WO2012080030A1 - System for connecting audio and video equipment in a daisychain - Google Patents

System for connecting audio and video equipment in a daisychain Download PDF

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Publication number
WO2012080030A1
WO2012080030A1 PCT/EP2011/071860 EP2011071860W WO2012080030A1 WO 2012080030 A1 WO2012080030 A1 WO 2012080030A1 EP 2011071860 W EP2011071860 W EP 2011071860W WO 2012080030 A1 WO2012080030 A1 WO 2012080030A1
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WO
WIPO (PCT)
Prior art keywords
interface
power supply
channel
relay line
input
Prior art date
Application number
PCT/EP2011/071860
Other languages
French (fr)
Inventor
Christophe Lauga-Larroze
Original Assignee
Stmicroelectronics (Grenoble 2) Sas
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Stmicroelectronics (Grenoble 2) Sas filed Critical Stmicroelectronics (Grenoble 2) Sas
Publication of WO2012080030A1 publication Critical patent/WO2012080030A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
    • H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
    • H04N21/436—Interfacing a local distribution network, e.g. communicating with another STB or one or more peripheral devices inside the home
    • H04N21/4363—Adapting the video stream to a specific local network, e.g. a Bluetooth® network
    • H04N21/43632—Adapting the video stream to a specific local network, e.g. a Bluetooth® network involving a wired protocol, e.g. IEEE 1394
    • H04N21/43635—HDMI
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G5/00—Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators
    • G09G5/003—Details of a display terminal, the details relating to the control arrangement of the display terminal and to the interfaces thereto
    • G09G5/006—Details of the interface to the display terminal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/02—Details
    • H04L12/12—Arrangements for remote connection or disconnection of substations or of equipment thereof
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/76—Television signal recording
    • H04N5/765—Interface circuits between an apparatus for recording and another apparatus
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
    • G09G2330/02—Details of power systems and of start or stop of display operation
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2370/00—Aspects of data communication
    • G09G2370/04—Exchange of auxiliary data, i.e. other than image data, between monitor and graphics controller
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2370/00—Aspects of data communication
    • G09G2370/10—Use of a protocol of communication by packets in interfaces along the display data pipeline
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2370/00—Aspects of data communication
    • G09G2370/20—Details of the management of multiple sources of image data
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/50—Reducing energy consumption in communication networks in wire-line communication networks, e.g. low power modes or reduced link rate

