JP2001237865A - Communication unit and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relieve a load of data transfer between devices connected to a serial bus. SOLUTION: The communication unit is provided with a serial bus 4 that transmits data, a magneto-optical disk 1 and an optical disk 2 that transmit data as a periodic isochronous packet to the serial bus 4, and an amplifier 3 that monitors the transmission of the isochronous packet from the magneto- optical disk 1 and the optical disk 2 via the serial bus 4 and starts reception of the isochronous packet via the serial bus when detecting the transmission of the available isochronous packet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication apparatus and method for transmitting data between a plurality of devices connected to a serial bus.

[0002]

2. Description of the Related Art Conventionally, devices provided with an interface for connecting to a serial bus conforming to the so-called IEEE1394 standard have been provided.

For example, a magneto-optical disk drive for recording / reproducing on / from a magneto-optical disk such as a so-called MD,
2. Description of the Related Art There has been provided an optical disk apparatus for reproducing data from an optical disk such as a CD, which has an interface for transmitting and receiving data to and from a serial bus according to a predetermined protocol.

Devices having an interface connected to the serial bus can transmit data as a stream to desired devices connected to the serial bus network.

[0005]

When a device connected to a serial bus network transmits and receives a stream in a coordinated manner, the device to which the stream is transmitted and received acts as a controller to control the other device. Was controlled as a target.

In this case, it is necessary for the controller to check and manage all the states in order to exchange streams.
It was putting a heavy burden on the controller.

The present invention has been proposed in view of the above situation, and has as its object to provide a communication apparatus and a method for reducing the burden of transmitting and receiving a stream via a serial bus network. And

[0008]

In order to solve the above-mentioned problems, a communication apparatus according to the present invention comprises a bus for transmitting data, and a first device for transmitting data to the bus as periodic packets. A second device that monitors periodic transmission of packets from the first device via the bus, and starts receiving the packets when the transmission of available packets is detected. .

A communication device according to the present invention includes a bus for transmitting data, a first device for transmitting data to the bus as periodic packets, and a status of the first device via the bus. And a second device that starts receiving the packet when the first device detects that the first device is in a state of transmitting a periodic packet.

[0010] A communication method according to the present invention provides a first method for transmitting data as periodic packets to a bus for transmitting data.
And a second step of monitoring the periodic packet transmitted in the first step via the bus and detecting the transmission of the available packet to start receiving the packet. Have

Further, the communication method according to the present invention includes a first step of transmitting data as a periodic packet to a bus for transmitting data, and monitoring a state of the first step, When detecting that a state of transmitting a periodic packet has been reached, a second step of starting reception of the packet is started.
And the step of

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows, as an embodiment of the present invention, a magneto-optical disk device 1 for recording / reproducing on / from a magneto-optical disk such as a so-called MD, and an optical disk device 2 for reproducing an optical disk such as a so-called CD. And a recording / reproducing device including an amplifier 3 for outputting audio.

In this embodiment, a plurality of devices such as a magneto-optical disk device 1, an optical disk device 2, and an amplifier 3 are connected by a serial bus 4 defined by IEEE1394. The magneto-optical disk drive 1 and the optical disk drive 2 pass audio signal packets to the serial bus 4, and the amplifier 3 receives the packets from the serial bus 4 and outputs them. The amplifier 3 outputs in real time in synchronization with reproduction in the magneto-optical disk device 1 and the optical disk device 2.

The magneto-optical disk drive 1 and the optical disk 2 are first devices for transmitting data as packets, and the amplifier 3 is a second device for receiving packets.

In the magneto-optical disk device 1 shown in FIG. 2, a CPU (central processing unit) 11 controls each part of the magneto-optical disk device 1. The RAM 11 has a CPU 11
The data and programs necessary for executing various processes are stored as appropriate. Interface 10
Executes an interface process for the serial bus 4. That is, the interface 10 sends the control data supplied via the serial bus 4 to the CPU 11 and encodes / decodes pulse-code modulation (PCM) audio data.
6 is output.

The encoder / decoder 16 controls the so-called ATRAC (adaptive transform ac) under the control of the CPU 11.
oustic coding).
PCM audio data provided from the interface 10 is encoded and output to the recording / reproducing system 13.

The CPU 11 controls the recording operation of the recording / reproducing system 13 and the optical pickup 14 based on the control data supplied from the amplifier 3 via the interface 10. The recording / reproducing system 13 adds an error correction code to the PCM audio data, performs predetermined modulation processing, and then supplies the data to the optical pickup 14 for recording in the designated area of the magneto-optical disk 15.

The data reproduced from the magneto-optical disk 15 by the optical pickup 14 is supplied to an encoder / decoder 16 after being subjected to error correction processing and predetermined demodulation processing in a recording / reproducing system 13. The encoder / decoder 16 converts the input reproduction data into PCM audio data by adaptive conversion acoustic decoding, and sends the PCM audio data to the interface 10. This PCM audio data is transmitted to the serial bus 4.

The CPU 11 has an interface 10
And sends a control command to the serial bus 4 via the.

The optical disk device 2 has basically the same configuration as the magneto-optical disk device 1. The optical disk device 2
The magneto-optical disk 15 in the magneto-optical disk device 1 is used for an optical disk, the recording / reproducing system 13 is used for a reproducing system,
The decoder 16 is replaced by a decoder, but the other parts have a common configuration.

In the amplifier 3 shown in FIG.
Controls each part of the amplifier 3. The RAM 32 has a CPU
A program to be processed by 31 is appropriately developed. The work RAM 33 stores data and the like necessary for the CPU 31 to execute various processes as needed. Operation panel 3
4 sends to the CPU 31 various operations on the amplifier 3 input by the user.

The interface 35 is connected to the serial bus 4
The CPU 31 and the control signal are transmitted to the D / A conversion circuit 36 and the PC.
Interface processing is performed for each of the M audio data. The D / A conversion circuit 36 converts the PCM audio data into a left channel analog audio signal and a right channel analog audio signal, and outputs the analog audio signal to a speaker (not shown) (not shown).

IEEE1394, which is a standard of the serial bus 4 of the recording / reproducing apparatus, has a CSR (control & status registry) having a 64-bit address space defined by ISO / IEC13213.
r) It conforms to the architecture.

FIG. 4 is a view for explaining the structure of the address space of the CSR architecture. The upper 16 bits are for each IE
This is a node ID indicating a node on EE1394, and the remaining 48 bits are used for designating an address space given to each node. The upper 16 bits are further divided into 10 bits of a bus ID and 6 bits of a physical ID (node ID in a narrow sense). Since a value in which all bits are 1 is used for a special purpose, it is possible to specify 1023 buses and 63 nodes.

Of the 256 terabytes of address space defined by the lower 48 bits, the space defined by the upper 20 bits is a 2048 byte CSR-specific register or IEEE.
The space is divided into an initial register space (private space), an initial memory space, and the like, which are used for an E1394-specific register. If the space defined by 20 bits is the initial register space,
Configuration ROM (configuration read only
memory), an initial unit space used for a node-specific application, a plug control register (PCRs), and the like.

The nodes are connected in a daisy chain format and a branch format. The connection configuration of the node is automatically recognized and set. This setting includes bus initialization and tree identification.
The identification is performed in the order of identification of the own node ID.

