METHOD AND SYSTEM FOR LOW COST, POWER EFFICIENT, WIRELESS TRANSPONDER DEVICES WITH ENHANCED FUNCTIONALITY

• US 20110248834A1
• Filed: 04/09/2010
• Published: 10/13/2011
• Est. Priority Date: 04/09/2010
• Status: Active Grant

• Current Assignee: Eigent Technologies Incorporated
• Original Assignee: Eigent Technologies Incorporated
• Inventors: Yu, Jin, Zhang, Yuzheng, Waddodagi, Ashok, Winters, Jack, Wang, James, WARNER, Robert
• Granted Patent: US 8,390,433 B2
• Time in Patent Office: Days
• US Class Current: 340/10.34
• CPC Class Codes: H04Q 2209/47 using RFID associated with sensors
• 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

This invention provides a method and system for inventorying wireless transponders, specifically referred to as RFID transceiver devices. The RFID transceiver devices are certifiable by a recognized standards body, such as EPCglobal, or are compatible with recognized standards but have higher functionality than typical passive RFIDs, and yet are implemented with techniques that lower cost and battery requirements. Backscatter techniques of standard passive RFIDs are used to keep cost and battery requirements low. To provide higher functionality, a microcontroller is used in the RFID, along with a battery, but the clock frequency of the microcontroller is adjusted, based on external input, to minimize battery requirements. In one embodiment, the microcontroller initially has a zero or near zero clock frequency. A comparator compares the received RF energy to a threshold, and when the threshold is exceeded, indicating the presence of a probe signal from an RFID reader, the microcontroller clock frequency is immediately increased, and further adjusted based on the received data. In an alternate embodiment, the clock frequency of the microcontroller is adjusted based on data from sensors, to keep the clock speed at the proper speed to adequately process the data while minimizing the power requirement of the microcontroller, and then create an input to modulate the backscattered signal to be transmitted by the RFID. The received data can also cause the microcontroller to request the sensors to generate sensing data at a faster rate, which in turn requires the microcontroller clock to increase to handle the increased sensor data. In an additional embodiment, multiple sensors are multiplexed to provide a single input stream to the microcontroller, reducing the microcontroller clock speed required, along with the overall cost of the microcontroller and sensors.

Claims

1. An RFID transceiver device for transmitting sensor data comprising:

a microcontroller with a clock, said clock having an adjustable speed that is changed by an external input signal,

backscatter circuitry associated with the microcontroller for transmission of a backscattered signal from the microcontroller to an RFID reader, and

a battery to power the microcontroller.

2. The RFID transceiver device of claim 1 wherein the speed of said clock is adjusted by the external input to minimize a power requirement.

3. The RFID transceiver device of claim 2 wherein the power requirement is a battery size.

4. The RFID transceiver device of claim 1 further comprising:

circuitry to instantly increase the speed of said clock from a low speed to a higher speed in response to a probe signal from the RFID reader.

5. The RFID transceiver device of claim 4 wherein said circuitry comprises a comparator and a switch to change the clock speed.

6. The RFID transceiver device of claim 5 further comprising:

a slicer to demodulate a data signal from the RFID reader.

7. The RFID transceiver device of claim 6 further comprising:

a diode circuit to rectify the data signal and charge a capacitor on both a positive and negative swing of the data signal.

8. The RFID transceiver device of claim 7 wherein the comparator and slicer speeds are adjusted for a “

close-to zero”

power standby mode and a wake up time short enough for proper operation of the RFID transceiver device.

9. The RFID transceiver device of claim 6 wherein the slicer and the comparator are one comparator circuit.

10. The RFID transceiver device of claim 6 wherein the slicer uses a reference signal level derived by filtering the level of the external input signal with a resistive and capacitive network.

11. The RFID transceiver device of claim 1 wherein a supply voltage to the microcontroller is adjusted to improve battery life based on the clock speed.

12. The RFID transceiver device of claim 1 further comprising at least one sensor coupled to the microcontroller.

13. The RFID transceiver device of claim 12 further comprising a special purpose logic circuit to handle a receiver function of the RFID transceiver device, while the microcontroller handles operation of the at least one sensor.

14. The RFID transceiver device of claim 13 further comprising a plurality of said sensors wherein the sensors are interfaced to the microcontroller through a multiplexer, said multiplexer being reconfigurable.

