JP2009159061A - Communication system, electronic apparatus and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication system achieving high-speed communication even when CEC apparatuses are included while ensuring compatibility with the CEC apparatuses and enabling excellent interlocking among devices, and to provide an electronic apparatus and a communication method. <P>SOLUTION: One-frame data of a CEC to be transmitted and received includes a start bit, a header block and at least one data block 33. The electronic apparatus has at least any one of a an initiator function and a follower function, and has a high-speed communication function using pulses during a data block period. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a communication system, an electronic device, and a communication method having a communication interface such as HDMI (High Definition Multimedia Interface) capable of transmitting pixel data of an uncompressed image in one direction at high speed.

  CEC (Consumer Electronic Control) is an HDMI option standard established with reference to P50, which is popular in Europe, and is a protocol that specifies a means of bidirectional serial communication using one signal line in an HDMI cable. is there.

  The transfer rate is as low as 416 bps (theoretical value). In addition, as a feature, devices connected by an HDMI cable can be connected by a bus connection, and each has a multi-master communication mode in which each can be an initiator and a follower.

  As a method of using CEC, for example, assuming a state in which a video (Video) playback device (Source) and a television receiver (hereinafter referred to as TV; (Sink)) are connected via HDMI, a TV remote controller (hereinafter also referred to as a remote controller) may be used. When the power is turned off, the information is transmitted from the TV to the video via the CEC, and the power of the TV and the video can be turned off at the same time.

Also, there is a usage in which a video channel is selected by switching the TV input at the same time when the video playback button is pressed.
With these functions, the user can operate the TV and video devices without changing the remote control.

  As a feature of CEC, in an HDMI system in which data is transferred in one direction from a source (Source) to a sink (Sink), it is possible to send data independently from the sink (Sink) to the source (Source). The communication line can take a transmission form mainly composed of TV.

  Patent Document 1 proposes a device for converting a high-level command from a host control unit into a CEC standard low-level electrical signal in the system, and a mounting method using the convenience of CEC.

Patent Document 2 also presents an example in which the use of CEC can be applied as an aid for signal transmission between HDMI connection systems, and the use of CEC capable of transmitting and receiving information within an HDMI connection system will be expanded in the future. I think that the.
JP 2006-135959 A JP 2007-006298 A

  The range of use currently assumed by the CEC is mainly to improve the convenience of user operation of the device, and the operation could be covered with a bandwidth equivalent to remote control communication. It is considered that an advanced time schedule is required when sending a message by CEC, and there is a possibility that a retransmission request may not be in time in the current low-speed CEC communication.

When it becomes necessary to implement functions beyond those required for conventional CEC, for example, a system that sends TV configuration information to a recorder or amplifier at the same time as turning on the TV and reconfigures the recorder or amplifier to an optimum state. Considering that the information is 1 Kbyte, it is necessary to pass a transfer time of nearly 20 seconds.
Even if this is implemented using a device that converts a high-level instruction into a low-level electrical signal as in the technique of Patent Document 1, the fundamental CEC standard protocol of 416 bps becomes a bottleneck and does not change.
The system can be practically used when the problem solved by the waiting time of 20 seconds after power-on is large, but if the information that must be sent from the TV is 1 Mbyte, a transfer time of 5 hours is required. It is never practical.

  In this way, even if each device connected by the HDMI cable is in a state where it can communicate with each other by CEC, when trying to implement some kind of high function, the transfer rate is always low, so the practicality becomes low. .

  In this way, with the spread of HDMI, communication devices suitable for CEC that can realize a transfer rate exceeding 416 bps, which is the standard transfer of CEC, when considering further convenience of the HDMI system and addition of high functions. is required.

In order to increase the transfer rate, it is necessary to express 0 and 1 with an electrical signal by a method not defined in the existing protocol.
As an existing technique for speeding up, for example, a high transfer rate can be realized by simply shortening the period representing a 1-bit signal.

