Harshitha's IOT-001 Level 1 Report

2 / 1 / 2025

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Task 1 - 3D Printer Task

In this task I leart and Understand the working of a 3D printer, STL files, slicing, and printer settings.I have printed a cute Squirrel and I took its STL file from Thingiverse and modified the dimensions based on my requirement using Creality slicer and transferred it to an SD card. Later the SD card was inserted into the 3D printer and it started printing.

Here are some printer settings

1. Nozzle Temperature - 180-220°C
2. Bed Temperature - 55-70°C
3. Layer Cooling - 100%

Task 2 - API

API stands for Application Programming Interface.Initially I learnt about API's and then I created a web weather app using HTML,CSS and Javacript.I used Open weather API to create this application.This task helped me to get familiarise with HTML,CSS and Javacrip.

click the below links for code

['index.html'] ['script.jss'] ['style.css']

Task 3 - Working with Github

GitHub is a developer platform that allows developers to create, store, manage and share their code. As a part of this task, we were supposed to fix an issue in the main file.

1. Forked the repository.
2. Created a new branch.
3. Corrected the error i.e. removed the ‘+1’.
4. Clicked on Commit changes.
5. Generated a pull request.

Task 4 - Getting familiar with the Command line on Ubuntu

learnt how command line on ubuntu works.I created a folder named test and created a blank file and listed that file into the folder.Then created 2600 folders in that folder and concatenated 2 text files containing random text and displayed them as shown below.

Task 5 - Working with Pandas and Matplotlib

I used Python's Matplotlib and Pandas libraries to plot line graphs, bar graphs, and scatter plots for a random dataset.

Task 6 - Create a Portfolio Webpage

I understood the basics of creating a webpage using HTML and CSS and how to make it responsive. Here is the picture of my Portfolio Webpage.

Task 7 - Writing Resource Article using Markdown

I wrote an article on Future of IIOT,using markdown.Markdown made it easier for me to write this article because of its simplicity. Its straightforward syntax and easy-to-use format allow for a clean and organized presentation. This simplicity not only enhances the writing experience but also ensures the content is accessible and visually appealing to readers.

['click here for article']

Task 8 - Tinkercad

I created my account in tinkercad and got familiarized to design circuits.Then I designed a circuit to estimate distance between an obstacle within range and the sensor using an ultrasonic sensor and simulated it and displayed on serial monitor.

Circuit Theory

A radar system using an ultrasonic sensor and servo motor detects objects by emitting sound waves and measuring the echo time to calculate distance. The servo motor rotates the ultrasonic sensor, allowing it to scan a wider area. This setup provides a simple yet effective method for object detection and ranging within a specified area.

['click here for simulation']

Task 9 - Speed Control of DC Motor

The speed of the DC motor can be controlled by varying the input voltage to the motor and the most common method of doing that is by using PWM (Pulse Width Modulation) signal. For controlling the rotation direction, we just need to inverse the direction of the current flow through the motor, and the most common method of doing that is by using an H-Bridge. The L298N is a dual H-Bridge motor driver which allows speed and direction control of two DC motors at the same time. As a part of this task, I used L298N motor driver, Arduino UNO board, potentiometer to control the speed of the DC Motor.

Task 10 - Led Toggle Using ESP32

*The experiment involves controlling an LED connected to an ESP32 microcontroller using a web server. here we learnt about *

1. ESP32 Board: The ESP32 board is a microcontroller that can connect to the internet via Wi-Fi.
2. LED Connection: An LED is connected to one of the GPIO pins on the ESP32 board.
3. Web Server: The ESP32 board hosts a web server that can be accessed using a web browser.
4. HTML Page: When a user accesses the web server, an HTML page is displayed with two links: "ON" and "OFF".
5. LED Control: When the user clicks on the "ON" link, the ESP32 board receives the request and turns on the LED. Similarly, when the user clicks on the "OFF" link, the ESP32 board receives the request and turns off the LED.

Task 11 - 555 IC Multivibrator

The 555 Timer IC is an integrated circuit used in a variety of timer, delay, pulse generation and oscillator applications. Using the 555 Timer IC in Astable mode, a circuit was designed with resistors in 2:1 ratio along with capacitors to get a duty cycle of 58.785%

Task 12 - Karnaugh Maps and Deriving Logic Circuit

I derived the truth table for the given situtaion ,which is given below .Then got to know that it resembeles XOR gate ,derived a K-Map for it and then I designed circuit using XOR gate and buzzer as shown below .The buzzer will activate only when door is open and key pressed or key not pressed and door is close.

