Method of using write—ok flag for radio frequency (RF) transponders (RF Tags)

• US 6,288,629 B1
• Filed: 05/23/1997
• Issued: 09/11/2001
• Est. Priority Date: 05/23/1997
• Status: Expired due to Term

• Current Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Original Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Inventors: Goldman, Kenneth Alan, Friedman, Daniel Joseph, Heinrich, Harley Kent, Cofino, Thomas Anthony
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Beaulieu, Yonel
• Application Number:
  US08/862,913
• Time in Patent Office: 1,572 Days
• Field of Search: 340/825.54, 340/505, 340/568, 340/572, 340/573, 342/41, 342/42, 342/50, 342/51
• US Class Current: 340/10.1
• CPC Class Codes: G06K 19/0707 the arrangement being capable of collecting energy from external energy sources, e.g. thermocouples, vibration, electromagnetic radiation G06K19/0702 takes precedence
• CPC Class Codes: G06K 19/0712 the arrangement being capable of triggering distinct operating modes or functions dependent on the strength of an energy or interrogation field in the proximity of the record carrier active means for hindering electromagnetic reading or writing G06K19/07336
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G11C 16/225 Preventing erasure, programming or reading when power supply voltages are outside the required ranges
• CPC Class Codes: G11C 5/142 Contactless power supplies, e.g. RF, induction, or IR

Abstract

A method of sending data from a base station to a passive RF tag and writing the data to a tag non-volatile memory which detects a “partial write”, where the tag voltage falls during the write process under the voltage sufficient to reliably write the tag non-volatile memory, is presented. The tag voltage is compared to a stable reference voltage during the time the tag memory is being written, and if the tag voltage falls below an acceptable level, a flag in the tag non-volatile memory is cleared.

Claims

1. A method of writing data to a passive RF tag non-volatile memory, comprising;

a) writing a signal to a tag volatile memory, the signal indicative that a tag supply voltage is sufficient to write the data to the tag non-volatile memory, the signal written before the data is written to the tag non-volatile memory;

then

b) changing the signal if the tag voltage becomes insufficient to write the data to the tag non-volatile memory during the time that the data is written to the tag non-volatile memory, wherein the signal is also changed to indicate that the tag voltage was insufficient each time that tag powers up from a state where the tag voltage was insufficient to run the tag electronics.

2. The method of claim 1, further comprising;

c) communicating the signal from the tag to a base station.

3. The method of claim 1, further comprising;

c) sending a command from a base station to the tag to verify the data; and

d) sending the data from the tag to the base station only if the tag supply voltage was sufficient to write the data to the tag non-volatile memory during the time that the data was being written to the tag non-volatile memory.

4. The method of claim 1, further comprising;

c) sending a command from a base station to the tag to verify the data;

d) resending the data from the base station to the tag; and

e) communicating from the tag to the base station if the tag supply voltage was insufficient to write the data to the tag non-volatile memory during the time that the data was being written to the tag non-volatile memory.

5. The method of claim 1, wherein the data written to the tag non-volatile memory is a lock status of data contained in the tag non-volatile memory, further comprising;

c) sending a command from a base station to the tag to query the lock status of the data contained in the tag non-volatile memory;

d) sending a status signal from the tag to the base station detailing whether the tag supply voltage was insufficient to write the data to the tag non-volatile memory at any time during the time that the lock status was being written to the tag non-volatile memory.

6. The method of claim 1, further comprising;

c) changing the signal that the tag supply voltage is sufficient to write the data to the tag non-volatile memory, the signal changed when the tag first powers up.

7. A method of writing data to a passive RF tag non-volatile memory, comprising;

a) comparing a defined percentage of a tag supply voltage to a stable reference voltage during the time that the data is being written to the tag non-volatile memory; and

b) recording whether the defined percentage of the tag supply voltage is less than the stable reference voltage at any time during the time that the data is being written to the tag non-volatile memory.

8. The method of claim 7, further comprising;

c) communicating the record produced in step b) from the tag to a base station.

9. The method of claim 7, further comprising;

c) sending a command from a base station to the tag to verify the data; and

d) sending the data from the tag to the base station only if the defined percentage of the tag supply voltage was never less than the stable reference voltage during the entire time that the data was being written to the tag non-volatile memory.

10. The method of claim 7, where the stable reference voltage is generated by a bandgap voltage generator.

11. The method of claim 7, further comprising;

c) sending a command from a base station to the tag to verify the data;

d) resending the data from the base station to the tag; and

e) communicating from the tag to the base station if the defined percentage of the tag supply voltage was less than the tag reference voltage at any time during the time that the data was being written to the tag non-volatile memory.

12. The method of claim 7, wherein the data written to the tag non-volatile memory is a lock status of data contained in the tag non-volatile memory, further comprising;

c) sending a command from a base station to the tag to query the lock status of the data contained in the tag non-volatile memory;

d) sending a signal from the tag to the base station with information whether the defined percentage of the tag supply voltage was less than the stable reference voltage at any timne during the time that the lock status was written to the tag non-volatile memory.