Definitions

  • the invention relates to connecting several sources of digital audio and/or video signals (DVD player, cable/satellite set-top box, computer. . . ) to playback equipment (TV set, monitor, projector, home cinema equipment. . . ).
  • DVD player digital audio and/or video signals
  • cable/satellite set-top box computer. . .
  • playback equipment TV set, monitor, projector, home cinema equipment. . . ).
  • HDMI and DisplayPort standards are today available for connecting various source devices to a playback device, the HDMI link being the most common as of the writing of this disclosure. These digital links enable transmission of uncompressed high-definition video and audio in one direction.
  • Version 1.4A of the HDMI standard provides for audio and remote control return channels (CEC standard).
  • the VESA DisplayPort standards, versions 1.1 A and 1.2, provide for a bidirectional auxiliary channel.
  • a point-to-point connection is used, i.e. the player device requires as many HDMI connectors as source devices to connect. Additional source devices need to be connected via HDMI switch boxes. Selecting the source device then becomes complex.
  • the SCART link was available, which allowed to connect a certain number of devices in a daisy chain. Selecting the source device was achieved by powering up the device and putting the other devices between the source and the player in standby.
  • an electronic device comprising an output interface having a high data-rate output channel, a medium data-rate bidirectional auxiliary channel, and a power supply relay line; an input interface having a high data-rate input channel, a medium data-rate bidirectional auxiliary channel, and a power supply relay line; and control circuitry designed to organize the relay of a data flow from the input channel towards the output channel, and the relay of data between the auxiliary channels of the input and output interfaces.
  • a power supply system is configured for powering the power supply relay line of one of the interfaces, so-called downstream interface, independently of supplying power to the device.
  • the interfaces and the control circuitry are powered by the power supply relay line of the other interface, so- called upstream interface.
  • the power supply system is configured for powering the device itself or the power supply relay line of the downstream interface under control of the control circuitry in response to a command received through the auxiliary channel of the upstream interface.
  • the high data-rate channels are designed to transport digital video and audio signals and the control circuitry is configured to organize the transmission of digital audio signals through the auxiliary channel of the input interface.
  • a method for managing multiple devices of the above type connected in a daisy chain through their input and output interfaces comprising the following steps performed by a master device located upstream in the chain: indentifying a target device in the chain; powering the power supply relay line of the downstream interface of the master device; for each intermediary device located between the master device and the target device, sending through the auxiliary channel of the upstream interface of the intermediary device a command for powering the power supply relay line of the downstream interface of the intermediary device; and sending through the auxiliary channel of the upstream interface of the target device a command for powering the target device.
  • a method for identifying multiple devices of the above type connected in a daisy chain through their input and output interfaces comprising the following steps performed by a master device located upstream in the chain: powering the power supply relay line of the downstream interface of the master device; for each slave device in the chain, sending through the auxiliary channel of the upstream interface of the slave device a command for powering the power supply relay line of the downstream interface of the slave device; and receiving through the auxiliary channel of the downstream interface of the master device identification data sent by the slave devices as the control circuitries of their interfaces are powered.
  • FIG. 1 schematically shows a link according to the VESA DisplayPort standards
  • FIG. 2 schematically shows a daisy chain of audio/video devices connected through DisplayPort links
  • FIG. 3 schematically shows an embodiment of a relay with DisplayPort interfaces incorporated in a device and associated to a power source of the device;
  • ⁇ figures 4a to 4c show four states of the relay of figure 3 in establishing a communication with a selected source.
  • Figure 1 schematically shows a DisplayPort link between a transmitter Tx and a receiver Rx.
  • the link includes up to 4 high data-rate single direction (Tx to Rx) lines or "Main Link Lanes" ML LnO to ML_Ln3; a medium data-rate bidirectional line AUX CH; a single direction (Rx to Tx) hot-plug detect line Hot Plug Detect; and a power source relay line DP PWR.
  • the data-rate on each main link lane ML Ln may reach 5.4 Gb/s, and the AUX CH line has a fast mode, called F- AUX, having a data-rate of 720 Mb/s.
  • the power supply relay line DP_PWR is designed to provide 3.3 V under 500 mA.
  • the DisplayPort link was initially designed to connect monitors or other display devices to computer units.
  • a devised application for the auxiliary channel AUX CH is to transmit to the computer unit signals that are produced by the peripherals connected to the monitor, such as a keyboard, a mouse, a camera, a microphone, and other peripherals connected to USB or other types of sockets of the monitor. This enables the connection of the monitor and all its peripherals to the computer unit through a single cable.
