JP2002291067A - Data transmission method, data transmission system and data transmission device - Google Patents

Abstract

(57) [Summary] PROBLEM TO BE SOLVED: To easily perform a process of displaying an operation status of another device by data transmission using a transmission network such as Bluetooth (trademark). SOLUTION: A command of a predetermined format can be bidirectionally transmitted between a remote control device and a controlled device controlled by the remote control device using a predetermined transmission network. In this case, by transmitting a first command for controlling the operation of the controlled device from the remote control device to the controlled device, the controlled device executes the operation specified by the command, and A second command having the same format as the first command is sent from the control device to the remote control device via the transmission network with data relating to the operation state of the controlled device, and the second command is received. Thus, the content of the second command is determined, and the operation status and the like can be displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission method and a data transmission system suitable for a wireless transmission system called, for example, Bluetooth (trademark), and a data transmission apparatus. The present invention relates to a technique suitable for processing when wireless transmission is performed between devices and devices that control these devices.

[0002]

2. Description of the Related Art In recent years, a wireless transmission system of a standard called Bluetooth (trademark) has been proposed and is being put to practical use. In this wireless transmission system,
Transmission of voice data for telephone communication, image data for facsimile, data for computer, etc. between multiple devices
The radio transmission is performed using the 2.4 GHz frequency band, and the radio transmission distance between the devices is, for example, several meters to 1 at the maximum.
A network of a relatively short distance of about 00 m is assumed. For each type of data to be transmitted, a profile is defined which defines how the data is transmitted. The details of the communication method will be described in an embodiment described later.
published by tooth SIG.

In the case of a wireless transmission system called Bluetooth, the Audio / Video Control Transport Protocol
By transmitting a command specified by a protocol called ol (hereinafter, referred to as AVCTP), any one device in the wireless network can control another AV device in the network. For example, a remote control device provided with a communication means of Bluetooth standard and an A controlled by a radio signal from the remote control device
V equipment is prepared, and AV
By transmitting data instructing the operation of the AV device using a command of the CTP protocol, various operations of the AV device can be controlled.

[0004] Data that can be wirelessly transmitted in accordance with the Bluetooth standard includes, for example, data that is displayed on a display unit of another device. By applying the process of wirelessly transmitting the data for display to, for example, the above-described remote control device and the AV device controlled by the remote control device, the operation status of the AV device, for example, the In this case, it is conceivable that the playback status such as the playback track number of the device is wirelessly transmitted to the remote control device and displayed on the display panel of the remote control device as numbers, figures, or the like.

[0005]

However, in order to transmit data for executing display, the remote control device needs to know the state of the other device (controlled device). Specifically, for example, the remote control device grasps what kind of function blocks the controlled device has and what specific functions can be executed by the function blocks, and the operation status of the grasped function blocks Must be transmitted from the remote control device to the controlled device, and in response to the command, the remote control device determines the state of the controlled device, and displays the operation status based on the determination. . Therefore, the control unit in the remote control device needs a storage unit for storing the function blocks of the controlled device controlled by this device, and determines the current operation status of the stored function blocks. Therefore, there is a problem that the processing for displaying is very complicated.

[0006] Here, the problem of the example in which the AV device is controlled by applying Bluetooth has been described. However, in the case where another similar transmission network is formed and the status of the device is displayed on another device. Have a similar problem. For example, IEEE (The Institute of Electrical
A similar problem arises when a wired network in which a plurality of devices are connected by a 1394 serial bus and a similar display process is performed by data transmission in the wired network. IE
Even in the case of a network using an EE1394 serial bus, the AVCTP for the Bluetooth standard described above is used.
As in the case of the protocol described above, the AV device connected to the network is controlled from another device by using a command of a predetermined standard (AV / C Command Transaction Set: hereinafter, referred to as an AV / C command). It is possible.

SUMMARY OF THE INVENTION It is an object of the present invention to facilitate the process of displaying the operation status of another device in data transmission using various transmission networks.

[0008]

SUMMARY OF THE INVENTION The present invention provides a bidirectional communication between a remote control device and a controlled device controlled by the remote control device using a predetermined transmission network. When the command transmission is possible, the remote control device transmits the first command for controlling the operation of the controlled device to the controlled device so that the controlled device receives the command. Executes the instructed operation, and uses a second command in the same format as the first command from the controlled device,
The data relating to the operation state of the controlled device is transmitted to a remote control device via a transmission network.

With this configuration, the remote control device can directly determine the operation specified by the data received in the form of a command and display the operation status of the controlled device based on the determination. become.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described.
This will be described with reference to the accompanying drawings.

[0011] In the present invention, Bluetooth (Blue
This is a wireless transmission system called tooth (trademark), which is applied to a wireless network formed by a plurality of devices. The wireless transmission system of the Bluetooth standard will be described later.

FIG. 1 shows a configuration of two devices 100 and 200 which are devices constituting the wireless network of the present embodiment. Here, the device 100 is an audio player, and the device 200 is an audio receiver. The audio player 100 reproduces audio data from a predetermined recording medium (here, a disk), and causes the short-range wireless processing unit 10 to wirelessly transmit the reproduced audio data. The audio receiver 200 performs a process of outputting the audio data received by the short-range wireless processing unit 10 from the connected headphone device.
It also functions as a remote control device for controlling playback on a PC.

The configuration of the audio player 100 is as follows.
The data reproduced from the recording medium by the disk reproducing unit 101 is supplied to the audio processing unit 103 under the control of the system control unit 102, and the audio processing unit 103 obtains digital audio data of a predetermined format.
The obtained audio data is stored in the audio player 100.
The wireless communication unit 10 supplies the wireless transmission using a predetermined channel. When the wireless processing unit 10 receives a command for controlling the operation of the audio player 100, the wireless processing unit 10 sends the received command to the system control unit 102, and the system control unit 102 executes the operation specified by the command. . Here, an AVCTP command is received. The details of the AVCTP command will be described later. Also, the audio player 1 of the present embodiment
At 00, the wireless processing unit 10 wirelessly transmits the operation status of the device as an AVCTP command under the control of the system control unit 102. The command indicating the operation status may include text data such as the track number, title, and lyrics of the audio (song) being reproduced.

The configuration of the audio receiver 200 is as follows.
The audio data received by the built-in wireless processing unit 10 is transmitted to the audio processing unit 2 under the control of the system control unit 203.
01, performs demodulation processing from data in the transmission format, supplies demodulated audio data to an audio output unit 202, performs output processing such as analog conversion and amplification, and is connected to the receiver 200. The headphone device 206 supplies the sound to the headphone device 206. A display unit 204 including a liquid crystal display panel and a driving circuit for the liquid crystal display panel is connected to the system control unit 203. Also, this audio receiver 2
The operation information of the key 205 arranged at 00 is supplied to the system control unit 203. When the operation of the key 205 is determined by the system control unit 203, a command corresponding to the determined key operation is generated, and the built-in wireless processing unit 10 is generated.
To wirelessly transmit commands. This command is also an AVCTP command.

When the radio processing unit 10 in the receiver 200 receives a command indicating the operation status of the playback device 100 from the audio playback device 100, the received command is supplied to the system control unit 203, and the command is transmitted to the system control unit 203. The system control unit 203 determines the instructed operation status. When the operation state is determined, the system control unit 2
Reference numeral 03 denotes a display on the connected display unit 204 regarding the determined operation status. If the received command indicating the operation status includes text data such as the track number, title, and lyrics of the audio (song) being reproduced, the track number and other numbers, and characters and the like based on the text data, The display may be displayed on the display unit 204 under the control of the system control unit 203.

An audio player 1 having the configuration shown in FIG.
00 and the audio receiver 200, and when performing wireless transmission by Bluetooth between the two,
Audio stream data is wirelessly transmitted from the audio player 100 to the audio receiver 200 using a predetermined wireless transmission channel. Also, a command instructing the operation of the playback device 100 is wirelessly transmitted from the audio receiver 200, which is a remote control device of the playback device 100. The wireless transmission channel used at this time is a different channel from the channel used for transmitting the stream data. Further, a command indicating the operation status of the playback device 100 is wirelessly transmitted from the audio playback device 100 to the audio receiver 200. The transmission channel of this command is basically the same as the channel on which the command is transmitted from the receiver 200.

In the communication system standardized as Bluetooth, one communication between two devices as shown in FIG.
In addition to one-to-one wireless transmission, it is possible to form a network with a large number of devices. For example, the audio receiver 200 can change the destination of a command so that another device including a Bluetooth-based wireless processing unit is provided. You can also send device control commands.

