JPH10290245A - Method and device for communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to select more than two kinds of communication system with one device without increasing the cost owing to an increase in circuit scale by allowing respective communication systems to use at least some of pieces of command data that different kinds of communication systems have in common. SOLUTION: When a 1394 interface is used, packet data generated by an interface(I/F) circuit 27 are sent to a 1394 input/output port 35 through a 1394 driver 31, When an RS-232C interface is used, the packet data generated by the I/F circuit 27 are sent to an RS-232C input/output port 37 through an RS-232C driver 33. At this time, at least some of command data for 1394 and command data for RS-232C are used in common. For example, the 1394 driver 31 and RS-232C driver 33 use all of command data which are received by respective communication system and have the same function in common.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a communication method and a communication apparatus, and more particularly, to connecting an AV device such as a digital VTR, a television receiver, a tuner to a bus, and connecting a digital video signal and a digital audio signal between these electronic devices. The present invention relates to a communication method and a communication device for transmitting and receiving signals and the like.

[0002]

2. Description of the Related Art In recent years, the processing capability of a central processing unit (CPU) used in a computer or the like has been improved, an operating system (OS) for operating hardware has been made compatible with graphics, the capacity of communication information on a network has been increased, and With the advancement of computerization or information compression technology, devices and systems that handle not only text information such as documents but also various information such as images and sounds in a complex manner have been widely used.

[0003] With the development of such multimedia technology, it has become possible to transmit all kinds of data in one form and all communication protocols via one digital I / F bus system. I have. In addition, a device supporting one communication protocol has a plurality of units therein, and it is possible to control each unit from the outside or exchange information with the outside.

For example, as an example of the digital I / F bus system, a digital video tape recorder (hereinafter, referred to as a digital video tape recorder)
AV devices such as VTRs, digital television receivers and tuners, and personal computers (hereinafter referred to as VTRs).
A communication system has been proposed in which PCs and the like are connected to each other using an IEEE 1394 (hereinafter referred to as 1394) serial bus, and digital video signals and digital audio signals are transmitted and received between these electronic devices. The outline of the 1394 system will be described below.

[0005] As shown in FIG. 8, for example, a 1394 system is used as a digital device from a digital I / F to a VGA.
(Video Graphics Array) A PC, a VTR, a digital camera (hereinafter, referred to as DCAM) from a digital I / F to a VGA output, and a digital camcorder (hereinafter, DVCR) are provided. And DVCR
And PC, between PC and VTR, and between VTR and DC
AM is connected to the AM by the 1394 serial bus.

[0006] Each of the above-mentioned digital devices has a
It has a function of relaying digital data and control data on a serial bus. The cable for the 1394 serial bus has three pairs of shielded pairs. Each pair of wires is used not only for transferring protocol signals and data, but also for supplying power, so that the entire system operates even if there are powered-off devices in the system. Is configured to obtain.

The basic configuration of each of the above digital devices includes an operation unit, a display unit, a user interface, a CPU for controlling the overall operation, creating packets during communication, and retaining addresses, and a digital I / O for a 1394 serial bus.
/ F and a switch unit for switching between a digital I / F and a deck unit, tuner unit or camera unit (not shown).

By the way, in the 1394 system,
As shown in FIG. 9, communication is performed in a predetermined communication cycle (125 μs). Data with a time axis, such as video data and audio data, is communicated by isochronous (synchronous) communication in which a transfer band is guaranteed at a fixed data rate, and control data such as control commands are required. Asynchronous (asynchronous) communication is performed irregularly accordingly.

In such communication, a cycle start packet is provided at the beginning of each communication cycle, and a period for transmitting a packet for isochronous communication is set subsequently thereto. At this time, by attaching a channel number to each packet for isochronous communication, isochronous communication of a plurality of channels can be performed simultaneously.

For example, when channel 1 is allocated to communication from a DVCR to a VTR, the DVCR sends out an isochronous communication packet of channel number 1 on the bus immediately after the cycle start packet. On the other hand, VTR
By monitoring packets on the bus and taking in packets with channel number 1, isochronous communication is performed between the DVCR and the VTR.

Similarly, when the channel number 2 is assigned to the packet from the DCAM to the PC, the packet of the channel number 2 is sent out on the bus after the packet of the channel number 1 so that the isolator between the DCAM and the PC. Chronos communication is performed, and isochronous communication between channel 1 and channel 2 is performed in parallel. Then, after transmission of all isochronous communication packets is completed in each communication cycle, a period until the next cycle start packet is used for asynchronous communication.

Next, bus management for enabling the 1394 serial bus system to operate will be described. The device serving as the bus manager first controls the bus communication by grasping the network structure and the connection state of all nodes, and defining each node ID and controlling the isochronous communication.

That is, in the above-described communication system, when power is turned on or when a new digital device is connected or disconnected, a node ID is automatically assigned to each device (node) according to the connection mode. (# 0 in FIG. 8,
The physical addresses of # 1, # 2, and # 3) are allocated by the following procedure based on the address program and the address table stored in the memory in the CPU, and the topology is automatically set.

The procedure for assigning node IDs will be briefly described below. This procedure consists of determining the hierarchical structure of the system and assigning a physical address to each node. Here, regarding each of the above digital devices, PC is Node A, DVCR is Node B, VTR is Node C, DCAM
Is a node D.

