I2C controller core from Opencores.org
Verilog VHDL C Tcl
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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.


  • 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


  • Revision 0.8 of the WISHBONE I2C Master Core specifications are available here. – Also see the FAQ page.


Check the FAQ page for information regarding Philips I2C/SMBus licensing information.


  • Design is available in VHDL and Verilog from OpenCores SVN via this link

Synthesis results

Push-button synthesis results for various targets.


  • A54SX16ATQ100-std: 352Modules@58MHz


  • FLEX: EPF10K50ETC144-3: 294LCELLs@82MHz
  • ACEX: EPF20K30ETC144-3: 257ATOMs@74MHz


  • Spartan-II: 2S15CS144-5: 229LUTs@82MHz
  • Virtex-E: XCV50ECS144-8: 230LUTs@118MHz


- CATC “Computer Access Technology Corporation is a user and supporter of the OpenCores I2C Soft IP Core”