JP2004007773A - Communication control method and communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication system connected through a P1394 serial bus, in which transmission and reception of information signals are not suspended between devices during bus reset. <P>SOLUTION: A command processing unit 2 transmits a command including a connection parameter registered in a CMT (connection management table) 4 to its own inter-device connection processing unit 3, if there is not any AVM (audio video manager) in the communication system. The inter-device connection processing unit 3 performs inter-device connection, according to the parameter. On the other hand, if there is an AVM, the command processing unit 2 transmits the command including the connection parameter registered in the CMT 4 to the AVM to leave inter-device connection processing to the AVM. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a communication system for transmitting digital data such as video data and audio data using a communication control bus such as a serial bus compliant with IEEE-P1394 (hereinafter abbreviated as “P1394 serial bus”). The present invention relates to a communication control method used and a communication system using the control method.

A system in which a plurality of electronic devices are connected by a communication control bus such as a P1394 serial bus that can mix control signals and information signals, and the information signals and control signals are communicated between these devices has been considered.

Figure 5 shows an example of such a system. This system includes four digital video tape recorders (hereinafter, "VTR"), one camcorder (hereinafter, "CAM"), one editing machine, and one computer. The devices are connected by a twisted pair cable of a P1394 serial bus. Since each device has a function of relaying information signals and control signals input from a twisted pair cable, this communication system is equivalent to a communication system in which each device is connected to a common P1394 serial bus.

(6) Data transmission in devices sharing a bus is performed by time division multiplexing every predetermined communication cycle (for example, 125 μsec) as shown in FIG. The management of the communication cycle on the bus is performed by synchronizing a predetermined device called a Cycle Master, for example, a synchronization packet (cycle start packet: hereinafter referred to as “CSP”) indicating that the editing machine is at the start of the communication cycle. By transmitting to the device, data transmission in the communication cycle is started.

The types of data transmitted during one communication cycle are synchronous data such as video data and audio data (hereinafter referred to as “Iso data”) and asynchronous data such as a connection control command (hereinafter referred to as “Async data”). ). Then, the Iso data packet is transmitted before the Async data packet. By assigning channel numbers 1, 2, 3,... N to each of the Iso data packets, a plurality of Iso data packets can be distinguished. After the transmission of the Iso data packets of all the channels is completed, a period until the next CSP is used for transmitting the Async data packets.

A device that intends to transmit an Iso data packet to a bus first secures a channel and a band necessary for data transmission. For this reason, a channel and a required band are applied to a predetermined device (Bus Manager: hereinafter, referred to as “BM”) for managing a bus channel and a band, for example, a computer. As shown in FIG. 7, the BM includes a register REG1 indicating the use state of each channel of the bus, and a register REG2 indicating the remaining capacity of the bus. A device that intends to transmit an Iso data packet sends a read command to these registers REG1 and REG2 using an Async data packet, and reads the contents of REG1 and REG2. Then, if there is an available channel and available capacity, the BM sends a write command for writing the channel and band that the user wants to use to REG1 and REG2 using the Async data packet. If writing to the registers REG1 and REG2 succeeds, output to the bus becomes possible.

FIG. 8 shows a basic configuration of a VTR, which is a device in the communication system shown in FIG. This VTR includes a deck unit 11 and a tuner unit 12, which are essential functional units as a VTR, a digital interface (hereinafter, referred to as "digital I / F") 13 for a P1394 serial bus, and a digital I / F 13, A switch box section 14 for switching and connecting the deck section 11 or the tuner section 12 and a communication control microcomputer 15 are provided. If the device is a CAM, there is a camera unit instead of the deck unit 11 and the tuner unit 12, and if it is an editing machine or a computer, there is a processing unit for video data and computer data.

電子 In the electronic device configured as described above, the communication control microcomputer 15 performs connection between the devices. FIG. 9 shows a table (Connection Management Table: hereinafter referred to as “CMT”) for managing layering of processing transmission between the application 1, the command processing unit 2, and the inter-device connection processing unit 3 of the communication control microcomputer 15 and inter-device connection information. 4) shows the structural view of FIG.

(4) The application 1 generates a command including parameters such as a communication partner and a band, and passes the command to the command processing unit 2. If a representative device (Audio Video Manager: hereinafter referred to as “AVM”) that manages the connection between devices in the entire communication system is present in the communication system, the command processing unit 2 passes the device connection process to the AVM, and executes the process. Leave. On the other hand, if the AVM does not exist, the parameter is passed to its own inter-device connection processing unit 3. The inter-device connection processing unit 3 executes the inter-device connection processing based on the parameters, and registers the parameters in the CMT 4.

