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Tag Memory definition and purpose

Tag Memory definition and purpose. Tag Memory and who defines what. LSB. MSB. User Data. 10 h. 1F h. 00 h. DSFID and/or User Data (TBD). 0F h. (optional). TDTS. HAG TDTS - NSI Bits Semantics. HAG/ PDP Ad Hoc. Memory Bank 01 – UII a/k/a EPC.

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Tag Memory definition and purpose

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  1. Tag Memory definition and purpose

  2. Tag Memory and who defines what LSB MSB User Data 10h 1Fh 00h DSFID and/or User Data (TBD) 0Fh (optional) TDTS HAG TDTS - NSI Bits Semantics HAG/ PDP Ad Hoc

  3. Memory Bank 01 – UII a/k/a EPC • Proposed new PC bit definitions shown in colors x10 x15 x17 x20 x00 x0F x14 x16 x18 x1F Zero fillto thewordboundary UII TagEncoding NSI/AFI CRC-16 Length PC - Protocol Control Checksum UII - Identifier Bit 17 Toggle: “0” – The next 8 bits are Part of NSI and UII is an EPC “1” – The next 8 bits are ISO AFIs Bit 15: User Memory Has Contents Bit 16: XPC – Extended PC bits present

  4. UII Bits • UII memory area is used to store unique object identifier based on TDTS standards. • TDTS standards currently support 64 & 96 bits tags • TDTS standards supports larger size tags for alpha-numeric encoding using SGTIN, GRAI & GIAI • Gen 2 supports up to 512 bits for this memory bank • User programmable • Tags can be filtered using the filter bits. Currently the filter bits are not defined for most identifiers.

  5. UII Bits - continued • One and Many type of assignment for filter bits • Lack of general strategy on filter bits. Filter bits must be defined by GSMP • TDT 1.0 only supports tag data from x20 • Currently cannot support multiple data structures in 512 bits • Need to support larger data structure in the future (Aerospace goes up to 222 bits)

  6. XPC Bits • XPC bits are used to store tag recommissioning information • These bits are sparingly used • Currently, XPC bits indicate that the tag is re-commissioned • Bit 16 of the PC Bits is used to identify the presence of XPC bits • Memory mapped at x210 and back scattered at x20 during singulation • If there are XPC bits, the UII will no longer start at x20 • We need to discuss the impact to TDT – How do we deal with TDT moving forward? • XPC bits allow additional read access at address x210

  7. NSI Bits • NSI are 9 bits and are part of the protocol control bits • Bit x17 determines if bits x18 to x1F are EPC or ISO controlled • Currently if the bit x17 is 0, bits x18 to x1F are all 0s • A process of NSI assignment has been drafted • Parameter to be indicated comes as a result of a vetted user requirement, i.e. from a Requirements Group, • Parameter to be indicated needs to be identified during the inventory round and harm may occur if the identification comes later in the tag reading process, • The request is considered by the TDTS Working Group, who decides whether and when the new assignment will be drafted into a new version of the TDS specification, following the normal EPCglobal Standards Development Process for drafting specifications. Final approval comes as part of the normal process of review and ratification of the entire TDS specification.

  8. HazMat Indicator – Background • NSI bits are there to accommodate the ISO application specific family identifiers, which has a very different purpose • A requirement has been expressed to have a HazMat indicator on tags whether or not they have user memory or extra bits in the TID or Reserved banks (“extra” meaning bits beyond those already assigned a use by the Gen2 spec). This implies that HazMat must be inferable by reading the EPC bank only. • It has also been hypothesized that it is necessary to have the HazMat indicator in the EPC bank for performance reasons (time to read), but the actual performance requirement has not been sufficiently quantified to know whether this hypothesis is true. • Similar discussion happened for filter bits but, it is still not used for filtering at the air interface level. Nevertheless, 35% of the TD-JRG responded that they require HazMat indicator and of which 45% stated that they require notification “right away” (a term not further defined in the survey)

  9. NSI Usage – Example Scenarios • Requirement for indication of HazMat using EPC memory • NSI bit is used to indicate right away application critical information such as HazMat material

  10. NSI Assignment Maintenance Table • This table will be part of the TDTS specification

  11. User Memory • User memory provides the extended memory to store object related information • Memory address space is unlimited • Bit 15 is used to identify the presence of data in user memory • Requires additional read(s) beyond the initial reader singulation to read user memory

  12. TID Memory • TID (Tag ID) memory stores tag and vendor info • sufficient to ID a tag’s optional features/custom commands • There are 2 currently-defined formats for the TID, differentiated via an ISO/IEC 15963 class-identifier 8-bit value (0xE0 or 0xE2): • a 64-bit TID,starting withE0(hex), followed by: • 8-bit Manufacturer ID (As registered in ISO/IEC 7816-6) • 48-bit Tag Serial Number (assigned by Manufacturer) • Must be Factory pre-programmed, Permanently locked • a 32-bit TID,starting withE2(hex), followed by: • 12-bit mask-designer ID (as assigned by GS1) • 12-bit tag model ID (assigned by mask designer) • Optional additional vendor-defined bits (e.g. Serial #) • TDTS WG may define extensions to this format • No current requirement to be pre-programmed or locked

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