I2C is a two-wire, bidirectional serial bus that provides a simple, efficient method of data exchange between devices. It is primarily used in the consumer and telecom market sector and as a board level communications protocol.
The OpenCores I2C Master Core provides an interface between a Wishbone Master and an I2C bus.
It is an easy path to add I2C capabilities to any Wishbone compatible system.

You can find the I2C specifications on Phillips web Site.
Work was originally started by Frédéric Renet. You can find his webpage here.
（Opencore上找到的，供大家参考）

Features

 

• Compatible with Philips I2C bus standard
• Multi-Master Operation
• Software programmable timing
• Clock stretching and wait state generation
• Interrupt or bit-polling driven byte-by-byte data-transfers
• Arbitration lost interrupt, with automatic transfer cancelation
• (Repeated)Start/Stop signal generation/detection
• Bus busy detection
• Supports 7 and 10bit addressing
• Fully static and synchronous design
• Fully synthesisable