WO1998049807A1

WO1998049807A1 - Bus control device and information processing system

Info

Publication number: WO1998049807A1
Application number: PCT/JP1998/001876
Authority: WO
Inventors: Soichi Isono; Hitoshi Ogawa; Katsumi Yamamoto
Original assignee: Hitachi, Ltd.
Priority date: 1997-04-30
Filing date: 1998-04-23
Publication date: 1998-11-05
Also published as: JPH10303949A

Abstract

A node connected ahead of a port is stored and a destination of a packet is discriminated, whereby a packet is transferred to a port which requires transfer of a packet, while a dummy signal having a lower dissipation power than at the time of packet transmission is sent to a port which does not require transfer of a packet. Thus, power consumption accompanied by the transfer of a packet to an unnecessary node is reduced in a state where bus collision is prevented.

Description

Description Knock control device and information processing system [Technical field]

The present invention relates to a bus control device and an information processing system, and more particularly to a bus control device and an information processing system suitable for power saving in a system to which a serial bus is applied.

(Background technology)

As a serial bus for information processing systems, the IEEE 1394 bus is a standard established by the United States Institute of Electronics and Electronics Engineers, Inc. (hereinafter referred to as IEEE). It is enacted as 95. Details of the IEEE1394 are disclosed in “IEEE Standard for a High Performance Serial Bus” issued by the IEEE.

Referring to FIG. 1, a description will be given of the cable connection specification of the IEEE 1394 bus _c . In FIG. 1, a plurality of devices are connected in a tree shape by cables. Each connected device is called a node.

In each node, a plurality of locations where cables are connected are provided. The point where the cable is connected is called a port.

In particular, in a node with three or more ports, the cable connection may be branched.

Buckets are sent and received between the nodes via cables. Command No. data is carried by sending and receiving this bucket.

In the IEEE 1394 specification, each node is considered to be connected to one virtual bus that is connected through one or more other nodes. For this reason, a bucket received from a certain node is sent to all nodes. As described above, a transmission path in which the entire connected transmission path acts as one virtual bus is called a virtual bus.

Figure 1 shows the packet transmission procedure performed by a conventional serial bus controller. A configuration example will be described.

For example, when sending a bucket from node # 0 to node # 1, first, node # 0 sends a bucket to node # 2. Then, node # 2 sends the packet received from node # 0 to node # 3 in addition to node #l. Thus, the bucket sent from node # 0 is transmitted to node # 1.

Here, the reason why node # 2 sends a packet to node # 3 is to prevent bus collision. A bus collision means that multiple nodes transmit buckets at the same time and interfere with each other.

Next, the operation when a certain node sends a bucket will be described.

A node sending a packet waits until the bus is free. The node monitors the signal of the cable connected to its own device, detects that no bucket is being sent, and determines that the bus is free. If the bus is free, it issues a bus use request signal, and if it gets the right to use the bus, it sends a bucket.

Thus, when another bucket is being transmitted on the bus, The sending of the packet is avoided.

The virtual bus also sends buckets to nodes that do not actually use the data and commands contained in the bucket. For this reason, there is a problem that power for transmitting and receiving unused buckets is wasted.

Also, if the sending of unused packets is simply omitted, a packet for transmitting another data is sent on a path where the bucket is not transmitted, depending on the use state of the bus. Bus collisions can occur when packets are transferred.

[Disclosure of the Invention]

A first object of the present invention is to reduce power consumption by transferring a bucket to an unnecessary node in a virtual bus.

A second object of the present invention is to prevent a bus collision in a virtual bus in a state where power consumption due to transfer of a bucket to an unnecessary node is reduced.

In order to achieve the first object, according to the first aspect of the present invention,

Multiple ports for sending and receiving serial signals to and from the other node to be connected In a bus control device capable of controlling a transmission path connected via the port as a virtual serial bus,

A first storage unit for storing information indicating the partner node connected to each of the ports in association with each port,

When transmitting a signal, a search unit for searching the first storage unit for port information in which information indicating a destination node to which the signal is to be transmitted is stored in association with the first storage unit;

This is achieved by providing a signal transmission unit for transmitting a signal to a port indicated by the information retrieved by the retrieval unit.

According to the second aspect of the present invention that achieves the first object,

Devices to be connected have a plurality of transmission lines connected by one-to-one serial signals, and the plurality of transmission lines constitute a virtual serial bus transmission line as a whole. At

A storage unit for storing a connection state in which the devices are connected,

For a signal to be transmitted, a discriminator for discriminating a path necessary for connecting a source and a destination of the signal and an unnecessary path,

This is achieved by providing a control unit for limiting the path through which the signal to be transmitted is transmitted to the path determined as the necessary path by the determination unit.