First, each node communicates with each other that the other node is connected by the 1394 serial bus that the other party is its parent. At this time, priority is given to the one transmitted to the other party first, and finally the parent-child relationship between the nodes in this system, that is, the hierarchical structure of the system and the root node which is a node that does not become a child to other nodes are determined. Is done.

Specifically, node D informs node C that the other party is a parent, and node B communicates to node A that the other party is a parent. Also, when node A informs node C that the other party is a parent and node C informs node A that the other party is a parent, Priority is given, and if the transmission by the node C is earlier, the node A is set as the parent of the node C. As a result, node A does not become a child to any other node, and in this case becomes a root node.

After the parent-child relationship of each digital device is determined, a physical address is assigned. The assignment of the physical address is basically performed by allowing the parent node to assign an address to the child node and further allowing each child node to assign an address in order from the child node connected to the port with the smallest port number. Done.

In the example shown in FIG. 8, when the parent-child relationship is determined as described above, first, the node A permits the node B to assign an address, and as a result, the node B assigns the physical address # 0 to itself. I do. Then, by transmitting this to the bus, it notifies other nodes that "physical address # 0 has been allocated".

Next, when the node A permits the node C to assign an address, the node A also permits the node D, which is a child of the node C, to assign an address. As a result, the node D assigns itself a physical address # 1, which is the next physical address after # 0, and sends this out onto the bus.

Thereafter, the node C self-addresses the physical address #
2 and sends it out on the bus, and finally, node A gives it its own physical address # 3 and sends it out on the bus. For details of the 1394 serial bus including the node ID assignment procedure, see “IEEE139
4 Serial Bus Specification ".

Next, the procedure of data transfer will be described. The data transfer becomes possible by giving the physical address as described above. In the 1394 serial bus system, the arbitration of the right to use the bus is performed by the root node prior to the data transfer. That is, 1394
In this case, as shown in FIG. 9, at a certain timing, only one channel of data is transferred, so it is necessary to arbitrate the right to use the bus first.

When each node wants to perform data transfer, it requests its parent node for the right to use the bus, and as a result, the root node arbitrates the request for the right to use the bus from each node. As a result, the node that has obtained the right to use the bus specifies the transmission speed before starting data transfer, and
The transmission destination node is notified of whether the transmission destination is bps, 200 Mbps, or 400 Mbps.

Thereafter, in the case of isochronous communication,
The source node starts data transfer on the specified channel immediately after receiving the cycle start packet transmitted by the root node, which is the cycle master, in synchronization with the communication cycle. The cycle master sends the cycle start packet to the bus and sets the time of each node.

On the other hand, in the case of asynchronous communication for transferring control data such as commands, arbitration for asynchronous communication is performed after synchronous transfer within each communication cycle is completed, and transmission from the source node to the destination node is performed. Data transfer is started. The above is the outline of the 1394 serial bus system.

As a conventional serial data communication system, in addition to the above-mentioned IEEE 1394 standard, RS-232
The C standard, the RS-422 standard, and the like still exist and are currently used. These standards are based on the Data Terminal Equipment (DTE)
It specifies the interconnection between the SDC and the data circuit-terminating equipment (DCE) using serial binary data exchange. These standards have been created and published by the American National Standards Institute (ANSI).

As another example of the digital I / F bus system, Universal Serial Bus Specification is used.
(Revision 1.0 January 15 1996), a universal serial bus (hereinafter referred to as USB) has been proposed. It has been devised as an external bus for connecting a PC and its peripheral devices. The outline of the USB system will be described below.

First, the USB connection mode will be described with reference to FIG. In FIG. 10, reference numeral 300 denotes a host computer such as a PC; 302, a root hub; and 304, a first device, which is a recording medium such as a hard disk. 306 is a composite device such as a camera-integrated VTR, 308 is a first hub, 310 is a second device, for example, here, a video camera, 312 is a third device.
The device here is, for example, a VTR. 31
4 is a second hub, 316 is a fourth device, here, for example, an input device such as a keyboard, and 318 is a fifth device, here, for example, a pointing device such as a mouse.

Here, the hub has a function for adding a USB device. The device is a terminal device including a USB bus interface (not shown). As shown in FIG.
The SB has a multi-star connection configuration in which a plurality of terminal devices are connected via each hub including the root hub 302 on the host computer 300.

The first device 304, the second device 310, the third device 312, and the fourth device 31
Since the host computer 300 has the access right to the sixth and fifth devices 318, data transfer between the devices is performed via the host computer 300. Therefore, bus arbitration between devices is not performed.

In USB, data transfer is 1 ± 0.0
This is performed in frames in units of 5 milliseconds. In FIG.
1 shows a structure of a frame in USB. This frame is packed with packets according to the purpose and transferred. U
In the SB, four types of packets are defined.
The first is a token packet, the second is a start-of-frame packet (hereinafter referred to as an SOF packet), the third is a data packet, and the fourth is a handshake packet. The frame is started by the SOF packet.

The host computer 300 transfers data to and from a plurality of devices by sequentially transmitting data transfer requests scheduled during the frame in advance. In the case of a large amount of data that does not fit in one frame, such as image data, the host computer 300 divides and transfers the large amount of data in frame units.

