JP2000022718A - Data transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To receive data transmitted from a node with high data transfer speed even at a node with low data transfer speed by constituting nodes by providing an area in which information to indicate the node at a transmitting origin by which the transmission is performed at present is stored. SOLUTION: The nodes mutually connected via a transmission bus are provided with storage means to store identification information to indicate the node at the transmitting origin by which data transmission is performed on the transmission bus at the present moment. In this system, the contents of a talker register at an IRM node B are read by using asynchronous transmission by a transmission and reception controller at a node C. Thus, an identification ID of a transmission node A is acquired as a talker ID by which the transmission is performed in a transmission channel which is desired to be received at present by the transmission and reception controller at the node C. Namely, an ID of the node at the transmitting origin by which the transmission is performed in the transmission channel on the transmission bus at the present moment is learned.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a data transmission system for transmitting data between a plurality of information processing devices connected to a bus.

[0002]

2. Description of the Related Art In recent years, an IEEE (Institute of Electrical and Electron) has been used as an interface for performing high-speed data transmission between various information processing apparatuses (hereinafter, referred to as nodes) such as computers, audio and video equipment.
ics Engineers) 1394-1995 standard is drawing attention.

FIG. 1 is a diagram showing an example of a network configuration using a plurality of information processing apparatuses (hereinafter, referred to as nodes) each having a data transmission interface based on the IEEE 1394 standard. In the example shown in FIG. 1, as each node, a CD (compact disk) player 10, an audio amplifier 20, a CD player 3
0, and the personal computer 40 is IEEE
Serial data transmission bus 100 based on 1394 standard
(Hereinafter simply referred to as a transmission bus 100).

In the IEEE 1394 standard, different transmission speeds (100 Mbps, 200 Mbps, 40 Mbps) are used.
(0 Mbps) are allowed to be mixed on one transmission bus. For example, in the connection form of FIG. 1, nodes having different transmission speeds such as a CD player 10: 100 Mbps amplifier 20: 200 Mbps CD player 30: 200 Mbps personal computer 40: 400 Mbps are connected to each other on transmission buses 100a to 100c. ing.

[0005] In data transmission based on the IEEE 1394 standard, according to a transmission format as shown in FIG.
Broadcast transmission is performed in isochronous transmission. In FIG. 2, a cycle start packet CS
Governs the reference time on the transmission bus 100,
Used for time correction in each node. The cycle start packet CS is transmitted at a transmission speed of 100 Mbps. Such a cycle start packet CS
Is transmitted, isochronous transmission is executed. The isochronous transmission is used when transmitting time-series data such as audio data and video data that need to be transmitted in real time. In the isochronous transmission, channel numbers 0, 1, 2,... N are assigned to each of a plurality of data packets, and simultaneous transmission between a plurality of different nodes is realized by time division. After the end of the isochronous transmission, a period until the next cycle start packet is used for the asynchronous transmission. Asynchronous transmission is intended for asynchronous data. In asynchronous transmission, a data packet has a transmission node ID and a reception node ID, and each node takes in a packet with its own ID.

One cycle consisting of the cycle start packet CS, isochronous transmission, and asynchronous transmission: a transmission cycle of 125 μsec is repeatedly executed.
Here, when the CD player 10 broadcasts the reproduced audio data, the CD player 1
0 uses the isochronous transmission to convert the reproduced audio data into data packets and transmit the data packets to the transmission bus 100b.
And 100c respectively. The CD player 30
A data packet from the CD player 10 is received via the transmission bus 100b, and is received.
To the personal computer 40 via. On the other hand, the audio amplifier 20 receives a data packet from the CD player 10 via the transmission bus 100c.

As described above, the audio data reproduced by the CD player 10 is broadcast to all the nodes connected on the transmission bus 100. However, in data transmission based on the IEEE 1394 standard,
High-speed data transmitted from a node with a high transmission rate cannot be received by a node with a low transmission rate.