  • each monitor includes an input DisplayPort interface and an output DisplayPort interface.
  • the input interface of each monitor is designed to accept multiple video flows.
  • the monitor extracts the flow to its attention and relays the others to its output interface, which is connected to the next monitor that achieves a similar operation.
  • the auxiliary channel is used in this case to identify the destinations of the video flows, the identifiers and capabilities of the monitors having been communicated to the computer unit through the auxiliary channels upon power on or connection of the monitors.
  • the power supply relay line DP PWR is not used.
  • a devised application for this line is to supply power to a low-power display device, such as an LCD display or a mini video projector.
  • Figure 2 schematically illustrates an exemplary daisy chain connection of audio/video devices El to E4 through DisplayPort links DPI to DP3. It is desired, for example, to connect a DVD player, a set top box STB, and an audio/video amplifier AVR to a television set TV.
  • Each device is equipped with a DisplayPort output interface and a DisplayPort input interface DP.
  • the meaning of "input” and “output” is to be interpreted relative to the direction of flow on the high data-rate main link lanes ML Ln.
  • a device is inserted in the chain by connecting its output interface to the input interface of the preceding device.
  • the device at the head of the chain is an audio/video playback device, the TV set in figure 3, capable of processing the audio/video flow of any of the other devices, or several at the same time (split screen, PIP, mosaic displays).
  • This digital daisy chain including the control circuitry for the DP interfaces in each device, could be designed in the same way as an analog daisy chain based on SCART links, i.e. the user powers on the device to watch, for instance El, and puts in standby all the devices (E2) located between the device to watch and the playback devices (E3, E4).
  • the DP interfaces in the standby devices (E2), powered by the standby system, are configured, in this mode, to relay the signals from their input link to their output link.
  • the amplifier E3 retrieves the audio flow and relays only the video flow VI to TV set E4.
  • the bidirectional auxiliary channels of the DP links may be used, for example, to transmit the remote control signals RC centrally received by one of the devices, here E3.
  • the location of a medium data-rate receiver device, like amplifier E3, is irrelevant. If amplifier E3 is placed at the tail of the chain, opposite the TV set, the audio flow to its attention may be transmitted to it via the auxiliary channels of the DP links. It is preferable in this case that the DP interfaces use version 1.2 of the standard, having an auxiliary channel with a data-rate sufficient for any compressed audio flow.
  • daisy chain may also be realized with HDMI 1.4 links, having channels dedicated to audio return and remote control.
  • FIG. 3 schematically shows an embodiment of a relay 10 with DisplayPort interfaces, included in a device and associated with a power source 12 of the device.
  • the bottom part of relay 10 corresponds to the input interface DPi.
  • the high data-rate input lines receive an audio/video flow AVi coming from the output interface of the next device in the chain.
  • Flow AVi shaped by a receiver circuit Ln Rx, is received on a first input of a multiplexer 14.
  • a second input of multiplexer 14 receives a local audio/video flow, i.e. from the device itself, through a conversion circuit CONV.
  • Multiplexer 14 is controlled by a circuit 16 in charge, in particular, of managing the auxiliary channel AUXi of the input interface and AUXo of the output interface.
  • This output interface DPo is shown at the top portion of relay 10.
  • the output of multiplexer 14 provides the outgoing audio/video flow AVo through a transmit circuit Ln Tx.
  • the power supply relay line DP PWRo of the output interface is designed to provide the necessary power supply to relay 10.
  • the internal power supply 12 of the device is not designed to supply power to relay 10.
  • the voltage and current values (3.3 V, 500 mA) specified for this line by the DisplayPort standards permit this.
  • the power supply relay line DP PWRi of the input interface is, in contrast, supplied by a dedicated output of the power supply 12 of the device, upon command of the control circuit 16.
  • Power supply 12 is moreover designed, upon command of control circuit 16, to supply the general power PWR of the device, or alternatively, the standby mode power supply SBY.
  • supply 12 In the absence of command from control circuit 16, supply 12 provides no power.
  • the necessary power for supply 12 to obey control circuit 16 may be provided, as shown, by line DP PWRo. Hence, supply 12 may be entirely disconnected from a main power source or the mains network.
  • Control circuit 16 may additionally be designed, as shown, to direct the local audio flow A Loc, or even a compressed video flow, towards the auxiliary channel AUXi of the input interface. This enables an audio playback device to be placed at the tail of the chain, and still transmit thereto, through the auxiliary channels, audio signals in reverse direction with respect to the direction of channels ML Ln. Moreover, the device may be provided with various other interfaces, such as USB or Ethernet, redirected or made available by control circuit 16 through the auxiliary channels of the input and output interfaces.
