Method for searching a plurality of RFID tags and apparatus
View Patent ↗A method for searching RFID tags and an RFID reader thereof are provided. Each of a plurality of RFID tags awaiting to be accessed has a UID composed of a plurality of bits. The method comprises dividing the plurality of bits of the UID into groups to generate a plurality of groups; selecting a first group and a first value for the first group; obtaining a search result according to a search command and the UIDs of the RFID tags; and analyzing the search result to determine whether at least one RFID tag corresponds to the first group and the first value. Each of the groups has n bits, where n is a positive integer greater than or equal to 1.
1. An RFID reader, for searching a plurality of RFID tags each having an UID composed of a plurality of bits, the RFID reader comprising:
a control unit configured to divide the plurality of bits into a plurality of groups each having n bits, and select a first group from the groups and a first value for the first group, wherein n is a positive integer greater than 1;
a communication protocol processing module, coupled to the control unit, configured to generate a search command according to the first group and the first value, wherein the RFID reader obtains a search result according to the search command and the UIDs of the RFID tags; and
an analyzing module, coupled to the communication protocol processing module and the control unit, configured to generate a control signal to control the control unit of the RFID reader, and further configured to analyze the search result to determine whether at least one RFID tag corresponds to the first group and the first value, the analyzing module further configured to:
generate the control signal having a first value in response to the search result indicating a collision due to more than one response from the RFID tags happens such that, according to the control signal, the control unit selects a group other than the first group from the groups, and
generate the control signal having a second value in response to the search result indicating a response from one of the RFID tags such that, according to the control signal, the control unit selects a value different from the first value for the first group.
2. The RFID reader as claimed in claim 1 , wherein the first group is one group, among the groups, having a most significant bit or a least significant bit of the plurality of bits.
3. The RFID reader as claimed in claim 1 , wherein the first value is in a range from 0 to 2 n −1, and wherein the control unit selects the first value according to a first predetermined sequence so that all values within the range can be selected.
4. The RFID reader as claimed in claim 3 , wherein, when the search result indicates that the collision happens, the analyzing module records the first value when the collision happens and generates the control signal.
5. The RFID reader as claimed in claim 4 , wherein the control unit increments or decrements the first value according to the control signal and the first predetermined sequence, selects a second group from the groups according to the control signal and a second predetermined sequence, and selects a second value for the second group.
6. The RFID reader as claimed in claim 5 , wherein the second value is in a range from 0 to 2 n −1, and wherein the control unit selects the first group and the first value again when the control unit further determines all values for the second value in the range have been selected.
7. The RFID reader as claimed in claim 3 , wherein, when the search result indicates that no reply is generated, the analyzing module generates the control signal having a third value, and wherein the control unit increments or decrements the first value according to the control signal and the first predetermined sequence.
8. The RFID reader as claimed in claim 3 , wherein, when the search result indicates that a reply is generated and no collision happens, the analyzing module records the reply and generates the control signal.
9. The RFID reader as claimed in claim 8 , wherein the control unit increments or decrements the first value according to the control signal and the first predetermined sequence.
10. The RFID reader as claimed in claim 1 , wherein the control unit ends a search procedure when the control unit further determines a value represented by n bits of the first group has been searched.
11. A method for searching a plurality of RFID tags each having a UID composed of a plurality of bits, the method comprising:
dividing, by a control unit of an RFID reader, the bits into a plurality of groups each having n bits, wherein n is a positive integer greater than or equal to 1;
selecting, by the control unit, a first group of the groups and a first value for the first group;
generating, by a communication protocol processing module of the RFID reader, a search command according to the first group and the first value, wherein a search result is obtained according to the search command and UIDs of the RFID tags;
analyzing, by an analyzing module of the RFID reader, the search result to determine whether at least one RFID tag corresponds to the first group and the first value;
generating, by the analyzing module, a control signal to control the control unit of the RFID reader, the control signal having a first value in response to the search result indicating a collision due to more than one response from the RFID tags happens, such that the control unit selects a group other than the first group from the groups; and
generating, by the analyzing module, the control signal to control the control unit of the RFID reader, the control signal having a second value in response to the search result indicating a response from one of the RFID tags, such that the control unit selects a value different from the first value for the first group.
12. The method as claimed in claim 11 , wherein the first group is one group, among the groups, having a most significant bit or a least significant bit of the plurality of bits.
13. The method as claimed in claim 11 , wherein the first value is in a range from 0 to 2 n −1, and wherein selecting the first value comprises selecting the first value according to a first predetermined sequence so that all values within the range can be selected.
14. The method as claimed in claim 13 , further comprising:
when the search result indicates that a collision happens, recording the first value when the collision happens and generating the control signal.
15. The method as claimed in claim 14 , further comprising:
changing the first value according to the control signal and the first predetermined sequence;
selecting a second group of the groups according to the control signal and a second predetermined sequence; and
selecting a second value for the second group.
16. The method as claimed in claim 15 , further comprising:
selecting the first group and the first value again when it is determined the second value has been selected.
17. The method as claimed in claim 13 , further comprising:
generating the control signal having a third value when the search result indicates that no reply is generated; and
changing the first value according to the control signal and the first predetermined sequence.
18. The method as claimed in claim 13 , further comprising:
recording a reply and generating the control signal when the search result indicates that the reply is generated and no collision happens; and
changing the first value according to the control signal and the first predetermined sequence.
19. The method as claimed in claim 11 , further comprising:
ending a search procedure when it is determined a value represented by n bits of the first group has been searched.