9.7.5.9 In-Band Interrupt (IBI) Detection and Handling

In-Band Interrupt (IBI) allows I3C target devices to initiate communication with the I3CC. The following types of IBIs are possible on an I3C bus:

• Hot-Join request from a Hot-Join capable target
• In-Band Interrupt request (IBI) from a target
• Controller-role request (CRR) from a Controller-capable target (Secondary Controller)

The I3CC must be enabled to detect (I3CC_SDA low) and receive the In-Band interrupt (IBI ID). The I3CC detects the IBI in the following scenarios:

• Upon detecting low on the I3CC_SDA input port after a Power-On-Reset (POR).
• Upon detecting an arbitration loss during an address phase of any controller-initiated transfer following a START condition (not RESTART).
• Upon detecting the I3CC_SDA input port going (not initiated by the controller) low following a STOP condition (target-initiated IBI).

The following table captures the key controls that are available that determine the response to the target-initiated IBIs and notification to the I3CC application on any rejected IBI (NACK).