Temperature and humidity sensors

Team Member

Chen Andi、Chen Miaoge、Chen Yingnan、Fang Ye

Background

With the advancement of smart home systems, agricultural monitoring, and industrial environmental control, real-time monitoring of ambient temperature and humidity has become increasingly important. Variations in temperature and humidity significantly impact human daily activities, industrial production, and the storage conditions of various products. Traditional temperature and humidity measurement instruments are often expensive or lack real-time data display capabilities. Therefore, designing a low-cost, real-time temperature and humidity monitoring system based on the DHT11 sensor and Arduino holds significant practical and educational value.

Objective

The objective of this project is to design and implement a real-time temperature and humidity monitoring system based on Arduino and the DHT11 sensor, capable of continuously acquiring environmental temperature and humidity data and displaying the results on an LCD1602 screen in an intuitive manner. The system is designed to fulfill the following functions:

• Real-time Data Acquisition: Accurately measures the current ambient temperature and humidity.
• Dynamic Data Display: Continuously updates the LCD screen to reflect the latest measurement data.
• Low Cost and High Scalability: Suitable for various applications such as smart home systems, agriculture, and warehouse environments, with potential extensions to wireless data transmission and other advanced functionalities.

Equipment Required

• DHT11
• Electronic display
• Arduino
• DuPont Line
• battery-9V

Experiment Steps

Circuit Connection

1.DHT11 Connection

• VCC (DHT11) → 5V (Arduino UNO)

The VCC pin of the sensor is connected to the 5V power supply pin on the Arduino to provide power.

• GND (DHT11) → GND (Arduino UNO)

The ground pin of the sensor is connected to the ground pin on the Arduino.

• OUT (DHT11) → Digital Pin 8 (Arduino UNO)

The data output pin of the DHT11 is connected to digital pin 8 on the Arduino for reading sensor data.

2.Power Connection

Connect the 9V battery to the Arduino power socket via the battery clip.

DHT11 Sensor Connected to Arduino UNO

Programming and Uploading Code

1.Installing Libraries

• In Arduino IDE, install the DHT Sensor Library by Adafruit and LiquidCrystal_I2C libraries.

2.Writing Code (Code details omitted)

• Include necessary libraries (DHT).
• Define the DHT11 sensor pin and type.
• In the loop() function, read temperature and humidity data and serial monitor.

3.Uploading Code

• Connect Arduino to the computer via USB cable.
• Select the correct board model and port.

 #include "DHT.h"
 #define DHTPIN 8       // Pin where the sensor is connected
 #define DHTTYPE DHT11  // Sensor type
 DHT dht(DHTPIN, DHTTYPE);
 void setup() {
 Serial.begin(9600); // Initialize the serial monitor
 dht.begin();        // Initialize the sensor
 }
 void loop() {
 float humidity = dht.readHumidity();            // Read humidity
 float temperatureC = dht.readTemperature();     // Temperature in Celsius
 float temperatureF = dht.readTemperature(true); // Temperature in Fahrenheit
 float temperatureK = temperatureC + 273.15;     // Temperature in Kelvin
 if (isnan(humidity) || isnan(temperatureC)) {
   Serial.println("Error reading data!");
   return;
 }
 // Output data to the serial monitor
 Serial.print("Temperature: ");
 Serial.print(temperatureC);
 Serial.print("°C, ");
 Serial.print(temperatureF);
 Serial.print("°F, ");
 Serial.print(temperatureK);
 Serial.println("K");
 Serial.print("Humidity: ");
 Serial.print(humidity);
 Serial.println("%");
 delay(2000); // Delay between readings
 }

Experiment Operation

Disconnect USB Power and Connect 9V Battery.

Observe Temperature and Humidity Data on the Display and Serial Monitor.

References

BU Y, LUO X, CHEN Y. Temperature and Humidity Acquisition System Based on Sensor DHT11[J]. Computer and Modernization, 2013, 1(11): 133.