Arduino Hardware I2C for AVR MCUs (plain c)  1.3
Arduino Hardware I2C for AVR MCUs (plain c) documentation
Data Structures
Here are the data structures with brief descriptions:
 CcfgCi2c slave parameters
 CcfgCi2c bus parameters
 Ci2cStatic ci2c bus config and control parameters
 CStructI2CSlaveCi2c slave config and control parameters