  • Figures 4a to 4d show different states of a relay of the type of figure 3 as it is used in a daisy chain of devices.
  • the powered devices are shown in bold lines, while the unpowered devices are shown in dotted lines.
  • the high data-rate channels of the relay are not shown; as regards their power supply, they behave like the auxiliary channels and control circuit 16.
  • Each intermediary device of the chain has a similar relay.
  • the end devices may be provided with only the input interface or the output interface, depending on whether the device is at the head or the tail of the chain.
  • One of the devices is a master device and designed to manage the other, slave, devices of the chain.
  • the master device is preferably chosen among those that are necessarily used, for example TV set E4 (figure 2). It could also be amplifier E3, in which case it would preferably be placed at the head of the chain, in front of the TV set.
  • Figure 4a shows a relay of a slave device in an initial state, where all the devices of the chain are powered off. Nor the relay, nor the device itself, is powered. Power supply 12 is inactive. There is no power consumption in the device.
  • an upstream device for instance the master device, supplies power to line DP PWRo.
  • the elements of the relay are powered and ready to operate.
  • the master device transmits on the auxiliary channel an identifier of a target device to enable.
  • This identifier can be the position of the device in the chain, each device having previously stored its position.
  • the identifier may also be a unique universal identifier previously stored by the master device.
  • the target device is downstream in the chain.
  • the control circuit commands supply 12 to power the line DP PWRi of the input interface DPi. This line supplies power to the relay of the next downstream device, which is in the state of figure 4b.
  • the relay is configured to operate as a bridge, i.e. multiplexer 14 (figure 3) is set to transmit the incoming flow AVi to the output interface DPo.
  • Control circuit 16 also transmits on channel AUXi the identifier it received on channel AUXo.
  • the device happens to be the target device.
  • the control circuit which recognized the identifier on channel AUXo, commands supply 12 to power on the device.
  • multiplexer 14 (figure 3) is set to transmit the local flow AV Loc to the output interface. If an audio receiver happens to be further down the chain towards the tail, the local audio flow is directed to the auxiliary channel AUXi of the input interface.
  • the steps of figures 4b and 4c are repeated for the downstream devices, until the audio receiver is reached.
  • the device is switched from a powered off state to a standby state, for instance in the case of a PVR that has been programmed for a recording.
  • the master device initially knows the composition of the chain.
  • the master may discover the devices of the chain during a discovery phase that can be performed systematically at each power on of the master device or at the request of the user each time he modifies the chain.
  • the steps of figures 4a to 4c are performed to enable one after the other the relays of the devices of the chain, like if the master were attempting to enable a device placed at the tail of the chain.
  • the master device is notified through the auxiliary channels according to the protocols defined by the DisplayPort standard. These protocols are namely designed for the devices that are being interconnected to mutually identify themselves.
  • the exchanged identification information may include a unique universal identifier, the mark and type of the device, the serial number, the data-rates and recognized formats of the flows. . .
  • the master device thus receives this information and may build a table of the devices of the chain and their positions.
  • the master device may moreover communicate the positions to the slave devices through the auxiliary channels for their storage, for example within their control circuit 16.
  • the slave devices could themselves maintain a table of the upstream devices, whose identifiers they receive through their auxiliary channels AUXi. Powering off of the whole chain may be performed as follows.
  • the user starts by turning off the master device.
  • This device powers off line DP PWRi of its input interface DPi.
  • the relay of the next downstream device is powered off.
  • the power supply 12 of this downstream device is disabled, including its line DP PWRi.
  • the devices of the chain are thus powered off one after the other, starting from the master device, at the head of the chain, towards the device at the tail of the chain.
  • any communication with the master device is immediately interrupted, so that a device that should stay on standby, for example for recording at a program time, would also be powered off.
  • a "negotiated" power off procedure is preferred.
  • the master device controls the power off of the devices one after the other starting from the last active device at the tail of the chain, through the auxiliary channels.
  • a dialogue can thus establish between the master device and the slave device before power off.
  • the slave device may ignore the power off command and stay in standby in order to perform recording, but behave with respect to the rest of the chain like if it were powered off, namely by powering off its DP PWRi pin.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Multimedia (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
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Abstract