['click here for the simulation']

Task 13 - Soldering Prerequisites

*Learnt about soldering ,how to use solder,soldering iron,soldering wick,flux,etc.Even got to know about desoldering using copper wire.I soldered LED to pref board.Then lighted up led using battery.A soldering iron is a hand tool that plugs into a standard 120v AC outlet and heats up in order to melt solder around electrical connections.Solder is a metal alloy material that is melted to create a permanent bond between electrical parts.Soldering flux is mainly used to prepare the metal surfaces before soldering by cleaning and removing any oxides and impurities.To desolder a joint, you will need solder wick which is also known as desoldering braid.

Task 14 - Active Participation

I participated in the "Cyber Intelligence", organised by Entrepreneurship Cell UVCE in association with the UVCE Graduates Association on 9th December, 2024 at University of Visvesvaraya College of Engineering.and we learnt about cyber intelligence and solving cyber threats.

Task 15 - Datasheets Report Writing

Introduction to the MQ-135 Gas Sensor

The MQ-135 gas sensor is widely used in air quality monitoring systems due to its ability to detect various gases, including ammonia (NH3), nitrogen oxides (NOx), alcohol, benzene, smoke, and carbon dioxide (CO2). Its features include a wide detection scope, fast response, high sensitivity, stability, long life, and a simple drive circuit​.

Specifications

1. Circuit Voltage (Vc): 5V ± 0.1V
2. Heating Voltage (Vh): 5V ± 0.1V
3. Load Resistance (RL): Adjustable
4. Operating Temperature: -10°C to 45°C
5. Storage Temperature: -20°C to 70°C
6. Relative Humidity: Less than 95%
7. Oxygen Concentration: Minimum 2% for accurate readings

Structure and Configuration

The MQ-135 sensor comprises an Al2O3 ceramic tube, a SnO2 gas sensing layer, gold (Au) electrodes, platinum (Pt) electrode lines, a Ni-Cr alloy heater coil, and a stainless steel anti-explosion network. It has six pins, four for signal output and two for heating current​(SNS-MQ135)​.

Sensitivity Characteristics

The sensitivity of the MQ-135 sensor varies for different gases and concentrations. Calibration involves adjusting the load resistance (RL) and measuring the sensor resistance (Rs) at specific gas concentrations.

Calibration Procedure

Initial Setup

1. Power Supply: Ensure a stable 5V supply.
2. Preheat Time: Allow the sensor to preheat for at least 24 hours.

Load Resistance (RL) Adjustment

1. Initial RL Value: Set RL to about 20 KΩ.
2. Calibration of Gases: Use known concentrations for calibration (e.g., 100 ppm NH3, 50 ppm alcohol, 100 ppm benzene).

Sensor Resistance Measurement

1. Baseline Measurement (Ro): Measure the sensor resistance in clean air.
2. Gas Exposure (Rs): Expose the sensor to the target gas and measure Rs.

Sensitivity Adjustment

1. Rs/Ro Ratio: Adjust RL to achieve the desired Rs/Ro ratio for specific gas concentrations.
2. Environmental Considerations: Account for temperature and humidity variations during calibration.

Freundlich Absorption Theorem Graph

the Freundlich Absorption Theorem graph is a logarithmic plot of the amount of gas adsorbed (q) against the pressure of the gas (P).

Key Features of the Graph

1. Curved Shape: The graph exhibits a curved shape, indicating that the amount of gas adsorbed increases non-linearly with pressure.
2. Increasing Adsorption: The amount of gas adsorbed increases as the pressure increases, indicating that higher pressures favor adsorption.
3. Saturation Point: At high pressures, the graph may exhibit a saturation point, where the amount of gas adsorbed levels off and no longer increases with pressure.

q = k * P^(1/n)

where:

• q is the amount of gas adsorbed
• k is the Freundlich constant
• P is the pressure of the gas
• n is the Freundlich exponent

For the MQ135 sensor, the Freundlich Absorption graph helps in understanding the adsorption properties of the sensing material and its interaction with different gases.

Application in Calibration

1. Measurement: Expose the sensor to a known gas concentration and measure the baseline sensor resistance (Ro).
2. Gas Exposure: Measure the sensor resistance (Rs) at various concentrations.
3. Adsorption Behavior: Use the Freundlich isotherm to understand adsorption behavior. Adjust (RL) to match the theoretical values predicted by the isotherm.

Typical Sensitivity Curves

NH3 Sensitivity

1. Concentration Range: 10 ppm to 300 ppm
2. Sensor Resistance (Rs): 30 KΩ to 200 KΩ at 100 ppm NH3
3. Sensitivity Slope Rate (α): ≤ 0.65

Alcohol Sensitivity

1. Concentration Range: 10 ppm to 300 ppm

Benzene Sensitivity

1. Concentration Range: 10 ppm to 1000 ppm