JP2005094189A - Communication system and method for restoring connection - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for restoring a connection easily in a communication system of IEEE1394. <P>SOLUTION: According to the inventive technology for restoring connection, a timer for restoring connection is set (S18) upon occurrence of bus reset (S14). An AV apparatus previously makes a connection table indicative of connection information with a connection partner before the occurrence of bus reset (S12) and executes processing for restoring connection (S28) with reference to that connection table (S22) after the occurrence of bus reset. Since the connection table is made previously, connection state before the occurrence of bus reset can be realized quickly and easily. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a communication technique for transmitting or receiving data, for example, a communication apparatus that performs communication based on the IEEE 1394 standard and a connection recovery method in the communication apparatus.

  There is an increasing demand for a home network in which a LAN (local area network) is laid in a home and AV equipment such as DTV (digital television) and D-VHS deck, other home appliances, computers and the like are connected. In recent years, as a high-speed bus interface for realizing a home network, there is an interest in IEEE 1394, which can easily connect various devices and enables high-speed transmission of information.

When data communication is performed according to the IEEE 1394 standard, a connection is set between nodes in order to connect a plug set to each node. In this data communication system, a bus reset occurs with a change in the topology connection of the bus, and after the established connection is released, the connection is dynamically reset in a new topology configuration. The output or input plug that has been connected before the bus reset continues transmission or reception for one second after the bus reset even if the connection is not established. In order to prevent transmission of AV (audio / visual) signals from being interrupted by a bus reset, the connection management application needs to establish a connection again during this one second.
JP 2000-49824 A

  In the current IEEE 1394 communication system, after the bus is initialized, each node detects the connection status with other nodes. At this time, for example, when a D-VHS IEEE 1394 cable is disconnected from the jack, the D-VHS cannot be recognized and a connection cannot be established. When the cable is inserted into the jack again, the D-VHS is recognized as a new device connection, and the connection is established after the bus reset.

  When the D-VHS cable is pulled out during transmission of AV data, the plugs stop input / output unless the cable is inserted within one second. When the cable is plugged in after 1 second has elapsed, it is necessary to start the connection management application and reset the connection by pressing an operation button such as a D-VHS playback button or recording button from the user side. However, this operation is troublesome for the user.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a technique capable of easily recovering a connection.

  In order to solve the above problems, an aspect of the present invention includes a connection setting unit that establishes a connection with another device and performs data communication, a control unit that stores connection information of the established connection in a storage unit, Provided is a communication device including a monitoring unit that detects the presence or absence of a partner device that has established a connection. In the communication apparatus according to this aspect, even when the monitoring unit detects that the counterpart device is no longer present, the control unit holds the connection information in the storage unit, and then the presence of the counterpart device is detected by the monitoring unit. If detected, the connection setting unit can restore the connection with the counterpart device based on the connection information.

  According to the communication device of this aspect, even if the cable of the counterpart device is once pulled out, the storage unit stores the connection information before disconnection, so based on this connection information, The connection setting unit can easily restore the connection. As a result, the communication device can autonomously return to the connection configuration before disconnection without receiving an operation instruction from the user, maintain data continuity, and eliminate user trouble. . It is preferable that the connection setting unit establishes a connection with the counterpart device on the serial bus compliant with the IEEE 1394 standard, and the control unit holds the connection information in the storage unit for a predetermined time from the occurrence timing of the bus reset. .

  Another aspect of the present invention provides a method for restoring a connection with another device. The method of this aspect includes a step of storing connection information of a connection with an already established counterpart device, a step of detecting that the counterpart device no longer exists, a step of setting a timer for connection recovery, When the presence of the counterpart device is detected before the end, a step of performing a connection recovery process based on the stored connection information is provided.

  According to the connection recovery method of this aspect, even when the partner device no longer exists, if the partner device is found by the end of the timer, it is easy to use the connection information before disconnection. It becomes possible to return to the original connection configuration.

  According to the present invention, even when the counterpart device is lost for a moment, it is possible to easily restore the connection using the information by holding the information at the time of connection.

  FIG. 1 is a conceptual diagram of a communication system implemented in the IEEE 1394 communication standard. In the IEEE 1394 communication system 1, each AV device 10a, 10b, 10c (hereinafter collectively referred to as "AV device 10") sets a virtual plug for logical signal connection. There are an input plug on the input side of the signal connection and an output plug on the output side. The AV device 10 can have a plurality of input plugs and output plugs.

