Radio frequency data communications device

A radio frequency identification device including a single integrated circuit having a microprocessor, a transmitter, a receiver, and circuitry configured to periodically switch from a sleep mode to a receiver-on mode and to perform tests to determine whether to further switch to a microprocessor-on mode, in which more power is consumed than in the receiver-on mode, because a valid radio frequency signal is present, the circuitry being configured to count transitions in the received signal to determine when the number of transitions within a predetermined time period fall within a predetermined range and then to determine when chip lock has occurred and then, when chip lock has occurred, to determine when frequency lock has occurred and then switch to a microprocessor-on mode, the circuitry being further configured to return to the sleep mode when counting transitions in the received signal determines that the number of transitions within a predetermined time period does not fall within the predetermined range, to return to the sleep mode when chip lock has not occurred in another predetermined time period, to return to the sleep mode when frequency lock has not occurred in yet another predetermined time period and to selectively disable the periodic switching from the sleep mode for a predetermined amount of time in response to a radio frequency command, wherein the selective disabling cannot be cancelled by a subsequent radio frequency command, the selective disabling comprising setting a countdown timer, the length of the predetermined amount of time being a variable amount and being selectable from a number of predetermined selectable amounts of time via a radio frequency command.

A method of operating a radio frequency identification device comprising:

• providing a receiver wake-up signal after a timer interval has elapsed, the timer interval being programmable by RF command from a remote interrogator to a user selectable value;
• asserting a bias control signal in response to the receiver wake-up signal to turn on a master receiver bias to provide electrical power to a radio receiver;
• determining when a radio frequency signal is being received by the radio receiver;
• determining when a first number of spread spectrum transitions of the radio frequency signal falls within a predetermined first range of numbers and occurs during a first predetermined interval;
• determining when a second number of spread spectrum transitions of the radio frequency signal falls within a predetermined second range of numbers and occurs during a second predetermined interval;
• and
• providing a microprocessor wake-up signal to a microprocessor that is co-integrated in a single integrated circuit with the radio receiver circuit when the first number of transitions occurs during the first predetermined interval and the second number of transitions occurs during the second predetermined interval.

A method of operating a radio frequency identification device comprising:

• determining, in a wake-up controller circuit, that a timer interval has elapsed, while the radio frequency identification device is in a sleep mode requiring a first power level;
• providing, when the predetermined interval has elapsed, a receiver wake-up signal to set the radio frequency identification device to a receiver-on mode requiring a second power level greater than the first power level;
• determining, when testing determines that the master receiver bias is present, when a radio frequency signal is being received by the radio receiver;
• enabling a master receiver bias when the radio frequency signal is present to set the radio frequency identification device to a test mode requiring a third power level greater than the second power level, the master receiver bias providing electrical power to a radio receiver, a clock and data recovery circuit and a voltage controlled oscillator;
• initiating the voltage controlled oscillator to oscillate at a first frequency;
• determining, by the wake-up controller, when a first number of spread spectrum transitions of the radio frequency signal occurs during a first predetermined interval;
• determining, by the wake-up controller, when a second number of spread spectrum transitions of the radio frequency signal occurs during a second predetermined interval;
• determining, during an interval of predetermined length, presence or absence of voltage controlled oscillator signal acquisition from the radio frequency signal by the clock and data recovery circuit;
• and
• providing a microprocessor wake-up signal from the wake-up controller to a microprocessor that is co-integrated in a single integrated circuit with the radio receiver circuit and the wake-up controller when the first number of transitions occurs during the first predetermined interval and the second number of transitions occurs during the second predetermined interval, the microprocessor wake-up signal setting the radio frequency identification device to a processor-on mode requiring a fourth power level that is greater than the third power level.