Even in the CEC protocol, considering the one-to-one case between the master and the slave, it is possible to increase the transfer rate by shortening the 1-bit period.
However, a feature of the CEC protocol is that a plurality of CEC devices are connected by bus.
For example, a TV, a recorder, and an AV amplifier are connected one by one between the TV / AV amplifier and between the TV / recorder via an HDMI cable, but the CEC device of the TV-AV amplifier-recorder is bus-connected on the circuit structure. .
Since such a connection is permitted, it is not possible to know what CEC device is connected in the bus, and therefore the transfer method cannot be changed even for transfer between limited devices.

As a specific symptom, a third CEC device that does not support high-speed transfer is connected in a situation where high-speed transfer is ignored between the sender and the receiver, ignoring the CEC standard protocol. Then, the third CEC device cannot monitor high-speed transfer.
For this reason, it can be considered that no one occupies the CEC bus and data is flowed on the CEC bus, thereby hindering high-speed communication.

  The present invention provides a communication system, an electronic device, and a communication method capable of high-speed communication even in a situation where CEC devices are mixed while ensuring compatibility with CEC devices, and capable of high-level cooperation between devices. It is in.

  A first aspect of the present invention is a communication system between electronic devices including a CEC device that can be connected to a communication cable that enables data transmission of video and audio, exchange of connected device information, and communication of device control data. The CEC frame data to be transmitted / received includes a start bit, a header block, and at least one data block, and the electronic device can have at least one of an initiator function and a follower function. It has a function of performing high-speed communication with pulses during the data block period.

  Preferably, the electronic device performs high-speed communication during a predetermined safe sample period.

  Preferably, the electronic device can perform early end-of-message processing by auxiliary information in high-speed communication.

  Preferably, in the high-speed communication, the electronic device can realize a transmission / reception change in which the roles of the initiator and the follower are changed in the frame during communication by auxiliary information.

  Preferably, the electronic device has a function of performing a negotiation between a high-speed transfer mode and a normal transfer mode by adding or not adding high-speed transfer mode data to high-speed transfer frame data.

  A second aspect of the present invention includes a CEC device that can connect a communication cable that enables data transmission of video and audio, exchange of connected device information, and communication of device control data, and includes an initiator function and a follower function. An electronic device that can have at least one of the functions, and one frame data of CEC to be transmitted / received includes a start bit, a header block, and at least one data block. It has a function to perform communication.

  According to a third aspect of the present invention, there is provided a communication method between electronic devices including a CEC device that can be connected to a communication cable that enables data transmission of video and audio, exchange of connected device information, and communication of device control data. The CEC frame data to be transmitted / received includes a start bit, a header block, and at least one data block, and the electronic device can have at least one of an initiator function and a follower function. High-speed communication using pulses is performed during the data block period.

  According to the present invention, the electronic device performs high-speed communication using pulses during a predetermined safe sample period of the data block.

  According to the present invention, high-speed communication is possible even in a situation where CEC devices are mixed while ensuring compatibility with CEC devices, and advanced cooperation between devices is possible.

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

  In this embodiment, after first explaining an example of a communication system, a normal communication protocol, a high-speed transfer protocol, and an interconnection with a normal CEC will be described.

  FIG. 1 is a diagram illustrating a configuration example of a communication system to which a communication method according to an embodiment of the present invention is applied.

  The communication system 100 in FIG. 1 is configured to enable high-level cooperation between CEC-connected devices by realizing high-speed communication while ensuring compatibility with existing CEC devices. Here, as an example, two HDD recorders 130 and 140 are connected to the TV 110 via HDMI.

  The TV 110 includes a display unit 111, a display switching circuit 112, a system control unit 113, a remote control (remote control) signal receiving unit 114, a user interface (I / F) 115, a memory 116, a CEC device 117, an HDMI receiver (Rx) 118, 119 and a tuner 120.