  The AV devices 10a and 10b include an input plug control register (iPCR: input plug control register) that controls input plug attributes and an input master plug register (iMPR: input master plug register) that controls attributes common to iPCRs. . The AV devices 10b and 10c include an output plug control register (oPCR: output Plug Control Register) that controls the attribute of the output plug and an output master plug register (oMPR: output Master Plug Register) that controls the attribute common to the oPCR. Is provided. Note that up to 31 plugs can be set in one AV device 10, and therefore, up to 31 iPCRs and oPCRs may be set in one AV device 10.

  In the example shown in FIG. 1, isochronous data is sent onto the bus 12 via the output plug of the AV device 10c, and the AV device 10a receives the isochronous data from the input plug. Similarly, isochronous data is sent to the bus 12 via the output plug of the AV device 10b, and the AV device 10a receives isochronous data from the input plug. In the IEEE 1394 communication system 1, a connection can be established simply by connecting a corresponding device on the bus 12, and there are two types of connection: a point-to-point connection and a broadcast connection.

  Connecting one output plug and one input plug via one channel is called a point-to-point connection. A point-to-point connection can only be released by the application that established it. As a situation of use, there is a case where a DTV as a controller establishes a connection to D-VHS and plays back or records AV data.

  Connecting one output plug to one channel is called a broadcast out connection, and connecting one input plug to one channel is called a broadcast in connection. A connection that does not specify the partner's plug is called a broadcast connection. An application that establishes a broadcast connection must establish only the plug of its own device, but the release may be performed on the plug of any device. As a situation of use, a specific channel is determined, the output device sends AV data to the channel without specifying the other device, and the input device also inputs AV data from the channel without specifying the other device. If you want to.

  The above is the connection management operation of each AV device 10 in the IEEE 1394 communication system 1. In the present invention, there is provided a technique capable of recovering a connection with a partner device even when the partner device with which the connection has been established no longer exists. For the sake of explanation, in the following example, a situation will be described in which the DTV is the main body, a connection is established to the D-VHS, and AV data is reproduced or recorded. Note that the present invention can be used not only for point-to-point connections but also for broadcast connections.

  FIG. 2 shows a configuration of the AV device 10 according to the embodiment of the present invention. The AV device 10 is connected to the IEEE 1394 bus 12 and functions as a communication device that performs data communication with devices on the bus 12. The AV device 10 shown in FIG. 2 is a DTV, and includes an AV data reproducing unit 20 including a tuner 22, an AV data processing unit 24, a monitor 26, and a speaker 28. The AV data processing unit 24 has a function of decoding digital TV broadcast waves received by the tuner 22 and supplying a video signal to the monitor 26 and an audio signal to the speaker 28. Note that the DTV is an example, and the AV device 10 may be another home appliance or a computer.

  The AV device 10 further has a communication function for performing data communication with an AV device such as a D-VHS on the IEEE 1394 bus 12. As a configuration for this, the AV device 10 includes a communication interface 30, a connection setting unit 32, a monitoring unit 34, a control unit 36, a timer 38, and a storage unit 40. The connection setting unit 32 establishes a connection with a device on the bus 12 and performs data communication. The connection setting unit 32 is a function realized by the connection management application, and has the function as the MPR described in FIG. When the DTV is connected to the D-VHS on the IEEE 1394 bus 12 and causes the D-VHS to record a TV program, the DTV connection setting unit 32 sets the output plug in itself, and the D-VHS To set the input plug. Further, when receiving AV data from the D-VHS, the DTV sets an input plug for itself and also causes the D-VHS to set an output plug. At this time, the AV data reproducing unit 20 decodes the AV data supplied from the D-VHS into a video signal and an audio signal, and supplies them to the monitor 26 and the speaker 28.

  In the AV apparatus 10 according to the present embodiment, the control unit 36 causes the storage unit 40 to store connection information of the established connection. The storage unit 40 is a memory such as a RAM, and stores this connection information in a connection table. The connection information includes an identifier for identifying a partner device to be connected and information indicating a connection state with the partner device. The identifier is preferably information for uniquely specifying a device such as a GUID (Global Unique Identifier). The information indicating the connection state includes information indicating the type of connection established with the counterpart device and whether the set plug is an input or an output.