An electronic device comprises an output interface having a high data-rate output channel, a medium data-rate bidirectional auxiliary channel, and a power supply relay line; an input interface having a high data-rate input channel, a medium data-rate bidirectional auxiliary channel, and a power supply relay line; and control circuitry designed to organize the relay of a data flow from the input channel towards the output channel, and the relay of data between the auxiliary channels of the input and output interfaces. A power supply system is configured for powering the power supply relay line of one of the interfaces, so-called downstream interface, independently of supplying power to the device. The interfaces and the control circuitry are powered by the power supply relay line of the other interface, so-called upstream interface.

Description

SYSTEM FOR CONNECTING AUDIO AND VIDEO EQUIPMENT IN A DAISYCHAIN
Field of the Invention
The invention relates to connecting several sources of digital audio and/or video signals (DVD player, cable/satellite set-top box, computer. . . ) to playback equipment (TV set, monitor, projector, home cinema equipment. . . ).
Background of the Invention
Digital links according to the HDMI and DisplayPort standards are today available for connecting various source devices to a playback device, the HDMI link being the most common as of the writing of this disclosure. These digital links enable transmission of uncompressed high-definition video and audio in one direction. Version 1.4A of the HDMI standard provides for audio and remote control return channels (CEC standard). The VESA DisplayPort standards, versions 1.1 A and 1.2, provide for a bidirectional auxiliary channel. In order to connect several source devices to a playback device with HDMI links, a point-to-point connection is used, i.e. the player device requires as many HDMI connectors as source devices to connect. Additional source devices need to be connected via HDMI switch boxes. Selecting the source device then becomes complex.
In the analog world, the SCART link was available, which allowed to connect a certain number of devices in a daisy chain. Selecting the source device was achieved by powering up the device and putting the other devices between the source and the player in standby.
Summary of the Invention
There is a need, in the digital world, to connect any number of source devices in a daisy chain with a playback device. It is in particular desired that the inactive devices of such a chain use little power.
These needs tend to be satisfied by an electronic device comprising an output interface having a high data-rate output channel, a medium data-rate bidirectional auxiliary channel, and a power supply relay line; an input interface having a high data-rate input channel, a medium data-rate bidirectional auxiliary channel, and a power supply relay line; and control circuitry designed to organize the relay of a data flow from the input channel towards the output channel, and the relay of data between the auxiliary channels of the input and output interfaces. A power supply system is configured for powering the power supply relay line of one of the interfaces, so-called downstream interface, independently of supplying power to the device. The interfaces and the control circuitry are powered by the power supply relay line of the other interface, so- called upstream interface.
According to an embodiment, the power supply system is configured for powering the device itself or the power supply relay line of the downstream interface under control of the control circuitry in response to a command received through the auxiliary channel of the upstream interface.
According to an embodiment, the high data-rate channels are designed to transport digital video and audio signals and the control circuitry is configured to organize the transmission of digital audio signals through the auxiliary channel of the input interface.
A method is also provided for managing multiple devices of the above type connected in a daisy chain through their input and output interfaces, comprising the following steps performed by a master device located upstream in the chain: indentifying a target device in the chain; powering the power supply relay line of the downstream interface of the master device; for each intermediary device located between the master device and the target device, sending through the auxiliary channel of the upstream interface of the intermediary device a command for powering the power supply relay line of the downstream interface of the intermediary device; and sending through the auxiliary channel of the upstream interface of the target device a command for powering the target device.
A method is also provided for identifying multiple devices of the above type connected in a daisy chain through their input and output interfaces, comprising the following steps performed by a master device located upstream in the chain: powering the power supply relay line of the downstream interface of the master device; for each slave device in the chain, sending through the auxiliary channel of the upstream interface of the slave device a command for powering the power supply relay line of the downstream interface of the slave device; and receiving through the auxiliary channel of the downstream interface of the master device identification data sent by the slave devices as the control circuitries of their interfaces are powered. Brief Description of the Drawings
Other advantages and features will become more clearly apparent from the following description of particular embodiments of the invention provided for exemplary purposes only and represented in the appended drawings, in which: ■ figure 1 schematically shows a link according to the VESA DisplayPort standards;
■ figure 2 schematically shows a daisy chain of audio/video devices connected through DisplayPort links;
■ figure 3 schematically shows an embodiment of a relay with DisplayPort interfaces incorporated in a device and associated to a power source of the device; and
■ figures 4a to 4c show four states of the relay of figure 3 in establishing a communication with a selected source.
Detailed Description of the Preferred Embodiments In order to connect several digital devices in a daisy chain, we intend to use a link having a single direction high data-rate channel (capable for instance of transmitting uncompressed high definition video signals), a medium data rate bidirectional channel (sufficient to transmit compressed audio signals), and a power supply relay line. The HDMI 1.4 and VESA DisplayPort standards define links that satisfy these needs. The DisplayPort standard is preferred because it is in part designed to connect devices in a daisy chain (up to 63 devices as of version 1.2), which means that protocols and circuits are already available for implementing a daisy chain connection.
