SD Specifications Part 1 UHS-II Simplified Addendum - SD Association

UHS-II Simplified Addendum Version 1.01©Copyright 2010-2013 SD Card AssociationOther application specific layers (**-TRAN) can be defined for future extension.In Chapter 6, the details of CM-TRAN are presented.6.1.1 Packet Types and Format OverviewFigure 6-2 illustrates the Transaction Layer Packet (TLP) types and format overview.CCMDHeaderR/WArgumentI/O AddressPLENPayload(only write CCMD)PLENDCMDHeaderR/WArgumentRsvdTMODEExtended ArgumentData AddressTLENRESHeaderNACKArgumentCMD_ECHO_BACKPayload(only read CCMD)PLENDATAHeaderPayload: Packet Type: Existence depends on transaction typeNotesPLEN : Length of payload field in CCMD or RESTMODE : Transfer mode to represent detailed transfer settingsTLEN : Transfer Length (total length of data transmitted during a transaction)CMD_ECHO_BACK : Argument of the preceding CMD is copiedFigure 6-2 : TLP Format OverviewIn Transaction Layer, four TLP types are defined to realize Legacy SD-compatible protocol and newfunctions of UHS-II native protocol. CCMD (Control CMD): control command packet for accessing to control registers in I/O space DCMD (Data CMD): data command packet for transferring data RES (Response): response packet associated with CCMD or DCMD DATA (Data payload): packet for data transmissionTLP consists of Header, Argument and Payload.Each type of TLP shall have a common "Header". Header includes ID fields for packet identification androuting information. "Argument" is used for setting supplementary information such as data length(PLEN, TLEN), address information (I/O address, data address) and other information exchangedbetween Host and Device (TMODE). Only DCMD has "Extended Argument" for setting more informationabout data length and address. "Payload" is the field for setting data payload to be transmitted.41