Electronic device and its power control method

• US 20020046355A1
• Filed: 10/04/2001
• Published: 04/18/2002
• Est. Priority Date: 10/05/2000
• Status: Active Grant

• Current Assignee: Renesas Electronics Corporation
• Original Assignee: NEC Corporation
• Inventors: Takeuchi, Junichi
• Granted Patent: US 7,036,031 B2
• Time in Patent Office: Days
• US Class Current: 713/320
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/3209 Monitoring remote activity, e.g. over telephone lines or network connections
• CPC Class Codes: G06F 1/3253 Power saving in bus
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

To provide an interface device and method of controlling power to achieve reduction in power consumption by presetting the transceiver in the standby state. When the physical layer (PHY) 10 makes a transition to a low power consumption mode, a standby signal (standby) for instructing the optical transceiver 30 to preset it into the low power consumption mode is brought into active and is output thereto. When the optical transceiver receives said standby signal, it is brought into the standby mode which is the low power consumption mode.

Claims

1. An electronic device comprising at least a transceiver and a physical layer which transmits and receives data to and from said transceiver, which communicates with another electronic device via a bus to which said transceiver is connected, wherein said physical layer comprises means which brings said transceiver from normal operation mode into low power consumption mode when said physical layer is in the low power consumption mode.

2. The electronic device as defined in claim 1, wherein said physical layer comprises means which outputs to said transceiver a standby signal which is a control signal to instruct said transceiver to change into the low power consumption mode in response to a transition of said physical layer into the low power consumption mode;

and

wherein said transceiver is configured to change from an operating state into a standby state which is the low power consumption mode when said standby signal instructs said transceiver to change into the low power consumption mode.

3. The electronic device as defined in claim 1, wherein said physical layer is configured to change into said low power consumption mode when a transmission/reception port of said physical layer which is connected to said transceiver is in a suspended state which is an interrupted state, or is in a suspended state and in a disconnected state.

4. The electronic device as defined in claim 1, wherein said physical layer comprises:

one or more transmission/reception ports;

a state machine circuit which controls transition of state for each port, said state being among a disconnected state, a suspended state which is the interrupted state, a resuming state which is a resuming process from said disconnected state or said suspended state to an active state and an active state; and

means which makes active a standby signal to output said standby signal, said standby signal being a control signal to instruct said transceiver connected to said transmission port to change into the lower power consumption mode, when a state of said transmission/reception port, state transition of said transmission/reception port being managed by said state machine circuit of said physical layer, is in the disconnected state, or when said transmission/reception port is changed into the suspended state in response to an instruction issued from another electronic device which is connected via said bus to said electronic device or from a higher level device of said electronic device.

5. The electronic device as defined in claim 1, wherein when said physical layer is in a resuming state which is a resuming process from a suspended state which forms said low power consumption mode, said physical layer makes inactive the standby signal;

and

wherein said transceiver is configured to change from the standby state which brings said low power consumption to the active state when said transceiver receives said inactive standby signal output from said physical layer.

6. The electronic device as defined in claim 1, wherein said electronic device comprises means which transmits a low speed tone signal having pulse components, the frequency of said pulse components being lower than a predetermined value as a tone signal which is transmitted for monitoring connection between said electronic device and another device which is connected thereto through a bus when said physical layer is in the low power consumption mode.

7. The electronic device as defined in claim 6, wherein said transceiver of said electronic device comprises a low speed signal detecting circuit which detects said low speed tone signal having pulse components, a frequency of said pulse components is lower than a specified value.

8. The electronic device as defined in claim 1, wherein said physical layer of said electronic device transmits a resuming signal to said bus when said physical layer changes to a resuming state which is a resuming process from the low power consumption mode,

said transceiver of one electronic device which has received said resuming signal which is transmitted to said bus from another electronic device connected to said bus notifies the physical layer of said one electronic device of the detection of said resuming signal when said transceiver detects said resuming signal at its signal detecting circuit, said physical layer of said one electronic device changes to the resuming state which is a resuming process from said low power consumption mode in response to said notification of said signal detection and makes inactive the standby signal which is a control signal to instruct said transceiver of said one electronic device to change into the low power consumption mode and outputs the standby signal;

and

said transceiver of said one electronic device changes to an active state from an standby state which is the low power consumption mode on receipt of said inactive standby signal by said transceiver.

9. The electronic device as defined in claim 8, wherein said electronic device outputs a continuous signal as said resuming signal to said bus from the beginning for the another electronic device connected to said electronic device via the bus without transmitting any tone signal for an initialization.

10. The electronic device as defined in claim 8, wherein said electronic device comprises means which transmits a low speed continuous signal having a speed lower than a specified value for a predetermined period of time from the beginning of said continuous signal when said electronic device transmits to said bus the continuous signal forming said resuming signal for the another electronic device connected to said electronic device via the bus.

