Standard interface that can be expanded in a variety of development boards
I2C Serial port to 8-bit parallel port , support expand into 8×8 = 64 at most
PCF8574 IO expansion chip with I2C interface, 8-bit parallel port output
Applicable to a variety of platforms including Arduino / AVR / ARM
With this module, you can use only 2 ports of your Arduino or Raspberry Pi board to control up to 8 digital I/O ports.