ShillehTek PCF8574 I2C serial interface adapter module with chip and blue potentiometer

PCF8574 I2C Serial Interface Adapter Module for 1602 & 2004 LCD Displays

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Convert 16-pin LCDs to a two-wire I2C interface to save microcontroller GPIO pins and streamline wiring; compatible with standard 1602 and 2004 character displays.

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Overview

Product Overview

The PCF8574 I2C Serial Interface Adapter converts the 16‑pin parallel connection of common character displays into a two‑wire I2C interface, letting you drive 1602 (16x2) and 2004 (20x4) modules with just SDA and SCL. Often called an “LCD backpack,” it solders to the display header and includes an onboard potentiometer for easy contrast tuning. Use the A0/A1/A2 solder pads to change the I2C address (default 0x27 or 0x3F) so multiple screens can share one bus, and remove the backlight jumper cap to disable the LED backlight for lower power when needed. Practical for Arduino and other microcontroller projects, this adapter preserves GPIO for sensors and actuators while simplifying wiring and setup; saves I/O pins and makes integration straightforward.

Questions & answers

Frequently asked questions

It is designed for common 1602 16x2 and 2004 20x4 character LCD modules that use a 16-pin parallel interface. It is commonly used with Arduino and other microcontroller projects that support I2C communication.
The adapter solders onto the LCD’s 16-pin header and changes the display connection to I2C, reducing wiring to SDA and SCL plus power. The onboard potentiometer lets you adjust LCD contrast after installation.
This module uses the I2C bus for communication through SDA and SCL. Its PCF8574-based design also provides A0, A1, and A2 solder pads for changing the I2C address when needed.
Use this adapter when a 1602 or 2004 character LCD needs to share a project with sensors, buttons, relays, or actuators. By using I2C instead of many parallel data pins, it preserves GPIO for other parts.
If the LCD powers on but text is faint or missing, adjust the onboard contrast potentiometer first. If using multiple I2C devices, confirm the adapter’s address, which is typically 0x27 or 0x3F and can be changed with A0/A1/A2 pads.

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What's included

Features & Specs

I2C Two-Wire Interface Converts the LCD's 16-pin parallel bus to a simple two-wire I2C connection for SDA and SCL.

GPIO Pin Saver Allows a full 1602 or 2004 character display to be driven using only two microcontroller pins.

1602/2004 Compatibility Designed with standard header pitch to solder directly onto 16x2 and 20x4 character LCD modules.

Onboard Contrast Potentiometer Includes a trim pot for easy, screwdriver-adjustable contrast tuning without extra components.

Address Selection Pads Provides A0/A1/A2 solder pads to change the I2C address for multiple displays on one bus.

Backlight Control Jumper Features a removable jumper to enable software or hardware control of the LCD backlight for power saving.

Compact Backpack Mount Solders to the display rear as an LCD backpack for cleaner wiring and professional-looking projects.

Reference

Documents

Full Product Manual ShillehTek PCF8574 I2C Serial Interface Adapter Module for 1602 2004 LCD | ShillehTek Product Manual In-depth setup guide with wiring, code examples, and troubleshooting.

Datasheet

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