To achieve the second objective above,

According to a third aspect of the present invention,

In the bus control device according to the first aspect,

An extraction unit for extracting, from the ports indicated by the information stored in the first storage unit, ports that have not been searched by the search unit;

A suppression signal transmission unit for transmitting a suppression signal, which is a suppression signal for suppressing signal transmission from another node and generated with lower power consumption than a normal signal, to the port extracted by the extraction unit. And is further provided by:

ADVANTAGE OF THE INVENTION According to this invention, about the port which is unnecessary for packet transmission, transmission of the packet from the port can be omitted. Therefore, the power consumption of the device provided with this port can be reduced. In addition, it is possible to suppress the transmission of buckets to nodes that are not necessary for bucket transmission. Therefore, it is possible to reduce power consumption in each connected device and in a system to which a plurality of devices are connected. Also, while the bucket is being transmitted to the required node, the transmission of the bucket from other nodes is suppressed, so that bus collision is prevented.

In particular, in a virtual bus system having a path in which a plurality of nodes are connected in series, unnecessary packets are prevented from being transferred one after another, so that the effect of reducing the power consumption of the entire system becomes remarkable. .

Furthermore, the bus connection form can be dynamically acquired while the virtual bus system is operating. For this reason, it is possible to easily cope with a change in the connection mode, for example, connection / disconnection or movement of a device.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a system constructed by connecting a plurality of devices to a virtual serial bus.

FIG. 2 is a configuration diagram showing a system to which the second embodiment of the present invention is applied. FIG. 3 is a block diagram showing the configuration of a node.

FIG. 4 is a block diagram showing a configuration of a personal computer.

FIG. 5 is a block diagram showing the configuration of the magnetic disk drive.

FIG. 6 is a block diagram showing the configuration of the serial bus control unit.

FIG. 7 is an explanatory diagram schematically showing connections between nodes.

FIG. 8 is an explanatory diagram showing the relationship between the definition of the received value and the received signal.

FIG. 9 is an explanatory diagram showing the relationship between the signal determination value and the logical values of the reception value and the transmission value.

FIG. 10 is an explanatory diagram showing a signal state name and a function to be assigned to each transmission value.

FIG. 11 is an explanatory diagram showing signal state names and assigned functions for each received value. -Fig. 12 is an explanatory diagram schematically showing the bit transfer method.

FIG. 13A-13D is an explanatory view showing the structure of a self-ID bucket. FIG. 14 is an explanatory diagram showing the configuration of the asynchronous bucket.

FIG. 15 is an explanatory diagram showing the configuration of an isochronous bucket.

FIG. 16 is an explanatory diagram showing the configuration of the ACK bucket.

FIG. 17 is an explanatory diagram showing the relationship between node numbers and port numbers.

FIG. 18 is an explanatory diagram showing the relationship between channel numbers and transfer destination port numbers.

FIG. 19 is a time chart showing the procedure of operation at the time of bus initialization.

FIG. 20 is a time chart showing the procedure of the transfer operation of the isochronous bucket.

FIG. 21 is a flowchart showing a procedure of processing in the bucket analysis unit. FIG. 22 is a block diagram showing a configuration of a serial bus control device to which the first embodiment of the present invention is applied.

[Best mode for carrying out the invention]

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, a first embodiment of the present invention will be described with reference to FIG. 1 and FIG.

In FIG. 22, the serial bus control device 40 according to the present embodiment is configured to include a storage unit 45, an arithmetic control unit 46, and an interface unit 47.

In the storage unit 45, information indicating each port in a device provided with the serial bus control device 40 is stored in a first storage area in advance, and the arithmetic control unit 46 executes processing. Therefore, a program describing the procedure is stored in advance. The arithmetic control unit 46 executes a process for controlling the serial bus.

The interface unit 47 connects the arithmetic processing unit 46 with the storage unit 45, and transmits and receives signals to and from the main function unit of the device provided with the serial bus control device 40. For transmitting and receiving signals to and from a port provided in the system.

The arithmetic processing unit 46 transmits information indicating that the nodes connected to the bus transmit a signal including information indicating each node, and acquire a node included in the signal when the bus is constructed. And the nodes connected to the ports are stored in the second storage area of the storage unit 45 in association with each port. Further, when transmitting a signal, a port in which a destination node to which the signal is to be transmitted is stored in association with a port stored in the second storage area of the storage unit 45. Search for. Then, the interface unit 47 is provided with information indicating a signal to be transmitted and an instruction to selectively transmit the signal indicated by the information to the searched port.

Further, the arithmetic processing unit 46 extracts ports excluding the searched ports from among the ports indicated by the information stored in the second storage area.

Then, the interface unit 47 is given information indicating a suppression signal for inhibiting transmission of a signal to the node and an instruction to transmit the suppression signal to the extracted node.