ＡＶHere, the AVM is a device such as a computer capable of managing the entire communication system. In order to become an AVM, it is necessary to write its own node ID into AVM registers (not shown) of all devices in the system, and the device that succeeds in this writing becomes the AVM. Each device can determine whether or not there is an AVM in the system based on whether or not a node ID is written in its own AVM register.

考 え る In a communication system configured as described above, consider a case where a bus reset occurs due to turning on / off the power of a device or disconnecting / connecting a device from / to a bus.

At this time, if the inter-device connection processing unit 3 executes the inter-device connection processing before the bus reset, when the bus reset occurs, the CMT 4 managed by the respective inter-device connection processing units 3 transmits the bus reset. Since the inter-device connection is reestablished based on the registered inter-device connection information, the inter-device connection before reset can be maintained.

{Circle around (4)} Once the AVM leaves device connection processing, if a bus reset or the like occurs, the device connection processing unit 3 does not hold the device connection information and cannot reconnect.

Therefore, if the AVM exists before the bus reset and disappears after the reset, or if the AVM changes before and after the reset, the device connection of the entire system after the reset is released. Recording and editing processing are interrupted.

Furthermore, when the AVM does not exist before the bus reset and appears after the reset, etc., each device only reestablishes its own connection before the reset and does not transmit the contents of the CMT to the AVM. The AVM needs to inquire of all devices about the contents of the CMT in order to grasp the connection status between devices in the entire system, and the number of communications may increase.

The present invention has been proposed in order to solve such a problem, and an object of the present invention is to provide a data communication method and an electronic device in which transmission and reception of information signals between devices are not interrupted at the time of a bus reset. And

Further, the present invention provides a data communication method and an electronic device that eliminate the need for the AVM to inquire each device of device connection information even if the AVM does not exist before the bus reset and appears after the reset. The purpose is to provide.

The present invention provides a communication control method used in a communication system in which a plurality of electronic devices are connected via a bus capable of communicating with a packet by mixing information signals and control signals, The electronic device outputs an information signal through an output plug or inputs an information signal through an input plug, and can make a one-to-one connection with another electronic device similarly connected to the communication system. It is possible to keep the connection information for each connection for each connection. The connection information does not contain information about the connection destination. If a bus reset occurs during communication, The connection state is reconstructed.

Here, the electronic device can perform a broadcast output that does not specify the electronic device to be input or a broadcast input that does not specify the output electronic device, and the connection information includes information related to the broadcast output or the broadcast input. Eggplant

It is desirable that the connection information includes information on connection protection.

接 続 Also, it is desirable that the connection information includes information on a band necessary for communication of the information signal.

In the communication control method according to the present invention, when the electronic device is connected or reconnected, the electronic device is similarly connected to the communication system, and the first register is transmitted to the bus management device having the first register indicating the use state of each channel of the bus. A command for reading the contents of the first register is received, and the contents of the first register are received. Based on the received contents of the first register and the channel of the bus which the user wishes to use, a command for rewriting the contents of the first register is issued. Send to the bus management device.

Further, in the communication control method according to the present invention, when the electronic device is connected or reconnected, the electronic device is connected to the communication system in the same manner, and the electronic device is transmitted to the bus management device having the second register indicating the available bandwidth of the bus. A command to read the contents of the register is transmitted, the contents of the second register are received, and the contents of the second register are rewritten based on the received contents of the second register and the bandwidth of the bus which the user desires to use. An instruction is sent to the bus management device.

Further, the present invention provides a communication system in which an information signal and a control signal are mixed and a plurality of electronic devices are connected via a bus capable of communicating with a packet, wherein the electronic device transmits the information signal via an output plug. The information signal is input through an output or an input plug, so that a one-to-one connection can be made with another electronic device similarly connected to the communication system, and connection information regarding the connection is transmitted to each connection. It is characterized by re-establishing the connection state before the occurrence of a bus reset when a bus reset occurs during communication, and the connection information does not include information on a connection destination. I do.

The electronic device constituting the communication system according to the present invention can perform a broadcast output without specifying the input electronic device or a broadcast input without specifying the output electronic device, and the connection information includes the broadcast output or the broadcast input. Include information about

(4) The connection information includes information on connection protection.

Furthermore, the connection information may include information on a band necessary for communication of the information signal.

In the communication system according to the present invention, when the electronic device is connected or reconnected, the electronic device is similarly connected to the communication system, and the first register is transmitted to the bus management device having the first register indicating the use state of each channel of the bus. A command for reading the contents is transmitted, the contents of the first register are received, and a command for rewriting the contents of the first register is issued based on the received contents of the first register and the channel of the bus which the user desires to use. The data is transmitted to the bus management device.