In the above four types of packets, packet fields are packed and transferred according to the purpose. US
In B, six types of packet fields are defined. The first is an 8-bit packet identification (Packet Ide
ntifier) field (hereinafter referred to as PID), the second is a 7-bit address field (hereinafter referred to as ADDR), and the third is a 4-bit endpoint (Endpoi).
nt) field (hereinafter referred to as ENDP), the fourth is an 11-bit frame number field, and the fifth is 1 to 1
A 1023-byte data field, and a sixth field is a 5-bit or 16-bit Cyclic Redundancy Checks field (hereinafter, a 5-bit field is referred to as CRC5 and a 16-bit field is referred to as CRC16). The above-described four types of packets are configured by a combination of these six types of packet fields.

FIG. 12 shows the structure of the above four types of packets. As shown in FIG. 12A, the token packet is composed of a combination of PID, ADDR, ENDP, and CRC5 fields. Further, as shown in FIG. 12B, the SOF packet is composed of a combination of fields of PID, frame number, and CRC5.
In addition, as shown in FIG.
It is composed of a combination of each field of PID, data and CRC16. As described above, the data field is 1
It is composed of data of 〜１０1023 bytes. Also,
As shown in FIG. 12D, the handshake packet is composed of only the PID.

In the USB, two transfer modes are defined. The first is that the average bit rate is 12
The second is a low-speed transfer mode in which the average bit rate is 1.5 Mbps.

In the USB, four data transfer methods are defined. The first is isochronous transfer. In the isochronous transfer, a transfer width, which is the amount of data transferred for each frame, and a transfer time from a transfer request to the start of transfer are guaranteed. Further, in the isochronous transfer, even if an error occurs in transfer data, it is impossible to make a retransmission request.

The second is an interrupt transfer. In the interrupt transfer, only input from each device to the host computer 300 is possible. In interrupt transfer, the priority of data transfer on the bus is set relatively high. The third is bulk transfer. In bulk transfer, the priority of data transfer is set to be the lowest among the four transfer methods.
The fourth is a control transfer. The control transfer is performed to transfer setup data for performing setup of each device.

[0037]

The above-mentioned 1394 serial bus system and USB system are communication systems which have been used relatively recently.
Conventional communication systems using -232C and RS-422 are still widely used today. Therefore, digital devices compatible with 1394, digital devices compatible with USB, R
At present, digital devices compatible with S-232C and RS-422 are present.

Therefore, it is expected that devices having both a 1394 interface and a USB interface, which have become mainstream in recent years, will be widely required. Also, 1394
It is expected that devices equipped with both an interface and an RS-232C or RS-422 interface will be widely required. Furthermore, 1394, USB, RS-23
It is expected that devices having a plurality of interfaces such as 2C will be widely required.

However, if two or more types of communication devices are provided in the same device in order to perform communication in two or more types, there is a problem that the circuit scale is increased and the cost is remarkably increased. .

The present invention has been made in order to solve such a problem, and enables one device to select two or more types of communication systems without increasing costs due to an increase in circuit scale. The purpose is to do.

[0041]

According to a communication method of the present invention, an arbitrary communication system is selected from a plurality of types of communication systems, and command data for controlling a device connected to a communication path is transmitted and received. The communication method thus configured is characterized in that at least a part of each of the plurality of command data provided in the plurality of types of communication systems is commonly used in each communication system.

Another feature of the communication method according to the present invention resides in that an arbitrary communication method is selected from a plurality of types of communication methods and command data for controlling a device connected to the communication path is transmitted. A communication method for transmitting and receiving, and generating control data of a device connected to the communication path based on the received command data, wherein each of the plurality of controls generated by the plurality of types of communication methods is provided. At least a part of the data is commonly used in each communication method.

Here, one of the above-mentioned plural types of communication systems is used.
One of them is a communication system based on the IEEE 1394 standard, a communication system based on the RS-232C standard,
A communication system conforming to the H.22 standard or a communication system conforming to the USB standard is included.

A communication device according to the present invention is provided for each of a plurality of types of communication systems, a plurality of communication means for transmitting and receiving command data for controlling devices connected to a communication path, and the plurality of communication devices. Decoding means for decoding the command data received by the means and generating control data for controlling the equipment connected to the communication path, wherein the decoding means The present invention is characterized in that common control data is generated for command data having the same function received in a system.

Here, the decoding means includes a storage means for storing control data for controlling the equipment connected to the communication path in advance, and a command data received by the plurality of communication means. Address generating means for generating an address of the storage means in which the control data is stored, wherein the address generating means has the same function that the plurality of communication means receives in the respective communication systems and has the same function. However, the same address in the storage means may be generated.

The command data having the same function received by the plurality of communication means in the respective communication systems is as follows:
The same code data may be used.

As one of the plurality of types of communication means, a communication means conforming to the IEEE 1394 standard, an RS
The communication means includes communication means conforming to the H.-232C standard, communication means conforming to the RS-422 standard, and communication means conforming to the USB standard.

Another feature of the communication apparatus according to the present invention is that a plurality of communication means are provided corresponding to a plurality of types of communication systems and transmit / receive command data for controlling equipment connected to a communication path. And supply means for supplying the command data to the communication means, and at least a part of the plurality of command data provided by the plurality of communication methods supplied by the supply means is common to each communication method. It is characterized by being.

