Hi Vasek, see ISO/IEC 18092 (or its freely available Ecma version ECMA-340) for a detailed description of the NFC protocol.
During the link activation phase, NFC devices perform an anticollision mechanism. For active mode communication this is done by collision aviodance (i.e. the targets will answer with a random delay and only if there is no other target alredy answering. Thus the target with the shortest random delay will win the anticollision). For passive mode communication there are two strategies: For 106kbps a binary search anticollision is used (all targets will answer synchronously with a pseudo-unique identifier (NFCID1), the initiator will detect bit collisions in the received identifier and re-request only targets that have the colliding bit either set or cleared...). For 212kbps and 424kbps a time slot based anticollision is used (each target will randomly choose one of the available time slots to answer with its NFCID2). After the anticollision the initiator has has a list of targets available for communication. The initiator can choose to either communicate with only one target or even activate multiple targets which can then be addressed through a device ID (DID) field in the NFC Data Exchange Protocol commands. However, current Android implementations usually limit communication to one device (even if the chipset could handle multiple devices). Best regards, Michael -- -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en --- You received this message because you are subscribed to the Google Groups "Android Developers" group. To unsubscribe from this group and stop receiving emails from it, send an email to android-developers+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
