7.5.2 Multi-Master Arbitration Support

The Bidirectional Control Channel in the FPD-Link III devices implements I²C compatible bus arbitration in the proxy I²C master implementation. When sending a data bit, each I₂C master senses the value on the SDA line. If the master is sending a logic 1 but senses a logic 0, the master has lost arbitration. It will stop driving SDA, retrying the transaction when the bus becomes idle. Thus, multiple I²C masters may be implemented in the system.

If the system does require master-slave operation in both directions across the BCC, some method of communication must be used to ensure only one direction of operation occurs at any time. The communication method could include using available read/write registers in the deserializer to allow masters to communicate with each other to pass control between the two masters. An example would be to use register 0x18 or 0x19 in the deserializer as a mailbox register to pass control of the channel from one master to another.