When a node is added to the bus, a bus reset signal changes all nodes to a special state, initializes the bus by clearing all topology information, and begins the next phase. After the bus is initialized, the information that each node knows is whether it is a branch node that is directly connected to a plurality of adjacent nodes or a leaf node that has only one adjacent node. ,
It's just that they are isolated and not connected.

FIG. 5 shows an example of a network constituted by leaf nodes and branch nodes. Nodes a, c and e are leaf nodes, and nodes b and d are branch nodes.

When bus initialization is complete, the tree recognition process performs tree recognition and converts the entire network topology into a single tree. One node in the tree is designated as the root, and all physical connections connected to that root point in the direction of the root node.

Then, a label is assigned to each connected port to designate a direction, and as shown in FIG. 6, a parent port (parent; p) connected in a direction close to the root,
Or a child (chil) connected to a node far from the root
d; ch) Assign a port. Assign the label off to ports that are not connected.

A node such as the node b in which all connection ports are recognized as children is a root node. The selection of the root node does not depend on the tree topology, and the leaf node may be the root node.

The next step is a Physic unique to each node.
This is a self-identification that gives an opportunity to select al_ID and identifies itself to the management element attached to the bus. This is necessary to achieve a low level of power management and to create a topology map of the system needed to determine the service capabilities of each data path.

The self-identification process employs a deterministic selection process. That is, the root node passes control of the media to the node associated with the connection port having the lowest number, and waits until the node sends an ident_done signal indicating that itself and all of its child nodes have identified themselves. I do. Thereafter, the root transfers control to the next upper port and waits for the processing of the node to be completed.

As described above, when the nodes related to all the ports of the root end the processing, the root itself identifies itself. Child nodes use the same process recursively, as shown in the following example. When the bus is idle for the duration of the subaction gap, it is clear that the self-identification process has been completed.

The self-identification is performed by transmitting one to four very short self-identification packets containing Physical_ID and other management information to the cable. The Physical_ID is a value obtained by simply counting how many times the node has passed through the node receiving the self-identification information before transmitting the self-identification packet. For example, the first node transmitting the self-identification packet selects 0 as Physical_ID, and the second node selects 1 as Physical_ID.

The management information included in the self-identification packet includes a gap timer setting code, a power supply code required to operate the related link layer, and various port states (not connected, connected to child, parent Connection), data rate limit.

FIG. 7 shows the state of the bus after the self-identification process has been completed. The label ch-i is assigned to each child port, and the node connected to this port is identified.

In the initial register space shown in FIG. 4, a CSR architecture exists as a basic architecture for node management. FIG. 8 shows the main C
It is a figure explaining offset address, name, and function of SR. The offset in FIG. 8 indicates an offset address from the address FFFFF0000000h (the number ending with h indicates hexadecimal notation) at which the initial register space starts. Bandwidth available register with offset 220h
ister) indicates a band that can be allocated to isochronous communication, and only the value of a node operating as an isochronous resource manager is valid. The maximum value is stored in the bandwidth available register when no bandwidth is allocated to isochronous communication,
Each time a band is allocated, its value decreases.

The channels available registers at offsets 224h to 228h are:
Each bit corresponds to each of the channel numbers from 0 to 63, and if the bit is 0, it indicates that the channel has already been allocated. Only the channels available register of the node operating as the isochronous resource manager is valid.

Returning to FIG. 4, a general ROM (read only) is stored at addresses 200h to 400h in the initial register space.
memory) A configuration ROM based on the format is arranged.

FIG. 9 is a view for explaining the general ROM format. A node that is a unit of access on IEEE1394 can uniquely identify a plurality of units that operate independently while using an address space in common among the nodes. The unit directory (unit_directories) can indicate the version and location of software for this unit. Bus info block (bus_info_bloc
The positions of k) and the root directory (root_directory) are fixed, but the positions of other blocks are specified by offset addresses.

FIG. 10 is a diagram showing details of the bus info block, the root directory, and the unit directory. Company_ID in the bus info block includes
An ID number indicating the manufacturer of the device is stored. The Chip_ID stores a unique ID unique to the device and unique in the world that does not overlap with other devices. In addition, according to the standard of IEC1883, IEC18
The first octet of the unit specification ID (unit_spec_id) of the unit directory of the device that satisfies 83
00h is written in the second octet, A0h is written in the second octet, and 2Dh is written in the third octet. Furthermore, the first octet of the unit switch version (unit_sw_version) is 01h, and the LSB of the third octet (l
1 is written in the east significant bit).

As shown in FIG. 11, the IEEE 1394 protocol includes a physical layer, a link layer, and a transaction layer.

Among them, the bus management provides basic functions for node control and bus resource management based on the CSR architecture. Only one node that performs bus management exists and operates on the bus.

The bus management node provides a management function to other nodes on the serial bus. The management functions include cycle master control and performance optimization, power supply management, transmission speed management, and configuration management.

The bus management function is roughly divided into three functions: a bus manager, isochronous resource management, and node control.

The node control enables inter-node communication in the physical layer, link layer, transaction layer, and application by means of CSR.

In isochronous resource management, synchronous data transfer called isochronous transfer is performed in addition to asynchronous data transfer. Isochronous resource management manages the assignment of the isochronous data transfer low band and the channel number. There is only one node that performs this management on the bus. This node is dynamically selected from nodes having the isochronous resource management capability after the bus initialization phase.

This node also determines a bus management node. In a configuration in which a bus management node does not exist on the bus, the isochronous resource management node performs a part of bus management functions such as power management and cycle master control.

It is the serial bus management service provided by the bus manager that interfaces the bus control to the application. The control interface includes a serial bus control request (SB_CONTROL.reques
t), serial bus control confirmation (SB_CONTROL.confirmatio
n), Serial bus event notification (SB_EVENT.indicatio
n) there. SB_CONTROL.request is used when an application requests bus management such as bus reset, bus initialization, and bus state information. SB_CONTRO
L.confirmation notifies the application of the result of SB_CONTROL.request from the bus management. SB_EVENT.indic
The ation is used to notify the application of events that occur asynchronously from the bus management to the application.

The protocol used for the IEEE 1394 data transfer includes synchronous data of an isochronous packet that needs to be transmitted periodically and asynchronous data of an asynchronous packet that allows data transmission and reception at an arbitrary timing. Real-time synchronization data is guaranteed.

In the data transfer, prior to the transfer, an attribution for requesting a bus use right and obtaining a license is performed.

In the asynchronous transfer, the transmitting node ID and the receiving node ID are sent as packet data together with the transfer data. When the receiving node confirms its own ID and receives the packet, it returns an acknowledge signal to the transmitting node. This ends one transaction.

In the isochronous transfer, the transmitting node requests an isochronous channel together with the transmission speed.
The channel ID is sent as packet data together with the transfer data. The receiving node confirms the desired channel ID and receives the packet. The required number of channels and the transmission speed are determined by the application layer.

The above is a rough data transfer method. These data transfer protocols are defined by three layers: a physical layer, a link layer, and a transaction layer.

The physical layer is a physical and electrical interface with the bus, and performs automatic recognition of node connection, arbitration of bus use rights between nodes on the bus (bus attribution), and the like.