For example, in the connection form shown in FIG. 1, the data transmission speed of the CD player 10 (100 Mbps)
s) is the data transmission speed of the CD player 30 (200 Mbps)
s) lower than. Therefore, this CD player 10
The data transmitted from the D player 30 at 200 Mbps cannot be received.
Also, it cannot be transmitted to the audio amplifier 20 via 0c.

That is, although 200 Mbps audio data reproduced and output from the CD player 30 is transmitted to the personal computer 40, the CD player 10
And it is not transmitted to the audio amplifier 20.
Thus, in transmission based on the IEEE 1394 standard,
If the transmission speed of the transmission source node is high, it cannot be received by a node having a low transmission speed.

[0010]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a data transmission system which enables a node having a low data transmission rate to receive data transmitted from a node having a high data transmission rate. I do.

[0011]

A data transmission system according to a first aspect of the present invention is a data transmission system for performing data transmission between a plurality of information processing apparatuses connected to each other via a transmission bus. At least one of the information processing devices includes a storage unit that stores identification information indicating the information processing device that is currently transmitting data on the transmission bus.

A data transmission system according to a second aspect of the present invention is a data transmission system for performing data transmission between a plurality of information processing apparatuses having different transmission speeds. Storage means for storing identification information indicating an information processing apparatus of a transmission source performing data transmission, and an information processing apparatus having a lower speed than the information processing apparatus of the transmission source exists between the information processing. At least one of the information processing devices recognizes the transmission source information processing device by reading out the storage content of the storage unit, and issues a transmission rate change request to the transmission source information processing device. Do.

[0013] A data transmission method according to a third aspect of the present invention is a data transmission method for performing data transmission based on the IEEE 1394 standard between a plurality of information processing apparatuses connected to each other via a transmission bus. At least one of the processing devices includes a storage unit that stores identification information indicating a source information processing device that is currently performing data transmission, and a transmission node that performs data transmission on the transmission bus includes Upon starting data transmission, at least one of the information processing devices includes a step of securing a transmission channel and a band used for the data transmission, and a step of storing identification information indicating the transmission node in the storage unit.
Execute

[0014]

FIG. 3 is a diagram showing a schematic configuration of a transmission interface circuit used in a data transmission system according to the present invention. The transmission interface circuit complies with the IEEE 1394 standard. In FIG. 3, the physical layer controller 1 is connected to a serial data transmission bus 100 (hereinafter simply referred to as a transmission bus 100) based on the IEEE 1394 standard via input / output ports 2a and 2b, respectively.

The physical layer controller 1 has an input / output port 2
While decoding the signal received via a or 2b into received data, the data packet to be transmitted is encoded. Further, the physical layer controller 1 performs initialization of a transmission operation and arbitration for obtaining a right to use the transmission bus 100 in response to various control commands from the transmission / reception controller 4 described later.

The link layer controller 3 packetizes time series data or various transmission control data to be transmitted, and extracts data packets from the received data. The transmission / reception controller 4 transmits time-series data such as audio or video data reproduced from an application layer such as a CD player or a DVD player to the transmission bus 10.
This is relayed to the link layer controller 3 so as to be broadcast on “0”. Further, the transmission / reception controller 4 restores the audio / video data from the received data packet as described above, and supplies this to an application layer such as an audio amplifier and an image display device.

The transmission interface circuit further includes a topology map register 5 and a speed map register 6 used when this node is selected as a bus manager, and a used channel register used when this node is selected as an IRM. 7, a bus capacity register 8, a bus manager ID register 9, and a talker register 10.

Hereinafter, a case where nodes A to D each having a transmission interface circuit as shown in FIG. 3 are connected to the transmission bus 100 in a form as shown in FIG. 4 will be described. The operation will be described. The maximum transmission speed of each of the nodes A to D is assumed to be: node A: 200 Mbps node B: 100 Mbps node C: 200 Mbps node D: 400 Mbps.

