Method and Circuit for Accessing RFID Tag

• US 20100073144A1
• Filed: 09/01/2009
• Published: 03/25/2010
• Est. Priority Date: 09/19/2008
• Status: Active Grant

• Current Assignee: Xueshan Technologies Inc. (Wi-LAN Inc.)
• Original Assignee: MStar Semiconductor Incorporated (MediaTek, Inc.)
• Inventors: HUANG, CHIH-HUA
• Granted Patent: US 8,698,600 B2
• Time in Patent Office: Days
• US Class Current: 340/10.400
• CPC Class Codes: H04Q 2209/47 using RFID associated with sensors
• CPC Class Codes: H04Q 2209/75 by polling or interrogating the sub-stations
• CPC Class Codes: H04Q 9/00 Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom

Abstract

A radio frequency identification (RFID) tag access method and a circuit applied to an RFID tag to determine whether to respond to a command sent by a reader are provided. According to the access method, an extra reference value is used for adjusting a parameter or a count value, so as to increase or decrease the probability of generating a condition matching with a command sent by the reader. Therefore, the probability of the tag being accessed is adjusted, and the tag carrying urgent information shall be accessed prior to the tag without urgent information.

Claims

1. A radio frequency identification (RFID) tag access method comprising steps of:

storing a first parameter and a first reference value in an RFID tag;

generating a count range according to the first reference value;

selecting a count value within the count range; and

determining whether the RFID tag responds to a query command sent by a reader according to the count value.

2. The access method as claimed in claim 1 further comprising a step of:

receiving a setting command sent by the reader, wherein the setting command comprises the first reference value.

3. The access method as claimed in claim 2, wherein the setting command further comprises a function enabling parameter for indicating whether the RFID tag uses the first reference value.

4. The access method as claimed in claim 2, wherein the reader sends the setting command before performing the query command.

5. The access method as claimed in claim 2, wherein the step of generating the count range according to the first reference value comprises:

adjusting the first parameter according to the first reference value to generate a second parameter; and

generating the count range according to the second parameter.

6. The access method as claimed in claim 5, wherein the step of adjusting the first parameter according to the first reference value comprises replacing the first parameter with the first reference value.

7. The access method as claimed in claim 5, wherein the step of adjusting the first parameter according to the first reference value comprises calculating the first parameter with the reference value to generate the second parameter wherein the second parameter is smaller than the first parameter.

8. The access method as claimed in claim 1, the step of storing the first parameter and the first reference value in the RFID tag further comprising storing a second reference value which is equal to or greater than 1, the access method further comprising:

subtracting the second reference value from the count value.

9. The access method as claimed in claim 1, wherein the RFID tag is in compliance with a generation 2 specification of an electronic product code operating in ultra high frequency or high frequency.

10. An RFID tag access method, comprising steps of:

storing a parameter and a reference value in an RFID tag, wherein the reference value is equal to or greater than 1;

generating a count range according to the parameter;

selecting a first count value within the count range;

subtracting the reference value from the first count value to generate a second count value; and

determining whether the RFID tag responds to a query command sent by a reader according to the second count value.

11. The access method as claimed in claim 10 further comprising a step of:

receiving a setting command sent by the reader, wherein the setting command comprises the reference value.

12. The access method as claimed in claim 10, wherein the RFID tag is in compliance with a generation 2 specification of an electronic product code operating in ultra high frequency or high frequency.

13. An access circuit, applied to an RFID tag, the circuit comprising:

a memory, for storing a first parameter and a first reference value;

a count value generating circuit, for generating a count range according to the first reference value and the first parameter, and selecting a count value within the count range; and

a controlling circuit, for determining whether the RFID tag responds to a query command sent by a reader according to the count value.

14. The access circuit as claimed in claim 13, wherein the reader sends a setting command having the first reference value to be set into the RFID tag.

15. The access circuit as claimed in claim 14, wherein the setting command further comprises a function enabling parameter for indicating whether the count value generating circuit uses the first reference value.

16. The access circuit as claimed in claim 14, wherein the reader sends the setting command before performing the query command.

17. The access circuit as claimed in claim 13, wherein the count value generating circuit comprises:

an adjusting circuit, for adjusting the first parameter to generate a second parameter according to the first reference value; and

a calculating circuit, for generating the count range according to the second parameter.

18. The access circuit as claimed in claim 17, wherein the adjusting circuit replaces the first parameter with the first reference value.

19. The access circuit as claimed in claim 17, wherein the adjusting circuit calculates the first parameter according to the first reference value to generate the second parameter wherein the second parameter is smaller than the first parameter.

20. The access circuit as claimed in claimed 13, wherein the memory further stores a second reference value which is equal to or greater than 1, and the count value generating circuit subtracts the second reference value from the count value.

21. An access circuit, applied to an RFID tag, the circuit comprising:

a memory, for storing a parameter and a reference value;

a count value generating circuit, for generating a count range according to the parameter, selecting a first count value within the count range, and subtracting the reference value from the first count value to generate a second count value; and

a controlling circuit, for determining whether the RFID tag responds to a command sent by a reader according to the second count value.

22. The circuit as claimed in claim 21, wherein the reader sends a setting command having the reference value to be set into the RFID tag.