Wemos Mini and I2C LCD example

Sometimes a nice big LCD is useful for your projects, in this example we will interface to an I2C LCD using our ESP32. Now these I2C LCD’s consist of 2 parts usually an HD44780 16×2 LCD and an I2C backpack which connects to the LCD exposing the standard power and I2C pins.

This is a typical module you can buy, you can see the backpack which is obviously on the back of the LCD

We will now look at the connections and a simple layout

Layout

Connect the pins as follows:

Remember the backpack and lcd connections are already made for you

Code

You will need an updated I2C LCD library, the original one I couldn’t get to work but this one does seem to work – LiquidCrystal_I2C-master

You will need to import this into the IDE as usual

Now my example below required the I2C address to be changed to 0x3F, a lot of the example I have looked at are 0x27

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x3F,16,2); // set the LCD address to 0x3F 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("Hello world");
lcd.setCursor(1,0);
lcd.print("ESP32 I2C LCD");

}

void loop()
{
}

All going well you should see the messages in the code on your LCD display

Link

You can pick up one these modules for under $3

1pcs Blue Display IIC/I2C/TWI/SPI Serial Interface 1602 16X2 LCD Module