The link layer performs cycle control for addressing, data check, transmission and reception of packets (isochronous and asynchronous), and isochronous transfer.

Then, a transaction layer (tran
In the saction layer), processing relating to asynchronous data is performed.

The types of transactions include a read (read) transaction, a write (write) transaction, and a lock transaction.

In a read transaction, a controller (request node) reads data in a memory at a specific address of a target (response node). The read transaction includes a 4-byte quadlet read and a 4-byte or more block read. The request node may be called an initiator instead of the controller.

In a write transaction, the controller writes data to a memory at a specific target address. Write transactions also include quadlet (4 bytes) write and block (4 bytes or more).

In the lock transaction, the reference data and the update data are transferred from the controller to the target, the reference data and the data of the target address are combined, and a process such as swap is performed to update the data of the address specified by the target.

As shown in FIG. 12, the read (read), write (write), and lock commands are realized by a request / response protocol in the transaction layer based on the CSR architecture.

The request / support / response confirmation shown in FIG. 12 is a service unit in the transaction layer. The transaction request is a packet transfer (TR_D
ATA.request) Transaction notification (TR_DATA.indicat
ion) is a notification that the request has arrived at the responding node, a transaction response (TR_DATA.response) is an acknowledgment transmission and a transaction confirmation (TR_DATA.confirmation)
Is acknowledgment reception.

The asynchronous transfer cycle in the transaction layer is 125 μs, and the asynchronous packet length is set so that the data transfer time on the bus is less than 62 μs.

One packet transfer process performed in the link layer is called a subaction, and there are two types, an asynchronous subaction and an isochronous subaction.

The asynchronous sub-action is a sub-action for transferring asynchronous (asynchronous) data, and an acknowledgment (delivery acknowledgment) is transferred from the target (response node) to the initiator (request node).

The isochronous subaction is a subaction for transferring isochronous (synchronous) data, and no acknowledgment is performed.

The sub-action includes an arbitration phase, a packet transfer phase, and an acknowledge face.

A node called a cycle master for generating a period of 8 kHz (125 μs) exists on the bus (the root node plays the role). As shown in FIG. 13, the cycle master transmits a cycle start packet at a cycle of 8 kHz.

The cycle start packet is broadcast to all nodes on the bus, and each node sets a cycle time in the packet in a cycle timer register. This makes it possible to adjust the time lag of each node even if the cycle start packet that normally arrives every 125 μs is delayed.

After receiving the cycle start packet, the isochronous packet transmitting node starts a transmission request operation,
Transmit a bus acquisition (after arbitration) packet. All nodes have completed the transmission of the isochronous packet and correspond to a subaction gap.

As shown in FIG. 13, in IEEE1394, data is divided into packets and transmitted in a time division manner on the basis of a cycle having a length of 125 μS. This cycle is created by a cycle start signal supplied from a node having a cycle master function (any of the devices shown in FIG. 1). The isochronous packet secures a band (a time unit but called a band) necessary for transmission from the beginning of every cycle. Therefore, in isochronous transmission, transmission of data within a certain time is guaranteed. However, if a transmission error occurs, there is no protection mechanism and data is lost. The above-described audio data is transmitted in the isochronous packet.

At a time when the bus is not used for isochronous transmission in each cycle, the node that has secured the bus as a result of arbitration sends out an asynchronous packet. In asynchronous transmission, reliable transmission is guaranteed by using acknowledgment and retry.
The transmission timing is not constant.

As shown in FIG. 14, the link layer is, like the transaction layer, a link request (LK_DATA.request) for requesting packet transfer to the responding node, and a link notification (LK_DATA.in) for notifying the responding node of packet reception.
dication), a link response (LK_DATA.response) for acknowledgment transmission from the responding node, and a link confirmation (LK_DATA.confirmation) service for acknowledgment reception of the requesting node.

As described above, data is transmitted in packets. Packets for transmitting data are basically divided into three types. These are the PHY packet of the physical layer, the primary packet and the acknowledge packet of the link layer.

The PHY packet is a self-ID packet used for self-node ID identification, a PHY configuration packet used for optimizing performance at the time of initializing the bus, and sent to a node (link layer) that is not automatically turned on. This is a link-on packet.

The acknowledgment packet contains ack_code 1
This is a byte packet, and is returned as a response from the responding node to the primary packet (excluding broadcast and isochronous packets) from the requesting node.

The primary packet is a packet used for user data transmission, and is divided into an asynchronous packet and an isochronous packet.

As shown in FIG. 15, in the first quadlet of the isochronous packet, data_length indicating the data length in the data field is arranged first in the order of transmission, and indicates the format of the isochronous packet.
tag follows.

Further, this quadlet has a channel identifying a channel to which an isochronous packet is sent.
l, transaction code (tra
nsaction code) and sy representing a synchronization code used for synchronizing video and audio are included in order.

The head quadlet has a header_CRC (circular redundancy code) for one quadlet, a data field for each quadlet, and a quadlet.
data_CRC follows. If the data field contains a value that is not a multiple of 4, the sender fills the data field with 0 ₁₆ data so that the data field is the full length of the quadlet.

The asynchronous packet is, for example, FC
Used for P (functional control protocol). This FCP will be further described later.

In IEEE1394, AV data is transferred in real time using isochronous packets.
A protocol is provided.

The AV protocol is Digital Interface for Co.
Defined as nsumer Electric Audio / Video Equipment. The AV protocol is specified by the audiovisual digital interface of consumer electronic products based on the IEEE1394 standard. The physical layer, link layer, and transaction layer protocols conform to those defined in the IEEE1394 standard.

The AV protocol mainly defines a real-time data transfer protocol using isochronous data transfer and isochronous data flow control.

As shown in FIG. 16, the AV protocol for real-time transfer specifies a common isochronous packet (CIP). CIP consists of a CIP header followed by a real-time
The data section of the AV data is stored in the data field of the isochronous packet.

The CIP header is located at the beginning of the data field of the synchronous packet, and contains information on the type of real-time data contained in the data field that follows.

As shown in FIG. 17, the CIP header has an EOH_n (end of CIP he) indicating the last quadlet of the CIP header.
ader), Form_n indicating an additional structure of CHF_n in combination with EOH, and CHF_n (CIP header field) which is a CIP header field of the nth quadlet.

If EOH_n is “0”, it indicates that another quadlet continues, and “1” indicates that it is the last quadlet of the CIP header. The additional structure of CHF_n is E
It depends on the structure of OH_0, Form_0, ..., EOH_n, Form_n.

This protocol transfers a source packet from an application on a device to an application on another device. It is assumed that the source packet on the transmitting side is of fixed length based on the type of data. The data rate is variable.

As shown in FIG. 18, the source packet on the transmitting side is transmitted as a plurality of isochronous packets divided into 1, 2, 4, or 8 data blocks.
The packet receiving side collects the data blocks in the isochronous packet, combines them, restores the data, and sends the restored data to the application.

Here, since the receiving side of the packet must assemble these packets and return to the original packets, a time stamp field necessary for restoring real-time data is prepared in the CIP header. When the device is activated, packets are transferred every cycle of the bus.

If there is no data to be sent here, an empty packet containing only a packet header and a CIP header is sent. CIP
The header includes a block count value and a data code (DVC) for detecting data block erasure during packet transfer.
R, MPEG).