  The HDD recorder 130 includes a CEC device 131, an HDMI transmitter (Tx) 132, a system control unit 133, a memory 134, an HDD 135, and a remote control signal receiving unit 136.

  The HDD recorder 140 includes a CEC device 141, an HDMI transmitter (Tx) 142, a system control unit 143, a memory 144, an HDD 145, and a remote control signal receiving unit 146.

In this embodiment, the source devices are HDD recorders 130 and 140, respectively, and different contents CNT0 and CNT1 are held in the HDDs 135 and 145, respectively.
The lists LST1 and LST2 of the contents CNT0 and CNT1 held in the HDDs 135 and 145 are stored in the respective memories 134 and 144, and the user USR knows the information in the HDDs 135 and 145 by viewing the lists. Can do.
In the case where normal (existing) CEC is used in such a communication system 100, the user uses the remote control to explicitly transmit the content information of the HDD recorder 130 from the remote control signal receiving unit 114 of the TV 110. .
Then, the system control unit 113 of the TV 110 sets the display switching circuit 112, enables the HDMI receiver 118 that receives the video of the HDD recorder 130, and sends a command input from the remote control signal reception unit 114 to the CEC device 117-CEC. The data is transmitted to the system control unit 133 of the HDD recorder 130 through the devices 131.

When the user USR wants to see the content information CNT1 of the HDD recorder 140, the user USR explicitly transmits that he wants to see the content CNT1 of the HDD recorder 140.
The system control unit 113 of the TV 110 sets the display switching circuit 112 to enable the HDMI receiver 119, and sends a command from the user USR to the system control unit 143 through the CEC device 117 and the CEC device 141.
As described above, the user USR must explicitly grasp the contents CNT0 and CNT1 of the HDD recorder 130 and the HDD recorder 140, and the system control unit 113 automatically activates the display switching circuit 112 as an effect of operating the device using the CEC. Just set in.

In this case, it cannot be said that the user has set the display switching circuit 112 of the TV 110 by himself and the operation before the use of CEC in which the command is sent from the remote control signal receiving units 136 and 146, has not been greatly improved.
If the TV system can collect the list LST1 stored in the memory 134 of the HDD recorder 130 and the list LST2 stored in the memory 144 of the HDD recorder 140 by the CEC and can centrally manage them in the memory 116. can be solved.
As a result, the user USR simply selects the list in the memory 116, and the system control unit 113 of the TV automatically sets the display switching circuit 112. The user USR does not recognize the HDD recorder 130 and the HDD recorder 140, and It can be used as an HDD recorder.

However, such a system is difficult with normal CEC. First, due to the slow CEC, the list cannot be updated immediately.
Therefore, the memory 116 needs to be managed using a nonvolatile memory. The reason is that, when using low-speed CEC, the TV needs to suck up the content information in the HDD recorders 130 and 140 over time, so it is not desirable to suck up the content information every time the power is turned on.
For this reason, an update time lag in the memory 116 may occur for the update of the contents of the HDD recorder 130 and the HDD recorder 140, which may result in inconvenience for the user.
Therefore, in this embodiment, a high-speed transfer protocol that will be described in detail later is adopted.

When the CEC can be increased according to the present invention, the TV 110 can immediately extract and manage the lists LST1 and LST2 of the HDD recorders 130 and 1402 even in the case of FIG.
Further, considering that an interface such as USB is mounted on the user interface (I / F) 115, input information such as a keyboard connected to the I / F 115 is used without stress on the HDD recorders 130 and 140 by using a high-speed CEC. Thus, one I / F can be shared between devices connected via HDMI.
Also, since CEC is a means capable of transmitting information from a sink to a source device, it is possible to use a TV as an output device as an input device by realizing high-speed CEC. This is possible with books.
For example, a current touch panel monitor is provided with an RS232C cable and a USB interface for outputting touch panel information in addition to AV input. This can be realized only with an HDMI cable.
As described above, according to the present embodiment, it is possible to remarkably widen the added value of TV and the range of cooperation between devices centering on the TV.