FIG. 2 is a diagram showing an example of the configuration of the short-range wireless processing unit 10 provided in the devices 100 and 200. The transmission / reception processing unit 2 to which the antenna 1 is connected performs high-frequency signal processing to execute wireless transmission processing and wireless reception processing. Signals transmitted and received by the transmission / reception processing unit 2 are transmitted on channels set at 1 MHz intervals in the 2.4 GHz band. However, the signal of each channel is subjected to a process called frequency hopping in which a transmission frequency is changed at a slot interval described later. If frequency hopping is performed for each slot, the frequency is switched 1600 times per second since one slot is 625 μsec, so that interference with other wireless communication is prevented. As a modulation method of the wireless transmission signal, a modulation method called GFSK (Gaussian filtered FSK) is applied. This modulation method is a frequency shift keying method in which the frequency transfer characteristic is band-limited by a low-pass filter having a Gaussian distribution.

The signal received by the transmission / reception processing unit 2 and the signal to be transmitted by the transmission / reception processing unit 2 are transmitted to the data processing unit 3
Performs the baseband processing. According to the Bluetooth standard, TDD (Time D
ivision Duplex) method, and the data processing unit 3
In this example, the processing of the transmission slot and the processing of the reception slot are performed alternately.

The data processing unit 3 is connected to a function processing block 20 via an interface unit 4 so as to supply received data to the function processing block 20 or to transmit data transmitted from the function processing block 20. The data processing unit 3 performs a process for setting a transmission slot. Processing for transmission in the transmission / reception processing unit 2, the data processing unit 3, and the interface unit 4 is executed under the control of the controller 5. As the controller 5, for example, a central control unit built in each device can be used. Apart from the central control unit, a dedicated controller prepared for short-range wireless communication may be used.

The transmission / reception processing unit 2, the data processing unit 3, and the interface unit 4 become the short-range wireless processing unit 10 for performing communication by Bluetooth.

The function processing block 20 connected to the short-range wireless processing unit 10 corresponds to a part that actually executes a function as a device. For example, in the case of the audio player 100, it corresponds to a portion for reproducing an audio signal from a medium. In the case of the audio receiver 200, it corresponds to a portion that performs output processing of a received audio signal. In addition, a portion where the devices 100 and 200 execute a process related to a command described later is also included in the functional processing block 20.

The short-range wireless communication unit 90 is connected to the device 10
In addition to the case where the device is incorporated in the device 0 or 200, the device may be configured as a device separate from the device main body and connected to the devices 100 and 200 externally.

Next, a method for performing wireless communication in a wireless network will be described. In the case of this example, the wireless communication is performed according to the Bluetooth standard as described above, and the wireless transmission method according to the Bluetooth standard will be described.

FIG. 3 is a diagram showing a protocol stack necessary for performing wireless communication by Bluetooth. The Bluetooth system-wide protocol is a core protocol that is a major part of the Bluetooth protocol,
It is divided into three categories: application software that manages application services, and a conformance protocol group for matching a communication protocol between a core protocol and an application.

The Bluetooth score protocol is composed of five protocols. Physical layer in order from the lower layer,
It consists of a baseband layer, a real data processing layer, and a logical link management layer.

The adaptation protocol group adapts the core protocol to the application software so that various existing application software can be used.
The conforming protocol group includes, for example, TCP / IP protocol, RFCO emulating a serial port.
MM protocol, device operated by user (HID: Human
Interface Device) driver. In transmitting AV / C data described later, a protocol that conforms to a profile corresponding to this conforming protocol group is prepared. The protocol configuration required for transmitting AV / C data will be described later.

As the physical layer, a frequency hopping type spread spectrum system using a 2.4 GHz frequency band is adopted. Transmission power is at most 100 mW
It is assumed that wireless transmission is performed over a short distance up to about 100 m. Further, the physical layer is configured so that the transmission power can be reduced to a minimum of -30 dBm by control from the link layer.

The baseband layer is defined as a protocol for interfacing actual transmission / reception data packets with the physical layer. This layer provides a communication link for transmitting and receiving data passed from an upper layer. At this time, frequency hopping management and time axis slot management are also performed. The baseband layer also manages packet retransmission and error correction and detection processing.

The link management layer is one of the protocols for interfacing transmission / reception packets on a communication link, and specifies the setting of a communication link and the setting of various communication parameters related to the link to the baseband layer. These are defined in the link management layer as control packets, and communicate with the link management layer of the opposite terminal as needed. This layer is directly controlled by a higher-level application as needed.

In the voice layer, after the link management layer sets a communication link through which data can be transmitted, voice data is transferred. The voice data here is mainly voice data for making a telephone call, and is dedicated to a relatively lower layer in order to minimize delay in data transmission when communicating with a wireless telephone or the like. Is provided.

The logical link management layer manages logical channels by a protocol that interfaces with the link management layer and the baseband layer. Transmission data other than audio data handled by the audio layer is provided to the ethical link layer from a higher-level application, but the actual data exchanged there is the size and timing of data packets transmitted and received in the baseband layer. It is passed without being conscious of. Therefore, the logical link management layer manages the data of the upper application as a logical channel,
Performs data division and data reconstruction processing.

FIG. 4 shows processing in each layer when wireless communication is performed between two devices. In the physical layer, a link of a physical wireless communication line is set, and the baseband layer is set. Then, packets are transmitted / received on the set link. In the link management layer, control packets are transmitted and received on a communication link management channel. In the logical link management layer, transmission and reception of user data packets are performed on logical channels. The user data corresponds to stream data, a command, and the like that are actually desired to be transmitted.

Next, a description will be given of a process of setting a physical communication frequency when wireless communication is performed by this method. FIG.
FIG. 3 is a diagram showing frequencies used in this method. As shown in FIG. 5, 1M from 2402MHz to 2480MHz
There are 79 communication frequencies at Hz intervals. Each transmitted packet is one of the 79 communication frequencies.
Occupies the communication spectrum. Then, the used communication spectrum changes (hops) randomly every 625 μsec.

FIG. 6 shows an example in which the communication frequency hops, and the transmission frequency randomly changes every 625 μsec from a specific timing t ₀ .
Since the communication frequency changes every 625 μsec, random hopping occurs about 1600 times per second, and as a result, the data is spread and transmitted in the band shown in FIG. Has been done.

In the case of Bluetooth, one unit of a packet is 625 μsec. However, it is also possible to transmit the packet by continuously using a plurality of the unit. For example, when two-way transmission is performed between two devices, it is not necessary for the communication in both directions to use the same number of packets, and there is a case where communication in only one direction uses a plurality of packets.

If all the transmitted packets are 625 μsec packets as shown in FIG. 7, frequency hopping is performed every 625 μsec as shown in FIG. On the other hand, as shown in FIG. 8, for example, when three packets are continuously used or when five packets are continuously used, the transmission frequency is fixed while the slot is continuous. You.

FIG. 9 shows a communication state between two devices. When one device performing wireless transmission is set as a master and the other device is set as a slave, one slot (625 μsec) is transferred from the master to the slave. During the period of the next slot, data of the slot configuration is transmitted from the slave to the master during the next one slot period (FIG. 9A).
B). Hereinafter, the alternate transmission is repeated as long as the transmission continues.
However, the frequency for wireless transmission is changed to frequency f (k), f (k + 1), f (k + 2)... For each slot as described above.

FIG. 10 is a diagram showing an example of a network configuration composed of a plurality of devices. In a communication system standardized as Bluetooth, not only one-to-one wireless transmission but also a network can be formed by a large number of devices. That is, when wireless transmission is performed between two devices, as shown in FIG. 10A, one device becomes a master, the other device becomes a slave, and the master M
Under the control of A11, bidirectional wireless transmission is performed between the master MA11 and the slave SL11. On the contrary,
As shown in FIG. 10B, for example, three slaves SL21, SL22, and S controlled by one master MA21.
L23 may be prepared and a network may be configured to perform wireless transmission between the four devices. FIG.
As shown in C, three masters MA31, MA32, M
A33 and a slave SL3 individually controlled by each master
1, SL32, SL33, SL34, SL35, SL3
After preparing 6 and configuring 3 networks,
The three networks can be connected to expand the network configuration. In any case, it is not possible to directly communicate between the slaves, and communication is always performed via the master.

A network composed of one master and a slave that directly communicates with the master is called a piconet. A network group having a plurality of masters (that is, a network group composed of a plurality of piconets) is called a caster net.

