I2C_LCD is an easy-to-use display module, It can make display easier. Using it can reduce the difficulty of make, so that makers can focus on the core of the work.

We developed the Arduino library for I2C_LCD, user just need a few lines of the code can achieve complex graphics and text display features. It can replace the serial monitor of Arduino in some place, you can get running informations without a computer.

More than that, we also develop the dedicated picture data convert software (bitmap converter)now is available to support PC platform of windows, Linux, Mac OS. Through the bitmap convert software you can get your favorite picture displayed on I2C_LCD, without the need for complex programming.

Features

Only 2 Arduino pins are occupied (Use I2C interface).

Supports standard I2C mode (100Kbit/s) and fast I2C mode (400Kbit/s).

Compatible with multiple communication logic levels: 2.8~5VDC.

Arduino library supported, use a line of code to complete the display.

Integrate 7 sizes of ASCll fonts, 5 graphics functions.

Provide dedicated picture data convert software (Bitmap Converter).

Most of the complex operation is processed by I2C_LCD independent controller, saving user controller resources.

Supports cursor function, can set up 16 cursor flicker frequency.

Supports 128 level backlight lightness adjustment.

Support 64 level screen contrast adjustment.

Support device address modification.

Supports 127 I2C_LCD work in parallel.

When debugging code, it can take the place of the serial monitor to monitor the program running state.

Two abnormal recovery methods are provided: reset and restore the factory settings.

Compatible with Grove interface and 4Pin-100mil interface (under the Grove socket).

4 symmetrical fixed hole design for easy user installation.

China style unique appearance.

Platforms Supported

Interface Function

Getting Started

Step 1: Install the latest version of Arduino IDE to your computer.

Step 2: Download and install the I2C_LCD library to Arduino IDE:

Open Arduino IDE, click Sketch -> Include library -> Add .ZIP library.

Find and select the I2C_LCD.zip file you just downloaded.

Restart the Arduino IDE.

Step 3: Chose the example project which you like. (Take "HelloWorld" project for example here.)

Click File > Examples > I2C_LCD > HelloWorld

Step 4: Connect I2C_LCD to your Seeeduino Vx board with Grove cable. Then connect Seeeduino Vx board to your computer.

Step 5: Select your board and serial port.

Select the board: Click Tools > Board > "Arduino Duemilanove or Diecimila"(Seeeduino V3.0 Or early version), "Arduino Uno"(Seeeduino Lotus or Seeeduino V4.0).

Select the COM: Click Tools -> Serial Port -> COMX(which connected with your board.)

Step 6: Upload the program and enjoy yourself!

I2C_LCD is an easy-to-use display module, It can make display easier. Using it can reduce the difficulty of make, so that makers can focus on the core of the work. We developed the Arduino library for I2C_LCD, user just need a few lines of the code can achieve complex graphics and text display features.

I2C LCD Hardware Overview

A typical I2C LCD display consists of a HD44780 based character LCD display and an I2C LCD adapter. Let’s get to know them one by one.

Character LCD Display

True to its name, these LCDs are ideal for displaying text/characters only. A 16×2 character LCD, for example, has an LED backlight and can display 32 ASCII characters in two rows with 16 characters on each row.

Why I2C (IIC) Type LCD?

If you plan to add a simple readable interface in your next project. alphanumeric LCD may be the most preferred one due to various factors such as low cost, easily programmable, having no limitation of displaying special & even custom characters.

But to use it directly with a microcontroller, you would need atleast 6 pins – RS, EN, D7, D6, D5, and D4 (with R/W pin permanently grounded for write operation). When you are engaged in a complex project bundled with large number of modules, you may face pin shortage for your microcontroller. In such situations, I2C LCD comes handy making use of only 2 pins (SDA & SCL) to talk to MCU, thereby saving atleast 4 pins. If you already have I2C devices, this LCD module actually uses no more pins at all.

Before moving further, lets see how an LCD can be controlled by I2C. In the image shown above, you can see a backpack module fitted to the back of the LCD. He does the work using an I/O expander PCF8574, that communicates with the micro-controller by I2C.

Remote 8-bit I/O expander PCF8574

The PCF8574 provides general purpose remote I/O expansion for most microcontroller families via the two-line bidirectional bus (I2C-bus). The device consists of an 8-bit quasi-bidirectional port and an I2C-bus interface.