First, when the power of each node is turned on or when a node is connected (or disconnected) to the transmission bus 100, the node that first detects this is connected to the transmission bus 100.
Send a bus reset up. When such a bus reset is supplied to each of the nodes A to D via the transmission buses 100a to 100c, the transmission interface circuit provided at each node performs bus initialization as described below.

In response to the bus reset, first, a root node is selected from the nodes A to D connected to the transmission bus 100, and further, an IR is selected from among these nodes.
An M (Isochronous Resource Manager) and a bus manager are respectively selected. The bus manager is for performing power management and optimizing bus performance when performing transmission using the transmission bus 100, and the IRM is for controlling the transmission bus 100.
Is used to perform bus management such as allocation of a transmission band and a transmission channel of each node.

Here, it is assumed that in the connection form shown in FIG. 4, node A is selected as a bus manager and node B is selected as an IRM. As a result, the node A as a bus manager recognizes all the nodes A to D connected on the transmission bus 100 and stores the self ID indicating each of the nodes A to D in the topology map register 5. Furthermore, 2
Transmission speed information between nodes indicating the maximum transmission speed between two nodes is stored in the speed map register 6.

For example, in the connection form shown in FIG. 4, between nodes D and A: 200 Mbps between nodes A and B: 100 Mbps between nodes B and C: 100 Mbps between nodes D and B: 100 Mbps between nodes D and C: 100 Mbps node Between A and C: The transmission speed information between nodes of 100 Mbps is stored in the speed map register 6.
Will be stored.

On the other hand, the node B selected as the IRM stores the identification ID of the node A as the bus manager in the bus manager ID register 9. When the bus initialization as described above is completed, a data transmission operation according to the transmission format as shown in FIG. 2 is started. Here, for example, when the node A sends time-series data such as audio or video data on the transmission bus 100, first, the asynchronous transmission is used to transmit the IRM.
The read command is transmitted to the used channel register and the bus capacity register of the node B (hereinafter, referred to as IRM node B) selected as described above.

In response to the read command, the IRM node B sets the used channel register 7 as shown in FIG.
And the contents stored in the bus capacity register 8 are read out and transmitted to the node A as a transmission node by using asynchronous transmission. Note that the asynchronous transmission is performed at a transmission speed of 100 Mbps.

The node A confirms the unused channel and the remaining capacity of the bus by taking in the contents stored in the used channel register 7 and the bus capacity register 8 transmitted thereto. At this time, if an unused channel exists and the remaining capacity of the bus is sufficiently ensured, the node A stores the transmission channel number and the bus capacity to be used for transmission in the used channel register and the bus capacity register of the IRM node B. A write command to the register is transmitted to the IRM node B together with the transmission channel number and the bus capacity for storage.

The IRM node B performs a write process to write the transmission channel number and the bus capacity transmitted from the node A into the use channel register 7 and the bus capacity register 8, respectively. The write processing result information indicating whether or not the information is transmitted to the node A. The node A determines whether or not the rewriting of the used channel register 7 and the bus capacity register 8 has succeeded based on the write processing result information transmitted from the IRM node B, and proceeds to the next step. At this time, when it is determined that the rewriting has been successful, the node A as the transmitting node uses the transmission channel number desired for transmission as described above to identify the ID of the source node that is currently transmitting.
The identification ID of the node A itself is written into the talker register 10 (hereinafter, referred to as talker ID). For example, if the transmission channel number desired to be transmitted is the transmission channel 1, the identification ID "A" of the node A is set as the talker ID corresponding to the transmission channel 1 in the talker register 10.
It is written to.

Next, the node A starts transmission of time-series data using the transmission channel 1 in the isochronous transmission. That is, the node A converts the time-series data to be transmitted into a data packet at 200 Mbps.
At the transmission speed of the transmission bus 100a. At this time, the transmission speed of the Node B is 200 Mbps.
Since the transmission speed is 100 Mbps, the node A does not transmit the data packet on the transmission bus 100b. That is, although the data transmitted from the node A is transmitted to the node D, it is not transmitted to the nodes B and C.