Another feature of the communication apparatus according to the present invention resides in that a plurality of communication means provided corresponding to a plurality of types of communication systems and transmitting / receiving command data for controlling devices connected to a communication path, respectively. Decoding means for decoding command data received by the plurality of communication means and generating control data for controlling equipment connected to the communication path, wherein the plurality of communication means comprises at least N And a second communication unit capable of transmitting and receiving M pieces of command data, wherein at least a part of the M pieces of command data is It is characterized by being included in N command data.

Here, one of the plurality of types of communication means includes a communication means conforming to the IEEE 1394 standard,
The communication means conforms to the S-232C standard, the RS-422 standard, or the USB standard.

[0051]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) An embodiment of the present invention will be described below with reference to the drawings. Figure 1 shows the SD (Standard Defin
ition) is a block diagram showing an embodiment in which the present invention is applied to a video camera for recording and reproducing a video signal, that is, a so-called SD video camera.

In FIG. 1, 1 is a lens, 3 is an imaging device such as a CCD, 5 is a camera processing unit, 7 is a recording medium such as a magnetic tape, 9 is a helical scan head (hereinafter, referred to as a head), and 11 is an error. A correction circuit (hereinafter referred to as an ECC circuit), 13 is a video signal processing circuit, 15 is a switching circuit, 17 is an audio signal processing circuit, and 19 is a subcode data processing circuit.

Further, reference numeral 21 denotes an associated data processing circuit (hereinafter, referred to as an accompanying data processing circuit).
AUX data processing circuit), 23 is an arithmetic processing unit (hereinafter referred to as MPU), 25 is a format circuit,
27 is an interface circuit (hereinafter referred to as an I / F circuit), 29 is a read-only memory (hereinafter referred to as a ROM), 31 is a 1394 driver, and 33 is an RS-232C.
Driver, 35 is 1394 input / output port, 37 is RS-
A 232C input / output port, 39 is a servo circuit, and 41 is a data bus.

The subject image taken through the lens 1 is
After being photoelectrically converted by the CCD 3, the camera processing unit 5 performs predetermined signal processing. As a result, a luminance signal Y and color difference signals U and V having a so-called 4: 1: 1 ratio are generated as digital video signals. These digital video signals generated here are supplied to the switching circuit 15 respectively.
Is input to

At the time of encoding, the switching circuit 15 controls the video signal processing circuit 1
The digital video signal generated as above is input to 3. The video signal processing circuit 13 performs compression coding processing such as blocking, discrete cosine transform (hereinafter referred to as DCT), quantization, and fixed-length coding on the 4: 1: 1 digital video signal. Will be applied.

At the time of encoding, a digital audio signal is transmitted from a circuit such as a microphone and an audio amplifier (not shown) via a switching circuit 15 to an audio signal processing circuit 17.
And is encoded. Further, at the time of encoding, the subcode data and the AUX data
23, the data is input to the subcode data processing circuit 19 and the AUX data processing circuit 21 and processed.

The video signal, audio signal, subcode data, and AU processed by the video signal processing circuit 13, audio signal processing circuit 17, subcode data processing circuit 19, and AUX data processing circuit 21, respectively.
Each signal of X data is input to the ECC circuit 11 via the data bus 41, where an error correction code is added. Then, the data is written from the head 9 to the magnetic tape 7 through a modulation circuit, a head amplifier, and the like (not shown).

On the other hand, at the time of decoding, a digital signal is reproduced from a track on the magnetic tape 7 by the head 9, and the reproduced digital signal is subjected to error correction processing by the ECC circuit 11. Of the digital signals output from the ECC circuit 11 to the data bus 41 as the block digital data, the video signal is
The decoding processing is performed by the video signal processing circuit 13 connected to 1 to generate a luminance signal Y and color difference signals U and V having a so-called 4: 1: 1 ratio. Each signal generated here is output to the outside via the switching circuit 15.

Of the digital signals output from the ECC circuit 11 as the block digital data, the audio signal is the same as the video signal, and
The audio signal is input to the audio signal processing circuit 17 via the input circuit 1 and subjected to a decoding process. On the other hand, the decoded subcode data and AUX data are input to the MPU 23 from the subcode data processing circuit 19 and the AUX data processing circuit 21 connected to the data bus 41, respectively.

The format circuit 25 receives the compressed and encoded video and audio data via the data bus 41. Here, when the video signal processing circuit 13 and the audio signal processing circuit 17 are performing the encoding operation, the video and audio data input to the format circuit 25 are, for example, before the ECC circuit 11 adds an error correction code. Data. Further, when the video signal processing circuit 13 and the audio signal processing circuit 17 are performing the decoding operation, the video and audio data input to the format circuit 25 are, for example, those after the error correction code is removed by the ECC circuit 11. Data.

Further, the subcode data and the AUX data output from the MPU 23 are input to the format circuit 25, respectively. These video data, audio data, subcode data and AUX data are reconstructed into DIF data (digital interface data) by the format circuit 25 and output to the I / F circuit 27. These DIF data are packetized by the I / F circuit 27.