Next, an operation when the serial bus control device 40 is applied to a system will be described with reference to FIG.

Here, an example will be described in which, among the nodes in the system configuration shown in FIG. 1, node # 2 is provided with a serial bus control device 40 to which the present invention is applied. The node provided with the serial bus control device 40 may be another node, and the number provided is not limited to one. For example, the serial bus control device 40 may be provided for all nodes.

In the system shown in FIG. 1, when a bucket is sent from node # 0 to node # 1, first, a bucket is sent from node # 0 to node # 2. Then, node # 2 sends the bucket received from node # 0 only to node # 1. Also, it sends a suppression signal to node # 3, and suppresses the sending of buckets from node # 3.

By operating as described above, it is possible to omit the transmission of the bucket and transmit only the inhibition signal to node # 3.

The power consumption for transmitting the suppression signal can be made smaller than the power consumption for transmitting the bucket. This is because the suppression signal may have a lower frequency than the bucket signal. Particularly, by using a DC signal as the suppression signal, it is possible to reduce power consumption.

In addition, since transmission of packets from node # 3 is suppressed, the power consumption of the entire system is reduced. If another node #N (not shown) is connected to node # 3, while a packet is being transferred from node # 0 to node # 2, or from node # 2 to node # 1, Buckets sent from the node #N onto the bus can be avoided by suppressing the sending of packets from the node # 3. Therefore, bus collision is prevented.

Next, a second embodiment of the present invention will be described with reference to FIGS.

Hereinafter, a case will be described in which a bus based on the IE EE 1394 specification is used as a virtual bus, but the bus to which the present invention is applied connects a plurality of devices with one-to-one serial signals. Any bus that uses the above connection collectively and enables data transfer equivalent to the virtual connection of each device to one bus may be used. The bus may be based on specifications.

In FIG. 2, an information processing system 100 in the present embodiment includes a personal computer (hereinafter, referred to as a PC) 30 and a magnetic disk device (hereinafter, referred to as an HDD) 31 and 3. 2, a CD-ROM reader (hereinafter referred to as CD-ROM) 3 3, a digital video tape recorder (hereinafter referred to as DVTR) 36, and a digital video disc reader (hereinafter referred to as DVD) It is configured to include 34, a digital camera 35, and a display device 37. As the display device 37, for example, a CRT display device, a liquid crystal display device, or the like can be used. It goes without saying that a television having an image input terminal can be used as the display device 37. Alternatively, image information may be input to the RF input terminal of the television via an RF converter or the like to display an image.

The PC 30 has two IE 13 94 ports 16-1 and 16-2.

HDD 31, 32 and CD-ROM 33 are connected to one port 16-1 of IE EE 1394 port provided in the PC 30, and the first IE EE 1 It is composed of 3 94 buses. The HDDs 31 and 32 and the CD-ROM 33 are used as ordinary external storage devices for the PC 30.

In addition, the other port 16 of the IE 1394 port provided in the PC 30 is used. 2, a DVTR 36, a digital camera 35, a DVD 34, and a display device 37 are connected to form a second IEEE 1394 bus different from the first IEEE 1394 bus. are doing. These are used for processing image information.

That is, image information digitized by the digital camera 35 and the DVD 34 is acquired, the acquired image information is stored by the DVTR 36, and an image indicated by the image information is displayed by the display device 37. be able to. The acquired image information can be directly displayed on the display device 37.

Further, a digital video tape in which image information is stored in advance may be reproduced using the DVTR 36 to acquire the image information.

In the present embodiment, the data capacity is large, and the first IE EE 394 bus to which the HDDs 31 and 32 and the CD-ROM device are connected, in which data having a small data capacity and frequent reading and writing are stored, has a large data capacity. Reading and writing are continuously performed for a long time. Data is stored. The DVD 34 and the DVTR 36 are connected to the second IEEE 1394 bus to be connected to operate independently. For this reason, it is possible to prevent the performance of the entire system from deteriorating when data having different read / write characteristics is transmitted by the same node.

Examples of data stored in the HDDs 31 and 32 and the CD-ROM device include, for example, programs.

Next, the configuration of each device will be described with reference to FIGS.

In FIG. 3, each device is configured to include a main function unit 41 for realizing a function unique to each device, and a serial bus control unit 42 for controlling the IEEE1394 bus.

With reference to FIG. 4 and FIG. 5, a configuration of the PC 30 and the HDD 31 will be described as a configuration example of the device.

First, the configuration of PC 30 will be described with reference to FIG.