In the communication system according to the present invention, at the time of connection or reconnection, the electronic device is similarly connected to the communication system, and transfers the contents of the second register to the bus management device having the second register indicating the available bandwidth of the bus. A bus management device transmits a command to read, receives the content of the second register, and issues a command to rewrite the content of the second register based on the received content of the second register and the bandwidth of the bus that the user wishes to use. To be sent to

According to the present invention, before and after the bus reset, the inter-device connection can be maintained regardless of the presence / absence or change of the electronic device that manages the inter-device connection of the entire system.

According to the present invention, the new AVM after the bus reset does not need to inquire connection information to each device. Since the process at the time of the bus reset is performed automatically, the user does not need to be conscious of the bus reset.

Hereinafter, the present invention will be described with reference to the drawings.
[1] Registration / deletion to CMT in the present invention [2] Processing at bus reset (2-1) When AVM does not exist before and after bus reset (2-2) AVM does not exist before bus reset and reset Cases Appearing Later (2-3) The AVM exists before the bus reset, and will be described in detail in the order in which it disappears after the reset.

[1] Registration / deletion to CMT according to the present invention FIG. 1 shows a layer diagram of processing transmission between the application 1, the command processing unit 2, and the inter-device connection processing unit 3 of the communication control microcomputer according to the present invention, and a structural diagram of the CMT. .

In the present invention, when the application 1 creates a command including connection parameters in response to a user operation, the command processing unit 2 assigns a connection ID uniquely determined in the device to each connection, and transfers the connection ID from the application 1. It registers with CMT4 with the parameter set. By passing this connection ID as a reply from the command processing unit 2 to the application 1, the application 1 thereafter only transmits a command using the connection ID, and the connection parameters are uniquely determined.

When the AVM does not exist in the communication system, the command processing unit 2 transmits a command including a connection parameter registered in the CMT 4 to the inter-device connection processing unit 3. The inter-device connection processing unit 3 executes inter-device connection processing according to the parameter. On the other hand, when an AVM exists, a command including a connection parameter registered in the CMT 4 is transmitted to the AVM, and the inter-device connection process is left.

When the command processing unit 2 receives a disconnection command for disconnecting a device from the application 1, the command processing unit 2 determines whether an AVM exists in the communication system. As described above, this release command is a command using the connection ID. Then, if no AVM exists, a release command is transmitted to its own inter-device connection processing unit 3, and if an AVM exists, a release command is transmitted to the AVM. After the own device connection processing unit 3 or the AVM performs the process of releasing the device connection, the command processing unit 2 deletes the connection ID and the parameter from the CMT 4.

Although the description has been given above of the portion for connecting the devices in each device, the AVM basically has the same configuration. The difference is that the AVM is configured to transmit and receive inter-device connection information with each device.

In the communication system shown in FIG. 5, consider a case in which, for example, playback is performed by CAM and recording is performed by VTR1, and an editing machine is operating VTR2 and VTR3.

FIG. 2 shows the CMT of the CAM at this time. In this figure, the output node ID of the parameter is the ID of the device outputting the information signal, in this case, the CAM node ID. The output plug number is the number of the plug that outputs the information signal, in this case, plug 0. The input node ID is an ID of a device that is inputting the information signal. In this case, since the CAM is in the reproduction mode and outputs the information signal to the bus, it is broadcast. The input plug number is a plug number for inputting the information signal. Here, since the broadcast output is performed, “don't care” is set. BW (Bandwidth) is a band required for transmitting an information signal. PB (Protect Bit) indicates whether or not the connection between devices is protected. In this case, it is 0 and is not protected. Connection ID = 1 is assigned to the inter-device connection having the above parameters.

Similarly, the CMT of the VTR 1 is shown in FIG. The broadcast of the output node ID of the parameter means that the input is from a default (fixed) channel.

(4) The CMT of the editing machine is shown in FIG. In this way, a case where an inter-device connection is established by a device that can manage another device such as an editing machine is called a one-to-one connection. In the case of one-to-one connection, PB is set to 1 because the connection between devices is protected.

(4) When the connection is broadcast, the connection between the devices is not normally protected. However, the connection between the devices can be protected by user setting. In this case, the command processing unit 2 receives a request for protection processing from the application 1. The command processing unit 2 sets PB of the corresponding connection ID on the CMT 4 to 1 when performing the protection processing, and sets PB to 0 when performing the protection release processing. However, in the case of a one-to-one connection, the PB is set to 1 at the time of registration because the connection is always protected when the connection is established.