When the 1394 interface is used, the packet data generated by the I / F circuit 27 is sent to the 1394 input / output port 35 via the 1394 driver 31. On the other hand, when the RS-232C interface is used, the packet data generated by the I / F circuit 27 is sent to the RS-232C input / output port 37 via the RS-232C driver 33.

When the 1394 interface is used or the RS
The user may select whether to use the −232C interface by operating an external selection switch (not shown) or the like, or the MPU 23 or the like may detect connection of the interface and automatically switch the interface.

The servo circuit 39 controls the running of the magnetic tape 7 according to an instruction signal from the MPU 23. Note that M
The PU 23 responds to instruction information input from an operation panel (not shown), and manages the operation mode and various state transitions of the entire system of the digital VTR.

The servo circuit 39 mainly has a function of constantly driving a rotating drum and a capstan (not shown). That is, in the servo circuit 39,
A capstan motor (not shown) for controlling the tape feed speed and a capstan FG (Frequency generator) for grasping the rotation status thereof, a drum motor for rotating the rotary drum, and checking of the rotation speed and rotation phase thereof Detectors FG, PG (Phase generato
r) are connected, and each is controlled by the servo circuit 39.

Command data for the SD video camera of this embodiment is externally input to the 1394 input / output port 35. FIG. 2 is a diagram showing a general format of 1394 command data input to the 1394 input / output port 35. In FIG. 2, CT / RC indicates a command type and a response code, each of which is a 4-bit code. The following Table 1 shows the codes of the command type, and Table 2 shows the codes of the response codes.

[0067]

[Table 1]

[0068]

[Table 2]

In FIG. 2, HA indicates a header address, and EHA indicates an extended header address. The header address is an 8-bit code, which is an identification code of a plurality of devices (sub devices) in one device connected to the communication interface (communication path). That is, the upper 5 bits of the header address indicate the sub-device type indicating the type of the sub-device, and the lower 3 bits are the sub-device number indicating the number of sub-devices of the same type indicated by the upper 5 bits. . The extension header address is a header address reserved for the future. Table 3 shows an example of the sub device type.

[0070]

[Table 3]

In FIG. 2, OPC indicates an operation code, and OPR indicates an operand. The operation code indicates the content of control for the digital device connected to the communication interface (communication path), and the operand indicates data required by the operation code. Table 4 below shows an example of operation codes and operands for reproduction.

[0072]

[Table 4]

The data length of the command shown in FIG.
If the data is in units of bytes and is less than an integral multiple of 4 bytes, data in which all bits are zero is packed at the end of the bit stream, and the data is made an integral multiple of 4 bytes as a whole.

When the command data for 1394 shown in FIG. 2 is expressed as shown in Tables 1 to 4, for example,
When you want the video cassette recorder (VCR) to perform normal playback, use “0x0021C336” (note that 0x
(Indicating hexadecimal notation)) is input to the 1394 input / output port 35. That is, the first "0x00" indicates the first four bits of the command data, which are fixed to 0, and the next four bits indicating the control command (see Table 1). Next “0x2
"1" indicates an 8-bit header address, the subdevice type is VCR (see Table 3), and the
This indicates that the device is the second device in the CR. Further, the following “0xC336” indicates the operation code and the operand obtained from Table 4.

When the code for normal reproduction is input to the 1394 input / output port 35, the I / F circuit 27 outputs a control signal for normal reproduction to the ROM 29 based on the input code. Is generated and input to the MPU 23. The MPU 23 reads control data from the ROM 29 in accordance with the generated address and controls a rotating drum and a capstan motor (not shown) via a servo circuit 39 to maintain a reproduction state.

On the other hand, the above RS-232C input / output port 3
7, command data for RS-232C is input from the outside. Here, in the present embodiment, the aforementioned 139
At least a part of the command data for the RS-232C and the command data for the RS-232C are commonly used.

For example, the 1394 driver 31 and the RS
Command data having the same function and received by each communication method in the -232C driver 33 are all commonly used. That is, the RS-232C transmits and receives M command data (an integer of 2 or more),
In 394, if N command data (N is an integer of 2 or more that satisfies N ≧ M) including command data having the same function as the M command data are transmitted and received, all of the M command data are transmitted. 1394 and RS-
232C. Or M
A part of the command data may be commonly used.

By doing so, the I / F circuit 27 and the MPU 2 that interpret command data and perform various controls are provided.
3 and the like, the communication system by 1394 and RS
It can be used in common with the -232C communication system, and it is not necessary to provide a plurality of communication devices for various communication systems in one digital device. Therefore, a digital device compatible with both the 1394 and RS-232C communication systems can be configured without increasing the circuit scale.

By the way, in RS-232C, usually 2
Digital devices are connected 1: 1. Therefore, the device identification code and device number are not required. Therefore, in the present embodiment, for example, “0x
RS-232C I / O port 3
7 is input. Table 5 below shows an example of an RS-232C playback code corresponding to the 1394 control code.

[0080]

[Table 5]

By omitting the device identification code, device number, and the like, the delay time due to command transfer can be reduced, and the RS-232C, which is a relatively low-speed interface, is used. It is convenient to do it.

The code for normal reproduction is RS-23.
When input to the 2C input / output port 37, the I / F circuit 27
Generates an address in the ROM 29 in which control data for normal reproduction is stored based on the input code, and inputs the generated address to the MPU 23. The MPU 23 reads control data from the ROM 29 in accordance with the generated address and controls a rotating drum and a capstan motor (not shown) via a servo circuit 39 to maintain a reproduction state.