Next, a description will be given of the types of links used for communication between devices using Bluetooth. In Bluetooth, SCO (Synchronous Connection-Oriented)
There are two types of communication links, a link and an ACL (Asynchronous Connection-Less) link, which can be properly used depending on the application purpose.

The SCO link is a connection type for performing one-to-one communication between a master and a specific slave, and is a so-called circuit-switched link. This link is mainly used for applications that require real-time properties such as voice. In this SCO link, a communication slot is reserved in advance at a constant interval in a communication link in the piconet, and even if other data is transmitted on the way, the data communication of the SCO link has priority. That is, for example, FIGS.
As shown in (1), an SCO communication slot is mutually transmitted between a master and a slave at regular intervals.

This SCO link can support up to three SCO links simultaneously for one master. In this case, there are a case where one slave supports three SCO links and a case where three different slaves support one SCO link respectively. Note that the SCO link does not have a retransmission function, and an error correction code is not added to a packet transmitted through the SCO link.

The ACL link is a so-called packet-switched connection type, in which a master and a plurality of slaves
One-to-many communication is possible. Instead of being able to communicate with any of the slaves in the piconet, the effective communication speed of each slave may change depending on the amount of data and the number of slaves. The SCO link and the ACL link can be used in combination.

In the ACL link, the number of slaves that one master can simultaneously communicate with is up to seven. However, only one ACL link can be set for each slave in one piconet, and one slave cannot set a plurality of ACL links at a time. In order to operate a plurality of applications with one slave, it is necessary to multiplex protocols of higher-level applications. Unless otherwise specified, single-slot ACL packets are used for communication between the master and the slave. In order for a slave to transmit a multi-slot ACL packet, permission from the master is required in advance. The master sends the multi-slot A from the slave
Although the transmission request of the CL packet can be rejected, the slave must always accept the transmission request from the master.

The master notifies the slave of only the upper limit value of the multi-slot, and it is up to the slave to determine whether to transmit the multi-slot ACL packet.
On the other hand, whether the ACL packet transmitted from the master is a single slot or a multi-slot depends entirely on the judgment of the master. Therefore, the slave must always be ready to receive all the multi-slot packets.

In an ACL packet, a single slot,
Apart from the definition of multi-slot, the following three packet communication methods are provided roughly. The first is an asynchronous communication system (Asynchronous transfer), the second is an isochronous communication system (Isochronous transfer), and the third is a broadcast communication system (Broadcast transfer).

The asynchronous communication system is a communication system for transmitting and receiving a normal packet. The data transmission speed is
It changes due to the amount of traffic of slaves existing in the piconet and packet retransmission due to deterioration of the communication line quality.

FIG. 12 shows an example in which three slaves (slaves 1, 2, and 3) in the same piconet communicate with each other in an asynchronous communication system. As shown in FIG. 12A, an ACL packet is sequentially transmitted from the master to each of the slaves 1, 2, and 3, and the slave that has received the ACL packet confirms reception with the master as shown in FIGS. 12B, 12C, and 12D. Packets have been returned.

In some cases, stream data such as audio data and video data may be transmitted by an ACL packet asynchronous communication system. When the stream data is transmitted by the asynchronous communication method, a time stamp is added to each ACL packet so that the receiving side can ensure the continuity of the stream data.

The isochronous communication system is a system in which a packet is always transmitted from a master to a slave within a predetermined time slot. In this method, a minimum delay of transmitted data can be ensured. In the case of the isochronous communication method, the slot interval needs to be agreed between the master and the slave before starting communication in the isochronous communication method as the maximum polling time.

The master can forcibly specify the maximum polling interval for the slave, and can reject a request for setting the isochronous communication system from the slave. However, the slave cannot specify the maximum polling interval to the master, and cannot request the setting of the isochronous communication.

FIG. 13 shows an example in which communication is performed between a master and a slave by the isochronous communication method. Figure 1
As shown in FIG. 3A, the master transmits an ACL packet to the slave within the maximum polling interval, and the slave that has received the ACL packet immediately receives the ACL packet.
As shown in B, a packet for confirming reception is returned to the master.

The broadcast communication system is set by setting the slave identifier in the packet header to zero. As a result, a broadcast packet can be transmitted from the master to all slaves. The slave that receives the same packet does not transmit a packet for acknowledgment of the reception. Instead of the acknowledgment being received by the slave, the master continuously transmits the broadcast packet a plurality of times. The master needs to notify all the slaves of the number of times of transmission before performing broadcast communication.

FIG. 14 shows an example in which communication is performed to all slaves in the piconet by the broadcast communication method. FIG. 14A
Indicates a transmission packet from the master, and FIG.
Shows the reception status of the three slaves 1, 2, and 3. In FIG. 14, when a packet is received by the slave, a portion marked with a cross indicates an example when the packet at the slave could not be received at that time. It can be surely broadcast to all slaves.

FIG. 15 is a diagram showing a communication example in which the SCO link and the ACL link are used together. FIG. 15A
15B shows a transmission packet from the master, and FIG.
Shows transmission packets from three slaves 1, 2, and 3. In this example, in a situation where the SCO packet on the SCO link is transmitted between the master and the slave 1 at a fixed period, the master sets three slaves 1, 2, 2, and 3.
3, an ACL packet is transmitted as needed. The broadcast packet is also repeatedly transmitted a predetermined number of times. While the broadcast packet is repeatedly transmitted, the SCO packet is transmitted at the timing when the SCO packet is transmitted.

Here, the setting parameters required for the isochronous communication system and the broadcast communication system are summarized in the following Table 1.
It becomes as shown in.

[0058]

[Table 1]

Next, the clock inside the master and the slave will be described. In this communication system, a frequency hopping pattern or the like is set using a clock provided in each device. The clocks of the master and the slave are, for example, 0 as shown in FIG.
It is set by the count value of a 28-bit counter from 27 to 27. One increment of this counter is 312.5 μsec, and this 312.5 μsec is the minimum time unit of the call and inquiry processing. Thus, 312.5μ
A 28-bit counter that counts up one by one every second has a period of about 23 hours, which enhances the randomness of the frequency hopping pattern.

31 set by the clock value of the 0th bit
The period of 2.5 μs is a time period of a transmission packet when the master makes a call and makes an inquiry. The period of 625 μsec set by the clock value of the first bit is a time period of the slot in which the communication frequency changes. The cycle of 1.25 ms set by the clock value of the second bit is a master or slave transmission / reception time cycle. Further, the cycle of 1.28 seconds set by the clock value of the twelfth bit is the clock timing of the time cycle for changing the reception frequency in inquiry and calling.

Each slave refers to the master's clock, adds a certain offset value to its own clock so as to match the master's clock, and uses the added clock for communication.

When calculating the frequency hopping pattern between the master and the slave, besides this clock, the 48-bit address assigned to each terminal is also used as a parameter. The 48-bit address is IEEE
This is an absolute address defined by an address method in accordance with the 802 specification and individually assigned to each Bluetooth terminal. FIG. 17 is a diagram showing an example of this 48-bit address configuration, in which the lower 24 bits are LAP.
(Lower Address Part), next 8 bits are UAP (Uppe
r Address Part), the remaining 16 bits are NAP (Non-si
gnificant Address Part).

In the generation of the frequency hopping pattern in the synchronization within the piconet, the LAP among the master addresses is used.
Total of 24 bits and lower 4 bits of UAP, total 28
Bits are used. As a result, a frequency hopping pattern based on the master address is given to each piconet. When shifting to the communication state, the slave is notified of the address of the master, so that each slave can independently calculate the same frequency hopping pattern as the master.

FIG. 18 is a diagram showing a configuration example for calculating a communication frequency. The lower 28 bits of the master address and the lower 27 bits of the 28-bit clock are supplied to the communication frequency selector 8 so that the communication frequency, which is a channel frequency hopping pattern, is uniquely determined. However, the calling frequency hopping pattern and the inquiry frequency hopping pattern are different from the channel frequency hopping pattern.

Next, the data structure transmitted between the master and the slave will be described. FIG. 19 is a diagram showing a packet format. Packets can be broadly divided into access codes, packet headers, and payloads.
Consists of three parts. The payload is set to a variable length according to the amount of data transmitted at that time.

FIG. 20 is a diagram showing the structure of the access code. The access code is composed of 68-bit or 72-bit data, indicates the destination of a transmission packet, and is a code added to all transmitted and received packets. Depending on the type of packet, there may be only this access code.

