KR20070120852A - Method for high speed cec protocol and multimedia device thereof - Google Patents

Abstract

A high-speed CEC communication method and a multimedia device using the same are provided to realize high-speed CEC communication to enable a user to control the multimedia device without delay. A CEC(Consumer Electronic Control) packet includes a CEC data bit with a second sampling interval smaller than a first sampling interval to transmit information configured by plural bits within the first sampling interval to determine one bit data of a first CEC method defined in HDMI(High Definition Multimedia Interface) standards. A high-speed CEC communication method is to transceive the CEC packet.

Description

High speed CEC communication method and multimedia device using the same {METHOD FOR HIGH SPEED CEC PROTOCOL AND MULTIMEDIA DEVICE THEREOF}

1A to 1C are timing diagrams showing timing of existing CEC signals.

2 to 3 illustrate problems in CEC signal processing.

4 is a timing diagram showing a sampling interval in CEC signal processing according to an embodiment of the present invention.

5 is a diagram illustrating CEC information processing with increased transmission speed according to an embodiment of the present invention.

*** Explanation of symbols for main parts of drawing ***

21: OPCODE <PLAY> 22: OPERAND [Foward]]

23: OPCODE <Deck Status> 24: OPERAND [Play]

31: OPCODE <Record On>

32: OPERAND [Digital Service Identification]

33: OPCODE <Record Status>

34: OPERAND [Recording Digital Service]

35: OPCODE <Record TV Screen>

The present invention relates to a high definition multimedia interface (HDMI), and more particularly, to a high-speed communication method of consumer electronic control (CEC) information of HDMI and a multimedia device using the same.

Recently, as multimedia contents are diversified, various multimedia devices for reproducing and transmitting various multimedia contents have been developed together, and interface technologies for simple and lossless signal connection between them have been developed.

The most representative multimedia interfaces are DVI and HDMI.

Digital Visual Interface (DVI) is a transmission standard established by a consortium formed by leading companies in the computer industry called DIGITAL DISPLAY WORKING GROUP to digitally connect monitors and PCs. The DVI standard has been widely applied to not only PCs and monitors but also commercial plasma displays and peripherals. Recently, HDMI standards, which are more suitable for high-definition multimedia environments, have been developed and commercialized.

HDMI is a high-speed multimedia interface that integrates and transmits uncompressed full digital audio and video signals, replacing the existing analog interfaces such as composite, S-video, and component video. Mainly applied to boxes and the like.

This HDMI is simple to process 5Gbps digital video and audio without compression, simple circuit, no quality deterioration, and copyright protection of content by HDCP (High-bandwidth Digital Content Protection). It has the advantage of being easy to use with a single cable connection. In addition, it is compatible with DVI, which is mainly used in the computer industry, and its application is a multimedia interface that is being developed.

Meanwhile, the HDMI standard defines a user electronic control (CEC) and a CEC bus that can easily control a plurality of networked multimedia devices. According to the CEC, control of multimedia devices connected via HDMI is individually controlled. Since it can be simply performed on one device without the user, the user can conveniently link the devices.

However, the above-mentioned CEC method has a weak response time due to its low communication speed. Therefore, when a user controls several multimedia devices using the CEC method, there is a possibility that a response delay that may be somewhat inconvenient occurs. high.

The purpose of the embodiment according to the present invention to improve the CEC method having a high probability of response delay with low communication speed is to enable high-speed CEC communication, the user can control the multimedia device without inconvenience caused by delay To provide a high-speed CEC communication method of HDMI.

In addition, another object of an embodiment according to the present invention, by enabling high-speed CEC communication, the user can control the multimedia device without the inconvenience caused by the delay, as well as fully compatible with the high-speed CEC of the existing CEC communication method To provide a communication method.

In addition, another object of an embodiment according to the present invention is to improve the existing CEC method with a high probability of response delay not only to control the multimedia device without inconvenience due to delay, but also completely with the existing CEC communication method The present invention provides a multimedia device to which a compatible high-speed CEC communication method is applied.

A high-speed CEC communication method according to an embodiment of the present invention for achieving the above object, in the CEC communication method of HDMI, the first sampling for determining the data 1 bit of the first CEC method defined in the HDMI standard And a second sampling interval to transmit a frame composed of a plurality of bits according to the high speed CEC communication method within the interval.