In FIG. 4, the PC 30 includes a main function unit 411 and two serial bus control units 42-1 and 42-2. The main function unit 4 11 comprises a central processing unit (hereinafter referred to as a CPU) 51 for calculating data and the like, a memory 52 for storing data and programs, and a data processor. It has a display section 53 for displaying, an input section 54 for receiving instructions from the operator, and a normal parallel bus 55 for connecting these.

Each of the two serial bus controllers 42-1 and 42-2 can operate a single serial bus. Further, the serial bus control unit 42-1 and the serial bus control unit 42-2 can operate independently of each other. Accordingly, the PC 30 can operate the two serial buses independently of each other. C In particular, the serial bus control unit 42-2—to which the DVTR 36 shown in FIG. Provides a dedicated path 56 for sending image data directly to the display. As a result, even when a moving image having a large amount of data is reproduced on the display unit 53, a large load is not applied to the parallel bus 55, and a reduction in the processing speed of the CPU 51 can be prevented. Next, the configuration of the HDD 31 will be described with reference to FIG.

In FIG. 5, the HDD 31 includes a main function unit 41 and a serial bus control unit 42.

The main function unit 41-2 includes a magnetic recording disk 57 for recording data, and a recording / reproducing control unit 58 for recording / reproducing data on / from the magnetic recording disk 57 overnight. It is composed.

The serial bus controller 42 includes three boats 16. Each of these ports is numbered and distinguished from each other. Hereinafter, these three ports are numbered 1, 2, and 3.

Similarly, other devices are configured to include a main function unit and a serial bus control unit. The main function unit has a configuration for realizing the function of each device, but since this can be realized by a generally known configuration, the description of the configuration of the main function unit in these devices is omitted. I do.

Further, the serial bus control unit can be configured in the same manner as the serial bus control unit 42 of the HDD 31. However, the number of ports provided by the serial control unit corresponds to the specifications required for the device. Next, the serial bus control unit will be described in detail with reference to FIG. In FIG. 6, a serial bus control unit 42 includes an arbitration control unit 61, a bucket receiving unit 62, a bucket transmitting unit 63, a bucket analyzing unit 64, and a bucket generating unit 6. 5, a node connection storage unit 66, a dummy signal generation unit 67, a port control unit 68, and a port transceiver 69.

The arbitration control unit 61 is for performing a process of acquiring the right to use the IEEE1394 bus.

The bucket receiving section 62 is for receiving and temporarily storing a bucket.

The bucket transmitting unit 63 is for transmitting a bucket.

The bucket analyzing unit 64 analyzes the type of the received bucket, the transmission source of the bucket, and the reception destination of the received bucket. The above-mentioned bucket generating section 65 is only for generating a newly transmitted bucket.

The node connection storage unit 66 stores a connection relationship between the own node provided with the serial bus control unit 42 and another node connected via the IEEE1394 bus.

The dummy signal generation section 67 is for generating a dummy signal to be transmitted to a port that does not transmit a bucket.

The port transceiver 69 is for transmitting and receiving signals to and from the IEEE1394 bus. The port transceiver 69 has two pairs of terminals A and B. The pair A has a twisted pair 70 connected thereto, and the terminal pair B has a twisted pair 71 connected thereto. Through these two pairs of twisted wire pairs 70 and 71, two sets of differential signals are input to and output from the IEEE1394 bus.

The port control unit 68 is for setting the input / output operation of the port transceiver 69 individually for each port transceiver.

Next, with reference to FIG. 6 and FIG. 21, an outline of a procedure in which the bucket analysis unit 64 instructs the dummy signal generation unit 67 on the port number to transmit the dummy signal is described. explain about.

The bucket analyzing unit 64 first analyzes the received bucket, and obtains a source ID (identifier) indicating the node that transmitted the bucket (S I1).

Next, the node number stored in the node storage unit 66 is compared with the node number indicated by the source ID, and a matching node number is detected (S12).

Next, the detected node number is converted into a port number (first port number) connected to the node to which the node number is assigned (S13). For example, the conversion can be performed according to the information indicating the correspondence relationship described later (see FIG. 17). Then, a port number (second port number) of a port other than the port indicated by the converted port number among the ports provided in the own node is obtained (S14). The dummy signal generation section 67 generates a dummy signal and sends it to the second port number obtained above (S15).

According to the present invention, the dummy signal is generated and transmitted with lower power consumption than when a normal signal is generated.

Next, the connection between nodes will be described with reference to FIG.

One packet is sent as two pairs of differential signals between the two nodes. Each pair is represented by A and B. Furthermore, the signals of A and B are interchanged and connected. For example, the positive signal of A signal is A-P, the negative signal of A signal is A-N, the positive signal of B signal is B-P, and the negative signal of B signal is B-N. Specifically, as shown in FIG. 7, A—P of node m is connected to B—P of node n, and A—N of node m is connected to B—N of node n. Also, BP of node m is connected to A-P of node n, and BN of node m is connected to A-N of node n.

