Circuit device, electronic device, communication system, and vehicle electronic key system
A circuit device is used in an electronic device including a receiver, a control circuit that performs processing on reception data received by the receiver using a clock signal, a transmitter that transmits transmission data generated by performing processing based on the reception data by the control circuit. The circuit device includes a time-to-digital conversion circuit that measures a time difference between a transition timing of a start signal based on the reception data and a transition timing of a stop signal based on the transmission data or the clock signal, and an output interface that outputs, to the control circuit, a measurement result of the time difference of the time-to-digital conversion circuit.
1. A circuit device used in an electronic device including a receiver, a control circuit that performs processing on reception data received by the receiver using a clock signal, a transmitter that transmits transmission data generated by performing processing based on the reception data by the control circuit, the circuit device comprising:
a time-to-digital conversion circuit that measures a time difference between a transition timing of a start signal based on the reception data and a transition timing of a stop signal based on the transmission data or the clock signal; and
an output interface that outputs, to the control circuit, a measurement result of the time difference of the time-to-digital conversion circuit,
wherein the time-to-digital conversion circuit measures the time difference between the transition timing of the start signal and the transition timing of the stop signal which chances at a transition timing of the clock signal.
2. The circuit device according to claim 1 , further comprising:
a clock signal generation circuit that generates the clock signal using a resonator and outputs the clock signal to the control circuit.
3. The circuit device according to claim 2 , wherein
the time-to-digital conversion circuit measures the time difference using the clock signal generated by the clock signal generation circuit.
4. The circuit device according to claim 1 , wherein
the control circuit outputs the start signal based on the reception data, and
the time-to-digital conversion circuit measures the time difference based on the start signal output from the control circuit.
5. The circuit device according to claim 4 , wherein
the control circuit outputs the stop signal when the processing of the reception data is completed, and
the time-to-digital conversion circuit measures the time difference based on the stop signal output from the control circuit.
6. The circuit device according to claim 1 , wherein
the control circuit performs counting processing of counting, by the clock signal, a processing time of the processing performed based on the reception data, and outputs, to the transmitter, the transmission data including a count value obtained through the counting processing and the measurement result of the time difference.
7. The circuit device according to claim 1 , further comprising:
a transmission circuit provided in the transmitter.
8. The circuit device according to claim 7 , wherein
the transmission circuit includes
a carrier signal generation circuit that generates a carrier signal of the transmission data based on the clock signal, and
a power amplifier that amplifies the carrier signal.
9. The circuit device according to claim 1 , wherein
the processing performed by the control circuit is encryption processing based on the reception data.
10. The circuit device according to claim 1 , wherein
the receiver is a device that receives the reception data by wireless communication, and
the transmitter is a device that transmits the transmission data by wireless communication.
11. An electronic device comprising:
the circuit device according to claim 1 ;
the control circuit;
the receiver; and
the transmitter.
12. The electronic device according to claim 11 , wherein
the control circuit obtains information on a processing time to complete the processing after receiving the reception data based on the measurement result of the time difference, and
the transmitter transmits the transmission data including the information on the processing time.
13. A communication system comprising:
the electronic device according to claim 11 ; and
a host device that transmits the reception data received by the electronic device to the electronic device, and receives, from the electronic device, the transmission data from the electronic device.
14. A circuit device used in a vehicle electronic key including a receiver, a control circuit that performs processing on reception data received by the receiver using a clock signal, a transmitter that transmits transmission data generated by performing processing based on the reception data by the control circuit, the circuit device comprising:
a time-to-digital conversion circuit that measures a time difference between a transition timing of a start signal based on the reception data and a transition timing of a stop signal based on the transmission data or the clock signal; and
an output interface that outputs, to the control circuit, a measurement result of the time difference of the time-to-digital conversion circuit,
wherein the time-to-digital conversion circuit measures the time difference between the transition timing of the start signal and the transition timing of the stop signal which changes at a transition timing of the clock signal.
15. A vehicle electronic key system comprising:
a vehicle electronic key including the circuit device according to claim 14 ; and
an in-vehicle device that transmits the reception data to the vehicle electronic key and receives the transmission data from the vehicle electronic key, wherein
the control circuit generates the transmission data based on the measurement result from the output interface, and
the in-vehicle device detects that wireless communication between the vehicle electronic key and the in-vehicle device is not directly performed based on the transmission data.