24.4.3.2 Bus Transfers

In I³C, a Controller initiates bus transfers, except for a few special cases such as an in-band interrupt or Hot-Join. Controller-initiated bus transfers always start with the I³C Reserved Address, whose value 7’h7E is ignored by I²C Targets. This makes it possible to detect whether there are any I³C Targets active on the bus, and if so, to then switch to Push-Pull mode for a more efficient transfer.

I³C extends I²C’s basic read and write concepts by adding commands, called Common Command Codes (CCC), which may or may not have an associated data sequence. Immediately following the Reserved address ACK, a CCC is sent, possibly followed by a data sequence.

Different Bus Transfers:

• Broadcast CCC Writes perform a write to all targets that are active on the bus.

  

• Directed CCC Writes perform a write to a single addressed target.

  

• Directed CCC Reads perform a read from a single addressed target.

  

• Private Write transfer if RnW=0, followed by a data sequence sent by the controller, with T=odd parity.

  

• Private Read transfer if RnW=1, followed by a data sequence sent by the target, until T=0 (no more data).