Figure 1 schematically shows a DisplayPort link between a transmitter Tx and a receiver Rx. The link includes up to 4 high data-rate single direction (Tx to Rx) lines or "Main Link Lanes" ML LnO to ML_Ln3; a medium data-rate bidirectional line AUX CH; a single direction (Rx to Tx) hot-plug detect line Hot Plug Detect; and a power source relay line DP PWR.
According to the VESA DisplayPort standard version 1.2, the data-rate on each main link lane ML Ln may reach 5.4 Gb/s, and the AUX CH line has a fast mode, called F- AUX, having a data-rate of 720 Mb/s. The power supply relay line DP_PWR is designed to provide 3.3 V under 500 mA. The DisplayPort link was initially designed to connect monitors or other display devices to computer units. A devised application for the auxiliary channel AUX CH is to transmit to the computer unit signals that are produced by the peripherals connected to the monitor, such as a keyboard, a mouse, a camera, a microphone, and other peripherals connected to USB or other types of sockets of the monitor. This enables the connection of the monitor and all its peripherals to the computer unit through a single cable.
It has also been devised to connect several monitors in a daisy chain to the computer unit. In this case, each monitor includes an input DisplayPort interface and an output DisplayPort interface. The input interface of each monitor is designed to accept multiple video flows. The monitor extracts the flow to its attention and relays the others to its output interface, which is connected to the next monitor that achieves a similar operation. The auxiliary channel is used in this case to identify the destinations of the video flows, the identifiers and capabilities of the monitors having been communicated to the computer unit through the auxiliary channels upon power on or connection of the monitors.
In the applications depicted above, the power supply relay line DP PWR is not used. A devised application for this line is to supply power to a low-power display device, such as an LCD display or a mini video projector. Figure 2 schematically illustrates an exemplary daisy chain connection of audio/video devices El to E4 through DisplayPort links DPI to DP3. It is desired, for example, to connect a DVD player, a set top box STB, and an audio/video amplifier AVR to a television set TV.
Each device is equipped with a DisplayPort output interface and a DisplayPort input interface DP. The meaning of "input" and "output" is to be interpreted relative to the direction of flow on the high data-rate main link lanes ML Ln. A device is inserted in the chain by connecting its output interface to the input interface of the preceding device. The device at the head of the chain is an audio/video playback device, the TV set in figure 3, capable of processing the audio/video flow of any of the other devices, or several at the same time (split screen, PIP, mosaic displays).
This digital daisy chain, including the control circuitry for the DP interfaces in each device, could be designed in the same way as an analog daisy chain based on SCART links, i.e. the user powers on the device to watch, for instance El, and puts in standby all the devices (E2) located between the device to watch and the playback devices (E3, E4). The DP interfaces in the standby devices (E2), powered by the standby system, are configured, in this mode, to relay the signals from their input link to their output link. The amplifier E3 retrieves the audio flow and relays only the video flow VI to TV set E4.
In addition, the bidirectional auxiliary channels of the DP links may be used, for example, to transmit the remote control signals RC centrally received by one of the devices, here E3. Moreover, the location of a medium data-rate receiver device, like amplifier E3, is irrelevant. If amplifier E3 is placed at the tail of the chain, opposite the TV set, the audio flow to its attention may be transmitted to it via the auxiliary channels of the DP links. It is preferable in this case that the DP interfaces use version 1.2 of the standard, having an auxiliary channel with a data-rate sufficient for any compressed audio flow.
It will be noted that such a daisy chain may also be realized with HDMI 1.4 links, having channels dedicated to audio return and remote control.
In this exemplary daisy chain setup, we mentioned that the unused devices between the watched device and the playback device were put in standby, not powered off, so that their DP interfaces remain powered and are able to ensure their relay function. Even when no device is used, it is desirable that the DP interfaces transmit the remote control signals intended to power on a selected device.
However, many devices consume significant power even in standby. This is the case, for example, of a video recorder, or PVR, that should be able to record a program, even in standby. If no recording is programmed, it is desired to power off the device, or put it in a deep standby mode that only supplies power to the circuits necessary for remote powering on.
It happens that the current required for the operation of the DP interfaces (also for the HDMI interfaces) is a relatively high, because these interfaces are designed to transmit high data-rate signals, up to 21.6 Gb/s for a 1.2 DisplayPort interface. A "deep standby" current is insufficient for supplying them. A solution is disclosed hereafter for supplying power only to the necessary interfaces in a daisy chain, while ensuring minimum power consumption, or even powering off of the unused devices. This solution will still allow remote powering on of a device even if the intermediary devices in the chain are powered off, or even disconnected from a power source.
Figure 3 schematically shows an embodiment of a relay 10 with DisplayPort interfaces, included in a device and associated with a power source 12 of the device. The bottom part of relay 10 corresponds to the input interface DPi. The high data-rate input lines receive an audio/video flow AVi coming from the output interface of the next device in the chain. Flow AVi, shaped by a receiver circuit Ln Rx, is received on a first input of a multiplexer 14. A second input of multiplexer 14 receives a local audio/video flow, i.e. from the device itself, through a conversion circuit CONV. Multiplexer 14 is controlled by a circuit 16 in charge, in particular, of managing the auxiliary channel AUXi of the input interface and AUXo of the output interface. This output interface DPo is shown at the top portion of relay 10. The output of multiplexer 14 provides the outgoing audio/video flow AVo through a transmit circuit Ln Tx.
The power supply relay line DP PWRo of the output interface is designed to provide the necessary power supply to relay 10. In other words, the internal power supply 12 of the device is not designed to supply power to relay 10. The voltage and current values (3.3 V, 500 mA) specified for this line by the DisplayPort standards permit this.
