The PCF8574_LH library provides a simple interface for controlling the PCF8574 I/O expander using the I2C communication protocol. It allows you to read and write values to the PCF8574's registers, ...

So you can connect up to 16 PCF8574 on one I2C bus, giving access to 16 x 8 = 128 IO lines. To maximize IO lines combine 8 x PCF8575 + 8 x PCF8574A giving 128 + 64 = 192 IO lines. Be sure to have a ...