Reference
http://www.wikipedia.org
http://www.cast-inc.com/cores/i2c/index.shtml
http://www.cast-inc.com/cores/i2c-hs/index.shtml
http://www.opencores.org/projects.cgi/web/i2c
http://www.nxp.com/acrobat_download/literature/9398/39340011.pdf
http://www.csie.ntu.edu.tw/~b94048/i2c_overview_2h__1116405506.pdf