In addition, the high-speed CEC communication method according to an embodiment of the present invention, a frame consisting of a plurality of bits according to the high-speed CEC communication method within the first sampling interval for determining the data 1 bit of the first CEC method defined in the HDMI standard A second sampling interval for transmitting the data, the first CEC communication method communicating with a device conforming to the first CEC communication method defined in the HDMI standard, and a high speed CEC communication method with a device conforming to the high speed CEC communication method. By doing so, it is characterized in that it is compatible with the first CEC communication method.

In addition, the multimedia apparatus according to an embodiment of the present invention may transmit the information consisting of a plurality of bits within a first sampling interval for determining one bit of data of the first CEC method defined in the HDMI standard. And transmit / receive a CEC packet including a CEC data bit having a second sampling interval smaller than the interval.

Embodiments of the present invention as described above will be described in detail with reference to the accompanying drawings.

1A to 1C are timing diagrams showing timings of a start bit and a data bit used in the CEC protocol defined in the HDMI standard. With reference to this, a transmission rate of a data frame for user electronic control (CEC) will be described.

First, the CEC Data Frame defined in the HDMI standard is defined as Start Bit + Header (1 byte + EOM + ACK) + OPCODE (1 byte + EOM + ACK) + OPERAND (1 byte + EOM + ACK). + ...)

Here, the start bit is a bit for indicating the start of the frame, and as shown in FIG. 1A, a maximum of 4.7 milliseconds (msec) is required to transmit the start bit. The thick solid line in Fig. 1A shows the ideal timing, and the lines except for the thick solid line show an acceptable timing region.

1B to 1C, data bits constituting the header block or data block take 2.75 msec to transmit one bit. As shown in Fig. 1A, an acceptable timing region is shown in Figs. 1B to 1C, and it can be seen that the sampling interval for determining the value of the data bit is defined as 1.85 to 1.25 msec, that is, 0.4 msec (400 ms). have.

The end of message (EOM) is used to signal the end of a message. If the value is '0', it indicates that there is another data. If the value is '1', the message is finished. . ACK is a confirmation information bit.

OPCODE represents an operation code. OPERAND contains the parameters needed by the OPCODE, and the OPCODE is defined for that unit. For example, when the unit is a VCR, various commands such as PLAY (playback) and RECORD (recording) are defined for the unit, and OPERAND is defined according to each OPCODE.

Like this, it consists of start bit (1 bit), header (10 bit), OPCODE (10 bit), and OPERAND (depending on which OPCODE is, but most of them are more than 10 bits and some OPERANDs are more than 7 bytes in size.) In order to transmit a frame, a transmission time of 170 to 400 msec is required only for sending and receiving messages associated with the CEC protocol, and in addition to the transmission time, additional message re-transmission or bus arbitration may occur. Considering both the time spent on bus arbitration, protocol processing time, and function operation time, there is a high possibility that a response delay will occur that a user may feel uncomfortable.

2 is a diagram illustrating an example of controlling a multimedia device using a CEC defined in the HDMI standard, and a user may play a playback device (TV device, for example, a DVD player) through a TV. FIG. 3 shows transmission / reception of CEC related signals in case of controlling.

First, the contents in <> are OPCODEs that display messages, and the contents in [] are OPERAND. Looking at the HDMI specification, the meaning and length of various OPCODEs and OPERANDs are defined.

Referring to <PLAY> [Foward], OPCODE <PLAY> 21 has a size of 1 byte and OPERAND [Foward] 22 also has a size of 1 byte. Here, the size of OPCODE <PLAY>, OPERAND [Foward] is the size excluding the EOM bit and the ACK bit.

In addition, referring to <Deck Status> [Play], OPCODE <Deck Status> (23) has a size of 1 byte and OPERAND [Play] (24) also has a size of 1 byte. Likewise, the size of OPCODE <Deck Status> and OPERAND [Play] is the size excluding the EOM bit and ACK bit.

The user sends a command to play the multimedia content forward, that is, a CEC frame called <PLAY> [Foward] from the TV to the PlayBek device, in response to the reply that the deck's status is currently playing, that is, <Deck Status> When the CEC frame called [Play] is transmitted from the PlayBek device to the TV, the total transmission time is calculated as follows.

First, we need two start bits (TV → Playbeck device, Playbeck device → TV), two headers (header indicating origin and destination, 1 byte + EOM + ACK), 2 bytes of OPCODE, and 2 bytes of OPERAND. And calculate the transfer time based on this,

Total bytes to send ⇒ 4 bytes (OPCODE + OPERAND) + 2 bytes (header) = 6 bytes,

Total transfer time ⇒ 6 x (8 bits + EOM + ACK) x 2.75 msec + 2 (2 start bits) x 4.75 msec ≒ 175 msec.

