Normally, once an I3C Target is assigned an I3C Dynamic Address, it will be retained until the Target is de-powered. However, an I3C Target will lose its I3C Dynamic Address as a result of the RSTDAA Broadcast CCC, since this resets all I3C Targets back to their initial state. After RSTDAA, I3C Targets that can also operate on a Legacy I2C Bus (per Q15.2, "Can I3C Devices operate on a Legacy I2C Bus?") would behave as I2C Targets, per the specification at Section 5.1.2.1.1.
Note: The RSTDAA Broadcast CCC is not normally used; it would only be used to assign a new Dynamic Address, or to return I3C Targets to their initial state.
An I3C Target could also lose its Dynamic Address under other circumstances, for example:
- The Device is reset by an out-of-band method, such as a pin-reset
- The Device is reset by a full Target Reset (starting with I3C v1.1) which can be invoked two different ways:
- RSTACT CCC with Defining Byte 0x02, followed by Target Reset Pattern (per the specification at Section 5.1.11.2)
- Two consecutive Target Reset Patterns (per the specification at Section 5.1.11.1)
- The Device goes into deepest-sleep (i.e., power down)
In the case of an I3C Device losing its Dynamic Address in non-standard ways, the Hot-Join mechanism allows the Target to notify the Controller of the event and receive a new Dynamic Address. In cases where the Controller has deliberately caused the Target to lose its Dynamic Address (e.g., by sending the RSTDAA CCC, or by causing a Target reset), the I3C Controller will start a new Dynamic Address Assignment process using the ENTDAA, SETDASA, or SETAASA CCC.
Note: See also Q20.1, "What is Offline, and what does it mean to be Offline Capable?" for Offline Mode for I3C Targets, where the Devices retain their Dynamic Addresses through a power-down or deepest-sleep cycle.