For a fixed length source packet, Form_0
= 0, Form_1 = 0 Two quadlet CIP headers are defined as standard. As shown in FIG. 19, two quadlets CI
There are two types of P headers. CIP shown in FIG.
Although the header has a SYT field, C shown in FIG.
There is no SYT field in the IP header. The device transfers real-time data as identified by the FMT header,
When a time stamp is required in the CIP header, a format having a SYT shown in FIG. 19A is used.

In this embodiment, real-time data is transferred using the format shown in FIG. The hatched portion in the figure is a portion used for determining whether or not the amplifier 3 can reproduce real-time data, which will be further described later.

[0098] These CIP headers are the node ID of the transmitting side.
SID (source node ID), DBS (data block size in quadlets)
It has a fraction number (FN), which is the number by which a data packet is divided into one source packet.

Since the maximum payload size in the 100 Mbps S100 mode specified in IEEE1394 is 256 quadlets, the DBS field is set to 8 bits. If all 8 bits are "0", it means that it is 256 quadlets. Then, from “00000001 ₂ ” to “111”
11111 ₂ "to one quadlet to 255
Increase sequentially to quadlets. Specifically, it is as follows.

00000000 ₂ = 256 quadlets 00000001 ₂ = 1 quadlet 00000010 ₂ = 2 quadlets 11111111 ₂ = 255 quadlets When a wider bandwidth is required for the 200 Mbps S200 mode or the 400 Mbps mode, the bus is transferred. One packet can include a plurality of data blocks.

As shown in FIG. 20, the number of data blocks to be divided is defined according to the value of FN. That is, “00” is not divided, “01” is divided into two, and “10” is divided into four.
Divide, "11" is divided into eight.

The CIP header has a QPC (quadlet padding count) representing the number of dummy quadlets 0 to 7 added after each source packet so that the source packet header can be divided into data blocks of the same size. SPH (source packet)
header), Rsv (re
served), DBC (continuity counter of data bl) which is a continuity counter for detecting the loss of a data block.
ock).

The value of QPC is smaller than the number of data blocks into which each source packet is divided so as to be encoded in FN. The value of QPC is smaller than the size of a single data block, as encoded in DBS. Therefore, the data block is not constituted by a quadlet to which all the data blocks are added.

If the value of SPH is 1, it indicates that the source packet has a source packet header. In the source packet header shown in FIG. 21, a time stamp (time stamp) is followed by a reservation (reserved).

The value of DBC points to the first data block following the CIP header in the bus packet. Lower FN
The bits contain the ordinal number in the source packet. The first data block of a source packet always has an ordinal value of zero. If FN is 0, all 8 bits of DBC are used to represent the ordinal number of the source packet.

As shown in FIG. 22, DBC bits indicating the order position of the data block are defined corresponding to the value of FN. That is, "00" is not divided, "01" is indicated by the lowest one bit, "10" is indicated by the lowest two bits, and "11" is indicated by the lowest three bits.

Further, the CIP header has an FMT (format ID) for identifying a format, an FDF (format dependent field) for indicating a field depending on the format, and a SYT in which a time stamp and the like are recorded.

When the FMT is “111111 ₂ ” (no data), the fields of DBS, FN, QPC, SPH and DBC are ignored,
Data blocks are not transferred. As shown in FIGS. 19 and 23, the most significant bit of FMT is SYT_available / SYT_n
Specify ot_available. An FDF is defined for each FMT.

Control such as start / stop of the data flow in the IEEE1394 standard is performed based on the concept of plugs and plug control registers. This introduces the concept of a plug to form a signal path logically similar to an analog interface. CSR (c
ontrol and status register).

FIG. 24 is a diagram for explaining the configuration of the PCR. PCR stands for oPCR (output plug control
l register), iPCR (input plug contr
ol register). In addition, the PCR includes a register oMPR (o
utput master plug register) and iMPR (input master plu
gregister). Each device does not have multiple oMPRs and iMPRs, but the oPCR corresponding to each plug
It is possible to have multiple iPCRs and iPCRs depending on the capabilities of the device. The PCR shown in FIG. 24 has 31 oPCRs each.
And iPCR. The flow of isochronous data is controlled by manipulating registers corresponding to these plugs.

FIG. 25 is a diagram showing the configuration of oMPR, oPCR, iMPR, and iPCR. FIG. 25A shows the configuration of oMPR, and FIG.
5B shows the configuration of the oPCR, FIG. 25C shows the configuration of the iMPR, and FIG. 25D shows the configuration of the iPCR. oMPR and iMPR
MSB side 2 bit data rate capability (data
In rate capability), a code indicating the maximum transmission rate of isochronous data that can be transmitted or received by the device is stored. oMPR broadcast channel based
(broadcast channel base) specifies the number of a channel used for broadcast output.

In the 5-bit number of output plugs on the LSB side of the oMPR, a value indicating the number of output plugs of the device, that is, the number of oPCRs is stored. In the 5-bit number of input plugs on the LSB side of the iMPR, a value indicating the number of input plugs of the device, that is, the number of iPCRs is stored. non-persistent extension field and pers
The istent extension field is an area defined for a future extension.

MSB of oPCR and iPCR on-line
Indicates the usage state of the plug. That is, if the value is 1, the plug is ON-LINE, and if the value is 0, the plug is OFF-LIN.
Indicates E. oPCR and iPCR broadcast connection counters
Indicates the presence (1) or absence (0) of a broadcast connection. oPCR and iPCR 6-bit point-to-point connection counter (point
-to-point connection counter) has the value of the point-to-point connection (point
-to-point connection).

A value of a channel number having a 6-bit width of oPCR and iPCR indicates a number of an isochronous channel to which the plug is connected.

The data rate (d
The value of (ata rate) indicates the actual transmission speed of the isochronous data packet output from the plug. oPCR
The code stored in the overhead ID having a 4-bit width indicates the bandwidth of the overhead of isochronous communication. The value of the payload having a 10-bit width of the oPCR indicates the maximum value of data included in an isochronous packet that can be handled by the plug.

In order to transfer isochronous data between devices via an IEEE1394 standard serial bus, it is necessary to connect an output plug of a device that transmits data and an input plug of a device that receives data using an isochronous channel. It is.

One input plug and one output plug are provided by the isochronous channel.
The relationship connecting g) is called a point-to-point connection. A point-to-point connection is released by the same application that established the connection.

An example of a point-to-point connection will be described with reference to FIG. In the figure, the first device 10
The first, second and third devices 102 and 103 are IEEE13
They are connected by a 94 standard serial bus.

The iPCR [0] of the first device 101 and the oPRR [1] of the third device 103 are connected by a point-to-point connection by channel # 1. The broken line in the figure is an isochronous data flow.

[0120] The iPCR [1] of the first device 101 and the oPRR [0] of the second device 102 are connected by a point-to-point connection by channel # 2 (channel # 1).

For data transfer through the serial bus, a broadcast connection (broadcast connect) is required.
option) can also be used.

A broadcast connection connects one input plug or one output plug to an isochronous channel. Connecting one output plug to an isochronous channel is called a broadcast-out connection, and connecting one input plug to an isochronous channel is called a broadcast-in connection. The broadcast process is established only by the device having the plug, but can be canceled by another device.