11. The electronic device as defined in claim 10, wherein said electronic device comprises a signal detecting circuit which is configured to detect said low speed continuous signal which is transmitted on said bus;

and

wherein said signal detecting circuit notifies said physical layer of signal detection when said signal detecting circuit detects reception of said low speed continuous signal.

12. The electronic device as defined in claim 1, wherein said physical layer of said electronic device terminates transmission of tone signal for monitoring bus connection to another electronic device connected to said electronic device via the bus when said physical layer of said electronic device is in the low power consumption mode.

13. The electronic device as defined in claim 12, wherein said electronic device and said another electronic device are constantly connected via said bus in use thereof.

14. The electronic device as defined in claim 1, wherein a bus cable is removably inserted into a bus connecting connector of the transceiver of said electronic device, said transceiver being adapted to make a connector connection signal active to output said connector connection signal to said physical layer when said bus cable is connected to said connector;

wherein said physical layer is adapted to transmit a connection monitoring tone signal via said transceiver to said bus on receipt of said connector connection signal which has changed from an inactive state to an active state when said bus cable is connected to said bus connecting connector of said transceiver of said electronic device; and

wherein said electronic device comprises means which controls said electronic device to terminate transmission of the connection monitoring tone signal if a response signal to said connection monitoring tone signal which has been transmitted to said bus is not received, said transceiver of said electronic device being set to the standby state which is the low power consumption mode.

15. The electronic device as defined in claim 14, wherein said physical layer of said electronic device which transmits the connection monitoring tone signal to said bus via said transceiver when said bus cable is connected to said connector of said transceiver of said electronic device is adapted to transmit the connection monitoring tone signal to another electronic device connected via said bus from said transceiver at predetermined time intervals if said physical layer receives the response signal to the connection monitoring tone signal which is transmitted to said bus.

16. The electronic device as defined in claim 1, wherein a bus cable is removably inserted into a bus connecting connector of the transceiver of said electronic device, said transceiver being adapted to make a connector connection signal active for outputting said connector connection signal to said physical layer when said bus cable is connected to said connector;

said physical layer of said electronic device which has received a transition of said connector connection signal from inactive to active state output from said transceiver when said bus cable is connected to said bus connecting connector of said transceiver in said electronic device is adapted to change to a resuming state which is a resuming process from a unconnected state and to transmit a continuous signal which forms a resuming signal to said bus via said transceiver; and

if there is no other electronic device which is to be connected to said electronic device via said bus, said physical layer of said electronic device changes to a suspended state which is the low power consumption mode and waits for the reception of the continuous signal which is transmitted on said bus from another electronic device to which said electronic device is connected.

17. The electronic device as defined in claim 7, wherein said transceiver comprises an output circuit for outputting a low speed signal having a pulse frequency lower than a specified value and a low speed signal detecting circuit as a circuit for transmitting and receiving a tone signal which is transmitted and received for monitoring the connection;

and

wherein said transceiver activates an output path for outputting the low speed signal and a detecting path for detecting the low speed signal and inactivates remaining circuits of said transceiver.

18. The electronic device as defined in claim 10, wherein said transceiver comprises a low speed signal detecting circuit, and

wherein when said transceiver is in the low power consumption mode, said transceiver activates said low speed signal detecting path and inactivates other transmitting and receiving circuits which constitute said transceiver.

19. The electronic device as defined in claim 1, wherein said electronic device performs long distance transmission of IEEE 1394 standard.

20. The electronic device as defined in claim 1, wherein said transceiver comprises an optical transceiver and said bus cable comprises an optical fiber cable.

21. The electronic device as defined in claim 19, wherein said physical layer of said electronic device comprises means which controls transition of a transmission/reception port connected to said bus to a suspended state in said physical layer of said electronic device in response to the presence or absence of the connection of a link layer which is a higher level layer of the physical layer in said electronic device or another electronic device connected to said bus.

22. A method for controlling power of an electronic device, wherein said electronic device comprises at least a transceiver and a physical layer for performing the transmission/reception of data to/from said transceiver and said electronic device performing communication with another electronic device via a bus to which said transceiver is connected, said method comprising the steps of:

bringing said transceiver into a low power consumption mode in response to a transition of said physical layer to the low power consumption mode.

23. The method as defined in claim 22, wherein said physical layer includes one or more transmission/reception ports, said transceiver being connected to one of said transmission/reception ports,

a state machine circuit which manages the connection state in said physical layer is adapted to control the state transitions for each of transmission/reception port among a disconnected state which is the disconnected state, a suspended state which is the interrupted state, a resuming state which is a resuming process from said disconnected state or said suspended state to an active state and an active state;

and

a standby signal which is a control signal to instruct said transceiver connected to said transmission port to change into the lower power consumption mode is made active and is output, when said transmission/reception port, state transition of which is managed by said state machine circuit of said physical layer, is in a disconnected state, or when said transmission/reception port is changed into a suspended state in response to an instruction issued by a higher level device of said electronic device or another electronic device being connected to said transceiver of said electronic device via said bus.

