I2C/IIC/SPI LCD Adapter Module for 1602/2004 Displays PCF8574 Serial Interface for Arduino

PCF8574 I2C / IIC LCD Adapter Module — 1602 & 2004 Display Interface

Reduce your LCD wiring from 12 pins to just 4 (VCC, GND, SDA, SCL) with this PCF8574-based I2C adapter module. Compatible with standard HD44780 1602 and 2004 character LCD displays, it plugs directly onto the LCD's 16-pin header and exposes a standard I2C interface — freeing up GPIO pins on your Arduino, ESP32, STM32, or Raspberry Pi for other peripherals.

Available in 1-piece or 3-piece packs.

Specifications

• IC: PCF8574 / PCF8574T I2C I/O expander
• Supply Voltage: 2.5V – 6V DC
• Interface: I2C (SDA + SCL, 2-wire)
• Default I2C Address: 0x27 (PCF8574) or 0x3F (PCF8574A)
• Address Configuration: A0/A1/A2 solder jumpers — up to 8 modules cascadable on one I2C bus
• Compatible Displays: HD44780 1602 (16×2) and 2004 (20×4) character LCDs
• Backlight Control: Jumper-selectable (insert jumper = backlight ON; remove = backlight OFF)
• Contrast Adjustment: Blue potentiometer (clockwise = increase contrast)
• I2C Connectors: 2 × 4-pin I2C headers (Dupont or dedicated I2C cable compatible)

Wiring (Arduino)

• VCC → 5V
• GND → GND
• SDA → Arduino A4 (Uno) / D20 (Mega) / D21 (Leonardo)
• SCL → Arduino A5 (Uno) / D21 (Mega) / D20 (Leonardo)

Arduino Library

Use the LiquidCrystal_I2C library (Frank de Brabander). Initialize with:

LiquidCrystal_I2C lcd(0x27, 16, 2); for 1602, or LiquidCrystal_I2C lcd(0x27, 20, 4); for 2004.

If address 0x27 doesn’t work, try 0x3F (PCF8574A variant). Use an I2C scanner sketch to confirm your module’s address.

Address Configuration (A0/A1/A2)

Short-circuit A0, A1, or A2 solder pads to change the I2C address. Default (all open) = 0x27. Up to 8 modules can share one I2C bus with unique addresses — useful for multi-display projects.

Contrast & Backlight Adjustment

• Turn the blue potentiometer clockwise to increase contrast (darker characters), counterclockwise to decrease
• If display shows blocks or nothing, adjust contrast first before debugging code
• Backlight jumper: installed = ON, removed = OFF (saves ~20mA)

Typical Applications

• Arduino Uno/Mega/Nano LCD display with minimal GPIO usage
• ESP8266/ESP32 status display (I2C native support)
• STM32 and AVR microcontroller LCD interface
• Multi-display I2C bus with cascaded modules
• Sensor data display, menu systems, and debug output

Package Contents

• 1 or 3 × PCF8574 I2C LCD adapter module (quantity as selected)

Enjoy free standard shipping on all orders over $199 USD. Orders are processed within 1–2 business days.

Not satisfied? Return any item within 90 days of purchase for a full refund or exchange. Items must be in original condition.

We are committed to quality, reliability, and customer satisfaction. Every product is carefully selected and tested to meet the highest standards.