Next, with reference to FIG. 8, the possible values of the signals A and B will be described.

FIG. 8 is a table showing the correspondence between the differential voltage of A or B at the receiving end and the actual value on the signal lines 70 and 71, that is, the received value. If the positive / negative difference is greater than +168 mV, the received value is “1”. If the positive / negative difference is less than 1168 mV, the received value is “0”. If +89 mV, the received value is assumed to be “Z”.

The fact that the received value is “Z” means that the signal is driven from either the A or B node. Nodes A and B drive signals with opposite polarities, for example, when not driven or when node A outputs a signal with positive polarity and node B outputs a signal with negative polarity Is either case.

FIG. 9 is a table showing the relationship between the reception value and the transmission value of the own node, and the transmission value of the partner node determined from the reception value and the transmission value.

When the transmission value is “Z”, it indicates that no signal is being output.

In this embodiment, the state indicated by the signal is combined with two sets of signals A and B, and information describing the state is transmitted and received.

With reference to FIGS. 10 and 11, the relationship between the combination of signals and the state indicated by the combined signal will be described. Each of the signals to be combined indicates one of the above “1”, “0”, and “Z”.

In particular, when both A and B are “Z”, and when both A and B are “1”, it indicates the contents common to the setting on the transmitting side and the judgment on the receiving side. That is, if both A and B are “Z”, it indicates that the bus is unused. This signal state is denoted as IDLE. If both A and B are “1”, it means that the bus is initialized and reconfigured. This signal state is expressed as BUS—RESET.

First, the setting on the transmitting side will be described with reference to FIG.

In FIG. 10, among the combinations of the transmission values of the two signals A and B forming the pair, seven states are defined, and for each state, the signal state name and the meaning of the signal are defined. . "TX-" at the beginning of the signal state name is a notation that indicates transmission.

If a plurality of signal state names and meanings are defined for the same state, they are distinguished by the state generated by the signal transmitted before that. This distinction will be described later.

Next, the criterion of the receiving side will be described with reference to FIG.

In Fig. 11, among the combinations of the received values of the two signals Α and Β forming a pair, nine states are defined, and for each state, the signal state name and the meaning of the signal are defined . The “RX—” at the beginning of the signal state name is a table that indicates reception. If multiple signal state names and meanings are defined for the same state, these are distinguished by the state generated by the signal received before. This distinction will be described below.

In the above transmitter settings and receiver criteria, the state names after “TX” and “RX” are PARENT—NOT I FY, CHILD—N 0 TIFY, I DENT—DONE, and SELF. One ID, one GRANT, one ROOT, one CONTENT ION, one PARENT, HANDSHAKE, and one CHILD, one HAND SHAKE are used only when resetting the bus immediately after a bus reset.

REQUEST and GRANT are used for arbitration to secure the right to use the bus during normal operation.

DATA-PRE FIX and DATA-END are used during bus reconfiguration and during bucket transfer during normal use.

Note that the nodes are connected in a ring shape, and there is a connection relationship of PARENT and CH I LD between the two nodes connected to each other. PARENT sends a bus grant to CH I LD. If there are three or more nodes, a hierarchy of connection relationships may occur. For example, in the system shown in FIG. 1, node # 2 is a PARENT of node # 0 and node # 1, and is a CH ILD of node # 3. At the highest level, the node without PARENT is called the root. In the system shown in Fig. 1, node # 3 is strong and becomes the root.

Next, with reference to FIG. 12, the operation of the A and B signals during the bucket transfer will be described.

The B signal raises and lowers the signal level in accordance with the data bits "1" and "0" transmitted at regular time intervals. The A signal is inverted when the same data continues in the B signal. The data transfer rate is 98.304 Mb / sec.

Next, the configuration of the bucket will be described with reference to FIGS. 13A to 16. First, the configuration of the se 1 ί—ID bucket will be described with reference to FIGS. 13A-13D. se 1 f — The ID bucket is used to determine the node number when reconfiguring the bus. In Figure 13A, the 0th se1f—ID bucket is a phy-ID field that stores the node number and a gap that indicates the duration of the IDLE state required to detect unused buses. — The first 4 bytes including cnt, p 0, p 1, and P 2 indicating the port status, and the last 4 bytes having the inverted value of the above 4 bytes Consists of

Figure 13 B—13D 1st, 2nd, and 3rd se 1 f—ID buckets are used to reconfigure nodes with four or more ports, depending on the number of ports. The bucket up to the required number is sent. That is, when the number of ports is j, j se1f-ID packets from the 0th to the (j1-1) th are transmitted.