The power supply relay line DP PWRi of the input interface is, in contrast, supplied by a dedicated output of the power supply 12 of the device, upon command of the control circuit 16. Power supply 12 is moreover designed, upon command of control circuit 16, to supply the general power PWR of the device, or alternatively, the standby mode power supply SBY.
In the absence of command from control circuit 16, supply 12 provides no power. The necessary power for supply 12 to obey control circuit 16 may be provided, as shown, by line DP PWRo. Hence, supply 12 may be entirely disconnected from a main power source or the mains network.
Control circuit 16 may additionally be designed, as shown, to direct the local audio flow A Loc, or even a compressed video flow, towards the auxiliary channel AUXi of the input interface. This enables an audio playback device to be placed at the tail of the chain, and still transmit thereto, through the auxiliary channels, audio signals in reverse direction with respect to the direction of channels ML Ln. Moreover, the device may be provided with various other interfaces, such as USB or Ethernet, redirected or made available by control circuit 16 through the auxiliary channels of the input and output interfaces.
Figures 4a to 4d show different states of a relay of the type of figure 3 as it is used in a daisy chain of devices. The powered devices are shown in bold lines, while the unpowered devices are shown in dotted lines. For sake of clarity, the high data-rate channels of the relay are not shown; as regards their power supply, they behave like the auxiliary channels and control circuit 16.
Each intermediary device of the chain has a similar relay. The end devices may be provided with only the input interface or the output interface, depending on whether the device is at the head or the tail of the chain.
One of the devices, preferably the one at the head of the chain, is a master device and designed to manage the other, slave, devices of the chain. The master device is preferably chosen among those that are necessarily used, for example TV set E4 (figure 2). It could also be amplifier E3, in which case it would preferably be placed at the head of the chain, in front of the TV set.
Figure 4a shows a relay of a slave device in an initial state, where all the devices of the chain are powered off. Nor the relay, nor the device itself, is powered. Power supply 12 is inactive. There is no power consumption in the device.
In figure 4b, an upstream device, for instance the master device, supplies power to line DP PWRo. The elements of the relay are powered and ready to operate. In addition, the master device transmits on the auxiliary channel an identifier of a target device to enable. This identifier can be the position of the device in the chain, each device having previously stored its position. The identifier may also be a unique universal identifier previously stored by the master device. In figure 4c, it happens that the device is not the target device because the control circuit did not recognize the identifier. The target device is downstream in the chain. The control circuit commands supply 12 to power the line DP PWRi of the input interface DPi. This line supplies power to the relay of the next downstream device, which is in the state of figure 4b. The relay is configured to operate as a bridge, i.e. multiplexer 14 (figure 3) is set to transmit the incoming flow AVi to the output interface DPo. Control circuit 16 also transmits on channel AUXi the identifier it received on channel AUXo. In figure 4d, the device happens to be the target device. The control circuit, which recognized the identifier on channel AUXo, commands supply 12 to power on the device. At the same time, multiplexer 14 (figure 3) is set to transmit the local flow AV Loc to the output interface. If an audio receiver happens to be further down the chain towards the tail, the local audio flow is directed to the auxiliary channel AUXi of the input interface. The steps of figures 4b and 4c are repeated for the downstream devices, until the audio receiver is reached.
As an alternative to the step of figure 4d, the device is switched from a powered off state to a standby state, for instance in the case of a PVR that has been programmed for a recording.
Of course, in order to define the target equipment, it is preferable that the master device initially knows the composition of the chain. The master may discover the devices of the chain during a discovery phase that can be performed systematically at each power on of the master device or at the request of the user each time he modifies the chain. During this phase, the steps of figures 4a to 4c are performed to enable one after the other the relays of the devices of the chain, like if the master were attempting to enable a device placed at the tail of the chain.
Each time a relay is enabled, the master device is notified through the auxiliary channels according to the protocols defined by the DisplayPort standard. These protocols are namely designed for the devices that are being interconnected to mutually identify themselves. The exchanged identification information may include a unique universal identifier, the mark and type of the device, the serial number, the data-rates and recognized formats of the flows. . . The master device thus receives this information and may build a table of the devices of the chain and their positions. The master device may moreover communicate the positions to the slave devices through the auxiliary channels for their storage, for example within their control circuit 16. The slave devices could themselves maintain a table of the upstream devices, whose identifiers they receive through their auxiliary channels AUXi. Powering off of the whole chain may be performed as follows. The user starts by turning off the master device. This device powers off line DP PWRi of its input interface DPi. As a result, the relay of the next downstream device is powered off. As a consequence, the power supply 12 of this downstream device is disabled, including its line DP PWRi. The devices of the chain are thus powered off one after the other, starting from the master device, at the head of the chain, towards the device at the tail of the chain.
According to this power off procedure, any communication with the master device is immediately interrupted, so that a device that should stay on standby, for example for recording at a program time, would also be powered off.
In order to avoid this, a "negotiated" power off procedure is preferred. The master device controls the power off of the devices one after the other starting from the last active device at the tail of the chain, through the auxiliary channels. A dialogue can thus establish between the master device and the slave device before power off. For example, the slave device may ignore the power off command and stay in standby in order to perform recording, but behave with respect to the rest of the chain like if it were powered off, namely by powering off its DP PWRi pin.