24. The method as defined in claim 22, wherein when said physical layer is in a resuming state which is a resuming process from a suspended state which forms said low power consumption mode, said physical layer makes inactive the standby signal which instructs said transceiver to be set to the low power consumption;

and

wherein said transceiver changes from the standby state to an active state in response to said inactive standby signal output from said physical layer.

25. The method as defined in claim 22, wherein a low speed tone signal having pulse components, the frequency of said pulse components being lower than a specified value is transmitted as a tone signal for monitoring connection between said electronic device and another device which is connected thereto through said bus when said physical layer in said one electronic devices is in the low power consumption mode.

26. The method as defined in claim 22, wherein a continuous signal having a rate lower than a specified value, for a predetermined period of time from the beginning of said continuous signal when the continuous signal which forms a resuming signal is transmitted to another electronic device connected to said one of the electronic devices when the physical layer of one electronic device is in a resuming state which is in the resuming process from the suspended state which brings the low power consumption mode;

and

wherein said transceiver of said another electronic device notifies said physical layer of said another electronic device of the signal detection when said transceiver of said another electronic device detects the reception of said low speed continuous signal at the signal detecting circuit which detects said low speed continuous signal.

27. The method as defined in claim 26, wherein said one electronic device transmits a continuous signal as a resuming signal from the beginning without transmitting any tone signal for initialization when said one electronic device transmits a resuming signal to said another electronic device connected to said one electronic device via said bus in the resuming state which is the resuming process from said low power consumption mode in the physical layer of said one electronic device.

28. The method as defined in claim 22, wherein a bus cable is removably inserted into a bus connecting connector of the transceiver of said electronic device, the method comprising the steps of:

said transceiver making a connector connection signal active to output said connector connection signal to said physical layer when said bus cable is connected to said connector;

said physical layer transmitting a connection monitoring tone signal via said transceiver to said bus in response to a transition of said connector connection signal from an inactive state to an active state when said bus cable is connected to said bus connecting connector of said transceiver in said one of electronic devices; and

if a response signal to said connection monitoring tone signal which has been transmitted to said bus is not received in one electronic device, transmission of the connection monitoring tone signal being terminated and said transceiver of said one of the electronic devices being set to the standby state which is the low power consumption mode.

29. The method as defined in claim 28, wherein the physical layer of said one of the electronic devices transmits a connection monitoring tone signal at predetermined time intervals to said other electronic device connected to said one of the electronic devices via the bus if the connection monitoring tone signal is transmitted via said transceiver to said bus cable which is connected to the bus connecting connector of the transceiver of said one of the electronic devices and a response signal to said connection monitoring tone signal transmitted to said bus cable.

30. The method as defined in claim 22, wherein a bus cable is removably inserted into a bus connecting connector of the transceiver of said electronic device, said transceiver being adapted to make a connector connection signal active for outputting said connector connection signal to said physical layer when said bus cable is connected to said connector;

said physical layer of said electronic device, in response to a transition of a transition of said connector connection signal from an inactive state to an active state, said connector connection signal being output from said transceiver when said bus cable is connected to said bus connecting connector of said transceiver in said electronic device, changes to a resuming state which is the resuming process from an unconnected state and transmits a continuous signal which forms a resuming signal to said bus via said transceiver; and

if there is no other electronic device which is to be connected to said electronic device via said bus, said physical layer of said electronic device changes to the suspended state which is the low power consumption mode and waits for the reception of the continuous signal which is transmitted on said bus from the other electronic device to which said electronic device is connected.

31. The method as defined in claim 22, wherein said electronic device performs long distance transmission of IEEE 1394 standard.

32. The method as defined in claim 22, wherein said transceiver comprises an optical transceiver and wherein said bus cable comprises an optical fiber cable.

33. The method as defined in claim 31, wherein said physical layer of said electronic device includes means for controlling transition of the transmission/reception port connected to said bus to the suspended state in said physical layer of said electronic device in response to the presence or absence of the connection of a link layer which is a higher level layer of the physical layer in its own electronic device or the other electronic device connected to said bus.

34. An interface device comprising at least a transceiver having a transmitting circuit and receiving circuit, which are connected to a bus;

and a physical layer for transmitting and receiving data to and from said transceiver, wherein said physical layer comprises means for setting said transceiver to low power consumption mode from normal operation mode in response to a transition of said physical layer to the low power consumption mode.