The preamble has a fixed 4-bit length in which patterns of 1 and 0 are repeated according to the LSB of the sync word. The trailer is composed of 4 bits that repeat 1 and 0 according to the MSB of the sync word. In each case,
It functions to remove the signal DC component of the entire access code. The 48-bit sync word is 64-bit data generated based on a 24-bit LAP in a 48-bit address. This sync word is used for piconet identification. However, a different sync word may be used in a packet used for an inquiry and a call in communication when the master address and clock cannot be obtained.

Here, the access code types are summarized in Table 2 below.

[0069]

[Table 2]

FIG. 21 is a diagram showing the structure of the packet header. The packet header is a part including parameters necessary for controlling a communication link in the baseband layer.

The 3-bit AM ADDR is an identification field for specifying a slave communicating in the piconet, and is a value assigned by the master to each slave. The 4-bit TYPE is a packet type type field that specifies what kind of packet the whole packet is.
1-bit FLOW is a field used for managing flow control of a packet communicated through the ACL link.

The 1-bit ARQN is a 1-bit field used to notify the packet transmitting side whether or not the received packet has an error. According to the Bluetooth standard, a response packet dedicated to acknowledgment is not prepared, and acknowledgment of the packet is transmitted to the source of the packet using the ARQN field. Depending on whether the value of this field is 1 or 0, the other party is notified that there is no error in the received packet or that there is an error.
The presence or absence of an error in the received packet is determined by the header error detection code added to the packet header of the received packet and the error detection code added to the payload.

The 1-bit SENQ is a field used to manage retransmission packets so that they do not overlap on the receiving side. When the same packet is retransmitted, the value is alternately inverted between 1 and 0 each time one packet is transmitted.

The 8-bit HEC is a field in which an error correction code of a packet header is arranged. This error correction code is g (D) = D ⁸ + D ⁷ + D ⁵ + D ² + D + 1
Is generated using the generator polynomial of. Upon its generation,
The initial value set in the 8-bit shift register for generating the error correction code sets the 8-bit UAP in the Bluetooth address described above. The address used here is the same as the address used when generating the access code. Table 3 below summarizes the initial values used to generate the error correction code.

[0075]

[Table 3]

In order to identify a piconet in communication,
A channel access code (CAC) generated based on the 24 bits of the LAP of the master address is used.
In order to synchronize communication within the piconet, it is necessary to synchronize the frequency hopping pattern and the time slot. In this case, if another master having the same LAP exists near the Can be eliminated by using HEC, which is an error correction code of the packet header, even if the synchronization happens to coincide.

The payload contains user data or control data actually transmitted and received between terminals. The user data includes data transmitted and received via the SCO link,
There is data transmitted and received through a packet-switched ACL link.

FIG. 22 is a diagram showing the configuration of the payload of the ACL link. It is composed of three parts: a payload header, a payload body, and an error detection code, and the entire length of the payload is variable. On the other hand, the payload of the SCO link has a communication slot reserved in advance periodically, so there is no retransmission of data packets, only the payload body, and no payload header and no error detection code.

The payload header is a portion including parameters necessary for controlling data in a layer higher than the baseband layer, and is data included only in the ACL link. FIG. 23 shows a configuration of a payload header of a single-slot packet, and FIG. 24 shows a configuration of a payload header of a multi-slot packet.

The 2-bit L included in the payload header
The _CH data is a field for identifying a logical channel that specifies what kind of data the data in the higher layer than the baseband layer is. SCO Link and ACL
The link is a link in the baseband layer, and its control is performed by information set in a packet header.
L_CH identifies a logical channel defined in a layer higher than the baseband layer, and L_CH is defined as shown in Table 4 below for three user logical channels.

[0081]

[Table 4]

1-bit FLOW is 1-bit data used to control the flow of data transmitted and received on the user logical channel. FLOW is managed for each user logical channel. By setting FLOW = 0 and returning data, the other party is temporarily interrupted in data transmission. When the receiving buffer becomes empty, FLOW =
By setting 1 and returning data, transmission of the data of the other party is restarted. The setting of the FLOW field is performed by the link management layer, but does not guarantee real-time data flow control. All real-time data flow control is managed by the baseband layer using the FLOW field in the packet header. Since all data in the control packet is processed in the link management layer, it is not passed to the logical link management layer. Therefore, the control packet is not affected by the flow control by FLOW, and its value is always set to 1.

The 5-bit or 9-bit LENGTH is
This field indicates the data length of the payload body in byte units. In the case of a single slot packet, it is 5 bits, and in the case of a multi-slot packet, it is a 9-bit field.

UNDEFINED is present only in the payload header of a multi-slot packet, is an undefined field at present, and is set to all zeros.

The payload body contains data of a length specified by LENGTH of the payload header. SC
In the O-link communication, since the payload of the data packet is composed of only the payload body, the data length is not specified by LENGTH. However, when a DV packet is used, the data length of the data portion is indicated.

The CRC is a 16-bit field indicating an error detection code, and is a code for detecting whether there is an error in the payload header and the payload. This error detection code is generated using a generator polynomial of g (D) = D ¹⁶ + D ¹² + D ⁵ +1. At the time of its generation, 1
The initial value set in the 6-bit shift register sets a 16-bit value obtained by adding 8 bits of zero to 8 bits of the UAP in the address described above. The address used here is the same as the address used when generating the access code, like the HEC.

Next, the packet type will be described. As described in the description of the packet header, the TYPE field specifies the packet type. Describing the designated packet type, there are a common packet commonly used for the SCO link and the ACL link, and a packet unique to the SCO link or the ACL link.

First, the common packet will be described. The common packet includes a NULL packet, a POLL packet,
FHS packet, DM1 packet, IQ packet, ID
There are packets.

A NULL packet is a packet composed of an access code and a packet header, and has no payload. The length of the packet is fixed at 126 bits. This packet is for transmitting and receiving the state of the communication link, and manages packet acknowledgment (ARQN) and flow control (FLOW). No acknowledgment of the packet for receiving this NULL packet is required.

The POLL packet, like the NULL packet, is a packet composed of an access code and a packet header, has a fixed length of 126 bits, and manages the state of the communication link. However, in the case of the POLL packet, unlike the NULL packet, even if there is no data to be transmitted, the POLL packet is received even if there is no data to be transmitted.
It is necessary to send a packet confirmation response.

The FHS packet is an important control packet for achieving synchronization within the piconet, and is transmitted when exchanging a clock and an address, which are essential parameters for establishing synchronization between the smart device and the slave. FIG.
FIG. 3 is a diagram illustrating a configuration example of a payload of an FHS packet. The payload of the FHS packet is composed of eleven fields, and a 16-bit error detection code is added to 144 bits of the eleven fields to generate 160
Consists of bits. The eleven fields forming the FHS packet will be described below.

The 34-bit parity bit is a field containing the parity for the sync word in the access code set in the FHS packet. The 24-bit LAP is the lower 24 bits of the address of the terminal transmitting the FHS packet. The two bits following the LAP are undefined fields and are set to zero. 2-bit S
R indicates that in the call, the master
This is a 2-bit field that specifies the number of repetitions when transmitting the D packet sequence and the scan cycle when the slave scans the ID packet sequence from the master.

The 2-bit SP is used in the inquiry
When the slave receives the IQ packet from the master,
This field is used to specify the time for the slave to perform the required call scan after transmitting the S packet to the master. The 8-bit UAP is the upper 8 bits of the address of the terminal transmitting the FHS packet. 16-bit NA
P is 16 bits other than the LAP and the UAP in the address of the terminal transmitting the FHS packet.

The 24-bit device class is a field indicating the type of the terminal. 3-bit AM ADD
R is a 3-bit field for the master to identify the slave. In the call processing, the slave identifier used in the piconet is specified in the FHS packet transmitted from the master to the slave. In the FHS packet transmitted by the slave as a response to the IQ packet from the master, AM ADDR needs to be set to 0 since it has no meaning.

The 26-bit CLK 27-2 is a field indicating the upper 26 bits of the clock of the terminal. This clock has a clock accuracy of 1.25 μs, and when transmitting an FHS packet, it is necessary to always set the clock value at that time. The 3-bit page scan mode is a field for designating a default paging scan mode supported by the terminal that transmitted the FHS packet.

Next, the DM1 packet will be described.
When a DM1 packet is transmitted / received via the SCO link, it always functions as a control packet. On the other hand, when data is transmitted / received through the ACL link, it is used not only to function as a control packet but also to transmit / receive a data packet.