In the above embodiment, an example in which command data having the same function and input to the 1394 input / output port 35 and the RS-232C input / output port 37 are the same in each communication system has been described. Even though the data itself is different, it is also possible to prevent an increase in circuit scale by making the control data generated from the ROM 29 based on the command data common to each communication system.

In this case, I / F circuit 27 and MPU
23 is a 1394 input / output port 35 and RS-232
At the C input / output port 37, the same control data is generated for command data having the same function and received by each communication method. That is, the I / F circuit 27 for generating the address of the ROM 29 in which the control data is stored in accordance with the command data received at each of the input / output ports 35 and 37 receives the command data having the same function received by the respective communication methods. Against the above ROM
Generate the same address at 29.

In the above embodiment, the IEEE 13
Although the description has been made using the 94 standard and the RS-232C standard, other standards (for example, the RS-422 standard) may be used. Further, not only communication devices supporting two communication standards but also communication devices supporting more communication standards can be configured without increasing the circuit scale by sharing command data.

In the above embodiment, the IEEE 13
The lower 2 of the control code according to the 94 standard and the RS-232C standard
Although the byte is common, the common part may have another configuration. Further, the code length for control is not limited to the above-described code length (4 bytes), and any code length can be applied.

(Second Embodiment) Hereinafter, a second embodiment according to the present invention will be described with reference to the drawings. FIG.
FIG. 1 is a block diagram showing an embodiment in which the present invention is applied to a video camera for recording and reproducing an SD video signal, that is, a so-called SD video camera. The difference between the second embodiment and the first embodiment is that the first embodiment includes the IEEE 1394 and the RS-232C as digital interfaces, but the present embodiment has the IEEE 1394 and the USB.
And

That is, in the present embodiment, the IEEE1394
A device that uses at least a part of each of a plurality of pieces of device control data generated based on command data or received command data between a communication device and a common device in each communication method is disclosed. In FIG. 3, the same parts as those of FIG.

In FIG. 3, reference numeral 45 denotes a bit inversion circuit;
7, a USB driver; and 49, a USB input / output port. To the format circuit 25 ', video and audio DIF data are directly input from the data bus 41, and the subcode data and AU
X data is input and converted to so-called DIF data. The DIF data output from the format circuit 25 'is packetized by the I / F circuit 27'.

The format circuit 25 'and I /
The F circuit 27 ′ is connected to the MPU 23 depending on whether the 1394 interface or the USB interface is used.
Is controlled to perform processing suitable for the interface selected by the user. When the 1394 interface is used, the data is sent to the 1394 input / output port 35 via the 1394 driver 31. On the other hand, when the USB interface is used, the signal is sent to the USB input / output port 49 via the bit inversion circuit 45 and the USB driver 47.

The bit discharging method at the time of data transmission differs between 1394 and USB. That is, in 1394, the most significant bit is transmitted first, while (MSB
First), in the USB, the least significant bit is transmitted first (LSB first). Therefore, when USB is used, the bit inversion of data transmitted and received by the bit inversion circuit 45 is performed. In the present embodiment, bit transposition is performed on data transmitted and received by USB based on 1394, but bit transposition is performed on data transmitted and received by 1394 on the basis of USB. Is also good.

Use the 1394 interface or US
The user may select whether to use the B interface by operating an external selection switch or the like (not shown), or the MPU 23 or the like may detect connection of the interface and automatically switch.

As shown in the first embodiment, for example,
When it is desired to have the VCR perform normal playback, a command data code such as “0x0021C336” is input from an external device. When the normal reproduction code is input from the 1394 input / output port 35, the I / F circuit 27 '
Generates an address in the ROM 29 in which control data for normal reproduction is stored based on the input code, and inputs the generated address to the MPU 23. The MPU 23 stores the control data in the ROM 2 according to the generated address data.
9 and controls a rotating drum (not shown) and a capstan motor (not shown) via a servo circuit 39 to maintain a reproducing state.

On the other hand, in USB, V
When normal playback is desired to be performed by the CR, a command data code is transmitted from a host computer (not shown) by, for example, the bulk transfer described above. In the bulk transfer, a token packet as shown in FIG. 4A is transmitted at the start frame of the bulk transfer. In the next frame, the host transmits a data packet as shown in FIG. The code such as the above-mentioned “0x0021C336” is included in the data field in this data packet. In the case of such a relatively small amount of data, the data field can include data up to 1023 bytes, so that transmission is completed in two frames.

Here, the PID in the above token packet
Will be described. Table 6 shows the values of the PID. As shown in Table 6, the first value of the PID is OUT indicating that data transfer from the host is started, the second is IN indicating that data transfer to the host is started, and the last is the device ID. SETUP indicating start of setup
It is. Note that all token packets are issued by the host.

[0096]

[Table 6]

On the other hand, there are two types of PIDs in the data packet. Table 7 shows the values of the PID in the data packet. If the data packet does not end in one frame, the first frame starts from DATA0, and DATA0 / DATA1 / DATA for each frame.
0 / …… is toggled. In the case of the present embodiment, since only one frame is transmitted for a data packet, only the data ID0 is used as the PID value.

