The tutorial assumes you are at least familiar with C-lang-like language. It is not meant to teach anyone how to code in AVR/Arduino from scratch. It's more like a getting started for anyone who has ...

The "PCF8574" chip is an I2C I/O expander that free some of your Arduino pins by controlling them over I2C. The PCF8574 is directly powered by the 5v rail of your arduino and let you control 8 I/O ...

A while ago I received a couple of I/O port expander modules that use the I 2 C protocol. Using that Chinese module, you can use only the SDA and SCL pins of your Arduino, or any microcontroller ...