When transmitted as a common packet on the SCO link or ACL link, it is defined as a control packet of the link management layer. However, when a DM1 packet is transmitted / received via the ACL link, it is not possible to determine whether the packet is a user packet or a control packet just by looking at the field (TYPE) specifying the packet type. Therefore, by setting the logical channel type field of the payload header to L_CH = 11, it is specified that the DM1 packet is a control packet for the link management layer. In the case of a data packet, L_CH = 01 or L_CH =
Set 10

An IQ packet is a packet broadcasted by the master in an inquiry, and is composed of only an inquiry access code. The ID packet is a packet transmitted by the master specifying a specific slave in a call, and is composed of only a call access code. The IQ packet and the ID packet are packets that are not defined in the type field of the packet header.

Next, an SCO packet which is a data packet transmitted and received on the SCO link will be described. S
CO packets are HVI packets, HV2 packets, H
It is composed of four types of V3 packet and DV packet.

[0100] The payload of the HV1 packet is composed of only the payload body, and contains 10 bytes of user data. Since the SCO packet is basically not retransmitted, the 10 bytes do not include an error detection code. Then, the data is subjected to 1/3 rate error correction encoding, and finally has a payload length of 240 bits.

The payload of the HV2 packet is also composed of only the payload body, and contains 20 bytes of data. These 20 bytes do not include an error detection code. Then, the data is subjected to a 2/3 rate error correction code, and finally has a payload length of 240 bits.

The payload of the HV3 packet is also composed of only the payload body, and contains 30 bytes of data. The 30 bytes do not include an error detection code. The 30 bytes are not subjected to error detection coding.

A DV packet is composed of an audio part having a fixed length of 10 bytes and a data part having a variable length of up to 9 bytes. The error correction code is not included in the 10 bytes of the audio portion, but the data portion is provided with a 2-byte error detection code for a maximum of 10 bytes obtained by expanding a 1-byte payload header.

The ACL packets transmitted and received on the ACL link include a DM1 packet, a DH1 packet, a DM3 packet, a DH3 packet, a DM5 packet, a DH5 packet, and an AUX1 packet. The payload of the DM1 packet includes a 1-byte payload header, a variable-length payload body of up to 17 bytes, and an error detection code. The configuration of the DH1 packet is the same as that of DM1. However, the payload is not error correction encoded. Therefore, variable length data of up to 27 bytes can be transmitted and received.

The payload of the DM3 packet is composed of a 2-byte payload header, a variable-length payload body up to a maximum of 121 bytes, and an error correction code.
The payload of these DM3 packets is subjected to a 2/3 rate error correction code. The structure of the DH3 packet is DM3
It has the same configuration as the packet. However, the payload is not error correction encoded. Therefore, variable length data of up to 183 bytes can be transmitted and received. DM5
The payload of the packet is a 2-byte payload header, a variable-length payload body of up to 224 bytes,
It is composed of a 2-byte error correction code.

The configuration of the DH5 packet is the same as that of the DM5 packet. However, the payload is not error correction encoded. Therefore, variable length data of up to 339 bytes can be transmitted and received. The AUX packet is the same as the DH1 packet when it does not include a 2-byte error detection code. That is, there is no AUX1 packet retransmission.
The payload body is increased by 2 bytes, so that variable length data of up to 29 bytes can be transmitted and received.

Next, a transition state in Bluetooth will be described. The transition state in this system is related to communication 3
It consists of a phase phase and a low power consumption mode related to the power consumption of the terminal. The three phases related to communication are divided into a standby phase, a synchronization establishment phase, and a communication phase. In the low power consumption mode,
There are three types: a park mode, a hold mode, and a sniff mode. FIG. 26 is a diagram showing an example of state transition, and there is a transition to the state indicated by the arrow.

The standby phase (S91) is a phase which is composed of one processing state and in which no packet is transmitted or received. Immediately after turning on the device,
When the communication link is disconnected, the terminal is in a standby phase. In this standby phase, there is no difference between the roles of the master and the slave.

In the synchronization establishment phase, an inquiry (S9
2) and call (S93). The inquiry is a first-stage processing state performed for establishing synchronization within the piconet. A terminal that intends to communicate for the first time always transitions to an inquiry after waiting. A call is a second-stage processing state performed to establish intra-piconet synchronization. Basically, a state transition is made from an inquiry. However, the first-stage processing of intra-piconet synchronization establishment is already completed in an inquiry state. If there is, the system may transition from waiting to calling directly.

In the inquiry, the roles of the master and the slave are clearly different. The master in this processing state continuously broadcasts the IQ packet regardless of whether or not there are slaves around. If there are slaves in the processing state of the inquiry around it,
Each time an IQ packet is received, the slave sends an FHS packet to the master to convey its attributes.
The FHS packet allows the master to know the address and clock of the slave.

FIG. 27 is a diagram showing processing performed by the master and the slave in the inquiry state. First, FIG.
As shown in FIG. 7A, when the central master transmits an IQ packet, as shown in FIG. 27B, slaves around it transmit an FHS packet to the master. in this way,
The master in the inquiry receives FHS packets from an unspecified number of slaves.

Here, a plurality of slaves simultaneously operate at a specific I
There is a problem in transmitting an FHS packet for a Q packet. When multiple FHS packets are transmitted at the same time, a packet collision occurs and the master transmits the FH
The S packet cannot be determined. In Bluetooth, in order to avoid such a collision, backoff is performed for a random time when transmitting an FHS packet. In other words, the slave does not transmit the FHS packet to the master for the IQ packet received for the first time, and then interrupts the reception of the IQ packet during a random time backoff. Thereafter, the slave resumes receiving the IQ packet, and immediately after receiving the IQ packet, transmits the FHS packet to the master. Slave is F
When the HS packet is received, the reception of the IQ packet is interrupted again while the reception of the IQ packet is backed off for a random time. Thereafter, this operation is repeated.

FIG. 28 is a diagram showing an outline of the processing at the master and slave in this inquiry.
A shows the transmission / reception state at the master, and FIG. 28B shows the transmission / reception state at the slave. Since the master does not notify the slave that the FHS packet has been received without error, the slave in the inquiry state is in a state where the FHS packet has been completely transmitted. However, since the same IQ packet is repeatedly broadcast for a certain period of time, the master receives a plurality of FHS packets for each slave in the inquiry processing state. After all, by continuing the inquiry for a certain period of time, the reliability of transmission and reception of the FHS packet is improved.

In the case of calling, the roles of the master and the slave are different. In this processing state, based on the information of the FHS packet transmitted and received by the inquiry, the master selects a slave to communicate with and transmits an ID packet to the slave. When confirming reception of the ID packet, the master transmits an FHS packet to the slave. This allows the slave to know the master's address and clock.

The ID packet transmitted and received here and the FHS
A call access code is used as the access code of the packet.

FIG. 29 shows an outline of the processing operation performed by the master and slave in the call. As shown in FIG. 29A, the master at the center transmits an ID packet to the slave, and the slave notifies the reception confirmation. In addition, as shown in FIG. 29B, the master transmits an FHS packet to the slave, so that the slave notifies the reception confirmation.

Unlike the processing for an unspecified number of slaves in the inquiry, the processing is exchanged between a specific slave and the master in the call. Since packet transmission and reception can be performed on a one-to-one basis, the master and the slave can perform processing while confirming the transmission and reception.

The slave that has received the ID packet from the master transmits the same ID packet to the master and notifies the master of the reception confirmation. Next, the master transmits an FHS packet to the slave to notify its own address and clock to the slave. When the slave receives the FHS packet without error, it transmits an ID packet to the master to confirm the reception. At this point, the address and the clock information necessary for the synchronization within the piconet are exchanged between the master and the slave together with the processing in the inquiry.

FIG. 30 is a diagram showing an example of processing between a master and a slave in a call. FIG. 30A shows a transmission / reception state at the master, and FIG. 30B shows a transmission / reception state at the slave. The communication connection phase shown in the state transition diagram of FIG. 26 includes connection (S94) and data transfer (S95).
Having. In the communication connection phase, the master and the slave synchronize within the piconet via the synchronization establishment phase, and are phases in which actual communication can be performed.
In the connected state, transmission and reception of data packets are not performed. The transmission and reception at this time are limited to a control packet for setting up a communication link, a security-related control packet, a control packet related to the low power consumption mode, and the like.

On the other hand, in the data transfer state, transmission and reception of data packets are permitted. After the synchronization establishment phase,
When transitioning to a connection for the first time, basically, the connection authentication and encryption between the master and slave must be completed.
You cannot move to data transfer. The roles of the master and the slave in the connection differ depending on the contents of the control packet managed therein.

Transmission and reception of data packets in data transfer are performed in accordance with the rules of master, slave and time slot. Further, when the terminal by data transfer disconnects communication or when a hardware reset is applied to the controller in the terminal, the terminal makes a state transition from data transfer to standby.