15. The RFID transceiver device of claim 1 where the external input signal is generated by a timer.

16. The RFID transceiver device of claim 1 where the external input signal is generated by a signal transmitted by the RFID reader.

17. The RFID transceiver device of claim 12 wherein the at least one sensor is controlled by a timer, with a period for the timer adjustable by a signal transmitted by the RFID reader.

18. The RFID transceiver device of claim 12 wherein data from the at least one sensor is stored by said microcontroller only during a critical condition.

19. The RFID transceiver device of claim 12 wherein data from the at least one sensor is stored at a faster rate during a critical condition.

20. The RFID transceiver device of claim 12 wherein data from the at least one sensor is stored in non-volatile memory of the microcontroller if the battery is at a predetermined low level, and is read later when the battery is at a higher level.

21. The RFID transceiver device of claim 12 wherein data is stored in a volatile memory of the microcontroller and is only saved to the non-volatile memory of the microcontroller when the microcontroller is awakened for other purposes.

22. The RFID transceiver device of claim 12 wherein data from the at least one sensor is time stamped with an initial free running real time clock until time synchronization is achieved, and a difference between the free running clock and synchronized clock is used to modify the timestamp.

23. The RFID transceiver device of claim 1 wherein modulation and demodulation is performed in software in the microcontroller.

24. The RFID transceiver device of claim 1 wherein a special type of the RFID transceiver device is identified by scrambling of an address of a data location or using a false address.

25. An RFID system comprising an RFID reader and an RFID transceiver device, for transmitting sensor data, with the RFID transceiver device comprising:

a microcontroller with a clock, said clock having an adjustable speed that is changed by an external input signal,

backscatter circuitry associated with the microcontroller for transmission of a backscattered signal from the microcontroller to the RFID reader, and

a battery to power the microcontroller.

26. The RFID transceiver device of claim 25 wherein the speed of said clock is adjusted by the external input to minimize a power requirement.

27. The RFID transceiver device of claim 26 wherein the power requirement is a battery size.

28. The RFID transceiver device of claim 25 further comprising:

circuitry to instantly increase the speed of said clock from a low speed to a higher speed in response to a probe signal from the RFID reader.

29. The RFID transceiver device of claim 28 wherein said circuitry comprises a comparator and a switch to change the clock speed.

30. The RFID transceiver device of claim 29 further comprising:

a slicer to demodulate data from the RFID reader.

35. The RFID transceiver device of claim 25 wherein a supply voltage to the microcontroller is adjusted to improve battery life based on the clock speed.

36. The RFID transceiver device of claim 25 further comprising at least one sensor coupled to the microcontroller.

37. The RFID transceiver device of claim 36 further comprising a special purpose logic circuit to handle a receiver function of the RFID transceiver device, while the microcontroller handles operation of the at least one sensor.

38. The RFID transceiver device of claim 37 further comprising a plurality of sensors wherein the sensors are interfaced to the microcontroller through a multiplexer, said multiplexer being reconfigurable.

39. The RFID transceiver device of claim 25 where the external input signal is generated by a timer.

40. The RFID transceiver device of claim 25 where the external input signal is generated by a signal transmitted by the RFID reader.

41. The RFID transceiver device of claim 36 wherein the at least one sensor is controlled by a timer, with a period for the timer adjustable by a signal transmitted by the RFID reader.

42. The RFID transceiver device of claim 36 wherein data from the sensor is stored only during a critical condition.

43. The RFID transceiver device of claim 36 wherein data from the at least one sensor is stored at a faster rate during a critical condition.

44. The RFID transceiver device of claim 36 wherein data from the at least one sensor is stored in non-volatile memory of the microcontroller if the battery is at a predetermined low level, and is read later when the battery is at a higher level.

45. The RFID transceiver device of claim 36 wherein data is stored in a volatile memory of the microcontroller and is only saved to the non-volatile memory of the microcontroller when the microcontroller is awakened for other purposes.

46. The RFID transceiver device of claim 36 wherein data from the at least one sensor is time stamped with an initial free running real time clock until time synchronization is achieved, and a difference between the free running clock and synchronized clock is used to modify the timestamp.

47. The RFID system of claim 25 wherein modulation and demodulation is performed in software in the microcontroller.

48. The RFID system of claim 25 further comprising middleware located in a host device that deals with a lower layer operation of the RFID reader, an on-the-air protocol, and retrieving and writing of data to and from specific locations in a memory of the RFID transceiver device while presenting an application level interface between a user and the RFID reader.