One broadcast out connection can be connected to one output plug, and one broadcast in connection can be connected to one input plug. One broadcast connection and a plurality of point-to-point connections can be simultaneously connected to one plug.

All connections connected to one plug use the same isochronous channel and transfer the same isochronous data flow. Multiple independent applications can connect point-to-point connections between the same input plug and output plug.

An example of a broadcast connection will be described with reference to FIG. In the figure, the first device 111,
Second device 112, third device 113, fourth device 11
Fourth and fifth devices 115 are connected by an IEEE 1394 standard bus 116. The broken line in the figure is an isochronous data flow.

The iPCR [1] of the first device 111 and the oPCR [0] of the fifth device are connected by two point-to-point connections. IPCR of the second device 113
[1] and oPCR [0] of the fifth device are connected by one point-to-point connection. Between iPCR [0] of the fourth device 114 and oPCR [0] of the fifth device,
They are connected by three point-to-point connections.

The oPCR [0] of the fifth device 115 and channel # 1 (channel # 1) are connected by a broadcast out connection. This channel # 1 is
IPCR [1] of the first device 111, iPCR of the second device 112
[0], iPCR [0] of the third device 113 and the fourth device 114
IPCR [0] is connected by broadcast in connection.

Next, the operation in the case of connecting the devices by the point-to-point connection will be described with reference to FIG.
This will be described with reference to FIG.

In step S111, a node operating as an isochronous resource manager is requested to acquire an isochronous communication channel for input / output connection setting. The node operating as an isochronous resource manager responds to this request and
The bit corresponding to the vacant channel of the channel available register of R is set to 0. In step S112, a request is made to the node operating as an isochronous resource manager to acquire a required band for isochronous communication. In response to this request, the node operating as the isochronous resource manager subtracts a value according to the requested bandwidth from the value of the bandwidth available register of the CSR.

In step S113, an unused device (iPCR [j]) is selected from the iPCRs for the input device, and the number of the isochronous channel to be used is obtained in the channel number (in step S111). Channel number), and 1 is set in the point-to-point connection counter. Step S114
, The output device specified by the user
From the CR, select an unused one (oPCR [k]), set its channel number to the same isochronous channel number as the number set in iPCR [j], and set its point-to-point connection counter to Set 1

As described above, when the channel and the band, the output plug and the input plug are secured, the channel secured from the output plug of the designated output device to the input plug of the designated input device is secured. The data is transmitted using the bandwidth.

FIG. 29 is a flow chart for explaining the operation when the input / output connection is released after the data transmission is completed. In step S121, the channel number of the oPCR [k] and the point-to-point connection counter are cleared for the output device, and the oPCR [k] is released as unused. In step S122, for the input device designated by the user, the channel number of the iPCR [j] and the point-to-point connection counter are cleared, and the iPCR [j] is released as unused.

In step S123, a request is made to the node operating as the isochronous resource manager to release the necessary band for the isochronous communication. In response to this request, the node operating as the isochronous resource manager adds a predetermined value corresponding to the released bandwidth to the value of the bandwidth available register of the CSR. In step S124, the node operating as the isochronous resource manager is requested to release the channel of the isochronous communication.
In response to this request, the node operating as an isochronous resource manager sets 1 to a corresponding bit of the channels available register of CSR.

In order to control the device based on the IEEE1394 standard, a functional control protocol (functi
onal control protocol (FCP) is provided. An AV / C command set used for controlling an AV device will be described as a specific example of the FCP using an asynchronous packet specified by IEEE1394 for transmission and response of a control command.

FIG. 30 shows a stack model of the AV / C command set. As shown in FIG. 28, the physical layer 111, the link layer 112, the transaction layer 113, and the serious bus management 114
Complies with 1394. FCP 115 is based on IEC61883. The AV / C command set 116 complies with the 1394TA specifications.

FIG. 31 is a diagram for explaining commands and responses of FCP 115 in FIG. FCP is IEEE139
4 is a protocol for controlling the AV devices on the above. As shown in FIG. 31, the controlling side is the controller, and the controlled side is the target. Transmission or response of an FCP command is performed between nodes using a write transaction of asynchronous communication of IEEE1394.
Upon receiving the data, the target confirms the receipt,
Returns an acknowledgment to the controller.

FIG. 32 is a diagram for explaining the relationship between the FCP command and the response shown in FIG. 31 in more detail. Node a and node b are connected via an IEEE1394 bus. Node a is the controller and node b is the target. Each of the node a and the node b has a command register and a response register prepared for each 512 bytes. As shown in FIG. 32, the controller transmits a command by writing a command message to the command register 123 of the target. Conversely, the target transmits a response by writing a response message to the response register 122 of the controller. The control information is exchanged using the above two messages as a pair. The type of command set sent by FCP is described in CTS in the data field of FIG.

FIG. 33 shows the data structure of an asynchronous packet of an AV / C command. The AV / C command set is a command set for controlling AV equipment.
(ID of command set) = “0000”. AV / C command frames and response frames are exchanged between nodes using the FCP. The response to the command is 100m to avoid burdening the bus and AV equipment.
within s. As shown in FIG.
The data of the asynchronous packet is composed of 32 bits in the horizontal direction, that is, one quadlet. The upper part in the figure shows the header part of the packet, and the lower part in the figure shows the data block. destination_ID
Indicates a destination.

[0139] CTS indicates the ID of the command set.
In the V / C command set, CTS = "0000". ctype / res
The ponse field indicates the functional classification of the command when the packet is a command, and indicates the processing result of the command when the packet is a response. Commands are broadly divided into (1) commands that control functions from outside (CONTRO
L), (2) Command for inquiring the status from outside (STATU
S), (3) Commands for inquiring externally whether control commands are supported (GENERAL INQUIRY (opcode support) or SPECIFIC INQUIRY (opcode and operands)
Is supported)), and (4) four types of commands (NOTIFY) requesting notification of a change in state to the outside.

A response is returned according to the type of command. The response to the CONTROL command is NOT I
MPLEMENTED (not implemented), ACCEPTED (accept), REJECTED (reject), and INTERIM (provisional). The response to the STATUS command is NOT IM
PLEMENTED, REJECTED, IN TRANSITION, and
There is STABLE (stable). GENERAL INQUIRY and SPECIFIC
The response to the INQUIRY command is IMPLEMENTED
(Implemented), and NOT IMPLEMENTED. NOT
The response to the IFY command is NOT IMPLEMENTE
D, REJECTED, INTERIM and CHANGED (changed).

[0141] The subunit type is provided to specify a function in the device.
er, Tuner, etc. are assigned. To determine when there are multiple subunits of the same type, use su
Addressing by bunit ID. The opcode represents a command, and the operand represents a parameter of the command. Additional operands are fields added as needed. Padding is also a field added as needed. data CRC (cyclic redundancy check)
Is used for error checking during data transmission.

FIG. 34 shows a specific example of the AV / C command. FIG. 34A shows a specific example of ctype / response. The upper part of the figure represents a command, and the lower part of the figure represents a response. “0000” is CONTROL,
“0001” is STATUS, “0010” is SPECIFIC INQUIRY,
NOTIFY is assigned to “0011” and GENERAL INQUIRY is assigned to “0100”. “0101 to 0111” are reserved and reserved for future specifications. Also, “1000” has NOT IM
PLEMENTED, ACCEPTED for “1001”, REJEC for “1010”
TED, IN TRANSITION for “1011”, IMPLEM for “1100”
ENTED / STABLE, CHANGED for “1101”, INT for “1111”
ERIM is assigned. “1110” is reserved and reserved for future specifications.

