Ever wanted to connect more Arduino's to transfer data or commands between them?What purpose? Maybe you don't have enough I/O Pins or Analog In's. Maybe you want to do separate tasks on the same project but still want to communicate between the Arduino's. Or maybe you just need to do a simple thing more complicated. There are many ways to send a command to another Microcontroller:UART - Requires pins 0 and 1. The problem with UART is that only one device can send data to another. And also it's already in use by the USB port of the Arduino to connect to the computer.DIGITAL I/O - Basically put a pin HIGH and read it on the other Arduino. But with this you have alimited number of commands and devices.I2C - I2C Requires Analog Pins 4 and 5 and two pull-up resistors. You can connect more than 100 Arduino's on the same 2 pins. It's simple, reliable and easy-to-use.
Ungeeignet ist der I²C-Bus zur Überbrückung größerer Entfernungen, wie es beispielsweise für Feldbusse typisch ist. Für Übertragungen zwischen verschiedenen Geräten mit getrennten Gehäusen ist der Bus nicht störsicher genug.