Arduino I2C Tutorials
I2C Communication: This Arduino tutorial covers using I2C to communicate with an EEPROM chip. Arduino to Arduino I2C: Using I2C to communicate between two Arduinos.
Posts
Arduino Wire Library for I2C communication
The Wire Library allows developer to communicate with I2C / TWI devices. On the Arduino boards with the R3 layout (1.0 pinout), the SDA (data line) and SCL (clock line) are on the pin headers close to the AREF pin. The Arduino Due has two I2C / TWI interfaces SDA1 and SCL1 are near to the AREF pin and the additional one is on pins 20 and 21. remark: TWI stands for Two Wire Interface and for most marts this bus is identical to I²C. The name TWI was introduced by Atmel and other companies to avoid conflicts with trademark issues related to I²C.
Firmata: a generic communicating protocol between microcontrollers and host computer
Firmata is a generic protocol for communicating with microcontrollers from software on a host computer. It is intended to work with any host computer software package. Right now there is a matching object in a number of languages. It is easy to add objects for other software to use this protocol. Basically, this firmware establishes a protocol for talking to the Arduino from the host software. The aim is to allow people to completely control the Arduino from software on the host computer. Firmata Remark: Currently Firmata library not included in Arduino IDE 1.5.1 yet ... Link: firmata.org Arduino Playground for Firmate