MDM331AID/Experiment 5

Experiment: Wi-Fi Connectivity and TCP/IP-Based Sensor Data Transmission Using ESP32

Aim

To configure and implement an IoT device using ESP32 to connect to a Wi-Fi network and transmit temperature and humidity data from a DHT11 sensor to a remote computer using TCP/IP communication.

Objectives

• To understand Wi-Fi connectivity in IoT devices.
• To interface a DHT11 temperature and humidity sensor with ESP32.
• To understand TCP/IP communication and socket programming.
• To establish a TCP connection between an ESP32 and a remote computer.
• To transmit and receive sensor data over a Wi-Fi network.

Components Required

Sr. No.	Component	Quantity
1	ESP32 Development Board (COG-E32)	1
2	DHT11 Temperature and Humidity Sensor (COG-MSBA)	1
3	USB Data Cable	1
4	Patch Cords	As required
5	Computer with Arduino IDE	1
6	Remote Computer connected to the same Wi-Fi network	1
7	Wi-Fi Network	1

Theory

Internet of Things (IoT) Device

An IoT device is a physical device equipped with sensors, processing capabilities, and communication interfaces. It collects data from its surroundings and transmits the information to another device or a remote server.

In this experiment, the ESP32 acts as the IoT device. The DHT11 sensor collects temperature and humidity readings, which are transmitted to a remote computer.

Wi-Fi Connectivity

Wi-Fi is a wireless networking technology based on IEEE 802.11 standards. It allows IoT devices to connect to a local wireless network and exchange information with other devices.

The ESP32 has built-in Wi-Fi connectivity, making it suitable for IoT communication experiments without requiring an additional Wi-Fi module.

TCP/IP Communication

TCP/IP is a protocol suite used for communication between devices over a network.

• IP (Internet Protocol): Provides addressing and routing of data packets between devices.
• TCP (Transmission Control Protocol): Provides reliable, ordered, connection-oriented data delivery.
• Socket: A software interface used by applications to send and receive data over a network.

In this experiment, the remote computer runs a TCP server that listens for incoming connections. The ESP32 acts as a TCP client and sends sensor readings to the server.

The basic communication flow is:

DHT11 Sensor
     |
     v
   ESP32
     |
     v
 Wi-Fi Network
     |
     v
Remote Computer
     |
     v
 TCP Server

DHT11 Sensor

The DHT11 is a digital temperature and humidity sensor. It provides temperature and relative humidity readings through a single digital data interface.

Typical measurement ranges are:

• Temperature: 0 C to 50 C.
• Relative humidity: 20 percent to 90 percent.

The DHT11 is suitable for basic environmental monitoring demonstrations. Its accuracy and measurement range are limited compared with more advanced sensors.

System Architecture

       DHT11 Sensor
            |
            v
     +----------------+
     |     ESP32      |
     |   TCP Client   |
     +----------------+
            |
        Wi-Fi Network
            |
            v
     +----------------+
     | Remote Computer|
     |   TCP Server   |
     +----------------+
            |
            v
      Display Sensor
           Data

Pin Connections

ESP32 Pin	DHT11 Pin	Description
3V3	VCC	Sensor power supply
GPIO 4	DATA	Digital data interface
GND	GND	Common ground

Note: The connections assume a compatible DHT11 module with clearly identified VCC, DATA, and GND pins. Verify the actual sensor-board pinout before making the connections.

Software Requirements

ESP32

• Arduino IDE
• ESP32 board support package
• DHT sensor library
• Wi-Fi library included with the ESP32 board package

Remote Computer

• Python 3
• TCP server program
• Wi-Fi connection
• Network access from the ESP32

Program 1: TCP Server on Remote Computer

The remote computer acts as a TCP server. It listens on port 5000 and displays the temperature and humidity data received from the ESP32.

Download the program:

TCP Server and ESP32 Client Programs ZIP

Program 2: ESP32 TCP Client

The ESP32 connects to the Wi-Fi network, reads the DHT11 sensor values, and sends the readings to the remote computer using TCP.

Download the program:

ESP32 TCP Client Program

Procedure

Step 1: Configure the Remote Computer

1. Connect the remote computer to the Wi-Fi network.
2. Find the local IP address of the remote computer using the appropriate network command.
3. Replace the example IP address in the ESP32 client program with the remote computer's actual IP address.
4. Save the TCP server program as tcp_server.py.
5. Run the server using Python:

<syntaxhighlight lang="bash"> python tcp_server.py </syntaxhighlight>

1. Ensure that the firewall allows incoming TCP connections on port 5000.
2. Keep the TCP server running while testing the ESP32.

Step 2: Configure ESP32

1. Connect the DHT11 sensor to the ESP32 using the specified pin connections.
2. Open Arduino IDE.
3. Install the DHT sensor library if it is not already installed.
4. Enter the Wi-Fi SSID and password in the ESP32 program.
5. Enter the remote computer's IP address in the ESP32 program.
6. Enter the TCP server port number in the ESP32 program.
7. Select the appropriate ESP32 board and COM port.
8. Upload the program.
9. Open the Serial Monitor at 115200 baud.
10. Observe the Wi-Fi connection status.
11. Observe the TCP connection status.
12. Observe the temperature and humidity values being transmitted.

Step 3: Verify TCP/IP Communication

1. Check that the remote computer reports an incoming TCP connection.
2. Observe the temperature and humidity data received by the TCP server.
3. Compare the transmitted values with the sensor readings displayed by the ESP32.
4. Verify that multiple sensor readings are received by the server.
5. Stop the ESP32 program or disconnect the device.
6. Observe the disconnection message on the TCP server.

Observations

Sr. No.	Temperature (C)	Relative Humidity (percent)	Transmission Status
1	Record measured value	Record measured value	Successful / Failed
2	Record measured value	Record measured value	Successful / Failed
3	Record measured value	Record measured value	Successful / Failed

Expected output on the remote computer:

TCP Server started
Waiting for ESP32 connection...
Connected by: ('192.168.1.105', 54321)
Received: Temperature: 28.0 C, Humidity: 65.0 %
Received: Temperature: 28.0 C, Humidity: 64.0 %
Received: Temperature: 29.0 C, Humidity: 64.0 %

The above values and IP addresses are illustrative examples, not actual measurements.

Result

An IoT application was implemented using an ESP32 and DHT11 sensor. The ESP32 successfully connected to a Wi-Fi network and transmitted temperature and humidity readings to a remote computer using TCP/IP socket communication.

Viva Questions

1. What is the role of Wi-Fi in an IoT application?
2. What is TCP?
3. What is the difference between TCP and UDP?
4. What is an IP address?
5. What is a TCP socket?
6. What is the difference between a TCP client and a TCP server?
7. Why is TCP considered a reliable communication protocol?
8. What is the function of the bind() function in Python socket programming?
9. What is the purpose of the listen() function?
10. What is the purpose of the accept() function?
11. What is the function of sendall() in Python?
12. Why should the remote computer's IP address be configured in the ESP32?
13. What is the difference between a local IP address and a public IP address?
14. Why is port 5000 used in this experiment?
15. How can the application be extended to store sensor readings in a database or cloud platform?