Next, the configuration of the asynchronous bucket will be described with reference to FIG. In FIG. 14, the asynchronous bucket is configured to have at least an asynchronous bucket among a bucket header and a data block.

The bucket header includes destination-ID indicating the destination node number, source-ID indicating the source node number, tcode indicating the type of bucket, and packet-type specified for each type of packet. — Speci fic information, packet—type—speci fic quadlet data, and | header—CRC to detect errors during transmission.

The data block is composed of d ata, d ata _C R C for error detection, and power.

Next, with reference to FIG. 15, a configuration of an isochronous bucket guaranteed to be sent at certain time intervals will be described.

The isochronous bucket is mainly used for transferring a large amount of data while maintaining a constant data transfer amount per unit time, such as for moving image reproduction. In an isochronous bucket, data is distributed to multiple buckets of equal capacity. In FIG. 15, the isochronous bucket is configured to include a bucket header and a detachable packet.

The bucket header includes ch anne 1 indicating a channel number, t c o de indicating a packet type, and he ad e r one C R R for detecting occurrence of an error during transmission.

And C. The channel number indicated by channe 1 above specifies the destination and the source node.

The above t c o de is a hexadecimal “A”.

The data block includes d ata and d ata — C R C for error detection.

Next, the configuration of the ACK bucket will be described with reference to FIG.

The ACK bucket is a packet indicating that an asynchronous bucket has been received. Immediately after receiving the asynchronous packet, the packet is transmitted while the sender of the asynchronous bucket has the right to use the bus. Sent.

In FIG. 16, the ACK packet is composed of a 4-bit ac k—co d e and a 4-bit a c k_p a r ty which is a two's complement of a c k—c o de. The above ack_pality is used to detect an error contained in the read bit.

Next, the connection state of the nodes stored in the node connection storage unit 66 (see FIG. 6) will be described with reference to FIGS.

First, the storage state of information for determining the transfer path of the asynchronous bucket will be described with reference to FIG.

In FIG. 17, this information is stored in a table format, and the node numbers are stored in association with the numbers of the ports to which the corresponding nodes are directly or indirectly connected.

Next, the storage state of information for determining the transfer path of the isochronous bucket will be described with reference to FIG.

In FIG. 18, this information is stored in a table format, and includes the channel number specified in the asynchronous packet and the number of the port to which the source and destination nodes are directly or indirectly connected. Are stored in association with each other.

Since an isochronous bucket may be sent to multiple nodes, multiple ports are associated with one channel number and sent to a port set to "1". .

Next, with reference to FIG. 19 and FIG. 20, the bus in this embodiment is controlled. Of the operation for the operation will be described.

In the system configuration according to the present embodiment, as shown in FIG. 2, two sets of IEEE 1394 buses are provided. However, since they operate in parallel, these two sets of IEEE 1394 buses are used. Among them, one set will be described. The operation of the bus connecting the PC 30, the HDD 31, the HDD 32, and the CD-ROM 33 will be described below as a typical example. The other system bus, which connects the PC 30, the DVTR 36, the digital camera 35, the DVD 34, and the display device 37, can be operated according to a procedure similar to the procedure described below. Of course. The node numbers in parentheses are the numbers set by the operations described below.

First, the procedure for setting the bus configuration during bus initialization will be described with reference to FIG.

In FIG. 19, in the initial state, the bus is in the BUS-RESET state.

When BUS-RESET is released at time t200, first, the connection relation of the tree structure is set.

At time t 201, the HDD 32 and the CD-ROM 33 are moved to the HDD 31,

PARENT — Output NOT I FY. On the other hand, HDD 31

CH I LD—NOT I FY is output to 32 and CD—ROM 33, and HDD 31 becomes a PARENT of HDD 32 and CD—ROM 33. CH I LD— NO

When T I FY is received, HDD32 and CD—ROM33 become PARENT_NO

Stop output of T I FY.

Next, at time t 202, the HDD 31 moves to PC 30 to PARENT—N

Output OT I FY. On the other hand, PC 30 outputs CH I LD —NOT I FY to HDD 31, and PC 30 becomes PARENT of HDD 31. CH I

Upon receiving LD—NOT I FY, HDD 31 sends PARENT—NOT I FY

CH I LD — Turn off NOT I FY output. PC 30 is the root.

At time t 203, the output of PARENT—NOT I FY is stopped by PC 3

When 0 is detected, PC 30 stops outputting CH I LD N 0 TIFY and sets the tree structure. The connection of the structure is determined.

Here, for the sake of explanation, the node that first outputs PARENT—NOT I FY and the output of HDD 32 and CD—ROM 33 \ The node that first outputs PARENT—N 0 TI FY A node may be any node that is connected to only one node, and may be any number of nodes. Even in such a case, it is needless to say that the connection relation can be set by a procedure similar to the procedure described above.