  Hereinafter, the normal communication protocol, the high-speed transfer protocol, and the interconnection with the normal CEC in this embodiment will be described.

[Normal CEC protocol]
2A and 2B are diagrams illustrating a normal CEC protocol.

In this case, the communication unit is performed in units of 1 frame. Frame (1) is composed of a start bit (Start Bit) (2), a header block (Header Block) (3), and several data blocks (Data Block) (4).
Data Block is 16 blocks at maximum and 1 block at minimum. The data block configuration (5) consists of a total of 10 bits, 8bit data (6), 1bit EOM (7), and ACK (8). Only the ACK is transmitted by the follower (slave).
As shown in FIG. 2B, all bits except for the start bit take the same timing diagram (9), start from the falling edge, and have the logic (with the polarity of the start time (Sample Time) (10) ( Logical 1 (11) and Logical 0 (12) are determined.
The start event (13) and sample time return to high (14, 15) that make up 1 bit have margins, but all are defined by the standard, and 1 bit is the standard. It has a length of 2.4 msec, which leads to a theoretical transfer rate value of 416 bps.
EOM is an abbreviation for End Of Message, which indicates the end of the Data Block, and means that the communication ends with the current Data Block. The follower can detect the end of the frame by detecting this EOM.

  FIG. 3 is a diagram showing a header block configuration (16) of a normal CEC protocol.

The header block is composed of 4 bits of initiator logical address (17), follower logical address (18), 1 bit EOM (7) and ACK (8), 10 bits in total. The header block identifies the sender and the receiver and performs bus arbitration to ensure communication.
A logical address is an address determined for each device category and has a priority.
The initiator (Initiator) that starts transmission constantly monitors the transmitted information, and if the initiator block logical address of the Header Block is not the transmitted address, it is assumed that the initiator (Initiator) with the higher priority has taken the bus right. Determine and wait for the next communication timing.
If the local address is detected, Data Block transmission is continued. In addition, if the output signal and the CEC bus state are different even during communication, it is determined that the error handling is in error handling. The error handling will be described later.

The function as a follower (Follower) must be supported by all devices (Device), and if a device detects Start Bit, first, whether the address of its own device is included in the header (Header) Is analyzed.
When the address of the own device is detected in the header, the ACK bit is manipulated to report the establishment of communication to the initiator.
After that, the ACK bit is manipulated for each data block, but if there is a bit that violates the bit timing diagram during reception, it is necessary to report to the initiator (Initiator). As a means for reporting, there is a technique called error handling.
When the follower detects a violation bit (for example, the 1-bit configuration is shorter than the standard), the follower (Follower) fixes the follower (Follower) low for 3.36 msec to 3.84 msec.
As described above, the initiator (Initiator) constantly monitors the signal being transmitted, so if there is no expected high impedance state, it is determined that the error handling from the follower (Error Follow) is transmitted. To interrupt.

  FIG. 4 is a diagram showing a CEC arbitration method and a signal free time.

The CEC standard defines a transmission prohibition period called Signal Free Time (26). All devices permit to become an initiator after confirming that the CEC bus is in an inactive state for the duration of Signal Free Time.
As a result, transmission of other initiators (Initiators) can be prevented from being hindered.
Also, the lost arbitration can be reduced by changing the transmission prohibition period according to the state of each device and shifting the transmission start timing of each device.

There are three types of Signal Free Time, and that of the initiator that performed the transfer in the previous Frame is 19.2 msec. If the previous frame is not an initiator, it is 14.4 msec. In the case of retransmission, it is 9.6msec.
Thereby, at the time of retransmission, it can preferentially become the next initiator (Initiator), and it is possible to prevent one initiator (Initiator) from dominating the band continuously.

