This is the PCF8574AP consists of an 8-bit quasi-bidirectional port and an i2C Serial Bus Interface. The PCF8574AP has a low current consumption and includes latched output with HIGH consumption and include latched output with high current drive capability for directly driving LEDS. It also possesses an interrupt which can be connected to the interrupt logic of the Microcontroller, by sending an interrupt signal on this line, the remote I/O can inform the microcontroller if there is incoming data on its ports without having to communicate via the i2C bus. This means that the PCF8574 can remain a simple slave device. This device is useful when you want to extend the IO pins of your Microcontroller using i2C Serial Communication Bus or SPI.

The Integrated PCF8574AP providing 8 ports INPUT / OUTPUT ports that can be manage using i2C serial communication. The following diagram below shows how to wire the PCF8574AP using OUTPUT series of LED served as indicator of our IO pins there are two diagram shows below one is the LED output and the tactile push button switch served as INPUT.

Required Component

  • Arduino Microcontroller, Teensy (TeensyDuino Integrated), ESP8266, STMXX
  • PCF8574AP Chip / PCF8574AP Board
  • Solder Less Bread Board
  • Jumper Wire

Wiring Guide

The first code below will test the circuit allow you to turn off and on a series of  connected LED’s to IO ports.

Source Code for OUTPUT

Source Code for INPUT


Download PCF8574AP Datasheet | PDF

Wiring the PCF8574AP 8bit Bidirectional IO Expander Driven i2C Communication Bus / SPI
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