[2] Processing at Bus Reset Next, processing at bus reset will be described.

(2-1) When there is no AVM before and after the bus reset When there is no AVM before the bus reset and no AVM after the bus reset, the command processing unit 2 of the CAM that has performed the broadcast output uses the CMT4. The above connection process is passed to its own inter-device connection processing unit 3. Similarly, the editor passes the one-to-one connection processing between the VTRs 2 and 3 registered on the CMT 4 to the inter-device connection processing unit 3. When the inter-device connection processing is actually executed, the inter-device connection is maintained. Here, the VTR 1 that has been performing the broadcast input need only be input from the default channel even after the reset.

Next, an example of a case where there is no AVM before the bus reset and no AVM after the bus reset will be described for a case where the recording operation between the CAM and the VTR 1 is stopped and the power of the CAM is turned off.

By stopping the video recording operation of the VTR 1 and the reproduction operation of the CAM, the CAM application 1 passes a command to release (disconnect) the broadcast output to the command processing unit 2. The command processing unit 2 passes this command to its own inter-device connection processing unit 3 because there is no AVM in the system. When the process of releasing the connection between devices is completed, the command processing unit 2 deletes the connection process corresponding to the connection ID of the release command notified from the application 1 from the CMT 4. Thereafter, when the power of the CAM is turned off, a bus reset occurs. After the bus reset, the editor issues a request for one-to-one connection processing to its own inter-device connection processor 3 because there is no AVM in the system. In the inter-device connection processing unit 3, the band and the channel are reacquired and the inter-device connection is reestablished, so that the editing operation between the VTR 2 and the VTR 3 by the editing machine is maintained.

(2-2) Case where AVM does not exist before bus reset and appears after reset Next, a case where AVM does not exist before bus reset and AVM appears after bus reset will be described. Here, it is assumed that the computer becomes an AVM and grasps the entire system.

(4) After the bus reset, the command processing unit 2 of the editing machine passes the one-to-one connection processing command to the AVM because the AVM exists in the system. The AVM passes the inter-device connection processing received from the command processing unit 2 of the editing machine to its own inter-device connection processing unit 3 to perform acquisition of a band and a channel and connection processing. After that, it is assumed that the operation between the VTR 1 and the VTR 4 is performed by the operation on the computer. In this case, the computer knows the band and the channel used by the editing machine, and performs the work such as editing using another channel. The AVM can forcibly release the connection between other devices if necessary to effectively use the entire bus.

(2-3) Case where AVM exists before bus reset and disappears after reset Next, a case where AVM exists before bus reset and AVM disappears after bus reset will be described. When the editing operation on the computer is completed, a bus reset is performed, and the computer exits the system management as the AVM, the editing machine knows that the AVM has disappeared, and sends a one-to-one connection command to its own device connection processing unit. Send to 3. Since the inter-device connection processing unit 3 of the editing machine executes the one-to-one connection processing according to this command, the editing work between the VTR2 and the VTR3 is continued. On the other hand, since the computer has exited the system management as the AVM and the CMT4 has been cleared, the connection between the VTR1 and the VTR4 is not re-established, and the connection between the VTR1 and the VTR4 operated on the computer remains released.

As described above, according to the present invention, the command processing unit 2 as the upper layer manages the CMT 4, checks the existence of the AVM, and transmits the processing on the CMT 4 to the AVM or its own inter-device connection processing unit 3. I do. Therefore, the connection between the devices on the system can be maintained regardless of the presence / absence and change of the AVM before and after the bus reset, and there is no need for the new AVM to inquire each device about the connection information on the CMT4.

For this reason, when a plurality of editing operations are performed, even if some editing machines or the like are disconnected and reconnected, the connection between the devices involved in the editing operation is cut off, but the other one-to-one connection is maintained. Since it is maintained, it is possible to conform to the principle that even if a device is inserted or removed on the P1394 system, other devices are not affected.

Further, according to the present invention, a unique connection ID is assigned to each connection, and the connection ID is registered in the CMT 4 together with the parameters passed from the application 1, so that the application 1 only needs to transmit a command using the connection ID. , The command processing unit 2 can uniquely determine a connection parameter and create a command using the parameter corresponding to the connection ID.

In the above example, the command using the connection parameters is transmitted and received between the command processing unit of each device and the command processing unit of the AVM. However, the AVM has the ability to manage the connection ID of each device. By providing the command, a command using the connection ID and the parameter is transmitted once, and after the command is registered in the CMT of the AVM, the command using the connection ID can be transmitted and received.

