Using multiple libraries together in Arduino - Mini Project: Build & Apply

Using multiple libraries together

📖 Scenario: You are building a simple Arduino project that reads temperature from a sensor and displays it on an LCD screen. To do this, you will use two libraries: one for the temperature sensor and one for the LCD display.

🎯 Goal: Create an Arduino sketch that uses the DHT library to read temperature from a DHT11 sensor and the LiquidCrystal library to show the temperature on an LCD screen.

📋 What You'll Learn

Include the DHT library for the temperature sensor

Include the LiquidCrystal library for the LCD display

Initialize both libraries correctly

Read temperature from the sensor

Display the temperature on the LCD

💡 Why This Matters

🌍 Real World

Many Arduino projects need to use more than one sensor or device at the same time. Knowing how to include and manage multiple libraries is essential for building real-world gadgets.

💼 Career

Embedded systems developers and IoT engineers often combine multiple hardware components and libraries to create functional devices. This skill is foundational for such roles.

1

Include libraries and create objects

Write the code to include the DHT.h and LiquidCrystal.h libraries. Then create a DHT object called dht with pin 2 and type DHT11. Also create a LiquidCrystal object called lcd with pins 12, 11, 5, 4, 3, 2.

Arduino

# Include the DHT and LiquidCrystal libraries

// Your code here

Need a hint?

Use #include to add libraries. Create objects with the exact names dht and lcd using the given pins.

2

Initialize sensor and LCD in setup()

Write the setup() function. Inside it, call dht.begin() to start the sensor. Also call lcd.begin(16, 2) to set the LCD size to 16 columns and 2 rows.

Arduino

#include 
#include 

DHT dht(2, DHT11);
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  // Your code here
}

Need a hint?

Remember to start both the sensor and the LCD inside setup().

3

Read temperature and display on LCD

Write the loop() function. Inside it, read the temperature using dht.readTemperature() and store it in a variable called temp. Then clear the LCD with lcd.clear(). Use lcd.print() to show the text "Temp: " followed by the temperature value and " C".

Arduino

#include 
#include 

DHT dht(2, DHT11);
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  dht.begin();
  lcd.begin(16, 2);
}

void loop() {
  // Your code here
}

Need a hint?

Use dht.readTemperature() to get the temperature. Clear the LCD before printing new text.

4

Display temperature continuously

Add a delay of 2000 milliseconds at the end of loop() to update the temperature every 2 seconds. Then print the temperature on the LCD as before.

Arduino

#include 
#include 

DHT dht(2, DHT11);
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  dht.begin();
  lcd.begin(16, 2);
}

void loop() {
  float temp = dht.readTemperature();
  lcd.clear();
  lcd.print("Temp: ");
  lcd.print(temp);
  lcd.print(" C");
  // Your code here
}

Need a hint?

Use delay(2000); to pause the program for 2 seconds.