The low power consumption mode refers to a mode for providing a low power consumption state of a terminal that transits from connection. The low power consumption mode includes three types: a park mode (S96), a hold mode (S97), and a sniff mode (S98). The park mode is a mode peculiar to a slave, and is a low power consumption mode in which synchronization within a piconet established by connection is maintained. The hold mode is a low power consumption mode in which both a smarter and a slave can be shifted. The hold mode is a mode in which synchronization within a piconet established by a connection is maintained, and in the case of a slave, a slave identifier given by a master is held. is there. The sniff mode is a low power consumption mode peculiar to the slave. In the same manner as the hold mode, the slave maintains the synchronization within the piconet established by the connection as it is, and holds the slave identifier given by the master. .

In the Bluetooth, a master / slave conversion can be performed between a master and a specific slave in a piconet.

The security-related processes executed in the connection state in the communication connection phase are roughly classified into two processes, authentication and encryption. In the authentication process, the connection between the user and a specific partner is determined to be permitted. The encryption process is to protect data being communicated from being intercepted by a third party.

[0125] Bluetooth security is managed by the concept of a link key. The link key is a parameter for managing one-to-one security between two specific terminals. This link key must not be disclosed to third parties.

As the link key, an initialization key used between terminals attempting connection for the first time is used. If a connection has been made in the past and the link key has been set as a parameter in the database, the setting is made. The used link key is used. The initialization key is generated using a PIN code from a higher-level application and internally generated data.

Although the general processing in the Bluetooth standard has been described above, in this example, audio and video devices (these devices are collectively referred to as AV devices) and the like by this short-range wireless transmission. Commands for controlling electronic devices and responses are also transmitted.

FIG. 31 is a diagram showing a transmission structure for transmitting the command and the response in a hierarchical structure. Here, the terminal transmitting the command is referred to as a controller. A terminal that receives the command and transmits a response to the source of the command is called a target. The relationship between the controller and the target is a different concept from the already described master and slave necessary for managing the communication connection, and basically any one may function as a master or slave terminal.

[0129] Above the baseband layer, there is a layer for processing L2CAP packets for transmitting data of a control protocol, and further thereon, AVCTP (Audio / Audio / Audio).
Video Control Transport Protocol) is prepared, and a protocol called AV / C command for controlling AV equipment is prepared on the protocol.

FIG. 32 shows an example of the data structure of an L2CAP packet for transmitting data of the protocol.
A header is added to the head of the section of the payload of the packet (portion indicated as L2CAP Header), and the data length (length) and the channel ID are indicated. Subsequent sections become actual information.

The section of information is AVCTP
A header and an AVCTP message are arranged. A
The data of the VCTP message is “0000” data (4 bits) indicating AV / C data,
Command type / response data (4 bits) indicating the command type and response type, data (5 bits) indicating the subunit type, and subunit I
D indicating data (3 bits), data (8 bits) of an operation code (opcode) indicating a function, and operant (operan) which is data associated with the function.
d: 8 bits) is the operand

[0], operand [1], and {operand [n] (n is an arbitrary integer). The data structure of AVCTP shown in FIG. 32 is obtained by applying a data structure defined as an AV / C command, which is a standard for transmitting device control data and the like over a network connected by a wired bus line.

FIG. 33 is a diagram showing a state where commands and responses are wirelessly transmitted between the controller and the target. When there is a user or the like at the terminal on the controller side and it becomes necessary to transmit a command to the target device, the controller establishes a connection to the target (step S31), and in the established connection, A / C command is transmitted from the controller to the target (step S32).
The target receiving this command transmits a response to the command to the controller (step S
33). Then, if necessary, processing for the command is executed on the target. If the command is a command for confirming the state of the target, the requested data is sent back to the controller as a response.

As shown in FIG. 34, when disconnection processing is executed by a user operation on the controller side or by a user operation on the target side, the setting for transmitting commands and responses is performed. Release connection processing is performed to release the connected connection (step S34).

Next, the AV / AV used in the system of the present embodiment will be described.
The configuration of the C command set (that is, AVCTP data) will be described with reference to FIGS. FIG.
Reference numeral 5 denotes a data structure of a section transmitted as an AV / C command in 8-bit units. The AV / C command is a command set for controlling an AV device.
CTS (command set ID) = "0000". An AV / C command frame and a response frame are exchanged. The response to the command is
For example, it is to be performed within a prescribed period. However, send a provisional response within the specified period,
In some cases, a formal response is sent after some time.

CTS indicates the ID of the command set. In the AV / C command set, CTS = "0000"
It is. The field of C type / response (ctype / response) 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. The types of commands and responses will be described later.

The subunit type is
It is provided to specify the function in the device. In order to determine when a plurality of subunits of the same type exist, addressing is performed using a subunit ID (subunit id) as a determination number. An operation code (opcode) as an operation code indicates a command, and an operand (operand) indicates a command parameter. Fields that are added as needed (additional o
perands) are also available. 0 after the operand
Data and the like are added as needed.

FIG. 36 shows a specific example of the AV / C command. FIG. 36A shows a specific example of the command type / response. The upper part of the figure represents a command, and the lower part of the figure represents a response. “0000”
Indicates a control (CONTROL), “0001” indicates a status (STATUS), and “0010” indicates a specific inquiry (SPECIFIC INQUE).
IRY), “0011” has NOTIFY (NOTIF
Y), “0100” contains a general inquiry (GE
NERAL INQUIRY) is assigned.
“0101 to 0111” are reserved and reserved for future specifications. No mounting is performed for “1000” (NO
T INPLEMENTED), “1001” is accepted (ACCEPTED), and “1010” is rejected (R
EJECTED), transition to “1011” (INT
RANSION), “1100” has mounting (I
MPLEMENTED / STABLE), "1101"
Is assigned a state change (CHNGED), and "1111" is assigned a provisional response (INTERIM). “11
10 "is reserved and reserved for future specifications.

FIG. 36B shows a specific example of the subunit type. “00000” is the video monitor, “0”
0011 ”is a disk recorder / player, and“ 001 ”
00 "is a tape recorder / player," 00101 "
Is a tuner, “00111” is a video camera, “1”
“1100” is a subunit type unique to the manufacturer (Vender unique), and “11110” is a specific subunit type (Subunittype 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. 36C shows a specific example of the operation code (operation code: opcode). There is an operation code table for each sub-unit type. Here, the operation codes are shown when the sub-unit type is a tape recorder / player. An operand is defined for each operation code. Here, “00h” is a value unique to the manufacturer (Vender dependent), “50h”.
h ”for search mode,“ 51h ”for time code,
"52h" is ATN, "60h" is open memory, "61h" is memory read, "62h" is memory write, "C1h" is load, "C2h" is record, "C3h" is Playback and rewinding are assigned to “C4h”.

FIG. 37 shows a specific example of an AV / C command and response. For example, when a playback instruction is given to a playback device as a target (consumer), the controller sends a command as shown in FIG. 37A to the target. Since this command uses the AV / C command set, CTS = "0000". As the command type (ctype), a command (CONTROL) for externally controlling the device is used, so that the c type is “0000” (see FIG. 36A). Since the sub unit type is a tape recorder / player, the sub unit type is "00100" (see FIG. 36B). id indicates the case of ID0,
id = 000. The operation code is “C3h” meaning reproduction (see FIG. 36C). The operand is "75h" meaning forward direction (FORWARD). Then, when played back, the target is
A response like 7B is returned to the controller. Here, since “accepted” is included in the response, the response is “1001” (see FIG. 36A). Except for the response, the rest is the same as FIG.

When transmitting a command composed of AVCTP data, the command is transmitted to a functional block called a subunit prepared in the device. That is,
Functional blocks in each device constituting the network can be represented by a unit called a subunit, and the subunits can be regarded as individually communicating. Here, a subunit configuration of the audio receiver 200, which is a device configuring the network of this example, and a transmission state in units of the subunit will be described with reference to FIG.

[0142] The audio receiver 200
00 is provided, and the panel subunit 230 transmits and receives AVDCP commands. As the wireless transmission path 990, for example, channels CHa to CHn (n is an arbitrary number) are prepared. The audio processing unit 201 includes a plug 211 and a subunit plug 22 of the receiver 200.
1 via the predetermined channel CHa of the wireless transmission path 990
And audio data as stream data is obtained on channel CHa.

