The I2C Module (commonly called I²C LCD Module) is a small add-on board that allows you to connect an LCD display (like 16x2 or 20x4 character LCDs) to a microcontroller using the I²C (Inter-Integrated Circuit) protocol. Normally, an LCD requires many pins (at least 6 data/control pins), but with the I2C module, you can control the LCD using just 2 pins (SDA & SCL). 🔹 Key Features Based on PCF8574 I/O expander IC. Allows serial communication with the LCD using I²C. Reduces wiring → from 6–8 pins to only 2 pins. Has a potentiometer (blue trimmer) to adjust display contrast. Has a jumper to turn the backlight ON/OFF. Default I²C address: 0x27 or 0x3F (can be changed by soldering address jumpers). Compatible with 5V and 3.3V microcontrollers. 🔹 Pin Configuration GND → Ground. VCC → Power supply (5V typically). SDA → Serial Data (connects to Arduino SDA). SCL → Serial Clock (connects to Arduino SCL). 🔹 How It Works The PCF8574 IC expands the microcontroller’s I²C signals into parallel signals needed for the LCD. Data is sent over the I²C bus (SDA, SCL). The module converts these signals to drive the LCD (RS, RW, EN, D4–D7). This makes it possible to control the LCD using only two pins, while still being able to print text, numbers, and custom characters. 🔹 Applications Arduino/ESP32/Raspberry Pi projects with LCD display. Sensor monitoring systems (temperature, humidity, pressure). DIY electronics, robotics, and automation. IoT projects where fewer pins are available. 🔹 Advantages Saves microcontroller pins. Easier wiring (only 4 wires needed). Adjustable contrast and backlight. Widely supported by Arduino libraries (e.g., LiquidCrystal_I2C). ⚡ Example Wiring with Arduino UNO: VCC → 5V GND → GND SDA → A4 SCL → A5