While the definition of In-Band Interrupts has not changed in I3C v1.1.1, some of the details of the Pending Read Notification contract (see specification Section 5.1.6.2.2) have been clarified. An I3C Target Device may only queue one active Pending Read Notification (i.e., a single message that will be read with either an SDR Private Read, or an HDR Generic Read) at a time; and it may now send another IBI if the I3C Controller  has not followed up to read the enqueued data for the Pending Read Notification:

  • This IBI may be a reminder, using the same Mandatory Data Byte value that was sent earlier (i.e., it cannot be another MDB value that is also used for Pending Read Notifications).
    • If so, then it is forbidden to use it to indicate that additional Pending Read Notifications are waiting (i.e., that they are active and are enqueued after this notification), and the Controller is not obligated to keep count of these IBIs.
  • Alternatively, this IBI may also indicate an error code or some other condition (i.e., due to delayed read).
    • However, the I3C Target must still keep the data available to read, if it can.
FAQ Type: 
I3C