Device, operation-mode control method, and recording medium

1. A device having a plurality of power states, the device comprising:

a communication processing circuit configured to communicate with a communication destination device connected via a cable;

a confirmation-signal receiving circuit configured to receive link pulses as a connection confirmation signal that is transmitted if connected to the communication destination device via the cable;

a controller circuit configured to determine a power state depending on whether the confirmation-signal receiving circuit receives the connection confirmation signal; and

a power circuit configured to control supply of electric power to at least one of the communication processing circuit and the controller circuit in accordance with the power state determined by the controller circuit, wherein

if the confirmation-signal receiving circuit does not receive the connection confirmation signal in a first power state where electric power is supplied to the communication processing circuit and the controller circuit, the controller circuit is configured to determine that a transition is to be made to a fourth power state where electric power is supplied to the communication processing circuit but no electric power is supplied to the controller circuit, and

if the communication processing circuit receives a start-up request signal for starting up the device, via the cable while in the fourth power state, the controller circuit is configured to determine that a transition is to be made to a power state where electric power is supplied to the controller circuit.

2. The device according to claim 1 , wherein

if the confirmation-signal receiving circuit does not receive the connection confirmation signal in a first power state where electric power is supplied to the communication processing circuit and the controller circuit, the controller circuit is configured to determine that a transition is to be made to a second power state where no electric power is supplied to the communication processing circuit and the controller circuit, and

if the confirmation-signal receiving circuit receives the connection confirmation signal in the second power state, the controller circuit is configured to determine that a transition is to be made to the first power state.

3. The device according to claim 2 , wherein

a reception signal line for the cable branches to the confirmation-signal receiving circuit and between an interface for the cable and the communication processing circuit,

the device further comprises a switch configured to switch between a connected state and a disconnected state of the reception signal line to the confirmation-signal receiving circuit, and

the switch is configured to be in the disconnected state while in the first power state, and the switch is configured to be in the connected state while in the second power state.

4. The device according to claim 2 , further comprising a setting-information memory configured to store setting information as to whether a transition is to be made to the second power state, wherein

if the confirmation-signal receiving circuit does not receive the connection confirmation signal, the controller circuit is configured to determine whether a transition is to be made to the second power state in accordance with the setting information acquired from the setting-information memory.

5. The device according to claim 1 , wherein if receiving the connection confirmation signal of equal to or more than a predetermined value in a unit of time, the confirmation-signal receiving circuit is configured to determine that the connection confirmation signal is received.

6. The device according to claim 1 , further comprising a nonvolatile memory storing a flag that is set in response to a transition being made to second power state where no electric power is supplied to the communication processing circuit and the controller circuit, to indicate the second power state, wherein

the controller circuit is configured to clear the flag in response to a transition being made to a third power state where no electric power is supplied to the communication processing circuit, the controller circuit, and the confirmation-signal receiving circuit, and

in a case where the confirmation-signal receiving circuit does not receive the connection confirmation signal, the controller circuit is configured to determine that a transition is to be made to the second power state if the flag is set in the nonvolatile memory, and determine that a transition is to be made to the third power state if the flag is not set in the nonvolatile memory.

7. The device according to claim 1 , wherein

a reception signal line for the cable branches to the confirmation-signal receiving circuit and between an interface for the cable and the communication processing circuit, and

a transmission signal line for the cable branches to the confirmation-signal receiving circuit and between an interface for the cable and the communication processing circuit.

8. The device according to claim 1 , wherein

if the confirmation-signal receiving circuit receives the connection confirmation signal while in the fourth power state, the controller circuit is configured to keep the fourth power state, and

if the confirmation-signal receiving circuit does not receive the connection confirmation signal while in the fourth power state, the controller circuit is configured to determine that a transition is to be made to a third power state where no electric power is supplied to the communication processing circuit, the controller circuit, and the confirmation-signal receiving circuit.

9. The device according to claim 1 , wherein

if the confirmation-signal receiving circuit receives the connection confirmation signal while in the fourth power state, the controller circuit is configured to keep the fourth power state,

if the confirmation-signal receiving circuit does not receive the connection confirmation signal while in the fourth power state, it is determined that a transition is to be made to a fifth power state where no electric power is supplied to the communication processing circuit and the controller circuit, and

if the confirmation-signal receiving circuit receives the connection confirmation signal while in the fifth power state, it is determined that a transition is to be made to the fourth power state.

10. The device according to claim 1 , wherein

if the confirmation-signal receiving circuit does not receive the connection confirmation signal while in the first power state, the controller circuit is configured to determine that a transition is to be made to a second power state where no electric power is supplied to the communication processing circuit and the controller circuit, and

if the confirmation-signal receiving circuit receives the connection confirmation signal while in the second power state, the controller circuit is configured to determine that a transition is to be made to the first power state.

