Why is “Specification Revision Field” of a “GoodCRC” Message Not Consistent with the Received Message Header? – KBA229728

Version 2

    Author: ShifangZ_26           Version: **

     

    Translation - Japanese: “GoodCRC”メッセージの“Specification Revisionフィールド”が、受信したメッセージヘッダと一致しないのはなぜですか?– KBA229728 - Community Translated (JA)

     

    Question:

    Why is “Specification Revision Field” of a “GoodCRC” message not consistent with the received Message Header?

     

    Answer:

    The “GOODCRC” message of the “Specification Revision Field” follows the below definition from the USB-PD 3.0 Specification. The details are documented in the USB-PD 3.0 Version 1.2 Specification as follows:

     

    The 2-bit Specification Revision field of a GoodCRC Message does not carry any meaning and Shall be considered as don’t care by the recipient of the Message. The sender of a GoodCRC Message Shall set the Specification Revision field to 01b when responding to a Message that contains 01b in the Specification Revision field of the Message Header. The sender of a GoodCRC Message May set the Specification Revision field to 00b or 01b or 10b when responding to a Message that contains 10b in the Specification Revision field of the Message Header.

     

    Since it is clearly documented in the USB-PD 3.0 specification that the GoodCRC message does not carry any meaning, the GoodCRC message may or may not be consistent with the message header. Since this message is also supposed to be disregarded by the recipient, end customers should not treat such inconsistency as a CCGx firmware issue.