49. The RFID system of claim 25 wherein a special type of the RFID transceiver device is identified by scrambling of an address of a data location or using a false address.

31. The RFID transceiver device of claim 31 further comprising:

a diode circuit to rectify the data signal and charge a capacitor on both a positive and negative swing of the data signal.

32. The RFID transceiver device of claim 31 wherein the comparator and slicer speeds are adjusted for a “

close-to zero”

power standby mode and a wake up time short enough for proper operation of the RFID transceiver device.

33. The RFID transceiver device of claim 31 wherein the slicer and the comparator are one comparator circuit.

34. The RFID transceiver device of claim 31 wherein the slicer uses a reference signal level derived by filtering the level of the external input signal with a resistive and capacitive network.

50. A method for reading data from an RFID transceiver device using an RFID reader, and for transmitting sensor data with the RFID transceiver device comprising the steps of:

providing a microcontroller with a clock and battery to power the microcontroller,

backscattering a signal from the RFID transceiver device with backscatter circuitry, transmitting the backscattered signal to the RFID reader, and

adjusting a speed of the clock using an external input signal.

51. The method of claim 50 wherein the step of:

adjusting the speed of the clock by an external input further includes the step of minimizing a power requirement.

52. The method of claim 50 further comprising the step of:

instantly increasing the speed of the clock from a low speed to a higher speed in response to a probe signal from the RFID reader.

53. The method of claim 52 wherein the speed of the clock is adjusted using a comparator and a switch to change the speed of the clock.

54. The method of claim 53 further comprising the step of:

demodulating data from the RFID reader using a slicer.

55. The method of claim 54 further comprising the step of:

rectifying the data signal with a diode circuit and charging a capacitor on both a positive and negative swing of the data signal.

56. The method of claim 55 further comprising the step of:

adjusting the comparator and slicer speeds for a “

close-to zero”

power standby mode and a wake up time short enough for proper receiver operation of the RFID transceiver device.

57. The method of claim 54 wherein the same comparator circuit is used for the slicer and the comparator.

58. The method of claim 57 further comprising the step of:

filtering the input signal level with a resistive and capacitive network to provide a reference signal level for the slicer.

59. The method of claim 50 further comprising the step of adjusting a supply voltage to the microcontroller to improve battery life based on the clock speed.

60. The method of claim 50 further comprising the step of:

obtaining data from at least one sensor coupled to the microcontroller.

61. The method of claim 60 wherein a special purpose logic circuit is used to handle a receiver function of the RFID transceiver device, while the microcontroller handles operation of the at least one sensor.

62. The method of claim 61 further comprising the step of:

interfacing a plurality of said sensors to the microcontroller through a multiplexer, said multiplexer being reconfigurable.

63. The method of claim 50 further comprising the step of:

generating a timer signal.

64. The method of claim 50 further comprising the step of:

adjusting the clock speed by a signal transmitted by the RFID reader.

65. The method of claim 60 further comprising the step of:

controlling the at least one sensor by a timer, with a period for the timer adjustable by a signal transmitted by the RFID reader.

66. The method of claim 60 further comprising the step of:

storing data from the sensor by said microcontroller only during a critical condition.

67. The method of claim 60 further comprising the step of:

storing data from the sensor at a faster rate during a critical condition.

68. The method of claim 60 further comprising the steps of:

storing data from the sensor in non-volatile memory of the microcontroller if the battery is at a predetermined low level, and reading the data later when the battery is at a higher level.

69. The method of claim 60 further comprising the steps of:

storing data in a volatile memory of the microcontroller and saving the data to the non-volatile memory of the microcontroller when the microcontroller is awakened for other purposes.

70. The method of claim 60 further comprising the step of:

timestamping data from the sensor with an initial free running real time clock until time synchronization is achieved, and using a difference between the free running clock and synchronized clock to modify the timestamp.

71. The method of claim 50 further comprising the step of:

performing software modulation and demodulation in the microcontroller.

72. The method of claim 50 further comprising the steps of using middleware located in a host device to deal with a lower layer operation of the RFID reader, providing an on-the-air protocol, and retrieving and writing of data to and from specific locations in a memory of the RFID transceiver device while presenting an application level interface between a user and the RFID reader.

73. The method of claim 50 further comprising the step of:

identifying a special type of the RFID transceiver device by scrambling of an address of a data location or using a false address.