FIG. 4 is a diagram showing a layered view of processing transmission between an application of a communication control microcomputer, a command processing unit, and an inter-device connection processing unit, and a structural diagram of a CMT in the present invention. FIG. 4 is a diagram showing the contents of a CMT possessed by a CAM in the present invention. FIG. 3 is a diagram showing the contents of a CMT possessed by a VTR 1 in the present invention. FIG. 4 is a diagram showing the contents of CMT possessed by the editing machine in the present invention. 1 is a diagram illustrating an example of a communication system using a P1394 serial bus. FIG. 3 is a diagram illustrating an example of a data structure on a bus in a communication system using a communication system using a P1394 serial bus. FIG. 3 is a diagram illustrating a method for securing channels and bands in a communication system using a P1394 serial bus. FIG. 6 is a diagram illustrating a basic configuration of a VTR in the communication system illustrated in FIG. 5. FIG. 6 is a diagram showing an application of a communication control microcomputer in the VTR shown in FIG. 5, a layering of processing transmission between a command processing unit and an inter-device connection processing unit, and a structure of a CMT.

Explanation of reference numerals

Reference Signs List 1 application 2 command processing unit 3 device connection processing unit 4 CMT

Claims (12)

In a communication control method used in a communication system in which a plurality of electronic devices are connected via a bus capable of communicating information and control signals in a packet,
The electronic device outputs the information signal through an output plug or inputs the information signal through an input plug, and has a one-to-one connection with another electronic device similarly connected to the communication system. It is possible to hold connection information on each connection for each connection, the connection information does not include information on the connection destination, if a bus reset occurs during communication, A communication control method comprising reconstructing a connection state before the occurrence of the bus reset. The electronic device can perform a broadcast output that does not specify an electronic device to be input or a broadcast input that does not specify an electronic device to be output, and the connection information includes information about a broadcast output or a broadcast input. 2. The communication control method according to claim 1, wherein: 2. The communication control method according to claim 1, wherein the connection information includes information on protection of the connection. The communication control method according to claim 1, wherein the connection information includes information on a band required for communication of the information signal. At the time of connection or reconnection, the electronic device is similarly connected to the communication system, and issues a command to read the contents of the first register to a bus management device having a first register indicating a use state of each channel of a bus. Transmitting, receiving the contents of the first register, and issuing a command to rewrite the contents of the first register based on the received contents of the first register and the channel of the bus which the user wishes to use, 2. The communication control method according to claim 1, wherein the transmission is performed to a device. Upon connection or reconnection, the electronic device transmits a command to read the content of the second register to a bus management device that is similarly connected to the communication system and has a second register indicating an available bandwidth of a bus. Receiving the content of the second register, and instructing the bus management device to rewrite the content of the second register based on the received content of the second register and the bandwidth of the bus that the user wishes to use. 2. The communication control method according to claim 1, wherein the transmission is performed. In a communication system in which a plurality of electronic devices are connected via a bus capable of communicating information signals and control signals and communicating in packets,
The electronic device outputs the information signal through an output plug or inputs the information signal through an input plug, and has a one-to-one connection with another electronic device similarly connected to the communication system. It is possible to hold connection information on each connection for each connection, the connection information does not include information on the connection destination, if a bus reset occurs during communication, A communication system for reconstructing a connection state before the occurrence of the bus reset. The electronic device can perform a broadcast output that does not specify an electronic device to be input or a broadcast input that does not specify an electronic device to be output, and the connection information includes information about a broadcast output or a broadcast input. The communication system according to claim 7, wherein: 8. The communication system according to claim 7, wherein the connection information includes information on protection of the connection. 8. The communication system according to claim 7, wherein the connection information includes information on a band required for communication of the information signal. At the time of connection or reconnection, the electronic device is similarly connected to the communication system, and issues a command to read the contents of the first register to a bus management device having a first register indicating a use state of each channel of a bus. Transmitting, receiving the contents of the first register, and issuing a command to rewrite the contents of the first register based on the received contents of the first register and the channel of the bus which the user wishes to use, The communication system according to claim 7, wherein the communication is transmitted to a device. Upon connection or reconnection, the electronic device transmits a command to read the content of the second register to a bus management device that is similarly connected to the communication system and has a second register indicating an available bandwidth of a bus. Receiving the content of the second register, and instructing the bus management device to rewrite the content of the second register based on the received content of the second register and the bandwidth of the bus that the user wishes to use. The communication system according to claim 7, wherein the communication is performed.

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