This post lists links to the Philips Semiconductors I2C-bus Specification, Version 2.1, January 2000 as referenced in Xilinx's AXI IIC Bus Interface v2.0 LogiCORE IP Product Guide Vivado Design Suite PG090 October 5, 2016 and links to the Xilinx LogiCORE product guide. It was written
Note: This post lists a backup location to Version 2.1 of the I2C specification at Berkely not a link to the specification at NXP (which owns Philips).
Links
Philips Semiconductors I2C-bus Specification, Version 2.1, January 2000 [backup link 1][backup link 2]
Xilinx's AXI IIC Bus Interface v2.0 LogiCORE IP Product Guide Vivado Design Suite PG090 October 5, 2016 [link][backup link]
Reference
Image from [link]