FIG. 3 is a diagram illustrating another example of controlling a multimedia device using CEC defined in the HDMI standard, and a so-called One Touch Record, that is, a user wants to record content displayed on a TV screen through a recording device. Is a diagram illustrating some transmission / reception of CEC-related signals.

Referring to FIG. 3, it can be seen that three CEC frames are required for one-touch recording. First, look at OPCODE <Record TV Screen> (35), <Record ON> (31), and <Record Status> (33), each having 1 byte size, OPERAND [Digital Service Identification] (32), [Recording Digital Service] 34 has sizes of 7 bytes and 1 byte, respectively. As described above, the size of OPCODE and OPERAND is the size excluding the EOM bit and the ACK bit.

In the case of [Digital Service Identification] 32, which is one of the OPERAND shown in Fig. 3, ARIB (Japanese method), ATSC (North American method), DVB ( European style) and so on, the number of Sub OPERAND is defined as 7 because the size is defined.

Based on this, the total transmission time of the user electronic control for the one-touch recording shown in FIG. 3 is calculated as follows.

First, three start bits (recording device → TV, TV → recording device, recording device → TV), three headers (header indicating origin and destination, 1 byte + EOM + ACK), 3 bytes of OPCODE, 8 bytes OPERAND is required and when calculating the transfer time,

Total bytes to send ⇒ 11 bytes (OPCODE + OPERAND) + 3 bytes (header) = 14 bytes,

Total transfer time ⇒ 14 x (8 bits + EOM + ACK) x 2.75 msec + 3 (three start bits) x 4.75 msec ≒ 400 msec.

Therefore, in some cases, a transmission delay may occur that the user feels uncomfortable, and a high speed CEC communication method is required to solve the problem.

1B to 1C, it can be seen that the sampling interval for determining the data bit value in the conventional CEC communication method is very broadly defined as about 0.4 msec (0.85 to 1.25 msec). Therefore, in the present invention, a high speed CEC communication method and apparatus are implemented using the advantages.

4 is a timing diagram of data bits according to an exemplary embodiment of the present invention. Referring to this, the sampling interval of the data bits is 10 ms (10 to 20 ms). It takes some time to transfer. That is, the present invention introduces high-speed signal processing within the existing sampling interval to enable inherent high-speed communication within a short interval of reading the data bits of the existing HDMI CEC.

The high speed signal processing introduced in the present invention is intended to increase the CEC transmission rate, and preferably has the data bit timing as shown in FIG. With the bit timing as shown in Fig. 4, it becomes possible to process data of 10 bits (1 byte + EOM + ACK) within the sampling interval 400 ms for determining the existing CEC data 1 bit value. (34 μs × 10 = 340 μs).

In FIG. 4, the maximum transmission time of one bit of data is set to 34 ms and the sampling interval is set to 10 ms. However, the present invention is not limited thereto. It may have a second sampling interval (a value other than 10 ms) to enable high-speed CEC communication within the interval (first sampling interval, 400 ms).

Referring also to FIG. 4, an acceptable timing is disclosed to represent logic '1' or logic '0'. For example, the earliest time for a low-high transition when indicating a logical 1 is set to 4, to represent logic '1', representing logic '1'. The latest time for a low-high transition when indicating a logical 1 is set to 8 ms, but this can be changed as much as you like. That is, the sampling interval (10 ms) and the allowable timing according to an embodiment of the present invention can be appropriately changed according to the situation, and preferably has a timing as shown in FIG.

FIG. 5 is a diagram illustrating how <Record On> [Digital Service Identification], which is one of the CEC frames for one-touch recording shown in FIG. 3, is changed according to an embodiment of the present invention in comparison with the conventional HDMI CEC. This will be explained as follows.

First, the case of following the conventional HDMI CEC communication method is shown, the start bit and the header part are shown, and the OPD <Record On>, which is composed of 1 byte + EOM + ACK, and [Digital Service Identification], which is an OPERAND having a size of 7 bytes. ] Is shown, it takes almost 252 msec transmission time to transmit all of them.

That is, in the conventional CEC communication method, the transmission time is 4.7 (start bit) + 2.75 × 10 (header) + 2.75 × 10 × 8 (OPCODE + OPERAND) = 252 msec.

