I2C to IO expansion module PCF8574

Discover the versatility of the PCF8574 I2C-to-IO expansion module and expand the capabilities of your projects without being limited by the number of available pins. Perfect for a wide range of applications:

• Membrane Keypad: Simplify the connection of your keypad and read each key via the I2C bus, saving valuable IO pins.
• LCD Displays: Transform displays with many pins, such as 16x2 or 20x4 character screens, for control with only two I2C pins.
• Digital Sensors: Connect digital sensors with a simple output to the PCF8574 and communicate via I2C, eliminating the need for multiple digital IO pins.
• LEDs and LED Strips: Efficiently manage the on/off status of LEDs via I2C, ideal for status indicators or simple visual displays.
• Buttons and Switches: Integrate multiple input elements seamlessly into your project, all read via a single I2C bus, for a tidy and efficient setup.
• Relay Boards: Control power circuits or other devices using the PCF8574, and significantly simplify your wiring diagrams.

The PCF8574 module opens the door to a world of possibilities, allowing you to realize complex projects without the limitations of the number of IO pins. Suitable for both hobbyists and professionals who want to take their projects to the next level.

Features:

• Voltage: 2.5 to 6V DC
• Jumpers allow you to set the I2C address as desired
• Provides 8 additional pins per module, which can function as both input and output pins
• Built-in pull-up resistors for the I2C bus
• Ability to connect up to 8 modules for pin expansion
• The module uses the PCF8574(T) or PCF8574A(T) chip; the "A" variant has a different I2C address

NOTE: For output signals requiring more than 10μA, an external pull-up resistor is necessary. Output signals below this threshold do not require an extra resistor and can deliver up to 25mA, as explained in datasheet sections 10.1 and 13.

Using multiple modules
Connecting more than three modules can result in an insufficiently high I2C pull-up resistance (lower than 333Ω), which can overload the I2C port of the microcontroller. In such cases, we recommend removing the pull-up resistors from the extra modules, so that only three modules are equipped with these resistors. These resistors can be recognized by their marking with the code 102 or 1001.