Claims

What is claimed is:
1. An electronic device comprising:
• an output interface having a high data-rate output channel, a medium data-rate bidirectional auxiliary channel, and a power supply relay line;
• an input interface having a high data-rate input channel, a medium data-rate bidirectional auxiliary channel, and a power supply relay line;
• control circuitry designed to organize the relay of a data flow from the input channel towards the output channel, and the relay of data between the auxiliary channels of the input and output interfaces; and
• a power supply system configured for powering the power supply relay line of one of the interfaces, so-called downstream interface, independently of supplying power to the device; wherein the interfaces and the control circuitry are powered by the power supply relay line of the other interface, so-called upstream interface.
2. The device of claim 1, wherein the power supply system is configured for powering the device itself or the power supply relay line of the downstream interface under control of the control circuitry in response to a command received through the auxiliary channel of the upstream interface.
3. The device of claim 1, wherein the high data-rate channels are designed to transport digital video and audio signals and the control circuitry is configured to organize the transmission of digital audio signals through the auxiliary channel of the input interface.
4. Method for managing multiple devices according to claim 2 connected in a daisy chain through their input and output interfaces, comprising the following steps performed by a master device located upstream in the chain:
• indentifying a target device in the chain;
• powering the power supply relay line of the downstream interface of the master device; • for each intermediary device located between the master device and the target device, sending through the auxiliary channel of the upstream interface of the intermediary device a command for powering the power supply relay line of the downstream interface of the intermediary device; and
• sending through the auxiliary channel of the upstream interface of the target device a command for powering the target device.
5. Method for identifying multiple devices according to claim 2 connected in a daisy chain through their input and output interfaces, comprising the following steps performed by a master device located upstream in the chain:
• powering the power supply relay line of the downstream interface of the master device;
• for each slave device in the chain, sending through the auxiliary channel of the upstream interface of the slave device a command for powering the power supply relay line of the downstream interface of the slave device; and
• receiving through the auxiliary channel of the downstream interface of the master device identification data sent by the slave devices as the control circuitries of their interfaces are powered.
PCT/EP2011/071860 2010-12-15 2011-12-06 System for connecting audio and video equipment in a daisychain WO2012080030A1 (en)

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FR1004897A FR2969329B1 (en) 2010-12-15 2010-12-15 SYSTEM FOR CONNECTING CHANNEL AUDIO AND VIDEO EQUIPMENT
FR1004897 2010-12-15

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Citations (3)

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JP2008283469A (en) * 2007-05-10 2008-11-20 Sharp Corp Repeater device, and control method thereof
US20090278763A1 (en) * 2008-05-06 2009-11-12 Xuming Henry Zeng System Having Capability for Daisy-Chained Serial Distribution of Video Display Data
US20100283324A1 (en) * 2008-12-11 2010-11-11 Synerchip Co., Ltd. POWER DELIVERY OVER DIGITAL INTERACTION INTERFACE FOR VIDEO AND AUDIO (DiiVA)

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US20100187903A1 (en) * 2007-12-17 2010-07-29 Wael William Diab Method and system for vehicular power distribution utilizing power over ethernet in an aircraft

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Publication number Priority date Publication date Assignee Title
JP2008283469A (en) * 2007-05-10 2008-11-20 Sharp Corp Repeater device, and control method thereof
US20090278763A1 (en) * 2008-05-06 2009-11-12 Xuming Henry Zeng System Having Capability for Daisy-Chained Serial Distribution of Video Display Data
US20100283324A1 (en) * 2008-12-11 2010-11-11 Synerchip Co., Ltd. POWER DELIVERY OVER DIGITAL INTERACTION INTERFACE FOR VIDEO AND AUDIO (DiiVA)

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