NXP Semiconductors QorIQ LS1012A Reference Manual

On each NYET response, the host controller also checks to determine whether this isthe last complete-split for this split transaction. Last was defined in Periodicinterrupt-do-complete-split . If it is the last complete-split (with a NYET response),then the transfer state of the siTD is not advanced (never received any data) and theActive bit is cleared. No bits are set in the Status field because this is essentially askipped transaction. The transaction translator must have responded to all thescheduled complete-splits with NYETs, meaning that the start-split issued by the hostcontroller was not received. This result should be interpreted by system software as ifthe transaction was completely skipped. The test for whether this is the last completesplit can be performed by XORing C-mask with C-prog-mask. A zero result indicatesthat all complete-splits have been executed.• MDATA (and Last)See above description for testing for Last. This can only occur when there is an errorcondition. Either there has been a babble condition on the full-speed link, whichdelayed the completion of the full-speed transaction, or software set up the S-maskand/or C-masks incorrectly. The host controller must set the XactErr bit and clear theActive bit.• NYET (and not Last)See above description for testing for Last. The complete-split transaction received aNYET response from the transaction translator. Do not update any transfer state(except for C-prog-mask) and stay in this state.• MDATA (and not Last)The transaction translator responds with an MDATA when it has partial data for thesplit transaction. For example, the full-speed transaction data payload spans frommicroframe X to X+1 and during microframe X, the transaction translator respondswith an MDATA and the data accumulated up to the end of microframe X. The hostcontroller advances the transfer state to reflect the number of bytes received.If Test A succeeds, but Test B fails, it means that one or more of the complete-splits havebeen skipped. The host controller sets the Missed Micro-Frame status bit and clears theActive bit.32.6.12.3.6 Complete-split for scheduling boundary cases 2a, 2bBoundary cases 2a and 2b (INs only) (see Figure 32-18) require that the host controlleruse the transaction state context of the previous siTD to finish the split transaction. Thetable below enumerates the transaction state fields.Chapter 32 Universal Serial Bus Interface 2.0QorIQ LS1012A Reference Manual, Rev. 1, 01/2018NXP Semiconductors 2053