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NFC Digital Protocol - CWI

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Type 4B Tag PlatformThe least significant nibble (b4 to b1) of Byte 1 contains the returned DID.Requirements 161: DID in ATTRIB ResponsePoll Mode12.6.2.1 The <strong>NFC</strong> Forum Device MUSTbe ready to receive a DID fieldwith 0 or the same value as sentbefore in the DID field of theATTRIB Command.The <strong>NFC</strong> Forum Device MAY treat a DIDfield with a different value as <strong>Protocol</strong> Error.Listen Mode12.6.2.2 The <strong>NFC</strong> Forum Device MUSTset the DID in the ATTRIBResponse to the same value asreceived in the DID field of thepreceding ATTRIB Command.If the DID is not supported by the<strong>NFC</strong> Forum Device, it MUST setthe DID to 0.NOTEA valid answer (same DID and valid CRC_B) to an ATTRIB command is the waythat an <strong>NFC</strong> Forum Device in Poll Mode verifies that the <strong>NFC</strong> Forum Device inListen Mode has been selected successfully.• The most significant nibble (b8 to b5) of Byte 1 codes the Maximum Buffer Length Index(MBLI). It is used by the <strong>NFC</strong> Forum Device in Listen Mode to inform the <strong>NFC</strong> ForumDevice in Poll Mode about its Maximum Buffer Length (MBL) to receive chained frames.The coding of MBLI is:• MBLI = 0 means that the <strong>NFC</strong> Forum Device in Listen Mode provides no informationabout its internal input buffer size.• MBLI > 0 is used to calculate the actual internal maximum buffer length (MBL)calculated with the following formula:MBL = FSC x 2 MBLI-1• The Higher layer – Response field includes the answer to the higher layer Command includedin the Higher layer – INF field of the ATTRIB Command.Requirements 162: Higher Layer – ResponsePoll Mode12.6.2.3 The <strong>NFC</strong> Forum Device MUST beready to receive an ATTRIBResponse with or without a Higher– layer INF field in response to anATTRIB Command with Higher –layer INF field.Listen Mode12.6.2.4 The <strong>NFC</strong> Forum Device MUSTrespond with an empty Higherlayer – Response to an ATTRIBCommand without Higher layer –INF field.The <strong>NFC</strong> Forum Device MAY respond with aHigher layer – Response to an ATTRIBCommand with Higher layer – INF field.The <strong>NFC</strong> Forum Device MAY also respondwith an empty Higher layer – Response to anATTRIB Command with Higher layer – INFfield, indicating that the Higher layerCommand is not supported.<strong>NFC</strong> <strong>Digital</strong> <strong>Protocol</strong> Page 126

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