However, when the node C is set to receive the transmission channel 1, the node C executes the forced reception subroutine as shown in FIG. Can be received. In FIG. 5, first, the transmission / reception controller 4 in the transmission interface circuit of the node C
By using the asynchronous transmission, the content of the used channel register 7 in the node selected as the IRM, that is, the IRM node B is read (step S
1) It is determined whether or not the desired transmission channel 1 set in the node C is currently in use (step S2). In this step S2, if it is determined that the desired transmission channel 1 is currently in use, the transmission / reception controller 4 then uses the asynchronous transmission to update the contents of the talker register 10 in the IRM node B. Read (Step S
3). By executing the step S3, the transmission / reception controller 4 in the node C acquires the identification ID of the transmission node A as the talker ID that is currently transmitting on the transmission channel 1 desired to be received. That is, at this time, the ID of the transmission source node transmitting on the transmission channel 1 on the transmission bus 100 is known.

Next, the transmission / reception controller 4 reads the contents of the bus manager ID register 9 in the IRM node B by using the asynchronous transmission again (step S4). By executing step S3, the transmission / reception controller 4 in the node C acquires the identification ID of the node A selected as the bus manager. Next, the transmission / reception controller 4 determines whether a node corresponding to the bus manager actually exists based on the identification ID (step S5). Step S5
, When it is determined that a node corresponding to the bus manager exists, the transmission / reception controller 4 reads out and acquires the contents of the speed map register 6 of the node selected as the bus manager by using asynchronous transmission. (Step S6). Next, based on the contents of the speed map register 6, the transmission / reception controller 4 determines the transmission speed S that can be transmitted in the transmission path from the transmission node A to the node C that is currently transmitting on the desired reception transmission channel. A determination is made (step S7). At this time, the data transmitted from the node A is transmitted to the node C via the node B, and the transmission speed of the node B is 100 Mbps between these nodes.
And the lowest possible transmission speed S is 100M
bps.

Next, the transmission / reception controller 4 transmits to the transmission node indicated by the talker ID acquired in step S3, that is, the node A, at the transmission available speed S by using the asynchronous transmission. (Step S8). On the other hand, if it is determined in step S5 that the node corresponding to the bus manager does not exist, the transmission / reception controller 4 of the node C is indicated by the talker ID acquired in step S3 by using asynchronous transmission. The transmission node A issues a transmission rate change request to perform transmission at the lowest speed of 100 Mbps (step S9).

Here, by executing the above step S8 or S9, the node A receiving the transmission rate change request
The current transmission speed is changed to the transmission speed specified by this transmission speed change request. In the example shown in FIG. 4, since the bus manager exists, the above-described step S8 is performed.
Alternatively, step S8 of S9 is executed. As a result, the transmission source node A sets the current transmission speed to the speed specified by the transmittable speed S, that is, 100 Mbps.
Change to Therefore, the node B shown in FIG. 4 can receive the data via the transmission bus 100b, and transmits the received data to the node C via the transmission bus 100c.

Therefore, first, 200 Mbps from node A
Although data transmission is performed only to the node D at the transmission speed of s, the transmission speed is automatically switched to 100 Mbps by executing the control as described above, so that the data from the node A can be received at the node C. It becomes. still,
In the above embodiment, the operation example in which the content of the talker register 10 of the IRM is read to confirm the transmission node and change the speed is described, but a transmission stop command is issued instead of the speed change. You may do it.

In the above-described embodiment, the transmitting node uses the used channel register 7 and the bus capacity register 8.
And access to the talker register 10 to secure the transmission channel and bus capacity to be used for transmission and to set the talker ID, but to allow other nodes other than the transmitting node to execute them. May be.

