The Offline capability allows a Target to become inactive on the I3C Bus at some times, but then return to normal activity later. The Offline capability is now indicated in the Target’s Bus Control Register (BCR).\

There are two basic types of Offline-capable Target:

  1. A Target that is fully inactive on the I3C Bus (e.g., is powered off) and only becomes active again as the result of some external event. Such a Target will then Hot-Join to get a new Dynamic Address.
  2. A Target that is inactive on the I3C Bus, but some portion of the Target is monitoring the Bus for either Target Reset, or the use of the Target’s Dynamic Address. The monitoring portion of the Target retains the Target’s Dynamic Address, even though the Target might be mostly powered-off or in deepest sleep.
    Such Targets can be awakened (i.e., re-activated) by a Target Reset or by the use of their Dynamic Address. They will take some time to become active on the Bus again, such as the RSTACT CCC recovery from Full Reset time. While they are offline, and while awakening, they will not be responsive to the Controller, nor will they record CCCs, nor will they necessarily retain state (e.g., the ENEC/DISEC CCCs); as a result, the Controller will have to wait until such Targets become active, and then might also need to configure them again. This is all by private contract (agreement).

See specification Section 5.1.10.2.5 for details, both in I3C v1.0 (which does not include Target Reset) and in I3C v1.1 (which does include Target Reset).

FAQ Type: 
I3C