SMBus specifications and example implementation on Silabs’ C8051F3xx and C8051F41x. App note here(PDF)
This application note describes the SMBus specification, how to configure and use the on-chip SMBus interface, and SMBus debugging techniques. Code examples written in C provide the general framework for most SM Bus Master and Slave implementations. An example that interfaces to a 256-byte EEPROM over a two-wire interface and supports multi-byte transfers is also included at the end of this note.