I3C Address Arbitration

The Address Header following a Start condition (but not a Restart condition) is subject to arbitration, meaning multiple devices on the bus may attempt to drive an address on the bus using SDA lines. The Controller may drive the SDA line to transmit the address of a device it intends to communicate with. The Target may drive the SDA line to transmit its own address while requesting for Hot-Join or In-Band Interrupt. The Address Header Arbitration process is described in Figure 1. The Target loses Address Arbitration when it releases the SDA line to transmit a ‘1’, but another device on the bus drives it low to transmit a ‘0’.

Important: The arbitrable Address Header is usually transmitted in Open-Drain configuration to allow legacy I2C devices on the bus to participate in the arbitration process as well. However, the Controller may transmit some or all parts of the Address Header in Push-Pull configuration to exclude I2C devices from the transaction.
Figure 1. Address Arbitration Process