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PCF8574 I2C to 8-Bit I/O Expander

The PCF8574 module is used to expand the input/output (I/O) ports over an I2C connection with 8-bit input/outputs. Use with microcontrollers (Arduino) over the I2C serial interface.

The device features an 8-bit bidirectional I/O port (P0–P7), including latched outputs with high current drive capability for directly driving LEDs. Each bidirectional I/O can be used as an input or output without the use of a data-direction control signal.

Three on-board jumpers allow for the selection of up to 8 I2C addresses, allowing up to 8 modules for 64 I/O pins can be connected to the same I2C interface. The module also features convenient input and output headers at each end so that additional modules can simply be daisy-chained without the need for additional wires.

To use this module with standard Arduino boards, download the HCPCF8574 library and example sketches.


PCF8574 I2C 8-Bit I/O Expander Addressing from


  • 2.5V to 6V VCC operation
  • Low Standby-Current Consumption of 10 μA Max
  • I2C to 8-bit Parallel-Port Expander
  • Open-Drain Interrupt Output
  • Compatible With Most Microcontrollers
  • Latched Outputs With High-Current Drive Capability for Directly Driving LEDs


  • 1 - VCC: 3.3V or 5V power supply
  • 2 - GND: Power Ground
  • 3 - SDA: I2C Data
  • 4 - SCL: I2C Clock

PCF8574 to Arduino UNO Connection

Arduino UNO to PCF8574 Connection and Drivers

Great article with links to Arduino Sketches and Library downloads.


PCF8574 I2C 8-Bit I/O Expander from

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PCF8574 I2C 8-Bit I/O Expander

Arduino Compatible 8 I/O Ports
  • Product Code: PCF8574-I2C-io-Expander
  • Availability: In Stock
  • $3.45 USD

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