FIG. 34B shows a specific example of the subunit type. “00000” for Video Monitor, “00011” for Disk recorder / Player, “00100” for Tape recorder
/ Player, Tuner for “00101”, Video Ca for “00111”
mera, Vendor unique for “11100”, sub for “11110”
Unit type extended to next byte is assigned. Note that a unit is assigned to “11111”, which is used when it is sent to the device itself, such as turning on / off a power supply.

FIG. 34C shows a specific example of the opcode. There is an opcode table for each subunit type,
Here, the opcode when the subunit type is Tape recorder / Player is shown. An operand is defined for each opcode. Here, “00h” is VENDOR-DEPEND
ENT, SEARCH MODE for “50h”, TIMECODE for “51h”,
ATN for “52h”, OPEN MIC for “60h”, RE for “61h”
AD MIC, WRITE MIC for “62h”, LOAD MEDI for “C1h”
UM, RECORD is assigned to “C2h”, PLAY is assigned to “C3h”, and WIND is assigned to “C4h”.

FIG. 35 shows a digital video cassette recorder (digita) as a specific example of an AV / C command and response.
l Video casette recorder (DVCR) is explained.
When playing back a DVCR (target), the controller sends a command such as A in FIG. 35 to the target.
Since this command uses the AV / C command set, CTS = "0000". Since a command (CONTROL) that controls functions from outside is used for ctype, ctype
= “0000” (see A in FIG. 35). subunit t
Since ype is a Tape recorder / Player,
ype = “00100” (see FIG. 35B). ID is I
This shows the case of D0, where ID = 000. The opcode is “C3h” meaning reproduction (see C in FIG. 35). The operand is “75h” meaning FORWARD. Then, when reproduced, the target returns a response as shown in B of FIG. 35 to the controller. Here, since accepted which means acceptance is included in response, resp
onse = "1001" (see FIG. 35A). respo
Except for nse, the other parts are the same as those in FIG.

Next, as an embodiment of the present invention, an operation of the recording / reproducing apparatus shown in FIG. 1 utilizing the above-described property of the serial bus 2 of the IEEE1394 standard will be described.

As described above, in the recording / reproducing apparatus,
The magneto-optical disk device 1 and the optical disk device 2 send out a stream to the serial bus 4, and the amplifier 3 receives and outputs the stream on the serial bus 4. The amplifier 3 performs reproduction synchronized with the magneto-optical disk device 1 and the optical disk device 2.

The following operation is performed in the magneto-optical disk drive 1
Since the present invention can be similarly applied to the optical disk device 2, the following description will be made with reference to the magneto-optical disk device 1 for simplicity.

As the first embodiment, the serial bus 4
A method in which the amplifier 3 performs reproduction synchronized with the magneto-optical disk device 1 by monitoring the above isochronous communication will be described.

As shown in FIG. 36, in step S11, the magneto-optical disk device 1 receives a reproduction command by an AV / C command. That is, the CPU 11 of the magneto-optical disk device 1 shown in FIG. 2 receives an AV / C instruction via the interface 10 connected to the serial bus 4.
This AV / C command is sent, for example, from a controller (not shown) connected to the serial bus 4.

In step S12, upon receiving this command, the magneto-optical disk device 1 sends data reproduced from the magneto-optical disk to the serial bus 4 as an isochronous packet, if possible.

The CPU 11 reads data from the magneto-optical disk 15 such as a so-called MD by the optical pickup 14. The read data is stored in the recording / reproduction system 13.
And PCM audio data by the encoder / decoder 16. This PCM audio data is transmitted to the serial bus 40 by the interface 10 as an isochronous packet.

If the reproduction cannot be started, for example, because the magneto-optical disk 15 is not mounted, the CPU 11 sends a failure message using an AV / C command. This command is also transmitted to the serial bus 4 by the interface 10.

As shown in FIG. 37, in step S21, the amplifier 3 constantly monitors the isochronous packet on the serial bus 4. That is, the CPU 31 of the amplifier 3 shown in FIG. 3 monitors the isochronous packet on the serial bus 4 via the interface 35 connected to the serial bus 4.

In step S22, when the CPU 31 finds an isochronous packet that can be output, the process proceeds to step S23, and otherwise returns to the previous step S21. By this step S22, data of a type that cannot be output by the amplifier 3, such as video data, is excluded.

Whether the amplifier 3 can output an isochronous packet is determined by the CIP shown in FIG.
Is determined from the data of The CPU 31 serving as a determination unit for determining whether to output an isochronous packet includes:
The channel available register held by the isochronous resource manager of the serial bus 4 is read to know the channel number to which the isochronous packet is output. Then, the CIP corresponding to the output channel number is confirmed.

In the CIP header shown in FIG.
The hatched portion is used to determine whether an isochronous packet can be output. That is, in the CIP header, EOH_0 = 0, Form_0 = 0 , DBS = 02 16, FN = 0 16, QPC = 0 16, SPH = 0 16, Rsv = 0 16, EOH_1 = 1, Form_1 = 0, FMT = 10 ₁₆ and FDF = 00 _{16 to} 02 ₁₆ are satisfied, it is determined that the isochronous packet can be output by the amplifier 3.

As described above, the condition DBS = 02 ₁₆ = 00000010 ₂ indicates that the size of the data block is 2 quadlets. Conditions FN = 0 _16, as shown in FIG. 20, indicating that not split the source packet into a plurality of data blocks. Conditions QPC = 0 ₁₆ indicates that the number of quadlet to be added subsequent to each source packet is zero. Conditions SPH = 0 ₁₆ indicates that the packet does not have a source packet header. Conditions FMT = 10 ₁₆ = 00010000 ₂ is, as shown in FIG. 23, the format of the data is the reserved, in this embodiment it is assumed that indicates the audio / music data which can be output by the amplifier 3 . Conditions _{FDF = 00 16 ~02 16 = 00000000} 2 ~00000010 2 is a AM824 data, and the sampling frequency is 3
2 kHz (00), a 44.1kHz (01), 48kHz (02 ), a field defined for the format that satisfies the condition FMT = 10 ₁₆ = 00010000 _2.

In step S23, the CP of the amplifier 3
U31 determines whether the isochronous packet determined to be output in step S22 can be obtained. In order to be able to acquire an isochronous packet, for example, it is necessary that the amplifier 3 is not occupied by another channel. CP
When U31 determines that the isochronous packet can be output, the process proceeds to step S24, and when it determines that the isochronous packet cannot be output, the process returns to step S21.

In step S24, the CP of the amplifier 3
U31 acquires and outputs an isochronous packet. The CPU 31 performs D / A conversion on the PCM audio data of the isochronous packet acquired through the interface 35.
The output is controlled via the conversion circuit 36.

The acquisition of the isochronous packet by the amplifier 3 is performed by monitoring whether the output plug of the output device indicated by the SID of the CIP header is connected to its own input plug by a point-to-point connection. This is done either by connecting to the channel that is present by broadcast-in connection.