Next, the node number is set from time t204. The root PC 30 outputs GRANT to the HDD 31. Upon receiving the GRANT, the HDD 31 outputs a GRANT to the HDD 32 of the port number 2 of the two CH I LDs, and outputs a DAT A—PREF FIX to the CD—ROM 33. The HDD 32 that has received GRANT has a node number of 0 because it has not received any se 1 f—ID packet yet. The HDD 32 transmits a DATA-PREFIX, a seIF-ID packet indicating the node number 0, a DATA-END, and an IDENT-D0NE signal to the HDD 31 in this order. The HDD 31 transfers the DATA-PREFIX from the HDD32, the se1f_ID bucket indicating the node number 0, and the DATA-END to the PC 30 and the CD-ROM 32.

When HDD 31 receives IDENT-DONE, it transmits DATA-PREFIX to HDD 32 at time t205 and stops outputting DATA-END to PC 30 and CD-ROM 33. When the HDD 32 receives the DATA-PREFIX, the HDD 32 stops outputting the IDENT-DONE signal, and the assignment of the 0th node is completed. At this time, the HDD 31 receives the ID bucket indicating the node number 0, se 1 f—The ID bucket is received at the port number 2, so that the node 0 is connected to the second port. Record in the management table.

At time t205, when the output of DATA-END from the HDD 31 stops, the PC 30 outputs GRANT again (time t206), and starts setting the next node number.

The HDD 31 receiving the grant also transfers the grant to the CD-ROM 33 for which the node number has not been determined. CD—ROM 33 is a se 1 f ID The node number is 1 because one packet was received. As in the case of HDD 32, DAT A- PRE FIX, se 1 f_ID bucket indicating node number 1, D ATA—END, and I DENT—DONE are output, and the first node is assigned. The application is completed. The HDD 31 receives the se 1f—ID bucket indicating the node number 1 on the port number 3, so that the node connection storage unit 66 confirms that the first node is connected to the third port. (See Fig. 6) Record gc in the node connection management table in.

From time t208, the second node number is similarly assigned to HDD31. Since the second node is the HDD 31 itself, “0” is set as the port number to indicate that there is no connected port. Record on the table.

At time t 209, upon receiving I DENT— DONE, the PC 30 determines that the setting of the numbers of the HDD 31 and all the nodes connected thereto has been completed, and gives the third node number to itself. Assigned, self-ID packet with node number 3 notifies other nodes by ID packet. The HDD 31 records that the third node is connected to the first port in the node connection management table in the node connection storage unit 66 (see FIG. 6).

As described above, the node number of each node is set, and connection information indicating the configured connection state is recorded in the node connection storage unit 66 (see FIG. 6).

In this embodiment, node numbers are set as shown in parentheses in FIG.

Next, with reference to FIG. 20, an operation at the time of transferring a bucket will be described.

In FIG. 20, at time t301, the PC 30 vigorously outputs DATA-PREF IX, an asynchronous bucket from the third node to the 0th node, and a DATA-END signal. Send to HDD31.

HDD 31 sends data PRE FI from the node number of the source and destination via the second port to which HDD 32 is connected, and syncs from node 3 to node 0. Transfer the NAS bucket and the DATA-END signal. At the same time, the HDD 31 receives the DATA-PREF IX signal generated by the dummy signal generator 67 (see Fig. 6) from the third port to which the CD-ROM 33 is connected. (DC voltage) is output. As a result, bucket transmission from the CD-ROM 33 is prevented.

At time t 302, when the HDD 32 outputs the data—prefix, acknowledgment packet, and data—end signal, the HDD 31 sends the data to the PC 30 that is the source of the immediately preceding cascade packet. To transfer. At this time, the HDD 31 continues to transmit DATA-PREF IX to the CD-ROM 33.

At time t303, the HDD 31 finishes outputting the DATA-END signal to the PC 30 and also stops transmitting the DATA-PREFIX to the CD-ROM 33.

The CD-ROM 33 detects that the bus IDLE state has continued from the time t303, and outputs a RE QUEST signal requesting the right to use the bus. Upon receiving the GRANT signal, at time t305, the CD-ROM 33 transmits the DATA-PREF IX, the asynchronous bucket from the first node to the third node, and the DATA-END signal. Send to HDD31. The HDD 31 transfers these to the PC 30 and sends a DATA-PREF IX signal to the HDD 32. As a result, bucket transmission from the HDD 32 is prevented. At time t306, PC 30 returns an ACK packet, and at time t307, HDD 31 sends DAT A__P to HDD 32 until transmission of DAT A-END to CD-ROM 33 is completed. REFIX continues to be sent.