[0098]

[Table 7]

As described above, the USB and 1394 differ in the bit discharging method at the time of data transmission. Therefore, in the USB, “0x00” in 1394 described above is used.
A code such as “21C336” is a code such as “0x0084C3CA” in which bits are transposed for each byte.
To arrive. Therefore, the bit inversion circuit 45 outputs “0x
0084C3CA ”is transposed into bits for each byte,
The code is converted into a code having a value of “0x0021C336” and output. In the present embodiment, the bit inversion circuit 45
Although provided separately from the SB driver 47, the USB driver 47 may be configured to have this function.

In the USB, when the transmission from the host is completed, the SD video camera according to the present embodiment notifies the host of the completion of communication using a handshake packet as shown in FIG. This handshake packet is composed of only the PID, and the meaning of the notification differs depending on the value of the PID.
Table 8 below shows the values of the PID.

[0101]

[Table 8]

In Table 8, ACK indicates that communication has been completed normally. NACK indicates that the data from the host has an error. In this case, the host repeats the same data transfer as described above. STALL indicates that the SD video camera according to the present embodiment has a state in which data cannot be transmitted or received for some reason.

When the host is notified by the ACK signal that the communication has been normally completed, the host transmits a token packet again to the SD video camera of this embodiment to receive a response code. Then, in the next frame, the SD video camera of this embodiment
Response code "0x" indicating that normal playback is possible
0921C336 ”is inserted into the data packet and transmitted to the host. When the data packet is normally received by the host, the host transmits an ACK handshake packet to the SD video camera of the present embodiment, Transmission / reception is completed.

In this embodiment, the control code and the response code are exchanged using only bulk transfer. However, for example, a USB interrupt transfer may be used in response. good. In such a configuration, interrupt transfer has a higher transfer priority than bulk transfer, so that a response can be reliably returned even when the amount of data on the communication path increases. Is good. When exchanging the control code and the response code, an isochronous transfer may be used instead of the bulk transfer.

Further, communication may be performed by adding additional information to a data packet for performing USB communication. FIG. 6 is a diagram showing a configuration of a data packet when additional information is added. FIG. 6A shows a configuration of the entire data packet, and FIG. 6B shows a configuration of a data field in the data packet. The data packet is transmitted by, for example, isochronous transfer. The data field of the data packet is transmitted at a fixed length from the start to the end of the communication.

In FIG. 6B, the first transmitted field is the data_length field. data_le
The data length of the ngth field is set to, for example, 1 byte. This field indicates the effective data length included in the data field in byte units. This data_
After the length field, a fixed_length_data field follows. This field is a fixed-length data field as described above. In this field, valid_da containing valid data to be actually decoded is included.
ta field and zero filled with zero value data
_Pad_byte field.

If the data length of the valid_data field matches the data length of the fixed_length_data field, the zero_pad_byte field is fixed
It does not exist in the d_length_data field. The value of the zero_pad_byte field is not limited to zero, and other data such as 0xFF can be used. fixed
The data length of the _length_data field is, for example, 15
Set to bytes.

In the data field shown in FIG. 6B, the RS_code field transmitted last is an error detection / correction code such as a Reed-Solomon code. In the present embodiment, for example, an 8-byte Reed-Solomon code is added. In the present embodiment, the Reed-Solomon code is used, but another error detection / correction code such as a Hamming code may be used.

FIG. 7 is a block diagram showing a case where the communication apparatus using the data packet shown in FIG. 6 is applied to an SD video camera. In FIG. 7, the same portions as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 7, reference numeral 51 denotes a second error correction circuit, and 53 denotes a second data bus.

For example, when the user wants the VCR to perform normal reproduction, the code whose value of the valid_data field is “0x0021C336” in FIG. 47 is input. At this time, since the valid data length is 4 bytes, the value of the data_length field is “0x04”.
Since the value of the data is actually a bit-transposed value for each byte, the bit-transposed value is converted to a normal value by the bit inversion circuit 45. Each of the converted data is transferred to the second data bus 53 via the second data bus 53.
And an error occurring on the communication path is detected and corrected. In the present embodiment, 4-byte correction is possible.

With the above configuration, NAC
Even in the case of isochronous transfer in which a retransmission request cannot be made due to K, the accuracy of data in communication can be increased. In addition, there is an advantage that the response at the time of data transfer can be performed at high speed by using the isochronous transfer having a relatively high priority. The above data configuration is not limited to the data length, the error detection / correction code, and the like, but may include other additional information. Also, data_
length field, fixed_length_data field,
It goes without saying that the number of bytes of the RS_code field and the like is not limited to the above configuration, and may be another configuration. In the present embodiment, the isochronous transfer is used, but the above configuration can be applied to other transfer methods such as bulk transfer.

[0112]

As described above, according to the present invention, when an arbitrary communication system is selected from a plurality of types of communication systems and command data for controlling a device connected to a communication path is transmitted and received. Since at least a part of the plurality of command data provided by the plurality of types of communication methods or the plurality of device control data generated based on the received command data is at least partially shared by the respective communication methods, In addition, a communication device that interprets command data or control data and performs various controls can be commonly used in each communication system, and a single device does not need to have a plurality of communication devices for various communication systems. As a result, it is possible to provide a communication device in which two or more types of communication methods can be selected, and in which a cost increase due to an increase in circuit scale is small.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an SD video camera according to an embodiment to which a communication device of the present invention has been applied.