A quasi-bidirectional I/O can be used as an input or output without the use of a control signal for data direction. The PCF8574 has a low current consumption and includes latched outputs with high current drive capability. It also possesses an interrupt line (INT) which can be connected to the interrupt logic of the microcontroller. By sending an interrupt signal on this line, the remote I/O can inform the microcontroller if there is incoming data on its ports without having to communicate via the I2C-bus. This means that the PCF8574 can remain a simple slave device.

I2C LCD Backpack

You can use this with LCD modules that have a HD44780-compatible interface with various screen sizes. The key is that your LCD must have the interface pads in a single row of sixteen, so it matches the pins on the backpack.

As shown in the above image, the backpack has 4 pins namely GND, Vcc, SDA and SCL.

Besides, the backpack has the following key features

LED jumper should be in position to turn on the back-light.

The blue potentiometer on the backpack bord adjusts contrast. Adjust it to a position where the characters are bright and the background does not have boxes behind the characters.

The three hardware address pins A0, A1 and A2 allow eight devices to be on the same I2C-bus. You can change the address of the device according to the status of each of these pins. The default address of the device is 0X3F (with PCF8574AT).

Note that backpack modules centered around PCF8574/PCF8574T (SO16 package of PCF8574 in DIP16 package) have a default slave address of 0×27. For those with PCF8574A/PCF8574AT chip, the default slave address will change to 0x3F. 

Once all the necessary connections are made, you can communicate with LCD using I2C.

Interfacing with Arduino

On Arduino UNO board, SDA (data line) is on analog pin 4, and SCL (clock line) is on analog pin 5. On the newer Arduino UNO (“R3″ layout), the SCL and SDA pins are available as separate pins. If you are using a different board, ensure that you connect the SDA and SCL pins. Power the board with 5V. The interfacing diagram is shown below.

You can get library from here. Add the library to your Arduino folder. We used the library NewliquidCrystal_1.3.4

Note: If you are using an Arduino board that works in 3.3V level, you need to use a level converter to communicate with the backpack.

Sample code for 16×2 LCD is given below. Upload the sketch to your Arduino board and you can see the LCD working. For 20×4 LCD, use the commented setup and comment the current setup.

/*  Sample Code for 16x2 / 20x4 character I2C LCD                                  

  Upon powering, the given strings get displayed on the LCD. Then you can open the

  Serial monitor and type in any characters to display */

#include <Wire.h>                // Comes with Arduino IDE                                

#include <LiquidCrystal_I2C.h>

                                  // Initialize the object with interfacing pins

LiquidCrystal_I2C lcd(0x3F, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);

void setup()

{

 Serial.begin(9600);            // Initialize serial communication at 9600 baudrate

 lcd.begin(16,2);               // Initialize 20X4 LCD and turn on backlight

 lcd.backlight();

 lcd.setCursor(0,0);            // Set cursor to column 1, line 1

 lcd.write(" 16x2 character ");

 lcd.setCursor(0,1);            // Set cursor to column 1, line 2

 lcd.write("    I2C LCD   ");

 delay(2000);                   // Display for sometime

 lcd.noBacklight();             // Turn off backlight

 delay(2000);                   // Turn on backlight again after sometime

 lcd.backlight();           

 lcd.clear();                   // Clear the display

 lcd.setCursor(0,0);

 lcd.write("Use Serial Mon");

 lcd.setCursor(0,1);

 lcd.write("Type to display"); 

}

/*  Use this setup for 20x4 character LCD

void setup()                            // Setup - Runs once

{

  Serial.begin(9600);                  // Initialize serial communication at 9600 baudrate

  lcd.begin(20,4);                      // Initialize 20X4 LCD and turn on backlight

  lcd.backlight();

  lcd.setCursor(0,0);                  // Set cursor to column 1, line 1

  lcd.write("  20x4 character  ");

  lcd.setCursor(0,1);                  // Set cursor to column 1, line 2

  lcd.write("      I2C LCD      ");

  lcd.setCursor(0,2);                  // Set cursor to column 1, line 3

  lcd.write(" Use Serial Monitor ");

  lcd.setCursor(0,3);                  // Set cursor to column 1, line 4

  lcd.write("  Type to display  ");    

}

*/

void loop()                            // Setup - Runs continuously

{

  if(Serial.available())                // True if any character has arrived

  {

    lcd.clear();                        // Clear the display

    while (Serial.available() > 0)

    {

      lcd.write(Serial.read());        // Display all the characters on LCD

    }

  }

}