Below it is shown a CEC frame according to an embodiment of the present invention. Referring to this, first, the start bit and the header part are the same as defined in the existing HDMI CEC.

This is for compatibility with the existing CEC communication method and the high-speed CEC communication method according to an embodiment of the present invention. For example, when a plurality of multimedia devices are connected via HDMI, all devices (device using a conventional CEC method + a device using a fast CEC method according to an embodiment of the present invention) are connected to the same CEC bus. In order for all devices connected to the same CEC bus to be compatible, the start bit and header portion of the CEC frame must use the existing CEC scheme.

In other words, since the header part contains the address of the source and destination of the frame, all the devices connected to the CEC bus share the information of which device is currently communicating with the device through the CEC bus only if the header part applies the existing CEC method. This enables interoperability.

In other words, the multimedia device according to an embodiment of the present invention communicates with the multimedia device according to the existing CEC scheme in the existing CEC scheme, and communicates with the multimedia device according to the high speed CEC scheme in the high speed CEC scheme to the existing HDMI CEC. Compatible with (so-called Backward Compatible)

That is, after the authority to use the CEC bus is set to one multimedia device, devices capable of communicating in a high speed CEC communication method may perform high speed CEC communication. However, in the conventional CEC communication method, high-speed CEC communication should be performed within a short interval of reading data bits, thereby achieving compatibility. At this time, devices that communicate with the existing CEC method can not read the contents, and do not have to know.

Referring to this point, when calculating the transmission time of the CEC frame according to an embodiment of the present invention shown in FIG.

Transmission time: 4.7 (start bit) + 2.75 × 10 (header) + 2.75 × 10 × 1 (OPCODE + OPERAND) = 60 msec, which is much lower than the existing 252 msec.

In other words, the start bit and the header part do not reduce the transmission time compared to the existing CEC. However, the OPCODE and OPERAND parts can reduce the transmission time to almost 1/8 level compared with the existing CEC.

As described above, even when considering only one CEC frame transmission called <Record On> [Digital Service Identification], the transmission time is remarkable. The user electronics that are connected to a plurality of multimedia devices and require complicated CEC frame transmission between them are required. Application of the present invention to control can drastically reduce the total transmission time, thereby avoiding the response delay which has been a conventional problem.

When the present invention as described above is applied to the HDMI CEC, not only is it compatible with the existing CEC standard, but also enables faster and faster CEC communication, and when the present invention is included in the HDMI standard in the future, the Intellectual Property Rights (Intellectual Property Rights, IPR) can also be secured.

As described above, the high-speed CEC communication method and the multimedia device applying the same according to an embodiment of the present invention improve the CEC method having a high probability of response delay due to low communication speed, thereby enabling high-speed CEC communication so that a user may There is an effect that can control the multimedia device without inconvenience.

High speed CEC communication method and a multimedia device applying the same according to an embodiment of the present invention according to an embodiment of the present invention is fully compatible with the existing CEC communication method and the user can control the multimedia device without inconvenience caused by delay It works.

The high-speed CEC communication method and the multimedia device using the same according to an embodiment of the present invention have the effect of securing intellectual property rights when included in the HDMI standard.

Claims (6)

CEC data bits having a second sampling interval smaller than the first sampling interval may be transmitted so that information consisting of a plurality of bits can be transmitted within a first sampling interval for determining one bit of data of the first CEC method defined in the HDMI standard. High speed CEC communication method for transmitting / receiving a CEC packet. The method of claim 1, wherein the high speed CEC communication method, The device conforming to the first CEC communication method defined in the HDMI standard communicates with the first CEC communication method, and the device conforming to the high speed CEC communication method communicates with the high speed CEC communication method, thereby making it compatible with the first CEC communication method. High speed CEC communication method characterized in that. The method of claim 2, The start bit and the header of the CEC packet according to the high speed CEC communication method maintain the same as the first CEC communication method. The method according to any one of claims 1 to 3, And said second sampling interval is 10 [mu] s. CEC data bits having a second sampling interval smaller than the first sampling interval may be transmitted so that information consisting of a plurality of bits can be transmitted within a first sampling interval for determining one bit of data of the first CEC method defined in the HDMI standard. Multimedia device for transmitting / receiving a CEC packet. The method of claim 5, The start bit and the header of the CEC packet maintain the same identity as the first CEC communication method defined in the HDMI standard, thereby transmitting / receiving a CEC packet compatible with the multimedia device using the first CEC communication method. .

Images