DLPU114A August 2024 – November 2024 DLPC8445
When the I2C host requests a data read, the Busy flag (bit 7 in the header byte) indicates the short status. If it is set the controller is busy and does not have a response to send back yet. The host can use the system busy bit as a check for the controller's availability to receive. When this bit is set, the rest of the bits of the response header shall be treated as don't care and no further bytes to be read. The expectation is that the host will keep reading from the controller for a response until this bit is cleared. When that occurs the response header is valid, and the remaining data is as per the command.
If the host abandons a read command midway or sends another command immediately after sending a read command, the response bytes in the controller buffer get discarded and the new command gets processed.
For the USB communication layer, the controller indicates the busy status by NAK response to the read request.