11. The device according to claim 10 , wherein

if the confirmation-signal receiving circuit receives the connection confirmation signal while in the fourth power state, the controller circuit is configured to keep the fourth power state,

if the confirmation-signal receiving circuit does not receive the connection confirmation signal while in the fourth power state, it is determined that a transition is to be made to a fifth power state where no electric power is supplied to the communication processing circuit and the controller circuit, and

if the confirmation-signal receiving circuit receives the connection confirmation signal while in the fifth power state, it is determined that a transition is to be made to the fourth power state.

12. The device according to claim 1 , wherein

if the confirmation-signal receiving circuit does not receive the connection confirmation signal while in a first power state where electric power is supplied to the communication processing circuit and the controller circuit, the controller circuit is configured to determine that a transition is to be made to a second power state where no electric power is supplied to the communication processing circuit and the controller circuit,

if the confirmation-signal receiving circuit does not receive the connection confirmation signal while in the second power state, the second power state is kept,

if the confirmation-signal receiving circuit receives the connection confirmation signal while in the second power state, the controller circuit is configured to determine that a transition is to be made to a fourth power state where electric power is supplied to the communication processing circuit but no electric power is supplied to the controller circuit,

if the confirmation-signal receiving circuit receives the connection confirmation signal while in the fourth power state, the controller circuit is configured to keep the fourth power state,

if the confirmation-signal receiving circuit does not receive the connection confirmation signal while in the fourth power state, it is determined that a transition is to be made to a fifth power state where no electric power is supplied to the communication processing circuit and the controller circuit, and

if the confirmation-signal circuit receives the connection confirmation signal while in the fifth power state, it is determined that a transition is to be made to the fourth power state.

13. The device according to claim 1 , further comprising a second controller circuit configured to determine a power state in a state where no electric power is supplied to the controller circuit, wherein

if the confirmation-signal receiving circuit does not receive the connection confirmation signal while in a first power state where electric power is supplied to the communication processing circuit and the controller circuit, the controller circuit is configured to determine that a transition is to be made to a sixth power state where electric power is supplied to the communication processing circuit, the second controller circuit, and the confirmation-signal receiver but no electric power is supplied to the controller circuit,

if the confirmation-signal receiving circuit receives the connection confirmation signal while in the sixth power state, the second controller circuit is configured to determine that a transition is to be made to the first power state,

if the communication processor receiving circuit a start-up request signal for starting up the device while in the sixth power state, the second controller circuit is configured to determine that a transition is to be made to a power state where electric power is supplied to the controller circuit,

if the confirmation-signal receiving circuit does not receive the connection confirmation signal while in a fourth power state where electric power is supplied to the communication processing circuit but no electric power is supplied to the controller circuit, it is determined that a transition is to be made to a fifth power state where no electric power is supplied to the communication processing circuit and the controller circuit, and

if the confirmation-signal receiving circuit receives the connection confirmation signal while in the fifth power state, it is determined that a transition is to be made to the fourth power state.

14. An operation-mode control method implemented by a device having a plurality of power states, the operation-mode control method comprising:

by a communication processing circuit, communicating with a communication destination device connected via a cable;

by a confirmation-signal receiving circuit, receiving link pulses as a connection confirmation signal that is transmitted if being connected to the communication destination device via the cable;

by a controller circuit, determining a power state of at least three power states depending on whether the confirmation-signal receiving circuit receives the connection confirmation signal; and

by a power circuit, controlling supply of electric power to at least one of the communication processing circuit and the controller circuit in accordance with the power state determined by the controller circuit and a current power state of the device, wherein

if the connection confirmation signal are not received in a first power state where electric power is supplied to the communication processing circuit and the controller circuit, a transition is made to a fourth power state where electric power is supplied to the communication processing circuit but no electric power is supplied to the controller circuit, and

if a start-up request signal for starting up the device is received, via the cable while in the fourth power state, a transition is made to a power state where electric power is supplied to the controller circuit.

15. A non-transitory computer readable recording medium including a computer program that when executed by a controller circuit of an information processing device having a plurality of power states, causes the controller circuit to perform a method comprising:

communicating, by a communication processing circuit of the information processing device, with a communication destination device connected via a cable;

receiving, by a confirmation-signal receiving circuit of the information processing device, link pulses as a connection confirmation signal that is transmitted if being connected to the communication destination device via the cable;

determining a power state states depending on whether the connection confirmation signal is received; and

supplying electric power to at least one of a communication processing circuit and a controller circuit of the information processing device in accordance with the power state determined, wherein

if the connection confirmation signal are not received in a first power state where electric power is supplied to the communication processing circuit and the controller circuit, a transition is made to a fourth power state where electric power is supplied to the communication processing circuit but no electric power is supplied to the controller circuit, and

if a start-up request signal for starting up the information processing device is received, via the cable while in the fourth power state, a transition is made to a power state where electric power is supplied to the controller circuit.