In FIG. 4, in Frame 1 (19), DeviceA (23) is an initiator, and DeviceB (24) is a follower for communication.
Meanwhile, DeviceC (25) waits for a state where the CEC line (Line) becomes inactive (communication of Frame 1 ends).
After the end of Frame 1, the count of Signal Free Time by each Device A, B, C starts, but since Device A is Frame 1 and an initiator, 19.2 msec Signal Free Time is set.
Since Device B and C are not initiators in Frame 1, they have a 14.4 msec Signal Free Time.
When a transmission request is issued to DeviceA and DeviceC after Frame1 ends, DeviceC's Signal Free Time ends before DeviceA. Therefore, in Frame2 (20), DeviceC becomes an initiator and starts communication.
Device A that wanted to become an initiator has activated CEC Line, so it stops counting Signal Free Time and starts operating as a follower.

Next, suppose Frame2 transfer fails for some reason and is retransmitted.
In this case, Signal Free Time set in DeviceC is 9.6 msec. Device A and B that were not initiators in Frame 2 have a 14.4 msec Signal Free Time.
At this time, even if there is a transmission request to Device A and B, it is Device C that ends the Signal Free Time earliest. Therefore, retransmission is prioritized, and in Frame 3 (21), Device C is a retry initiator (Re-try Initiator) ( 27).
After Frame3 ends, SignalA and B are 14.4 msec, and DeviceC is 19.2 msec Signal Free Time.
If a transmission request is generated in Device A and Device B at the end of Frame 3, since the Signal Free Time of each other is the same, a conflict (29) occurs in Frame 4 (22), and bus arbitration is performed.
In this example, DeviceB obtains the bus right and DeviceA becomes arbitration lost (28).
At the end of Frame4, DeviceA and DeviceC are 14.4 msec, and DeviceB is 19.2 msec.

The normal CEC protocol has been described above.
Next, the high-speed transfer protocol in this embodiment will be described.

[High-speed transfer protocol]
FIG. 5 is a diagram showing a CEC protocol for high-speed communication according to the present embodiment.

Since Start Bit (30) and Header Block (31) need to be equally understood by any follower, they have the same configuration as a normal protocol, but perform high-speed communication in Data Block (32, 33). To improve the transfer rate.
However, since the standby device monitors the CEC bus active, if the high-speed communication with a short pulse is always performed during the data block period, the standby device may determine that the CEC bus is inactive.
In order to avoid this problem, a high-speed bit timing diagram (34) is adopted as shown in FIG.
As described above, high-speed transfer is possible without malfunctioning the standby device of the normal protocol by performing high-speed transfer during the Safe sample period (35) period.

In the high-speed bit timing diagram, the Start event and Return to High timings are assumed to have numerical values equivalent to the logical 1 of the normal bit timing diagram, as shown in FIG.
In the Safe sample period, serial communication of 1bit and 10μsec is performed and information of 40bit in total is transmitted. The remaining period after the end of the Safe sample period is maintained at the high level (High) as in the normal Logical 1.

Asynchronous communication is adopted as the high-speed communication protocol in the Safe sample period.
FIG. 6 is a diagram illustrating an example of an asynchronous communication protocol.

The 40-bit information includes 4 bytes of data (37), 1 bit of start bit (36), odd parity bit (38), 2 bits of auxiliary data (39), and 4 bits of ACK (40).
In data example 1 of Fig. 6, 4 bytes data is Byte0 = 0x8d, Byte1 = 0x46, Byte2 = 0xa0, Byte3 = 0xd2, and in data example 2, Byte0 = 0x01, Byte1 = 0x13, Byte2 = 0x85, Byte3 = 0xff A high bit in the signal represents Logical 1, and a low bit represents Logical 0.
The ACK is output at the end of the Data Block as well as the normal protocol, but at the time of high-speed transfer, the last ACK bit of the Data Block is ignored and the 4-bit ACK in the Data Block is used. Auxiliary data realizes early EOM and transmission / reception changes as auxiliary information.