  FIG. 3 shows an example of connection information in the connection table stored in the storage unit 40. In this example, it is indicated that “input of point-to-point connection” is set as the connection state. As described above, the DTV operates as an input of a point-to-point connection when, for example, AV data from the D-VHS is reproduced. Other examples of the connection state include “point-to-point connection output”, “broadcast connection input”, and “no connection request”. For example, at the end of playback from the D-VHS, the point-to-point connection is disconnected, and the connection state of the connection table shown in FIG. 3 is updated to “no connection request”. The above is an example of a connection state when a connection is established by the DTV as a subject. However, when the connection is set by the D-VHS as a subject, “broadcast connection output” also exists as the connection state.

  When a topology change occurs, such as when a new device joins the bus 12 or a connected device is removed from the bus 12, a bus reset signal is transmitted to all nodes on the bus, and all topology information is cleared. The The monitoring unit 34 has a correspondence list of GUIDs and node IDs of devices that existed on the bus 12 before the bus reset, detects a device that exists on the bus 12 after the bus reset, and detects the bus 12 It recognizes devices that have been removed from the network or devices that have been added to the bus 12. In this way, the monitoring unit 34 monitors the nodes existing on the bus 12, and detects the presence / absence of a partner device that has already established a connection.

  In the present embodiment, even if the monitoring unit 34 detects that the partner device with which the connection has been established does not exist on the bus 12, the control unit 36 holds the connection information in the storage unit 40, and the presence of the non-existence is confirmed. It is not deleted from the storage unit 40 for a predetermined time from the detected timing. As a result, when the cable of the counterpart device is physically reconnected to the bus 12 within a predetermined time, the connection setting unit 32 quickly and easily restores the connection using the connection information stored in the storage unit 40. It becomes possible. This predetermined time is set longer than the time by the isochronous resource delay process, that is, 1 second. The timer 38 may set the connection recovery grace time to about 10 seconds, for example. In order to secure the time for inserting the cable and to prevent the output stop time of the AV data reproducing unit 20 from being too long, it is appropriate to set it to about 10 seconds.

  FIG. 4 shows a connection recovery process flow according to the embodiment. First, the connection setting unit 32 establishes a connection with a device on the bus 12 and performs data communication (S10). That is, the AV device 10 that is a DTV transmits or receives AV data to or from a partner device, for example, D-VHS. At this time, the control unit 36 creates a connection table using the connection information of the established connection and stores it in the storage unit 40 (S12).

  When a bus reset occurs by pulling out the D-VHS cable (S14), an isochronous resource delay process defined in the IEEE 1394 standard is executed (S16). The connection is released by the bus reset, but in the isochronous resource delay processing, if the plug state before the bus reset is maintained for 1 second and the connection management application sets the connection again during this period, the bus reset is crossed. Thus, the AV data signal can be maintained. If the connection with the D-VHS is established within 1 second after the bus reset, it means that the connection resetting process by the isochronous resource delay process is successful, and the subsequent recovery process is not performed. If a bus reset is generated in response to the D-VHS cable being pulled out, the D-VHS is not detected on the bus 12, so that the connection resetting process by the isochronous resource delay process is not performed. .

  In parallel with the isochronous resource delay processing, the connection recovery processing according to this embodiment is performed simultaneously. For the restoration process, the control unit 36 sets the connection restoration timer 38 to a predetermined time, for example, 10 seconds, using the bus reset as a trigger (S18). Until the timer expires, the contents of the connection table in the storage unit 40 are retained. The monitoring unit 34 acquires the device information, that is, the GUID of the device connected on the IEEE1394 bus 12 after the bus reset (S20), and detects the presence or absence of the partner device that established the connection before disconnection. Then, the detection result is supplied to the control unit 36. Subsequently, the control unit 36 refers to the connection table stored in the storage unit 40 (S22) and grasps the connection state before the bus reset.

  With reference to the connection state included in the connection table, if there is no connection request before the bus reset (N in S24), this connection recovery processing flow is terminated, but there is a connection request. If yes (Y in S24), it is determined whether the counterpart device is on the bus 12 based on the detection result by the monitoring unit 34 (S26). If the counterpart device exists (Y in S26), the recovery processing of the connection with the counterpart device is performed based on the connection information included in the connection table (S28). Normally, if there is a partner device, the connection is reset by isochronous resource delay processing. If this fails, the connection can be restored in step S28. . Therefore, the connection recovery process according to the present embodiment can also play an auxiliary role in the isochronous resource delay process. By holding the connection information necessary for establishing a connection in advance, it is possible to quickly and easily restore the connection, and automatically restore the connection without bothering the user. Is possible.