The panel subunit 230 can be functionally divided into an operation instructing section 231 for issuing a command based on a key operation and a display processing section 232 for displaying based on a received command. Panel subunit 2
The command issued by the operation instructing unit 231 in 30 is transmitted to a predetermined channel CHb of the wireless transmission path 990 via the subunit plug 222 and the plug 212.
Also, the subunit plug 2 is connected via the channel CHb.
The command received by the panel sub-unit 230
Is sent to the display processing unit 232 to perform display processing based on the command.

The subunit plugs 221 and 222
The plugs 211 and 212 are processed as if they were virtually plural, and a plurality of circuits for physically processing signal input and output do not always exist. For example, the transmission / reception processing unit 2 and the data processing unit 3 shown in FIG. 2 can be used in a time-division manner to function as if there are a plurality of subunit plugs and plugs.

Although the configuration of the audio player 100 in terms of transmission is not shown, in the case of the audio player 100 as well, the panel subunit that controls the operation of the device by receiving a command uses the system control unit. It is configured.

Next, the structure of AVCTP, which is a device control command transmitted in the present embodiment, will be described. As already described, AVCTP, which is a protocol for device control data of this example, is an Audio / Video Control Trunk.
An abbreviation for ansport Protocol. The data configuration of the L2CAP packet for transmitting the data of the protocol is the configuration shown in FIG. 32 described above.

Here, in the case of this example, a device controlled by the data of the AVCTP protocol already has a panel subunit as shown in FIG.
When performing control using this panel subunit,
For example, control is performed using a pass-through command.

FIG. 39 is a diagram showing the structure of a pass-through (PASSTHROUGH) command of the present example transmitted to the panel subunit. Although the pass-through command is originally for sending a command for controlling the operation of the device, in the case of the present example, the display command is issued from the audio player 100 to the audio receiver 200 using the pass-through command. Commands can be sent. FIG. 39 shows a configuration example of a pass-through command as this display command.

First, as shown in FIG. 39A, the command type is control (Control), which is data for controlling the state of the other party.
The Panel Subunit of the partner device is specified. Note that a unit (equipment) may be specified instead of the subunit. In the operation code section, vendor-dependent data indicating that the data is specified by a specific vendor (device maker) is arranged.

As operand data, first, a company ID and an ID for Bluetooth (Bluetooth SIG) are used.
Is arranged. In the subsequent operand section, data specified by the vendor is arranged. In the case of this example, data instructing display is arranged in the section of the operand.

FIG. 39B shows details of the data instructing the display of the section of the operand.
A code of a category indicating the TP protocol is arranged, followed by display data indicating display instruction data as a function type, and finally data to be displayed (specific to the function type). Data) is placed.

FIG. 39 shows data to be displayed.
As shown in FIG. 3C, the data is composed of information type data and data specific to the information type. As information types, for example, as shown in FIG. 40, four types of transport state, track number, counter value, and text are defined here.

In the case of the audio player 100, for example, the transport state corresponds to operation mode information of a device such as a playback state and a stop state. Specifically, for example, codes corresponding to operation states such as playback, recording, stop, fast forward, rewind, playback pause, recording pause, fast forward playback, and rewind playback are assigned as 1-byte data.

The track number corresponds to the track number which is the number of the program (song) being reproduced. For example, a 2-digit track number is specified as 2-byte data.

The counter value corresponds to a value indicating the reproduction time of the music being reproduced. For example, 4 bytes are assigned, and the reproduction time is indicated by the value of the hour, minute and second frame.

The text corresponds to text data such as characters related to the song being reproduced (eg, song title, player name, album title name, lyrics, commentary, etc.). Which type of data is being sent is indicated by the information type. Then, in the section following the information type (data specific to the information type), the above-described various data used for display is arranged. However, in the case of this example, the data is not directly used for display, but the content specified by the data is determined by the receiving device, and the display mode set by the receiving device is used. Is displayed.

FIG. 41 shows an example of transmission data in the case of text data. In the case of text data, the data is transmitted as variable length data, data of the character code type is arranged first, data relating to the data length of the text data is arranged, and finally actual text data is arranged and transmitted. You.

The packet configuration shown in FIG. 39 is an example when the command is display command data. When the command is an instruction command for an operation, the data section specific to the function type or function includes Data indicating the corresponding operation is arranged.

The device that has received the command configured as described above may return a response as data for confirming that the command has been received to the transmission source. When the response is transmitted as described above, a process of retransmitting the display command data when the response cannot be confirmed at the transmission source can be considered.

AVCT structured as shown in FIG.
The display command data of the protocol P is transmitted from the transmitting side (the audio player 100 in this example) wirelessly periodically at relatively short intervals. For example, the operation state of the audio player 100 is transmitted every several seconds in the format described above.

On the side receiving the display command data (in this example, the audio receiver 200 functioning as a remote control device of the audio player), when the display command data is received, the display command data instructs. The content is determined, and based on the determined content, display data in a format that can be displayed on the display unit 204 of the receiver 200 is generated to display the operation state of the audio player or the like. Specifically, for example, when data of an operation state such as a reproduction mode is received, the operation state is displayed on the display panel of the display unit 204 by a graphic or a character. When a track number being reproduced is received, the track number is displayed by a numeral. When the data of the counter value being reproduced is received, the number of hours, minutes, and seconds as the counter value is displayed by a numeral. Further, when the text data is received, the character indicated by the text data is displayed on the display panel by scroll display or the like.

Then, when the content of the received display command data changes from the content received last time, the characters and figures to be displayed on the display panel are changed to corresponding ones.
For those whose value changes at any time, such as the counter value, the counter value is advanced with the passage of time from the hour, minute, and second values at the time when the display command data is received, and the display command data of the next counter value is changed. At the time of the reception, the deviation of the displayed counter value may be corrected. For example, when the counter value is displayed in units of one second, the display command data of the counter value may be transmitted every second, and the receiving side may not need to update the counter value. . By doing so, the counter value can be accurately displayed on the receiving device that functions as the remote control device.

The data of the operating state may be transmitted when the operating state of the audio player changes. By doing so, it is sufficient to perform wireless transmission only when there is a change in operation, and the transmission efficiency is improved. Also, on the display side, the operation state at that time can be accurately displayed.

When the track number which is the number of the program being reproduced is changed, data of the track number, text data related to the music of the track number, or the like may be transmitted. By doing so, the track number and the text display become a display corresponding to the music currently being reproduced.

As described above, in the case of this example, the display command data is transmitted from the audio player 100, which is the controlled device controlled by the remote control device, using the AVCTP command, which is the operation control protocol. The status of the controlled device can be accurately displayed on the display panel of the audio receiver 200, which is a remote control device, simply by sending it as needed. In this case, the audio receiver 200 does not need to send a command for ascertaining the operation state of the controlled device to the controlled device, and only needs to perform display based on the received display command command. It just gets easier. Also, the audio player 10
The data to be sent as display command data from 0 is data for notifying the operation status and the like, and may be set as to how to display on the receiver side. It is not necessary to know whether it can be performed, and the control processing for display is simplified from this point as well.

In the embodiments described so far,
Although the example has been described in which display data is transmitted over a network that performs wireless transmission according to a standard called Bluetooth, the present invention is also applicable to a case where similar control commands and display commands are transmitted over another wireless transmission network. It goes without saying that the processing can be applied.

[0167] Also, as for the subunits provided in the device, an example of an audio device has been described, but other device configurations such as a video device may be used.

Further, the present invention can be applied to a transmission network in which each device is directly connected via a wired bus line. For example, IEEE (The Institute of Electri)
caland Electronics Engineers) It can be applied to a bus line called 1394 system. In this case, each of the above-mentioned commands for grasping the operation status and the like can be performed using the AV / C command in the asynchronous communication, and the transmission of the stream data can be executed in the isochronous communication.

[0169]

According to the present invention, the remote control device can directly determine the operation specified by the data received in the form of a command, and display the operation status of the controlled device based on the determination. become. Therefore, the remote control device does not need to issue a command for grasping the operation status of the controlled device, and control processing for grasping the operation status is not required, and the received command is determined, and based on the determination, for example, Display and the like need only be performed, and the operation status of the controlled device can be easily grasped and displayed. In addition, the controlled device only needs to send a command for informing the operation status as needed, and it is not necessary to send data for directly instructing display.

In this case, the command from the controlled device is:
By periodically sending from the controlled device, the operation status of the controlled device can be periodically judged on the remote control device side, and appropriate display according to the operating status at that time is possible. Become.

Also, the command from the controlled device is transmitted when the operating condition of the controlled device changes, so that when the operating condition of the controlled device changes, the command from the remote control device side is output. Can be surely displayed.