A radio frequency identification device comprising:

• a radio receiver having an output;
• a wake-up timer circuit providing a receiver wake-up signal to the radio receiver at predetermined intervals to change a state of the radio frequency identification device from a sleep mode requiring a first power level to a second mode requiring a second power level greater than the first power level;
• a radio frequency signal detection circuit having an input coupled to the radio receiver output, the radio frequency signal detection circuit setting the radio frequency detection device to a third mode requiring more power than the second mode when a radio frequency circuit is detected;
• a wake-up controller circuit having an input coupled to the radio receiver output, the wake-up controller circuit first testing the radio frequency signal to determine when a first number of spread spectrum transitions of the radio frequency signal occurs during a first predetermined interval, the wake-up controller circuit then testing the radio frequency signal to determine when a second number of spread spectrum transitions of the radio frequency signal occurs during a second predetermined interval;
• a clock and data recovery circuit including a phase-locked loop, the clock and data recovery circuit having an input coupled to the radio receiver output, the clock and data recovery circuit determining, during an interval of predetermined length, presence or absence of voltage controlled oscillator signal acquisition from the radio frequency signal;
• and
• a microprocessor having a data input coupled to the radio receiver output and a control input coupled to the wake-up controller circuit, the wake-up controller circuit providing a microprocessor wake-up signal to the microprocessor when the first number of transitions occurs during the first predetermined interval, the second number of transitions occurs during the second predetermined interval and the wake-up controller determines presence of voltage controlled oscillator signal acquisition from the radio frequency signal, the microprocessor wake-up signal setting the radio frequency identification device to a processor-on mode requiring a fourth power level that is greater than the third power level.

A radio frequency identification device comprising:

• a radio receiver having an output and a control input;
• a microprocessor having a data input coupled to the radio receiver output and having a control input;
• a timer having an output coupled to the control input of the radio receiver, the timer providing an output signal to the radio receiver control input changing a state of the identification device from a sleep mode requiring a first power level to a second mode by turning the radio receiver in the identification device on in response to a first criterion, the radio receiver requiring a second power level greater than the first power level, the timer being programmable by RF command from a remote interrogator to a user selectable value;
• and
• a wake-up controller circuit including an output coupled to the microprocessor control input, the wake-up controller circuit changing the state of the identification device from the second mode to a third mode when a second criterion is met, the third mode requiring a third power level greater than the second power level, the wake up controller circuit providing an output signal to the microprocessor control input changing the state of the identification device from the third mode to a fourth mode when a third criterion is met, the fourth mode requiring a fourth power level greater than the third mode.

A radio frequency communications device including an integrated circuit comprising:

• a transmitter;
• a receiver;
• a circuit configured to periodically check if a radio frequency signal is being received by the receiver;
• a timer configured to set a time period for the checking, the timer having a frequency locked loop;
• a current controlled oscillator forming a part of the frequency locked loop, the frequency locked loop being configured to recover a clock frequency from the received signal to provide a recovered clock signal when the circuit determines that a signal is being received and to supply the recovered clock signal to the transmitter;
• a variable value divider coupled to the output of the frequency locked loop, the value of the divider being programmable to a user selectable value in response to a radio frequency signal received by the receiver so as to program the time period of the checking, wherein the device is configured to receive and process commands from an interrogator transmitting a radio frequency signal and to enable the frequency locked loop only during processing of a command to calibrate the timer to a clock frequency recovered from a received command, the integrated circuit being configured to switch between a sleep mode, a receiver-on power mode in which more power is consumed than in the sleep mode and in which the checking takes place, and a microprocessor-on power mode in which more power is consumed than in the receiver-on power mode.

A method for conserving power in a radio frequency identification device defined by a single integrated circuit including a microprocessor and receiver, the method comprising:

• periodically switching the single integrated circuit from a sleep mode to a receiver-on mode based on a timer interval that is programmable by RF command from a remote interrogator to a user selectable value and performing the following tests to determine whether to further switch to a microprocessor-on mode, in which more power is consumed than in the receiver-on mode, because a valid radio frequency signal is present:
• (a) determining if any radio frequency signal is present and, if so, proceeding to step (b);
• (b) determining if the radio frequency signal is modulated and has a predetermined number of transitions per a first predetermined period of time and, if so, proceeding to step (c);
• and
• (c) determining if the modulated radio frequency signal has a predetermined number of transitions per a second predetermined period of time different from the first predetermined time, and, if so, switching from the receiver-on mode to the microprocessor-on mode.