ESP32 I2C LCD in Arduino IDE | PCF8574 I2C LCD Module

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	ESP32 I2C LCD in Arduino IDE | PCF8574 I2C LCD Module
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In this tutorial, you’ll learn how to use ESP32 (or ESP8266) with the I2C LCD Display module (PCF8574) in Arduino IDE. We’ll be using the LiquidCrystal_I2C library with I2C Wire.h library in Arduino Core to interface LCD 16×2 display via the I2C bus.

The library APIs are very similar to the standard LiquidCrystal library in Arduino that we’ve used in this previous tutorial. Except for the fact that it does use the I2C bus instead of parallel (4-Bit) data mode. Which does save a lot of GPIO pins and very suitable for many projects.

We’ll be using this a lot in future tutorials, so I hope you can follow and do all the LABs listed below successfully. Without further ado, let’s get right into it!

In this tutorial: 4 LABs

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Requirements For This Tutorial

Prior Knowledge

• ESP32 I2C Communication Tutorial

Software Tools

• Arduino IDE For ESP32 (Setup Guide)

Hardware Components

You can either get the complete course kit for this series of tutorials using the link down below. Or just refer to the table for the exact components to be used in practical LABs for only this specific tutorial.

• Get The ESP32 Full Course Kit (List of components)

I2C LCD Module (PCF8574)

The I2C IO expander IC (PCF8574) is commonly used as a cheap solution to implement an I2C LCD interface that replaces the classic parallel connection to the LCDs (at least 6 pins) with an easy to use I2C bus (only 2 pins).

Moreover, it’s shared with all I2C devices on the bus, so you can still have so many other modules/sensors connected on the same bus. In this previous article, I’ve demonstrated everything about this IC using its datasheet and build a driver library (in Embedded-C) for this IC. You can check it out if you’re interested in learning more about it.

In this section, we’ll only discuss the important things in order to get started with these modules as quickly as possible and control them with ESP32 or ESP8266 boards.

I2C LCD Module Default Address

The default address for the PCF8574 IC as stated in its datasheet is shown in the figure down below. It also shows you that 3 bits of the address are actually controllable by the user. You can solder these solder bridges to change the I2C address of the device.

This will allow multiple I2C LCD modules to be connected on the same I2C bus at the same time which we’ll be doing actually hereafter (in LAB21).

Changing The I2C LCD Module Default Address

As you know, the 3 non-fixed value bits in the address allow us to make 8 different combinations. And potentially be able to use up to 8 different I2C LCD devices on the same bus at the same time.

Here, I’ll solder the A0 bridge which forces the LSB in the address to become 0. Therefore, the I2C device address is now 0x26 instead of the default value 0x27.

Now, I’ve got 2 I2C LCD modules with 2 unique addresses (0x27, 0x26). And those are the two I’ll be using in LAB21 to show you how to use multiple I2C LCDs with ESP32 at the same time. All of this information does apply to any number of modules up to 8 on the same bus.

ESP32 (or ESP8266) LiquidCrystal_I2C LCD in Arduino

In this section, I’ll show you the library we’ll be using (LiquidCrystal_I2C), how to install it in Arduino IDE, how to make the ESP32 to I2C LCD module connections, and what are different API functions available to use in the library.

Installing LiquidCrystal_I2C Library in Arduino IDE

The library we’ll be using is called “LiquidCrysal_I2C”. It can be added manually by visiting GitHub and downloading the files to the Arduino directory. Or just by using the library manager within Arduino IDE itself, and this is what we’ll be doing hereafter.

Open Arduino IDE. Go to Sketch > Include Library > Manage Libraries…

And search for the LiquidCrystal I2C library and hit install. It’ll be automatically installed and added to your default Arduino libraries directory. If, for some reason, it didn’t complete properly. Then, you can try adding it manually after downloading it from GitHub.

ESP32 I2C LCD Module Connection

The connection between ESP32 & I2C LCD module should be as follows. Note that the Wire library by default uses the I2C0 module & its default pins are GPIO21 & GPIO22, as we’ve stated in the previous I2C tutorial.

ESP8266 I2C LCD Module Connection

The connection between ESP8266 NodeMCU & I2C LCD module should be as follows

Using ESP32 LiquidCrystal_I2C Library in Arduino

Here are the exact steps you need to follow in order to use this library in your projects with a line-by-line code explanation.