Early EOM and transmission / reception change are necessary means for improving transfer efficiency. In order to complete one frame communication in accordance with the CEC protocol, one data block is required at the minimum, and a band occupation of 2.4 msec × 10 bits = 24 msec occurs.
On the other hand, if the transmission of information is completed in the 1-bit period in the data block by high-speed communication, it is not efficient if empty transmission occurs and the frame ends in the remaining 7-bit period. For this purpose, an early EOM is used to immediately acquire an ACK even in the first bit of the Data Block. However, since the bandwidth occupation on the CEC bus has occurred even after the transfer is completed, it is necessary to be careful when sending the next frame, and once communication is interrupted, until the next transfer, A transmission prohibition band by Signal Free Time is added.
In this case, in the exchange of a short message, since the length of the frame does not change, the total occupied bandwidth does not change from the normal protocol.
Therefore, the problem can be avoided by also having means for transmission / reception change. Send / Receive changes can continue communication between devices while occupying up to 16 data blocks of bandwidth by switching the role of initiator and follower between frames during communication. .

  FIG. 7 is a diagram illustrating an example of communication using the early EOM and the Auxiliary bit of transmission / reception change.

  There is no change in the framework of the Data Block configuration (41), but from Bit7 (42) to Bit2 (43), DeviceA is the initiator and DeviceB is the follower (Follower). When displayed, Bit1 (45) and Bit0 (46) cause a transmission / reception change in which DeviceB becomes an initiator and DeviceA becomes a follower.

  FIG. 8 is a diagram illustrating a communication example when only the early EOM is used.

In this case, when the data to be transmitted up to Bit2 (48) in the Data Block configuration (47) is completed, an early EOM is issued in Bit2.
When the follower detects early EOM, it can determine that the frame has ended and can start analyzing the message opcode and processing the data.
The initiator (Initiator) sends an invalid bit in which all the Safe sample bits are high to Bit 1 (49) Bit 0 (50) after the early EOM.
In addition, this invalid bit can be used to prevent buffer overrun and underrun when the system throughput is lower than the transfer rate.
If the initiator system fails to prepare the data by the next bit, an invalid bit will be generated, and the receiving side will determine that communication without a start bit by Sample Timing is an invalid bit, and this bit will be Ignore it and wait for the next bit.
The overrun of the reception buffer is avoided by a retransmission request using the ACK bit. This makes it possible to match the CEC throughput to the system throughput.

In addition, as shown in FIG. 4, CEC regulates the Signal Free Time to shift the transmission start timing between devices, thereby reducing arbitration lost and preventing one device from occupying the bus bandwidth. . However, these restrictions are not necessary in a state where the CEC is connected on a one-to-one basis, and the signal free time in such a form is a major factor for lowering the transfer rate.
In the normal protocol, the device that was the previous initiator can send data next 19.2 msec after the end of communication due to limitations of Signal Free Time.
On the other hand, the signal free time of the device that was a follower is 14.4 msec. When there are only two devices, the follower can know that the initiator has not sent the data using the EOM bit or other means, and the device that was the follower Since it is possible to control the next time to become a follower, it is not necessary to secure 19.2 msec which is a signal free time for preventing one device from occupying a band.

  FIG. 9 shows a method for increasing the transfer efficiency while complying with the Signal Free Time defined in the standard.

When Device A (51) transmits data to Device B (52), Device A becomes an initiator (53) and Device B becomes a follower (54), and communication is started.
START Bit, Header Block, etc. are sent from DeciceA to DeviceB (58).
When it is necessary to transmit data exceeding the maximum number of data blocks 16 defined in the standard, the communication of the initiator (53) does not end. At this time, if the transmission / reception change = 1 and the early EOM = 0 state (59) are set in the last high-speed communication of Data Block 16, DeviceB becomes the initiator (Initiator) (57) and communication starts for the next communication.
In this case, START Bit and Header Block are sent from DeviceB to DeviceA (60), and Data Block1 is sent from DeviceA to DeviceB (61).
By doing so, the second transmission from Device A to Device B can use 14.4 msec (56) instead of 19.2 msec (55) for Signal Free Time, thereby enabling efficient communication.
In addition, by using it together with the priority of the logical address, it can also be used when you want to occupy the bus between two devices when multiple devices are connected.

