### Project 20 How humid & hot is the air

**1.Introduction**

Temperature and humidity is vital to our well beings. In this lesson, we will learn how to measure the temperature and humidity of our surroundings using a DHT11 Temperature and Humidity Sensor and a 1602 LCD.

**2.Hardware required**

- EASY plug controller Board x1
- USB cable x1
- EASY plug cable x2
- EASY plug 1602 I2C Module x1
- EASY plug DHT11 Temperature and Humidity Sensor x1

We will first learn a little about this DHT11 Temperature and Humidity Sensor.

![](media/image-20251126155445687.png)

This DHT11 Temperature and Humidity Sensor features a digital temperature and humidity sensor complex with a calibrated digital signal output. It can detect temperature and humidity of the surroundings. It has excellent quality, fast response, anti-interference ability and high cost performance advantages. Below are its specifications:

- Supply Voltage: +5 V
- Temperature range: 0-50 °C error of ± 2 °C
- Humidity: 20-90% RH ± 5% RH error
- Interface: Digital
- Size: 42*20mm
- Weight: 4g

**3.Connection Diagram**

Now, connect the DHT11 module to the D10 port of the controller board, and LCD module to IIC port using the EASY plug cables.

![](media/image-20251126155545022.png)

**4.Sample Code**

Connect the board to your PC using the USB cable; copy below code into Arduino IDE, and click upload to upload it to your board.

```c
#include <Wire.h>    // Place file “Wire.h” under the directory “library” of Arduino 
#include <LiquidCrystal_I2C.h>  // Place file “LiquidCrystal_I2C.h” under the directory “library” of Arduino
#include <dht11.h>     //Place file “dht11.h” under the directory “library” of Arduino
dht11 DHT;
#define DHT11_PIN 10
LiquidCrystal_I2C lcd(0x27,16,2);  // set the LCD address to 0x27 for a 16 chars and 2 line display 

void setup()
{
  lcd.init();                      // initialize the lcd 
  lcd.init();
  // Print a message to the LCD.
  lcd.backlight();
  lcd.setCursor(0,0);
  lcd.print("Humid(%),Temp(C)");
} 

void loop()
{
  int chk;
  chk = DHT.read(DHT11_PIN);    // READ DATA
  lcd.setCursor(3,1);
  lcd.print(DHT.humidity,1);
  lcd.setCursor(11,1);
  lcd.print(DHT.temperature,1); 
  delay(1000);
}
```

**5.Result**

After power is on, first line of LCD displays “Humid(%),Temp(C)”, second line displays current temperature and humidity. Values will be updated per second.

![](media/image-20251126155943845.png)