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Library and Arduino code for LCD2004 display with I2C

In this tutorial, we will explore how to use the LCD2004 display with I2C communication. This setup allows you to display text across four lines, making it ideal for various applications. We'll cover the required wiring, code snippets, and how to implement the functionality effectively.

We will be using the LiquidCrystal_I2C library to manage the LCD display. This library simplifies the interaction with the LCD by handling the I2C communication for you. For a comprehensive understanding, be sure to check the video for visual guidance (in video at 00:00).

Hardware Explained

The primary component for this project is the LCD2004 display, which features 20 columns and 4 rows for text output. It communicates using I2C, allowing for fewer connections compared to traditional parallel connections. This makes it suitable for projects with limited pin availability on the Arduino.

The I2C interface uses two lines, SDA (data line) and SCL (clock line), which connect to the corresponding pins on the Arduino. The LCD also requires power and ground connections. In this setup, we will connect the display to a 5V power source, which can be provided directly from the Arduino.

Datasheet Details

• Ensure proper power supply to avoid damage.
• Use pull-up resistors on SDA and SCL lines if necessary.
• Check I2C address; commonly 0x27 for this display.
• Keep connections short to minimize interference.
• Confirm that the library is correctly installed before uploading code.

Wiring Instructions

To wire the LCD2004 display with I2C to the Arduino, follow these connections:

• Connect the VCC pin of the LCD to the 5V pin on the Arduino.
• Connect the GND pin of the LCD to a GND pin on the Arduino.
• Connect the SDA pin of the LCD to the A4 pin on the Arduino.
• Connect the SCL pin of the LCD to the A5 pin on the Arduino.

If your Arduino board has different I2C pins, make sure to adjust the connections accordingly. The video also demonstrates an alternative wiring configuration (in video at 01:30).

Code Examples & Walkthrough

Let's look at a simple example of initializing the LCD and displaying a message. The following snippet sets up the LCD and prints "Hello, world!" on the screen.

lcd.begin(); // Initialize the LCD
lcd.backlight(); // Turn on the backlight
lcd.print("Hello, world!"); // Display message

This code initializes the LCD and activates the backlight. Then, it displays the message on the first line of the LCD. The backlight is essential for visibility in low-light conditions.

Next, we will examine a more complex example that displays dynamic data, such as voltage readings.

lcd.setCursor(0,0); // Set cursor to the first line
lcd.print("Voltage: "); // Display voltage label
float v = 8.254; // Example voltage value
lcd.print(v); // Print voltage value

In this excerpt, we set the cursor position to the first line and print a voltage label followed by the actual voltage value. This allows you to display real-time measurements in a user-friendly format.

For additional functionality, you can implement serial input to allow users to enter characters via the serial monitor and display them on the LCD.

if (Serial.available()) { // Check for serial input
  lastChar = Serial.read(); // Read the last character
  lcd.write(lastChar); // Display character on LCD
}

This code checks if there is any data available on the serial port. If so, it reads the last character entered and displays it on the LCD. This interaction enhances the user experience by allowing for dynamic displays based on user input.

For the complete code, please refer to the full program loaded below the article.

Demonstration / What to Expect

When you run the code, you should see the initial message displayed on the LCD, followed by the voltage readings and any characters entered through the serial monitor. Ensure that the connections are secure to avoid any display issues. If the LCD does not show anything, double-check the wiring and the I2C address (in video at 02:15).

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