The high-speed communication protocol has been described above.
Next, interconnection with a normal CEC will be described.

[Interconnection with normal CEC]
In order to maintain compatibility with the normal CEC protocol, it is necessary to switch between the high-speed transfer mode and the normal transfer mode for communication.
In the case of a CEC topology with two devices, DeviceA and DeviceB, capable of high-speed transfer, each device may always be in a high-speed transfer state, but if DeviceC that supports only normal transfer is incorporated in the topology, DeviceA-B It is necessary to perform high-speed communication between the devices and perform normal transfer between DeviceA-C and BC. And since it is a multi-master system, it cannot know when a normal transfer message is sent from DeviceC.
Therefore, even if a message arrives from DeviceC to DeviceA after performing high-speed transfer between DeviceA and B, DeviceA takes in the message in the high-speed transfer mode.
In order to avoid this problem, negotiation with the high-speed transfer mode bit is performed at the beginning of the high-speed transfer frame.

  FIG. 10 is a diagram illustrating a timing diagram of the high-speed transfer mode Bit.

The high-speed transfer mode Bit is embedded and transmitted in Bit 7 (63) which is the first bit of the Data Block configuration (62).
The high-speed transfer mode bit timing diagram (64) is different from the normal timing diagram.
Low (Low) is maintained for a period of 0.5 msec from Start event (65), and High (High) is maintained for a period of 0.5 msec from First Return to High (66).
Furthermore, Low (Low) is maintained for 0.5 msec from Return to Low (67), it returns to High with Second Return to High (68), and remains High until 2.4 msec.
A normal transfer device does not transmit such data. Even in asynchronous communication of the high-speed transfer protocol, since odd parity is used so that the parity becomes 1 in the case of All-0, such data is not transmitted.
The transfer without the high-speed transfer mode bit is determined to be a normal transfer, and Device A can switch to the normal transfer mode and perform reception seamlessly.

In addition, by providing this high-speed transfer mode bit, in the unlikely event that high-speed transfer is attempted for normal transfer DeiveC, DeviceC determines that the handshake bit is a falling edge with an interval that is too short, and ensures an error. Handling (Error Handling) can be generated, and communication can be interrupted without malfunction.
This is specified in the CEC compliance test that the follower must generate error handling if the falling edge period of the CEC line is less than the specified timing. It comes from being.
Therefore, any CEC device that does not have a high-speed mode can reliably generate error handling by detecting a falling edge interval that is too short.
Also, compared to the normal Logical 1 timing diagram, the location of Return to High is slightly different. This is to keep the CEC line high (high) / low (low) for at least 0.4 msec, which is the minimum sampling interval that the CEC must have in order to ensure falling detection.

By providing the high-speed transfer mode bit in this way, it becomes possible to detect inconsistencies between the high-speed transfer device and the normal transfer device, but the state of retrying by switching the transfer mode is inefficient.
Therefore, a method of securing a high-speed transfer device list in the system and registering in advance which devices can perform high-speed communication is effective in improving transfer efficiency.
For this purpose, there is a method of performing broadcast communication. Broadcast communication is used to form a topology by simultaneously communicating its own address to all devices in the topology at the time of connection, so it is also possible for devices in the topology to be able to communicate at high speed. Notification is possible.

According to the present invention, high-speed communication is realized while ensuring compatibility with a normal CEC device, thereby enabling high-level cooperation between CEC-connected devices.
Further, since CEC is a means capable of transmitting information from a sink to a source device, by realizing high-speed CEC, for example, as shown in FIG. 1, a TV as an output device is input. A single HDMI cable can be used.
For example, a current touch panel monitor is provided with an RS232C cable and a USB interface for outputting touch panel information in addition to AV input. This can only be achieved with an HDMI cable.
As described above, according to the present embodiment, it is possible to remarkably widen the added value of TV and the range of cooperation between devices centering on the TV.

