I2C Backpack – PCF8574 I2C Interface for Character LCDs

The I2C Backpack is a compact module that adds I2C communication to standard character LCDs using the PCF8574 I/O expander. It reduces the numerous parallel connections to just two data lines, simplifying wiring for Arduino, Raspberry Pi, and other microcontrollers. Ideal for projects needing a display with minimal pin usage.

Key Specifications

What You Can Build With This

• Digital clock with temperature display
• System status monitor for IoT devices
• Menu-driven interface for robotics projects
• Portable data logger with screen output

Compatibility

Works with any 5V or 3.3V microcontroller that supports I2C, including Arduino Uno, Nano, Mega, Raspberry Pi, ESP8266, and ESP32. Simply solder the backpack to the LCD's 16-pin header, connect VCC, GND, SDA, and SCL.

Wiring Notes

For Arduino Uno, connect SDA to A4 and SCL to A5. On newer boards with dedicated I2C pins, use those. Ensure pull-up resistors (typically 4.7kΩ) are present on SDA and SCL lines if not built-in. The backpack operates at 5V but is tolerant of 3.3V I2C signals.

Why Buy from Compoden

Every component is sourced from verified suppliers and tested for compatibility before listing. We've spent 10 years building projects for makers, schools, and institutions across India. Ships from Bengaluru in 3-5 days. If defective on arrival, replace within 7 days.