13. The method of claim 7, further comprising;

recording that the defined percentage of the tag supply voltage is less than the stable reference voltage when the tag first powers up.

14. The method of claim 7, where the stable reference voltage is provided by a bandgap voltage generator.

15. The method of claim 7, where the stable reference voltage is provided by a diode drop circuit.

16. The method of claim 7, where the stable reference voltage is provided by an n-channel FET threshold voltage circuit.

17. The method of claim 7, where the stable reference voltage is provided by an n-mirror voltage source.

18. The method of claim 7, where the stable reference voltage is provided by the voltage controlling a voltage controlled oscillator, the oscillation frequency of the voltage controlled oscillator compared with a frequency standard.

19. A method of writing data to an RF tag memory, comprising:

a) generating a signal indicative that a tag supply voltage is sufficient to write the data to the tag memory;

then

b) changing the signal if the tag voltage becomes insufficient to write the data to the tag memory during the time that the data is written to the tag memory, wherein the signal is also changed to indicate that the tag voltage was insufficient each time that tag powers up from a state where the tag voltage was insufficient to run the tag electronics.

20. The method of claim 19, further comprising:

c) communicating the signal from the tag to a base station.

21. The method of claim 19, further comprising:

c) sending a command from a base station to the tag to verify the data; and

d) sending the data from the tag to the base station only if the tag supply voltage was sufficient to write the data to the tag memory during the time that the data was being written to the tag memory.

22. The method of claim 19, further comprising:

c) sending a command from a base station to the tag to verify the data;

d) resending the data from the base station to the tag; and

e) communicating from the tag to the base station if the tag supply voltage was insufficient to write tke data to the tag memory during the time that the data was being written to the tag memory.

23. The method of claim 19, wherein the data written to the tag memory further comprises a lock status of data contained in the tag memory, the method further comprising:

c) sending a command from a base station to the tag to query the lock status of the data contained in the tag memory;

d) sending a status signal from the tag to the base station detailing whether the tag supply voltage was insufficient to write the data to the tag memory at any time during the time that the lock status was being written to the tag memory.

24. The method of claim 19, further comprising:

c) changing the signal that the tag supply voltage is sufficient to write the data to the tag memory, the signal changed when the tag first powers up.

25. A method of writing data to a passive RF tag memory, comprising:

a) comparing a defined percentage of a tag supply voltage to a stable reference voltage during the time that the data is being written to the tag memory; and

b) recording whether the defined percentage of the tag supply voltage is less than the stable reference voltage at any time during the time that the data is being written to the tag memory.

26. The method of claim 25, further comprising:

c) communicating the record produced in step b) from the tag to a base station.

27. The method of claim 25, further comprising:

c) sending a command from a base station to the tag to verify the data; and

d) sending the data from the tag to the base station only if the defined percentage of the tag supply voltage was never less than the stable reference voltage during the entire time that the data was being written to the tag memolry.

28. The method of claim 25, wherein the stable reference voltage is generated by a bandgap voltage generator.

29. The method of claim 25, further, comprising:

c) sending a command from a base station to the tag to verify the data;

d) resending the data from the base station to the tag; and

e) communicating from the tag to the base station if the defined percentage of the tag supply voltage was less than the tag reference voltage at any time during the time that the data was being written to the tag memory.

30. The method of claim 25, wherein the data written to the tag memory further comprises a lock status of data contained in the tag memory, the method further comprising:

c) sending a command from a base station to the tag to query the lock status of the data contained in the tag memory;

d) sending a signal from the tag to the base station with information whether the defined percentage of the tag supply voltage was less than the stable reference voltage at any time during the time that the lock status was written to the tag memory.

31. The method of claim 25, further comprising:

c) recording that the defined percentage of the tag supply voltage is less than the stable reference voltage when the tag first powers up.

32. The method of claim 25, wherein the stable reference voltage is provided by a diode drop circuit.

33. The method of claim 25, wherein the stable reference voltage is provided by an n-channel FET threshold voltage circuit.

34. The method of claim 25, wherein the stable reference voltage is provided by an n-mirror voltage source.

35. The method of claim 25, wherein the stable reference voltage is provided by the voltage controlling a voltage controlled oscillator, the oscillation frequency of the voltage controlled oscillator compared with a frequency standard.

36. A method of sending data from a base station to a radio frequency (RF) transponder (RF tag), the RF tag having a memory including a first memory portion and a second memory portion, the second memory portion including an “

intention to write to memory”

field, comprising;

a) writing information in the second memory portion;

then

b) writing the data to the first memory portion;

then

c) checking whether the data was successfully written to the first memory portion; and

then

d) clearing the information from the second memory portion after successful writing the data to the first memory portion.

37. The method of claim 36, wherein the information written in the second memory portion comprises a single bit.

38. An RF tag, comprising:

a first tag memory for holding data written to the tag;

a second tag memory comprising an “

intention to write to memory field”

, wherein the “

intention to write to memory field”

is written before the data is written to the first tag memory, and wherein the “

intention to write to memory field”

is cleared after successfully writing the data to the first tag memory.

39. The RF tag of claim 38, wherein the seeond tag memory comprises a single bit.