It is a figure which shows the structural example of the communication system to which the communication method which concerns on embodiment of this invention is applied. It is a figure which shows the protocol of normal CEC. It is a figure which shows the Header Block structure of a normal CEC protocol. It is a figure shown about the arbitration method and signal free time (Signal Free Time) of CEC. It is a figure which shows the CEC protocol of high speed communication. It is a figure which shows the example of the protocol of asynchronous communication. It is a figure which shows the example of communication using the early bit of EOM and the Auxiliary bit of transmission / reception change. It is a figure which shows the example of communication at the time of using only early EOM. It is a figure which shows the method for raising transfer efficiency, complying with Signal Free Time prescribed | regulated on the standard. It is a figure which shows the timing diagram of high-speed transfer mode Bit.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Communication system, 110 ... TV, 111 ... Display part, 112 ... Display switching circuit, 113 ... System control part, 114 ... Remote control (remote control) signal receiving part, 115 ... User interface (I / F), 116 ... Memory, 117 ... CEC device, 118, 119 ... HDMI receiver, 120 ... Tuner, 130 ... HDD recorder, 131 ... CEC device, 132 ... HDMI transmitter (Tx), 133 ... system control unit, 134 ... memory, 135 ... HDD, 136 ... remote control signal receiving unit, 140 ... HDD recorder, 141 ... CEC device, 142 ... HDMI transmitter (Tx), 143 ... System controller, 144 ... Memo 145, HDD, 146, remote control signal receiver.

Claims (11)

A communication system between electronic devices including a CEC device that can connect a communication cable that enables video and audio data transmission, exchange of connected device information, and communication of device control data,
One frame data of CEC to be transmitted / received includes a start bit, a header block, and at least one data block,
The electronic device
It can have at least one of initiator function and follower function,
A communication system having a function of performing high-speed communication using pulses during the data block period. The electronic device
The communication system according to claim 1, wherein high-speed communication is performed during a predetermined safe sample period. The electronic device
The communication system according to claim 1, wherein early end-of-message processing is possible with auxiliary information in high-speed communication. The electronic device
The communication system according to claim 1, wherein in high-speed communication, transmission / reception change in which roles of an initiator and a follower are switched between frames during communication can be realized by auxiliary information. The electronic device
The communication system according to claim 1, wherein the communication system has a function of performing negotiation between a high-speed transfer mode and a normal transfer mode by adding or not adding high-speed transfer mode data to high-speed transfer frame data. A communication cable that enables video and audio data transmission, exchange of connected device information, and communication of device control data can be connected, includes a CEC device, and has at least one of an initiator function and a follower function Possible electronic equipment,
One frame data of CEC to be transmitted / received includes a start bit, a header block, and at least one data block,
An electronic device having a function of performing high-speed communication using pulses during the data block period. The electronic device according to claim 6, wherein high-speed communication is performed during a predetermined safe sample period. The electronic device according to claim 6, wherein early end-of-message processing is possible with auxiliary information in high-speed communication. The electronic device according to claim 6, wherein in high-speed communication, transmission / reception change in which the roles of the initiator and the follower are switched between devices during communication can be realized during the communication by auxiliary information. The electronic device according to claim 6, wherein the electronic device has a function of negotiating a high-speed transfer mode and a normal transfer mode by adding or not adding high-speed transfer mode data to high-speed transfer frame data. A communication method between electronic devices including a CEC device that can connect a communication cable that enables transmission of video and audio data, exchange of connected device information, and communication of device control data,
One frame data of CEC to be transmitted / received includes a start bit, a header block, and at least one data block,
The electronic device
It can have at least one of initiator function and follower function,
A communication method for performing high-speed communication using pulses during the data block period.

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