Step1– Include the Arduino Core I2C wire library + LiquidCrysal I2C library as well

Step2– Define an object of the LiquidCrystal_I2C and pass to it (the I2C device address, Num of cols in LCD, Num of rows in LCD)

Step3– Now, you can initialize the LCD in the setup function and turn ON its backlight LED

Step4– Just write whatever you want to the LCD using the print function as follows

Other Functions (APIs) You Can Use in different projects:

• home() – Return to the home position (0, 0)
• setCursor() – Set the cursor position (x, y)
• cursor() – Show the cursor
• noCursor() – Hide the cursor
• blink() – Make the cursor blink in its location
• noBlink() – Turn OFF cursor blink animation
• display() – Turn ON the display (written text will show up)
• noDisplay() – Turn OFF the display to save power (text remains in memory)
• scrollDisplayLeft() – Shift the entire display to the left by one position (needs to be called repeatedly)
• scrollDisplayRight() – Shift the entire display to the right by one position (needs to be called repeatedly)

Components For This Tutorial’s LABs

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ESP32 LiquidCrystal_I2C LCD Module – Static Text

• Include the libraries
• Define an object of LiquidCrystal_I2C, set its parameters, and initialize the LCD
• Print “Hello World!” at home position
• Set the cursor to the 2nd row & print another string of text

ESP32 I2C LCD Static Text – Arduino Code Example

The code example down below does the following: We start with defining an object of LiquidCrystal_I2C, set its parameters, and initialize the LCD. Then, we’ll print “Hello World!” at the home position. Next, we’ll set the cursor to point at the 2nd row and print another string of text. And that’s all!

The Full code Listing

Choose the board, COM port, hold down the BOOT button, click upload and keep your finger on the BOOT button pressed. When the Arduino IDE starts sending the code, you can release the button and wait for the flashing process to be completed. Now, the ESP32 is flashed with the new firmware.

The connection between ESP32 & I2C LCD module should be as follows.

Here is The Result

ESP32 LiquidCrystal_I2C LCD Module – Scrolling Text

• Include the libraries
• Define an object of LiquidCrystal_I2C, set its parameters, and initialize the LCD
• Write a 2-lines message
• Shift the entire display to the right 7 times, then to the left 7 times, and repeat!

ESP32 I2C LCD Scrolling Text – Arduino Code Example

The Full code Listing

Choose the board, COM port, hold down the BOOT button, click upload and keep your finger on the BOOT button pressed. When the Arduino IDE starts sending the code, you can release the button and wait for the flashing process to be completed. Now, the ESP32 is flashed with the new firmware.

Demo Video For The Result

Click The image to watch the demo video on YouTube

ESP32 LiquidCrystal_I2C LCD Module – Custom Characters

• Include the libraries
• Define an object of LiquidCrystal_I2C, set its parameters, and initialize the LCD
• Create your custom character using any tool (like this online tool)
• Write a string to the LCD and append to it the new character you’ve just created and added

Display Custom Characters – Arduino Code Example

The LCD display’s controller (Hitachi HD44780) supports up to 8 custom characters that you can create and store on the LCD itself. Then you can send the Index of each custom character to be displayed later. Maybe 8 custom characters are not enough for your project, but it’s one little extra feature that you can occasionally use.

The Full code Listing

Choose the board, COM port, hold down the BOOT button, click upload and keep your finger on the BOOT button pressed. When the Arduino IDE starts sending the code, you can release the button and wait for the flashing process to be completed. Now, the ESP32 is flashed with the new firmware.

Here is The Result

ESP32 Multiple I2C LCDs Modules (in Arduino)

• Include the libraries
• Define two objects of LiquidCrystal_I2C, set their parameters, and initialize both LCDs
• Print “Hello LCD-1 !” at the home position on LCD1
• Print “Hello LCD-2 !” at the home position on LCD2

Don’t forget to change the default address for one of the 2 I2C LCD modules as shown earlier in the diagram below (just to recall it).

Connect Multiple I2C LCDs With ESP32 – Arduino Code Example

In this example, we’ll be defining two I2C LCD objects with similar parameters except for the address. The 1st LCD will be @ 0x26 and the 2nd one will be @ 0x27.

We’ll initialize both of them, and write a different message on each LCD to check that addressing is working as it should be. And that’s all about this LAB.

The Full code Listing

Choose the board, COM port, hold down the BOOT button, click upload and keep your finger on the BOOT button pressed. When the Arduino IDE starts sending the code, you can release the button and wait for the flashing process to be completed. Now, the ESP32 is flashed with the new firmware.

Here is The Result

ESP32 I2C LCD Applications

ESP32 I2C LCD module can be used in so many applications as we’ll see in future tutorials. I’ll keep updating this series of tutorials by adding more applications and techniques that may help you in your projects. Drop me a comment if you’ve got any questions or suggestions, I’ll be glad to help!

Related Tutorials Based On ESP32 I2C LCD

• ESP32 I2C Tutorial
• ESP32 LM35 Temperature Sensor
• ESP32 Keypad Interfacing
• ESP32 I2C RTC Interfacing
• And More…

Learn More About I2C LCD Module in Depth

• Build Your Own I2C LCD Library (in Embedded-C)

You can also check the ESP32 Course Home Page ????  for more ESP32 tutorials divided into sections based on categories. This may be helpful for you in case of searching for a specific tutorial or application.

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