can emulate a keyboard/mouse via USB
• Fewer external components

Used in: HID (Human Interface Device) applications

5. Arduino Due

• Based on ARM Cortex-M3 (32-bit)

• 54 digital pins, 12 analog inputs
• More powerful than ATmega-based boards

Used in: High-speed computing tasks, industrial use

6. Arduino Pro Mini

• Very compact
• No USB port (needs external USB-to-serial)
• Low power consumption
Used in: Embedded low-power applications

7. Arduino Lilypad

• Washable and sewable

• Designed for wearable applications

Used in: E-textiles, smart clothing

2.Explain the Architecture of ZigBee

1. Introduction to ZigBee

ZigBee is a wireless communication protocol based on the IEEE 802.15.4 standard. It is

designed for low power, low data rate, and short-range communication, making it ideal
for IoT and embedded systems such as home automation, industrial control, and smart
agriculture.

2. Features of ZigBee

• Operates at 2.4 GHz (global), 868 MHz (Europe), 915 MHz (USA)
• Low data rate: 20 kbps to 250 kbps
• Low power consumption
• Supports up to 65,000+ nodes in a network
• Range: 10–100 meters
• Mesh, star, and tree topologies supported

3. ZigBee Architecture Overview

The ZigBee architecture consists of four main layers, built on the IEEE 802.15.4 physical
and MAC layers:
4. Layers of ZigBee Architecture

A. Physical (PHY) Layer

• Handles modulation, demodulation, transmission, and reception of data.

• Defines the frequency, bit rate, and modulation scheme.
• Uses O-QPSK (Offset Quadrature Phase Shift Keying) for 2.4 GHz band.

B. MAC (Medium Access Control) Layer

• Controls access to the wireless medium.

• Responsible for frame validation, acknowledgments, and collision avoidance.
• Manages beacon frames in beacon-enabled networks.

C. Network (NWK) Layer

• Handles routing, network formation, joining/leaving of devices.

• Supports star, mesh, and tree topologies.
• Assigns 16-bit network addresses to devices.

D. Application Layer

• Includes Application Support Sublayer (APS), ZigBee Device Objects (ZDO), and
user applications.

▪ Application Support Sublayer (APS)

• Provides interface between NWK and application.

• Manages data formatting, security, and binding.

▪ ZigBee Device Object (ZDO)

• Responsible for device roles, network discovery, and service discovery.

5. ZigBee Device Types

ZigBee has 3 types of devices:

Device Type Description

Coordinator Starts and manages the network. Only one per network.
(ZC)

Router (ZR) Routes data, can allow other devices to join the network.
End Device Limited functionality. Sleeps to save power. Communicates through a
(ZED) router or coordinator.
6. ZigBee Network Topologies

ZigBee supports:

• Star topology
• Tree topology
• Mesh topology (preferred for reliability and scalability)

Mesh topology allows multiple paths for data transmission, improving fault tolerance.

7. Applications of ZigBee

• Home automation (e.g., smart lighting, door locks)

• Smart meters and energy monitoring
• Industrial automation
• Wireless sensor networks
• Healthcare monitoring systems