Looking for model PCF8574 IO Expansion Board


PCF8574 IO Expansion Board

PCF8574 IO Expansion Board
PCF8574-IO-Expansion-Board-1.jpg\ 300x225

PCF8574, I2C interface, 8-bit parallel port
Primary Attribute

Category: Modules
Brand: Waveshare

International: Website
Chinese: 官方网站
Onboard Interfaces





The PCF8574 IO Expansion Board is used as a remote 8-bit I/O expander for I2C-bus. Up to 8 PCF8574, IO Expansion Board can be connected to the I2C-bus, providing up to 64 I/O ports.
The PCF8574 IO Expansion Board features an I2C pinheader on one side and an I2C connector on the opposite side. Hence, it’s more flexible to connect the board to your development system. The board also supports I2C cascading, allowing the use of multi modules connected to the I2C bus at the same time by connecting the pinheader and connector.


  • Chip: PCF8574
  • Working voltage: 3.3V/5V
  • IO: 8
  • Interface: I2C


Pin Description
VCC 3.3V/5V
GND Power ground
SDA I2C data input
SCL I2C clock pin

Hardware connection

PCF8574 Raspberry Pi Description
Board order
VCC 5V Power input
GND GND Power ground
SDA 3 I2C data input
SCL 5 I2C clock pin

This should do what you want. There are a few oddities: only the 9 I/O pins appear in pcb (the jumpers and the I2C connections won’t translate in to pcb.) As well it is possible to daisy chain boards like this:

you need to move the rightmost board towards the left most board to make the connection, due to a Fritzing oddity the other direction will not connect.

when that is done the connections in breadboard go green to indicate connection and rats nest lines appear in schematic indicating the connection.

this is the part that you need to download and load in to Fritzing:

pcf8574-io-expansion-board.fzpz (10.1 KB)


Thank you very much for the quick response here it is early morning but tomorrow I calmly do the tests to see how I am doing