FIG. 2 is a diagram illustrating a general format of command data for 1394.

FIG. 3 is a block diagram showing a configuration of an SD video camera according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a data format transmitted from a host in bulk transfer.

FIG. 5 is a diagram showing a data format of ACK returned by the SD video camera of the present embodiment in bulk transfer.

FIG. 6 is a diagram illustrating a configuration of a data packet according to the present embodiment.

FIG. 7 is a block diagram showing a configuration of an SD video camera using the data packet of FIG. 6;

FIG. 8 is a diagram showing a connection configuration of an IEEE 1394 serial bus.

FIG. 9 is a timing chart showing an example of communication using an IEEE 1394 serial bus.

FIG. 10 illustrates an example of a USB connection mode.

FIG. 11 is a diagram showing a USB data transfer unit.

FIG. 12 is a diagram showing a packet used for USB data transfer.

[Explanation of symbols]

 23 arithmetic processing unit (MPU) 25 format circuit 27 interface circuit (I / F circuit) 29 read-only memory (ROM) 31 1394 driver 33 RS-232C driver 35 1394 input / output port 37 RS-232C input / output port 45 bit reverse circuit 47 USB Driver 49 USB I / O Port 51 Second Error Correction Circuit 53 Second Data Bus

Claims (19)

[Claims] 1. A communication method for selecting an arbitrary communication method from a plurality of types of communication methods and transmitting and receiving command data for controlling a device connected to a communication path, A communication method characterized in that at least a part of a plurality of command data provided in a plurality of types of communication systems is commonly used in each communication system. 2. An arbitrary communication method is selected from a plurality of types of communication methods, command data for controlling a device connected to a communication path is transmitted and received, and based on the received command data, A communication method adapted to generate control data of a device connected to a communication path, wherein at least a part of each of the plurality of control data generated by the plurality of types of communication methods is determined by each communication method. A communication method characterized by being commonly used. 3. The communication method according to claim 1, wherein one of the plurality of types of communication systems includes a communication system conforming to the IEEE 1394 standard. 4. The communication method according to claim 1, wherein one of the plurality of types of communication systems includes a communication system conforming to the RS-232C standard. 5. The communication method according to claim 1, wherein one of the plurality of types of communication systems includes a communication system conforming to the RS-422 standard. 6. The communication method according to claim 1, wherein one of the plurality of types of communication systems includes a communication system conforming to a USB standard. 7. A plurality of communication means provided corresponding to a plurality of types of communication systems, respectively, for transmitting and receiving command data for controlling a device connected to a communication path, and receiving the command data by the plurality of communication means. Decoding means for decoding command data and generating control data for controlling the equipment connected to the communication path, wherein the decoding means receives the plurality of communication means in the respective communication systems. A communication device for generating common control data for command data having a function. 8. The decoding means according to claim 1, wherein said decoding means stores control data for controlling a device connected to said communication path in advance and said command data received by said plurality of communication means. Address generation means for generating an address of the storage means in which the control data is stored, wherein the address generation means converts the plurality of communication means into command data having the same function received by the respective communication methods. The communication device according to claim 7, wherein the same address is generated in the storage means. 9. The communication apparatus according to claim 7, wherein the command data having the same function and received by the plurality of communication units in the respective communication systems use the same code data. 10. The communication apparatus according to claim 7, wherein one of the plurality of types of communication means includes communication means conforming to the IEEE 1394 standard. 11. The communication device according to claim 7, wherein one of the plurality of types of communication means includes a communication means conforming to the RS-232C standard. 12. The communication apparatus according to claim 7, wherein one of the plurality of types of communication means includes a communication means conforming to the RS-422 standard. 13. The communication device according to claim 7, wherein one of the plurality of types of communication means includes a communication means conforming to a USB standard. 14. A plurality of communication means provided corresponding to a plurality of types of communication systems for transmitting and receiving command data for controlling a device connected to a communication path, and supplying the command data to the communication means. A communication device, comprising: a supply unit, wherein at least a part of each of the plurality of command data provided by the plurality of communication systems supplied by the supply unit is common to the communication systems. 15. A plurality of communication means provided respectively corresponding to a plurality of types of communication systems, for transmitting and receiving command data for controlling devices connected to a communication path, and for transmitting command data received by the plurality of communication means. Decoding means for decoding and generating control data for controlling equipment connected to the communication path, wherein the plurality of communication means are capable of transmitting and receiving at least N pieces of command data. And second communication means capable of transmitting and receiving M pieces of command data, wherein at least a part of the M pieces of command data is included in the N pieces of command data. Communication device. 16. The communication apparatus according to claim 14, wherein one of the plurality of types of communication means includes communication means conforming to the IEEE 1394 standard. 17. The communication apparatus according to claim 14, wherein one of the plurality of types of communication means includes a communication means conforming to the RS-232C standard. 18. The communication apparatus according to claim 14, wherein one of the plurality of types of communication means includes a communication means compliant with the RS-422 standard. 19. The communication apparatus according to claim 14, wherein one of the plurality of types of communication means includes a communication means conforming to a USB standard.