Product Description

The PCF8574T I2C I/O Expansion Board is an 8-bit I/O expander module designed to add additional digital input/output ports to microcontroller and development-board projects using the I2C communication interface. It is useful when the available GPIO pins on a controller are insufficient for connecting multiple switches, LEDs, sensors, displays, and other peripherals.

Based on the PCF8574T chip, the module provides 8-bit parallel I/O expansion while requiring only the I2C communication lines from the host controller. Up to 8 PCF8574-based modules can be connected on the same I2C bus when different I2C addresses are configured, providing up to 64 additional I/O ports.

The board features an I2C pin header on one side and an I2C connector on the opposite side, making wiring convenient and supporting I2C cascading between multiple modules. It is suitable for use with platforms such as Arduino and Raspberry Pi.

Features

Based on PCF8574T I/O expander IC
Provides 8-bit parallel I/O expansion
Uses the I2C interface
Up to 8 modules can be connected to the same I2C bus
Supports up to 64 I/O ports using multiple modules
I2C pin header and connector provided on opposite sides
Supports convenient I2C cascading
Reduces the number of GPIO pins required from the host controller
Compatible with Arduino and Raspberry Pi
Suitable for compact embedded and DIY projects

Specifications

Parameter	Specification
Product Type	I2C I/O Expansion Board
Main IC	PCF8574T
I/O Channels	8-bit parallel I/O
Communication Interface	I2C
Maximum Modules on I2C Bus	Up to 8
Maximum Expanded I/O	Up to 64 I/O ports
I2C Connection	Pin header + connector
Cascading	Supported
Compatible Platforms	Arduino, Raspberry Pi and other I2C-capable controllers
Package	1 × PCF8574T I2C I/O Extension Board

Working Principle

The PCF8574T communicates with a microcontroller through the I2C bus, typically requiring only the I2C communication lines. The host controller sends commands through the I2C interface, and the PCF8574T provides access to its 8 digital I/O pins.

This allows a controller with limited GPIO availability to control or read additional digital devices. Multiple compatible boards can be connected to the same I2C bus using different addresses, expanding the available I/O capacity.

I2C Cascading

The board is designed with an I2C pin header and I2C connector on opposite sides. This arrangement makes it convenient to connect multiple boards together.

When multiple PCF8574 modules are used with different valid I2C addresses, up to 8 modules can share the I2C bus, providing up to 64 I/O ports in total.

Applications

The PCF8574T I/O Expansion Board can be used for:

Arduino projects
Raspberry Pi projects
GPIO expansion
LED control
Push-button and switch interfaces
Relay control
Keypad interfaces
Digital sensor interfacing
Display control
Home automation
Robotics projects
Industrial control prototypes
IoT projects
Embedded system development

Package Includes

1 × PCF8574T I2C I/O Extension Board

Product Disclaimer

The module is an I2C digital I/O expansion board and does not function as an analog input expansion board.
The maximum number of modules depends on the available and configurable I2C addresses of the specific PCF8574 variant and board design.
Ensure that the connected devices operate within the electrical limits of the PCF8574T and the development board being used.
Product images are for illustration and representation purposes only. The actual product may slightly differ in appearance, colour, design, or component placement from the images shown due to manufacturing variations and production batches.

FAQs

1. What is the PCF8574T I2C I/O Expansion Board?

The PCF8574T I2C I/O Expansion Board is an 8-bit digital I/O expander that adds additional GPIO ports to a microcontroller through the I2C interface.

2. Which IC is used on this board?

The board is based on the PCF8574T I/O expansion IC.

3. How many I/O ports does one board provide?

One PCF8574T board provides 8 digital I/O ports.

4. What communication interface does the board use?

It uses the I2C communication interface.

5. Can I use this board with Arduino?

Yes. The board can be used with Arduino development boards that support I2C communication.

6. Can I use it with Raspberry Pi?

Yes. It can be connected to a Raspberry Pi through its I2C interface.

7. How many PCF8574 boards can be connected together?

According to the supplied product information, up to 8 PCF8574 boards can be connected to the same I2C bus.

8. How many I/O ports can be obtained using 8 boards?

Eight boards can provide up to 64 I/O ports, subject to the available I2C addresses and the specific board configuration.

9. Does the board support I2C cascading?

Yes. The board is designed to support I2C cascading, allowing multiple compatible modules to be connected to the same I2C bus.

10. Why is GPIO expansion useful?

GPIO expansion is useful when a microcontroller does not have enough available digital pins for all the required switches, LEDs, sensors, relays, displays, or other peripherals.

11. Does the PCF8574T provide analog inputs?

No. The PCF8574T is intended for digital I/O expansion, not analog signal measurement.

12. Can the I/O pins be used as inputs?

Yes. The PCF8574T provides configurable digital I/O functionality that can be used for interfacing with digital input devices.

13. Can the I/O pins be used for output control?

Yes. The expanded I/O ports can be used for suitable digital output applications such as controlling LEDs and other compatible digital devices.

14. How does the board connect to a microcontroller?

The board connects through the I2C bus, using the appropriate I2C communication connections along with the required power connections.

15. What makes the board convenient for cascading?

It has an I2C pin header on one side and an I2C connector on the opposite side, allowing another I2C module to be connected conveniently.

16. Can multiple boards share the same I2C bus?

Yes. Multiple compatible PCF8574 modules can share the same I2C bus when their addresses are configured appropriately.

17. Is this board suitable for robotics?

Yes. It can be used to expand digital I/O for robotics projects, including switches, indicators, control signals, and other digital peripherals.

18. Can it be used for home automation?

Yes. It can be used for expanding digital control and input connections in home automation and IoT projects.

19. Can I use it to control LEDs?

Yes. The expanded digital I/O ports can be used for suitable LED control applications.

20. Can I connect switches or push buttons?

Yes. The digital I/O ports can be used to interface with switches and push buttons.

21. Can it be used with relays?

Yes, it can provide digital control signals for suitable relay interfaces. For higher-current or electrically isolated loads, an appropriate driver circuit or relay module should be used rather than connecting the load directly.

22. Is the board suitable for keypad projects?

Yes. Its multiple digital I/O ports make it useful for interfacing with suitable keypads and button arrays.

23. Does the board require special software?

The host controller needs an appropriate I2C and PCF8574 control library or code to communicate with the board.

24. Is the board suitable for IoT projects?

Yes. It can expand the available digital I/O of controllers used in IoT and automation systems.

25. What is included in the package?

The package includes:

1 × PCF8574T I2C I/O Extension Board

26. Does the package include an Arduino or Raspberry Pi?

No. The package contains only the PCF8574T I2C I/O Expansion Board.

27. Does the board include external sensors or relays?

No. Sensors, relays, LEDs, switches, controllers, and other external components are not included unless specifically stated.

28. What is the main advantage of the PCF8574T board?

Its main advantage is that it allows a microcontroller to obtain additional digital I/O ports using the I2C interface, helping save the controller's native GPIO pins.

29. What projects can use the PCF8574T expansion board?

It can be used in Arduino projects, Raspberry Pi projects, robotics, IoT, home automation, keypad interfaces, LED control, relay control, embedded systems, and prototyping.

30. Is this board suitable for beginners?

Yes. Its simple I2C-based interface makes it useful for electronics learning, prototyping, and beginner microcontroller projects involving GPIO expansion.

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