Anticollision mechanism for an NFC device
An anticollision method for an NFC device wherein, in reader mode, a variation of a piece of information representative of the amplitude of the signal in an antenna of the device is monitored, and if this piece of information exceeds a threshold, the device is switched to the card mode.
1. A method, comprising:
in a reader mode of operation of a near-field communication (NFC) device, monitoring, by the NFC device, a variation of a piece of information representative of an amplitude of a signal in an antenna of the NFC device; and
when the variation of the piece of information exceeds a threshold, switching, by the NFC device, from the reader mode of operation to a card mode of operation.
2. The method of claim 1 wherein said piece of information corresponds to a voltage level received by a demodulator of the device.
3. The method of claim 1 wherein said threshold corresponds to a variation of 30%.
4. The method of claim 1 wherein the monitoring comprises monitoring a variation of an amplitude of an envelope of the signal.
5. A device, comprising:
near-field communication (NFC) control circuitry; and
NFC transmission circuitry coupled to the NFC control circuitry, wherein the NFC control circuitry, in a reader mode of operation,
monitors an indication of an amplitude of a signal in the NFC transmission circuitry;
compares a variation in the indication of the amplitude to a threshold variation; and
when the variation in the indication of the amplitude exceeds the threshold variation, switches from the reader mode of operation to a card mode of operation.
6. The device of claim 5 wherein the NFC transmission circuitry comprises an antenna, an amplifier, a demodulator and a capacitor, and the monitoring comprises monitoring an amplitude of an envelope of a signal detected by the demodulator.
7. The device of claim 5 wherein the threshold variation is a variation of 30 percent.
8. A system, comprising:
one or more nodes, which, in operation, receive and output signals; and
near-field communication (NFC) router circuitry coupled to the one or more nodes, wherein the NFC router circuitry, in a reader mode of operation:
monitors an indication of an amplitude of a signal in the NFC transmission circuitry;
compares a variation in the indication of the amplitude to a threshold variation; and
when the variation in the indication of the amplitude exceeds the threshold variation, switches from the reader mode of operation to a card mode of operation.
9. The system of claim 8 wherein the monitoring comprises monitoring a variation of an amplitude of an envelope of a signal.
10. The system of claim 8 , comprising NFC transmission circuitry coupled to at least one of the one or more nodes.
11. The system of claim 8 , comprising one or more application processors coupled to the NFC router circuitry.