[0034]

As described above in detail, according to the present invention, in the transmission interface circuit based on the IEEE 1394 standard, an area (talker ID) for storing information (talker ID) indicating a transmission source node which is currently transmitting. A register 10) is provided. Therefore, if the contents of the IRM node are confirmed using the asynchronous transmission, not only the transmission channel and the bus capacity of the data currently flowing on the transmission bus but also the transmission source node which is transmitting at the present time can be recognized. become able to do. That is,
Not only a node having a high transmission rate but also a node having a low transmission rate can know the transmitting node which is currently transmitting on the transmission bus.

Therefore, a node having a low transmission rate can receive data from a node having a high data transmission rate by making a request to the transmitting node to change the rate using asynchronous transmission. is there. Incidentally, a node with a high transmission speed can know all the IDs of all the nodes that are transmitting at the current time by actually receiving the data flowing on the transmission bus. However, since there is a moment when the transmission channel is secured but transmission is not performed, all the transmission nodes cannot be always grasped by the method of actually receiving data as described above. . on the other hand,
In the present invention, by monitoring the IRM, it is possible to reliably grasp all the transmitting nodes.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a connection configuration by a plurality of nodes having a transmission interface based on the IEEE 1394 standard.

FIG. 2 is a diagram showing a transmission format based on the IEEE 1394 standard.

FIG. 3 is a diagram showing a configuration of a transmission interface circuit applied to the data transmission system of the present invention.

FIG. 4 is a diagram showing a node connection mode for explaining the operation of the present invention.

FIG. 5 is a diagram showing a flow of a forced reception subroutine executed based on the data transmission system of the present invention.

[Brief description of reference numerals]

 4 Transmission / Reception Controller 5 Topology Map Register 6 Speed Map Register 7 Channel Register Used 8 Bus Capacity Register 9 Bus Manager ID Register 10 Talker Register

Claims (7)

[Claims] 1. A data transmission system for performing data transmission between a plurality of information processing devices connected to each other via a transmission bus, wherein at least one of the information processing devices is A data transmission system comprising storage means for storing identification information indicating an information processing apparatus of a transmission source performing data transmission. 2. The information processing apparatus according to claim 1, wherein each of the information processing apparatuses recognizes a source information processing apparatus that is currently performing data transmission on the transmission bus by reading out the storage content of the storage unit. Item 2. The data transmission system according to Item 1. 3. The data transmission system according to claim 1, wherein each of said information processing apparatuses stores its own identification information in said storage means when starting said data transmission. 4. The data transmission system according to claim 1, wherein:
2. The data transmission method according to claim 1, wherein the data transmission is performed by isochronous transmission based on the IEEE 1394 standard, and the reading of storage contents from the storage unit is performed by asynchronous transmission. Transmission system. 5. A data transmission system for performing data transmission between a plurality of information processing apparatuses having different transmission speeds, wherein at least one of the information processing apparatuses includes information on a transmission source currently transmitting data. A storage unit for storing identification information indicating a processing device, wherein when an information processing device that is slower than the transmission source information processing device exists between the information processing devices, A data transmission system, wherein at least one of the data transmission systems recognizes the transmission source information processing device by reading out the storage content of the storage unit, and issues a transmission rate change request to the transmission source information processing device. 6. The data transmission system according to claim 1, wherein:
394 standard, wherein the data transmission is executed by isochronous transmission based on the IEEE 1394 standard, and the reading of storage contents from the storage means and the request for changing the transmission speed are executed by asynchronous transmission. The data transmission system according to claim 5, wherein 7. A data transmission method for performing data transmission between a plurality of information processing devices connected to each other via a transmission bus based on the IEEE 1394 standard, wherein at least one of the information processing devices is Storage means for storing identification information indicating the information processing apparatus of the transmission source performing data transmission, wherein the transmission node performing data transmission on the transmission bus starts the data transmission, At least one of the steps of: performing a step of securing a transmission channel and a band used for the data transmission; and a step of storing identification information indicating the transmission node in the storage unit.