Next, as a second embodiment, the amplifier 3
A method of monitoring the state of the magneto-optical disk device 1 and acquiring and outputting the isochronous packet when the magneto-optical disk device 1 starts transmitting the packet will be described.

In the following embodiment, for the sake of simplicity, the description of the same parts as those in the first embodiment will be omitted.

As shown in FIG. 38, the magneto-optical disk device 1 receives the AV / C command in step S31, and transitions to the reproduction mode in step S32. Then, in step S33, the reproduced data is transmitted to the serial bus 4 as an isochronous packet.

As shown in FIG. 39, in step S41, the amplifier 3 checks the status of the magneto-optical disk device 1 as a target device. Amplifier 3 is AV
By using the / C command, one connected device at a time
Subfunction of the OPEN DESCRIPTOR command (subfu
The read right of the disc status descriptor (disc status descriptor) is obtained by one READ OPEN of the nction).

As shown in FIG. 40, the OPEN DESCRIPTOR command includes an opcode for storing an OPEN DESCRIPTOR for acquiring authority to access a descriptor, a descriptor_identifier for identifying data to be accessed, and a sub-function (operation) to be executed by the target. su
bfunction).

As shown in FIG. 41, the operation executed by the target is determined by the subfunction. That is, CLOSE (00 ₁₆ ) cancels use of the descriptor, READ OPEN (01 ₁₆ ) opens the descriptor for reading only (open), and WRITE OPEN (03 ₁₆ )
Opens the descriptor for reading and writing.

At step S42, the amplifier 3
Source Plug Status Area by AD DESCRIPTOR command
Information Block-Plug Status Information Block-O
Disc Status Des from peration Mode Information Block
Read the criptor and check if it is in playback mode during playback.

As shown in FIG. 42, the OPEN DESCRIPTOR command is used to read data from the descriptor.
The opcode that stores ESCRIPTOR, the descriptor_identifier that identifies the data to be accessed, and the read descriptor read_r that is stored by the target
esult_descriptor, data length read from target data_length, and start address of read address
This is a format having an oprand that includes

As shown in FIG. 43, Source Plug Status
Area Info Block (source_plug_status_area_info_blo
ck) is a compound indicating the number of remaining bytes in this block
_length and info_block_type as source_plug_status
“8802 ₁₆ ” indicating _area_information_block and primary
_fields_length, number_of_source_plug, plug_st
Has atus_info_brock.

[0171] The number_of_source_plug field is
Specify the number of rce plugs and overlap this info_block (ne
st) Indicates the number of plug_status_info_blocks that are present. plug_sta
tus_info_block indicates the status of each plug.

As shown in FIG. 44, Plug Status Inform
ation Block (plug_status_info_block) is compound_
length, “8805 ₁₆ ” indicating info_block_type as info_block_type, primary_fields_length, and plug_numb
er and secondary_fields. plug_number
Following the field is an info block defined to overlap plug_status_info_block.

As shown in FIG. 45, the following info blo
The type of ck is defined to be valid for the plug status info block. Currently defined plug_status_
For info_block, Info Block Type is “8806 ₁₆ ”, Info
Block Name has "operating_mode_info_block".

As shown in FIG. 46, Op indicating the operation mode
erating Mode Information Block is compound_length
And info_block_type as oprating_mode_info_block
“8806 ₁₆ ”, primary_fields_length, and opera
ting_mode_specific_information.

[0175] As shown in FIG. 47, operating_mode field, the plug contains a "C3 _16" indicating that reproduces the AV object (play). This operatio
By reading out n_mode, it is possible to detect whether or not the playback mode is set.

When the necessary information is obtained, the amplifier 3 closes (closes) the disk status descriptor by the CLOSE command shown in FIG. 41 to release the read right.

If the target device is in the reproduction mode, the process proceeds to step 43, and if not, the process returns to step S41.

In step S43, the amplifier 3 determines to acquire the isochronous packet. When the amplifier 3 acquires the isochronous packet, the process proceeds to step S44, and when the isochronous packet is not acquired, the process proceeds to step S41.
Return to

In step S44, the amplifier 3 acquires and outputs the isochronous packet sent from the magneto-optical disk device 1. The amplifier 3 can input data by either connecting the output plug of the target device and its own input plug in a point-to-point manner, or by broadcasting-in to the output channel indicated by the output plug of the target device. it can.

Note that in the second embodiment,
As described in the first embodiment, in the CIP header shown in FIG. 19A, whether a packet can be output may be determined based on a value of a hatched portion.

Next, as a third embodiment, the magneto-optical disk device 1 for transmitting the isochronous packet notifies the amplifier 3 that the stream is transmitted, and the amplifier acquires and outputs the stream according to the notification. The method will be described.

As shown in FIG. 48, the magneto-optical disk device 1 receives a reproduction command by an AV / C command in step S51, and notifies the amplifier 3 of sending an isochronous packet in step S52. For this notification, for example, a NOTIFY command of an AV / C command can be used.

FIG. 49 is a diagram for explaining a NOTIFY command and a response. There is a NOTIFY command (A in FIG. 49) as a command for requesting notification of a state change to the outside. By using this command, a change in the state of the target device (magneto-optical disk 1) is detected.
When the target device receives the NOTIFY command,
An INTERIM response (B in FIG. 49) is returned to the device (amplifier 3) on the controller side. CHANGED response when the status of the target device changes (C in FIG. 49)
To the controller side device.

FIG. 50 is a flowchart for explaining the processing on the target side. In the magneto-optical disk device 1 on the target side, in step S211, it is determined whether a NOTIFY command has been received from the amplifier 3 on the controller side. As this NOTOFY command, a Disc Status NOTIFY command is used.

Upon receiving the NOTIFY command, the magneto-optical disk device 1 transmits an INTERIM command to the amplifier 4. If a NOTIFY command is not received, step S
Return to 211.

The magneto-optical disk device 1 executes step S21.
When the INTERIM command is sent in step 2,
At 213, it is determined whether the state has changed. When the AV / C command is sent to the magneto-optical disk device 1 and a playback command is sent to change the state, the process proceeds to step S214, and a CHANGE command indicating that the state has changed is sent. If the state does not change, the process returns to step S213.

In step S53 of FIG. 48, the magneto-optical disk device 1 sends the reproduced data to the serial bus 4 as an isochronous packet.

As shown in FIG. 51, in step S61, the amplifier 3 waits for the notification of the output of the isochronous packet from the magneto-optical disk device 1. As described above, this notification is made by the CHANGE command for notifying that the magneto-optical disk device has changed to the reproduction state.

As a prerequisite for starting this step S61, the amplifier 3 needs to send a NOTIFY command to the magneto-optical disk drive 1 to confirm the INTERIM RESPONSE. This process corresponds to steps S211 and S212 in FIG.

In step S62, the amplifier 3
It is determined whether or not a notification that reproduction has been started has been received from the magneto-optical disk device 1. The amplifier 3 proceeds to step S63 when receiving the notification, and returns to step S61 when not receiving it.

More specifically, as shown in step S221 of FIG. 52, in this step S62, the amplifier 3
Indicates that the state has changed from the magneto-optical disk device 1.
Judge whether to receive CHANGE RESPONCE.
Of course, the changed state must correspond to playback.