In the case of an isochronous bucket, the channel number is determined, the bucket is passed only to the required port, and a DATA- PRE FIX signal is output to the other ports. According to the specification, since an ACK bucket is not returned for an isochronous bucket, the DATA-PREFIX signal is released without waiting for the ACK bucket.

As described above, in the present embodiment, since a DC-less DATA- PRE FIX signal is transmitted to a port that does not need to transmit a bucket, waste of power consumption for transmitting a high-speed bucket is reduced. it can. Note that a signal with a frequency lower than that of a normal bucket signal should be used as a signal to suppress the transmission of a bucket from that port, as long as no other node detects an empty bus. Can In FIG. 20, if the HDD 31 does not output any signal to the CD-ROM 33 from time t301 to time t303, the CD-ROM 33 determines that the bus is in an unused state. And output a REQUEST signal. In this case, the CD-ROM 33 can be made to wait if the REQUE ST signal is ignored by the arbitration control unit 61 in FIG. 6 until the time t 304 of the HDD 31. Therefore, even in this case, the same effect as the above-described procedure can be obtained. INDUSTRIAL APPLICABILITY The present invention is applicable not only to the bucket transmission system but also to all systems for transmitting data between nodes using a bus.

The present invention is not limited to the disclosed embodiments, but includes various modifications included in the spirit set forth in the claims.

Claims

The scope of the claims

1. A bus controller that has multiple ports for transmitting and receiving serial signals to and from the other node to be connected and that can control the transmission path connected via the ports as a virtual serial bus At

First storage means for storing information indicating the partner node connected to each of the ports in association with each port,

When transmitting a signal, a search for searching the first storage means for information on a first port in which information indicating a destination node to which the signal is to be transmitted is stored in association with the information. Means,

Signal transmitting means for transmitting a signal to the first port;

Extracting means for extracting, from the ports indicated by the information stored in the first storage means, a second port which has not been searched by the search means;

A suppression signal for suppressing transmission of a signal from another node, the suppression signal being transmitted with a suppression signal generated with lower power consumption than a normal signal to the second port. Bus control device.

2. The bus control device according to claim 1,

The first storage means,

Means for determining a source node of a signal received by each of the ports,

Means for storing the obtained node in association with the port that has received the signal.

3. The bus control device according to claim 1,

The suppression signal sending means includes means for sending a signal having a power consumption smaller than the power consumption at the time of bucket transmission.

4. The bus control device according to claim 1,

The suppression signal sending means includes means for sending a DC signal.

5. The bus control device according to claim 1,

The suppression signal transmitting means transmits a signal having a frequency lower than that of the bucket signal. Including steps.

6. A device to be connected has a plurality of transmission lines connected by one-to-one serial signals, and the plurality of transmission lines constitute a virtual serial bus transmission line as a whole. Control device,

Storage means for storing a connection state in which the devices are connected to each other;

A determination means for determining, for a signal to be transmitted, a path necessary for connecting a source and a destination of the signal, and an unnecessary path;

And control means for limiting a path through which the signal to be transmitted is transmitted to a path required by the determination means and a path determined by the determination means.

Bus control device.

7. The bus control device according to claim 6, further comprising:

A pseudo-use state generating means for generating a pseudo-use state from the connected device, which can be regarded as a path in use state,

The pseudo-use state generating means sets the path determined as an unnecessary path by the determination means to the pseudo-use state.

8. The bus control device according to claim 6, further comprising: when a path determined as a necessary path by the determination unit is used, a bus use right from the path determined as an unnecessary path by the determination unit. A bus use right control means that does not allocate the use right of the bus even if the request is made.

9. a plurality of information processing devices having ports for transmitting and receiving serial signals to and from the other information processing device to be connected;

A bus connecting the plurality of information processing devices

An information processing system comprising: a bus control device according to claim 1 or 8, wherein at least one of the plurality of information processing devices includes the bus control device according to claim 1.

10. analyzing the received bucket to determine a destination ID indicating the destination node of the bucket;

Comparing the node number stored in the node storage unit with the node number indicated by the destination ID, and detecting a matching node number;

The detected node number is connected to the node with the node number. Converting the first port number to

Generating a second port number by obtaining a port number excluding the first port number among the ports provided on the own node;

Generating a dummy signal with lower energy than at the time of generating the packet signal; and transmitting the dummy signal to the second port.

And a bus control method.

11. The bus control method according to claim 10, wherein the step of generating the dummy signal includes the step of generating a dummy signal having lower power consumption than at the time of bucket transmission.

12. The bus control method according to claim 10, wherein the step of generating the dummy signal includes a step of generating a DC voltage.

13. The bus control method according to claim 10, wherein generating the dummy signal includes generating a signal having a lower frequency than the bucket signal.