A command from the controlled device is transmitted when the number of the program being reproduced by the controlled device changes, so that when there is a change in the program number such as the playback track number, the command is transmitted. This can be reliably displayed on the remote control device side.

Further, the transmission network for transmitting this command is a radio transmission network, and the first and second commands are transmitted using the first channel secured in the radio transmission network. Thus, the first command for controlling the controlled device and the second command for grasping the operation status of the controlled device can be efficiently wirelessly transmitted using one channel in the wireless transmission network. become.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a configuration of an audio player and an audio receiver according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating an example of a configuration of a transmission device according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating an example of a protocol stack.

FIG. 4 is an explanatory diagram illustrating an example of a hierarchical structure of wireless transmission.

FIG. 5 is an explanatory diagram showing an example of setting a transmission frequency.

FIG. 6 is an explanatory diagram showing a state of frequency hopping.

FIG. 7 is an explanatory diagram showing an example of the arrangement of single slot packets on a time axis.

FIG. 8 is an explanatory diagram showing an example in which single-slot packets and multi-slot packets are mixed on a time axis.

FIG. 9 is an explanatory diagram showing an example of a transmission state between a master and a slave.

FIG. 10 is an explanatory diagram illustrating an example of a network configuration.

FIG. 11 is a timing chart showing a communication example of an SCO link.

FIG. 12 is a timing chart showing a communication example in the asynchronous communication system.

FIG. 13 is a timing chart showing a communication example of the isochronous communication method.

FIG. 14 is a timing chart showing a communication example of the broadcast communication system.

FIG. 15 is a timing chart showing a communication example in a case where an SCO link and an ALC link are used together.

FIG. 16 is an explanatory diagram showing a configuration example of clock data.

FIG. 17 is an explanatory diagram showing a configuration example of an address.

FIG. 18 is a configuration diagram illustrating an example of processing for generating a frequency hopping pattern.

FIG. 19 is an explanatory diagram showing an example of a packet format.

FIG. 20 is an explanatory diagram showing a configuration example of an access code.

FIG. 21 is an explanatory diagram showing a configuration example of a packet header.

FIG. 22 is an explanatory diagram showing a configuration example of a payload.

FIG. 23 is an explanatory diagram showing a configuration example of a payload header of a single slot packet.

FIG. 24 is an explanatory diagram showing a configuration example of a payload header of a multi-slot packet.

FIG. 25 is an explanatory diagram showing a configuration example of a payload of an FHS packet.

FIG. 26 is an explanatory diagram illustrating an example of a state transition of a device.

FIG. 27 is an explanatory diagram showing a communication example of an inquiry.

FIG. 28 is a timing chart illustrating an example of an inquiry process;

FIG. 29 is an explanatory diagram showing a communication example of a call.

FIG. 30 is a timing chart showing a processing example of a call;

FIG. 31 is an explanatory diagram showing an example of a hierarchical structure in AVDCP.

FIG. 32 is an explanatory diagram illustrating an example of a packet configuration during AVDCP data transmission.

FIG. 33 is an explanatory diagram showing an example of connection establishment and command and response transmission in AVDCP.

FIG. 34 is an explanatory diagram showing an example of a release connection in AVDCP.

FIG. 35 is an explanatory diagram showing an example of a data structure in AVDCP.

FIG. 36 is an explanatory diagram showing a specific example of an AV / C command.

FIG. 37 is an explanatory diagram showing a specific example of a command and a response of an AV / C command.

FIG. 38 is a block diagram illustrating an example of a configuration as viewed from data transmission according to an embodiment of the present invention.

FIG. 39 is an explanatory diagram showing a configuration example of a display command command according to an embodiment of the present invention.

FIG. 40 is an explanatory diagram showing an example of an information type according to an embodiment of the present invention.

FIG. 41 is an explanatory diagram showing an example at the time of text data transmission according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Antenna, 2 ... Transmission / reception processing part, 3 ... Data processing part,
4 Interface unit, 5 Controller, 8 Communication frequency selection unit, 10 Short-range wireless processing unit, 20 Function processing block, 100 Audio player, 101 Disk playback unit, 102 System control unit, 103 Audio processing unit, 200: audio receiver, 201: audio processing unit, 202: audio output unit, 203: system control unit, 204: display unit, 205: key, 21
1, 212: plug, 221, 222: subunit plug, 230: panel subunit, 231: operation instruction unit, 232: display processing unit, 990: wireless transmission path

Claims (18)

[Claims] A system capable of bidirectionally transmitting a command of a predetermined format between a remote control device and a controlled device controlled by the remote control device using a predetermined transmission network. In the data transmission method to be applied, by transmitting a first command for operation control of the controlled device from the remote control device to the controlled device over the transmission network, the controlled device can transmit the first command. Executes the operation instructed by the command, and transmits data relating to the operation state of the controlled device to the remote control device via the transmission network using a second command having the same format as the first command from the controlled device. A data transmission method designed to send data. 2. The data transmission method according to claim 1, wherein the remote control device receiving the second command performs a process of displaying an operation state specified by the command. 3. The data transmission method according to claim 1, wherein the second command is periodically transmitted from the controlled device. 4. The data transmission method according to claim 1, wherein the second command is transmitted when an operation state of the controlled device changes. 5. The data transmission method according to claim 1, wherein the second command is transmitted when the number of a program being reproduced by the controlled device changes. 6. The data transmission method according to claim 1, wherein the transmission network is a wireless transmission network, and the first and second commands use a first channel secured in the wireless transmission network. A data transmission method designed to be transmitted. 7. Data transmission capable of bidirectionally transmitting a command of a predetermined format between a remote control device and a controlled device controlled by the remote control device using a predetermined transmission network. In the system, as the controlled device, first communication means for bidirectionally transmitting and receiving a command of the above format to and from the remote control device; and instructing by the first command received by the first communication means. And a first control means for causing the first communication means to transmit a second command relating to an operation state, and performing bidirectional communication with the controlled device as the remote control device. A second communication means for transmitting and receiving a command of the above format; and
And the second command is transmitted to the second
A data transmission system comprising: a second control unit that controls display of an operation status instructed by a command when the communication unit receives the command; and a display unit that performs display under the control of the second control unit. 8. The data transmission system according to claim 7, wherein the first control means of the controlled device causes the first communication means to periodically transmit the second command. 9. The data transmission system according to claim 7, wherein the first control means of the controlled device transmits the second command when an operation state of the controlled device changes. 10. The data transmission system according to claim 7, wherein the controlled device includes a reproducing unit, and when a number of a program being reproduced by the reproducing unit changes, the first control unit transmits the second program. A data transmission system that sends out these commands. 11. The data transmission system according to claim 7, wherein the transmission network for performing communication between said first communication means and said second communication means is a wireless transmission network, and wherein said first and second communication means are wireless communication networks. A data transmission system in which the second command is transmitted using the first channel secured in the wireless transmission network. 12. A data transmission device connected to a predetermined network, comprising: communication means for performing bidirectional communication with another device connected via the network; processing means for executing a predetermined operation; The operation specified by the first command received by the communication unit is executed by the processing unit, and a second command including data on the operation status of the processing unit is converted into a command of the same format as the first command. A data transmission device comprising: a control unit configured to transmit data from the communication unit. 13. The data transmission device according to claim 12, wherein said control means causes said communication means to periodically transmit said second command. 14. The data transmission apparatus according to claim 12, wherein said control means causes said second command to be transmitted when an operation state of said processing means changes. 15. The data transmission apparatus according to claim 12, wherein said processing means is playback means for playing back data from a predetermined medium, and said control means is adapted to be adapted when said playback means changes the number of a program being played back. Is a data transmission device for transmitting the second command. 16. The data transmission apparatus according to claim 12, wherein the transmission network with which the communication means communicates with another device is a wireless transmission network, and wherein the first and second commands are transmitted by the wireless transmission network. A data transmission device configured to transmit using the first channel secured in the data transmission device. 17. A data transmission device connected to a predetermined network, comprising: a communication unit for performing bidirectional communication with another device connected via the network; an operation instruction unit; a display unit; A first command for operation control for executing the operation designated by the instruction means is transmitted from the communication means, and a second command having the same format as the first command and indicating the operation status is received. A data transmission device provided with control means for causing the display means to display the operation status instructed by the second command. 18. The data transmission device according to claim 17, wherein the transmission network with which the communication means communicates with another device is a wireless transmission network, and the first and second commands are transmitted by the wireless transmission network. A data transmission device configured to transmit using the first channel secured in the data transmission device.