Method for Discovering a Plurality of NFC-B Devices by a NFC-B Reader and Corresponding NFC-B Reader

摘要

A discovered NFC-B listen mode device is put to SLEEP state only when there are one or more NFC-B listen mode devices yet to be discovered. An optimal value for the number of time slots indicated in a command is computed based on a combination of whether an empty time slot was detected and/or collision was detected and/or an NFC-B listen mode device was discovered in a discovery cycle. The compliance with the NFC Forum Activity Specification allows the direct activation of an NFC-B listen mode device, and thus speeds up the data transfer phase and consumes much less power.

主权项

1. A method for identifying a plurality of Near Field Communication-type B devices operating in a listen mode (NFC-B listen mode devices) by a Near Field Communication-type B device operating in a poll mode (NFC-B poll mode device) during more than one collision resolution cycles, each collision resolution cycle starting with a first command sent by the NFC-B poll mode device and including a number of time slots less than or equal to a maximum number, a first collision resolution cycle including one time slot, the method comprising:
when the NFC-B poll mode device is to start another collision resolution cycle after a current collision resolution cycle is ended, increasing, by the NFC-B poll mode device, the number of time slots with respect to the number of time slots of the ended current collision resolution cycle if and only if no NFC-B listen mode device has been identified during the ended current collision resolution cycle and no empty time slot has been detected during the ended current collision resolution cycle; and when a NFC-B listen mode device is identified within a time slot of a current collision resolution cycle, sending, by the NFC-B poll mode device to the identified NFC-B listen mode device, a second command for putting the identified NFC-B listen mode device in a sleep state, the second command being sent within a subsequent time slot of the current collision resolution cycle except for the NFC-B listen mode device lastly identified within the last collision resolution cycle.