In step S63, the amplifier 3 determines whether or not an isochronous stream can be obtained. When the amplifier 3 is in a state where it can be acquired, in step S64, it acquires and outputs an isochronous packet. The amplifier 3 returns to the first step S61 unless it is in a state where it can be acquired.

As described above, in the present embodiment, when a stream is transmitted / received synchronously between devices connected by the serial bus 4 network, the stream is not controlled by a special controller but emphasized. The transmission / reception of the stream is realized by the operation described in FIG.

In the present embodiment, an example is shown in which the magneto-optical disk device, the optical disk device, and the amplifier are connected to a serial bus, but the present invention is not limited to this. The present invention can be applied to data transfer between devices having an interface conforming to the serial bus standard.

[0195]

When synchronous communication is performed between serial buses of the so-called IEEE1394 standard, processing can be dispersed by emphasizing each device, and there is no need for a single controller to manage all processes. . For example,
When a plurality of streams are flowing on the bus, which stream to acquire can be determined by the acquiring device.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing an entire configuration of a recording / reproducing apparatus.

FIG. 2 is a block diagram illustrating a configuration of a magneto-optical disk device.

FIG. 3 is a block diagram illustrating a configuration of an amplifier.

FIG. 4 is a diagram showing a structure of an address space of the CSR architecture.

FIG. 5 is a diagram illustrating an example of a state of a cable after completion of bus initialization.

FIG. 6 is a diagram showing a state where tree identification is completed.

FIG. 7 is a diagram illustrating an example of a cable state after a self-recognition phase.

FIG. 8 is a diagram illustrating addresses, names, and functions of the CSR architecture.

FIG. 9 is a diagram illustrating a format of a general ROM.

FIG. 10 is a diagram illustrating the configuration of a bus info block, a root directory, and a unit directory.

FIG. 11 is a diagram showing a configuration of an IEEE1394 protocol.

FIG. 12 is a diagram showing a transaction service.

FIG. 13 is a diagram showing a cycle of an IEEE1394 bus.

FIG. 14 is a diagram showing a link layer service.

FIG. 15 is a diagram showing a format of an isochronous data block packet.

FIG. 16 is a diagram showing a CIP header and real-time data.

FIG. 17 is a diagram showing a CIP header.

FIG. 18 is a diagram illustrating transfer of a source packet.

FIG. 19 is a diagram showing a 2-quadlet CIP header.

FIG. 20 is a diagram illustrating FN code assignment.

FIG. 21 is a diagram illustrating a format of a header of a source packet.

FIG. 22 is a diagram showing the position of a data block sequence.

FIG. 23 is a diagram illustrating FMT code assignment.

FIG. 24 is a diagram showing a configuration of a PCR.

FIG. 25 is a diagram showing the configuration of oMR, oPCR, iMR, and iPCR.

FIG. 26 is a diagram showing a point-to-point connection between devices.

FIG. 27 is a diagram illustrating a broadcast connection between devices.

FIG. 28 is a flowchart showing an operation of connecting input and output.

FIG. 29 is a flowchart illustrating an input / output disconnection operation.

FIG. 30 is a diagram showing a stack model of an AV / C command.

FIG. 31 is a diagram showing the relationship between FCP commands and responses.

FIG. 32 is a diagram showing the relationship between FCP commands and responses in more detail.

FIG. 33 is a diagram illustrating a data structure of a packet of an AV / C command.

FIG. 34 is a diagram illustrating a specific example of an AV / C command.

FIG. 35 is a diagram showing a specific example of a command and a response of an AV / C command.

FIG. 36 is a flowchart showing processing of the magneto-optical disk device and the optical disk device according to the first embodiment.

FIG. 37 is a flowchart showing a process of the amplifier according to the first embodiment.

FIG. 38 is a flowchart showing processing of a magneto-optical disk device or an optical disk device according to the second embodiment.

FIG. 39 is a flowchart showing processing of the amplifier according to the second embodiment.

FIG. 40 is a diagram showing an OPEN DESCRIPTOR command.

FIG. 41 is a diagram showing an operand of a subfunction.

FIG. 42 is a diagram showing a READ DESCRIPTOR command.

FIG. 43: Source Plug Status Area Information Bloc
It is a figure showing k.

FIG. 44 is a diagram showing a Plug Status Information Block.

FIG. 45 is a diagram showing currently defined ingo blocks overlapping plug_status_info_block.

FIG. 46 is a diagram illustrating an Operating Mode Information Block.

FIG. 47 is a diagram showing an operating_mode field.

FIG. 48 is a diagram illustrating processing of the magneto-optical disk device and the optical disk device according to the third embodiment.

FIG. 49 is a diagram showing a NOTIFY command and a response.

FIG. 50 is a flowchart showing processing on the target side.

FIG. 51 is a flowchart showing processing of the amplifier according to the third embodiment.

FIG. 52 is a flowchart showing processing on the controller side.

[Explanation of symbols]

1 magneto-optical disk drive, 2 optical disk drive, 3 amplifier, 4 serial bus, 10 interface, 1
1 CPU, 15 magneto-optical disk, 31 CPU, 34 operation panel, 35 interface

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5B077 AA01 AA23 BB06 FF11 FF13 5K028 AA06 AA11 KK32 MM05 RR00 5K032 AA01 AA03 BA15 BA16 CA13 CD01 DB19 DB22

Claims (12)

[Claims] 1. A bus for transmitting data, a first device for transmitting data to the bus as periodic packets, and monitoring for transmission of periodic packets from the first device via the bus. And a second device that starts receiving the packet when detecting the transmission of the available packet. 2. The method according to claim 1, wherein the packet is periodically transmitted as a channel having a predetermined bandwidth.
2. An ochronous packet.
The communication device as described. 3. The packet has a field describing the type of format of the packet, and the second device determines whether or not the packet is usable based on the value of the field. The communication device according to claim 1. 4. A bus for transmitting data, a first device for transmitting data to the bus as periodic packets, and a status of the first device is monitored via the bus. When the device detects that the device is in a state of transmitting a periodic packet, the second device starts receiving the packet.
A communication device comprising: 5. The communication device according to claim 4, wherein the packet is an isochronous packet that is periodically transmitted as a channel having a predetermined bandwidth. 6. The state indicates an operation mode of the first device. When the second device detects that the operation mode has been reproduced, the second device initiates reception of the packet. The communication device according to claim 4, wherein: 7. The communication device according to claim 6, wherein the second device acquires a right to read the state of the first device, reads the state, and releases the right to read. . 8. The communication device according to claim 4, wherein the second device has a determination unit that determines whether or not the packet is available based on a header of the packet. 9. A first step of transmitting data as a periodic packet to a bus for transmitting data, and monitoring and utilizing the periodic packet transmitted in the first step via the bus. A second step of starting reception of the packet upon detecting possible transmission of the packet. 10. The communication method according to claim 9, wherein said packet is an isochronous packet transmitted periodically as a channel having a predetermined bandwidth. 11. A first step of transmitting data as a periodic packet to a bus for transmitting data, and monitoring the state of the first step, wherein the first step transmits a periodic packet. A second step of starting reception of the packet when the state is detected. 12. The communication method according to claim 11, wherein said packet is an isochronous packet periodically transmitted as a channel having a predetermined bandwidth.