  When there is no counterpart device in S26 (N in S26), the control unit 36 waits for the counterpart device to be connected to the bus 12 until the timer expires. In IEEE 1394, when a counterpart device is connected to the bus 12, a bus reset occurs. Therefore, the monitoring unit 34 monitors the bus reset until the timer expires, and if a bus reset occurs before the timer expires. (N of S32, S14), the steps from S16 to S26 are repeated. At this time, if a partner device is found in S26, a connection recovery process is executed based on the connection information (S28). If no bus reset occurs until the timer expires (Y in S32), the connection state in the connection table is updated to “no connection request” (S34), and this connection recovery flow is terminated.

  In the connection recovery flow described above, when one second or more has elapsed after the bus reset has occurred, AV data transfer is stopped. During this time, a guidance message for explaining the situation to the user is displayed on the monitor 26. You may let them. Further, when the connection restoration process is unsuccessful due to the end of the timer, the output of the DTV may be switched to the digital TV broadcast received from the tuner to reproduce the TV program.

  In the above, this invention was demonstrated based on the Example. The present invention is not limited to this embodiment, and various modifications thereof are also effective as an embodiment of the present invention.

  As such a modification, in the embodiment, communication between devices connected to a bus has been described. However, the present invention can also be applied to communication between devices by wireless connection. In particular, in wireless communication supported by IEEE 1394, connection recovery processing can be performed in the same procedure as in the above-described embodiment. Further, the present invention is not limited to communication using IEEE1394, and can be applied to other communication protocols.

  Further, the connection recovery process when the cable is pulled out from the AV device has been described above. For example, the present invention can also be applied as a technique for absorbing chattering that occurs when the cable is inserted into the AV device. . Chattering occurs when the connector is in a contact state and a non-contact state alternately in a short time when the cable is inserted. Once the control unit 36 detects the device, the control unit 36 sends connection information to the storage unit 40. Store it. Subsequently, even if the electrical contact is turned on and off by chattering and a bus reset occurs each time, as long as the timer 38 does not end, the connection information is retained, so that a stable bus state is finally obtained. After that, it is possible to establish a connection with the counterpart device.

It is a conceptual diagram of the communication system implement | achieved in the communication standard of IEEE1394. It is a block diagram of AV equipment concerning an example. It is a figure which shows an example of the connection information of a connection table. It is a figure which shows the restoration process flow of a connection.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Communication system, 10 ... AV apparatus, 12 ... Bus, 30 ... Communication interface, 32 ... Connection setting part, 34 ... Monitoring part, 36 ... Control part, 38 ... Timer, 40 ... Storage section.

Claims (7)

A connection setting unit that establishes a connection with another device and performs data communication;
A control unit for storing connection information of the established connection in the storage unit;
A monitoring unit that detects the presence or absence of a partner device that has established a connection,
Even when the monitoring unit detects that the counterpart device no longer exists, the control unit holds connection information in the storage unit, and then the presence of the counterpart device is detected by the monitoring unit In addition, the connection setting unit restores the connection with the counterpart device based on the connection information.   The communication apparatus according to claim 1, wherein the control unit holds the connection information in the storage unit until a predetermined time elapses from a predetermined timing.   The communication apparatus according to claim 2, wherein the control unit deletes the connection information from the storage unit when a predetermined time is exceeded.   The connection setting unit establishes a connection with a counterpart device on a serial bus conforming to the IEEE 1394 standard, and the control unit causes the storage unit to hold connection information for a predetermined time from the occurrence timing of the bus reset. The communication device according to claim 2, wherein:   The communication apparatus according to claim 4, wherein the predetermined time is longer than 1 second.   The communication device according to claim 1, wherein the connection information includes an identifier of a counterpart device and a connection type. A method for restoring a connection with another device,
Storing connection information of a connection with an already established partner device;
Detecting that the counterpart device no longer exists;
Setting a timer for connection recovery;
If the presence of the partner device is detected before the timer expires, a step of performing connection recovery processing based on the stored connection information;
A connection recovery method comprising:

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