HDMI full signal and USB keyboard and mouse low-speed signal multiplexing optical transmission system and method

Abstract

The HDMI full signal and USB keyboard and mouse low-speed signal multiplexing optical transmission system comprises a transmitting end and a receiving end which are connected through an optical fiber link, and each of the transmitting end and the receiving end comprises an optical transmitting module, an optical receiving module, an HDMI interface module, a level conversion circuit, a USB keyboard and mouse interface module, an FPGA module and a power supply circuit. According to the method, a differentiation strategy of high-speed signal direct connection and low-speed signal processing is adopted. TMDS signal direct connection: three pairs of TMDS data and one pair of TMDS clock signals are not processed by the FPGA and are directly transmitted by the optical transmitting module. Therefore, data processing delay and bandwidth bottleneck possibly brought by the FPGA are avoided, real-time performance and high fidelity of high-definition video signal transmission are ensured, and images are free of delay and compression damage. And low-speed signal intelligent fusion: combining and transmitting the low-speed signal of the HDMI and the USB signal through an FPGA (Field Programmable Gate Array). The characteristic that low-speed signals work intermittently is fully utilized, and waste caused by independently laying a large number of optical fibers for the signals is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical fiber communication technology, and in particular to an HDMI full signal and USB keyboard and mouse low-speed signal multiplexing optical transmission system and method. BACKGROUND

[0002] With the rapid development of digital multimedia technology, the high-definition multimedia interface (HDMI) has become a de facto standard for connecting video source devices (such as computers, game consoles, and Blu-ray players) and display devices (such as monitors, televisions, and projectors). The HDMI interface can simultaneously transmit uncompressed high-definition video, multi-channel audio, and related control signals, providing users with an integrated audio-visual experience. At the same time, the Universal Serial Bus (USB) interface, particularly the low-speed USB signals used for connecting keyboards and mice (HID devices), is the core channel for user interaction with computer systems.

[0003] In certain specific application scenarios, such as conference rooms, command and control centers, digital signage, professional studios, and high-end home theater systems, there is a common need to transmit the audio and video signals of one or more source devices and the corresponding keyboard and mouse control signals to one or more display and control points located remotely. Traditional copper cable solutions, such as standard HDMI cables and USB extension cables, have obvious limitations in transmission distance due to signal attenuation and electromagnetic interference (typically, the effective transmission distance of HDMI 2.0 is not more than 15 meters). When the distance exceeds this limit, there will be problems such as severe signal quality degradation, flickering, black screen, and even complete device recognition failure.

[0004] To overcome the distance limitations of copper cables, optical-electric conversion and optical fiber transmission technology has been introduced. There are already a variety of HDMI optical fiber extender or optical transceiver products in the prior art. The basic principle of these products is to convert HDMI electrical signals into optical signals at the transmitting end, transmit them over long distances, losslessly, and with anti-interference, and then convert the optical signals back to HDMI electrical signals at the receiving end for output to the display device. However, such existing HDMI optical-electric transmission systems typically have one or more of the following technical defects and limitations:

[0005] Single function, unable to integrate control signals: Most traditional HDMI optical transceivers only focus on transmitting signals defined in the HDMI protocol itself. HDMI signals contain three pairs of high-speed TMDS (transmission minimized differential signal) channels, a pair of TMDS clock channels, and low-speed control signals such as device detection (HPD), display data channel (DDC, including I2C bus of SDA and SCL), etc. These systems are not designed to transmit user interaction signals from other interfaces (such as USB) at the same time. This means that if the user needs to operate the source device (such as a computer) remotely, an independent USB extension system (such as a USB fiber optic extender) must be deployed, which not only increases the complexity and cost of the system, but also causes wiring difficulties, device management difficulties, and other problems.

[0006] System complexity and high cost: In order to achieve the simultaneous long-distance transmission of HDMI and USB signals, users are forced to use two independent optical and electrical transmission systems: an HDMI optical transceiver and a USB optical transceiver. This requires the use of two independent optical fibers or more complex fiber bundles, resulting in a doubling of hardware costs, installation costs, and maintenance costs. At the same time, two systems need independent power supply, further increasing the complexity of deployment.

[0007] Signal timing and coordination problems: The normal handshake and operation of HDMI devices rely on the strict timing of their low-speed signals (especially HPD and DDC). When HDMI signals and USB signals are transmitted through two physically independent systems, slight timing differences may occur due to different path delays. In extreme cases, this timing mismatch may affect the correct identification and enumeration of the source device to the display device, resulting in a decrease in system stability.

[0008] Low utilization of fiber resources: Some existing solutions may use multi-core optical fibers, but usually only for transmitting high-speed HDMI signals, and the bandwidth of low-speed signal channels is not fully utilized, resulting in waste of fiber resources and failure to maximize system function integration.

[0009] Therefore, there is an urgent need in the art for an innovative solution that can efficiently and reliably integrate HDMI full signals (including high-speed TMDS signals and low-speed control signals) and USB keyboard and mouse signals into a single fiber transmission system. SUMMARY

[0010] To address the aforementioned technical problems, the first objective of this invention is to provide an optical transmission system that multiplexes HDMI full signal and USB keyboard and mouse low-speed signals. This system simplifies cabling, reduces costs, improves the utilization rate of optical fiber resources, and ensures the coordination and stability of HDMI and USB signals during long-distance transmission. The second objective of this invention is to provide a method for optical transmission that multiplexes HDMI full signal and USB keyboard and mouse low-speed signals.

[0011] To achieve the first objective mentioned above, the present invention adopts the following technical solution:

[0012] An optical transmission system for multiplexing HDMI full signal and USB keyboard and mouse low-speed signal includes a transmitter and a receiver connected by an optical fiber link. Each transmitter and receiver includes an optical transmitter module, an optical receiver module, an HDMI interface module, a level conversion circuit, a USB keyboard and mouse interface module, an FPGA module, and a power supply circuit. The power supply circuit supplies power to the transmitter or the receiver.

[0013] The HDMI interface module at the transmitting end receives the HDMI signal from the source device. The TMDS signal in the HDMI signal is directly transmitted through a set of optical transmitting modules. The optical receiving module at the transmitting end transmits the TMDS signal to the HDMI interface module at the receiving end.

[0014] The level conversion circuit at the transmitting end converts the low-speed signal level in the HDMI signal into a level that the FPGA module can recognize; the USB keyboard and mouse interface module at the transmitting end converts the USB keyboard and mouse signals into UART serial signals.

[0015] The FPGA module connects to one set of optical receiving modules and another set of optical transmitting modules, enabling bidirectional communication between the FPGA module at the transmitting end and the FPGA module at the receiving end. The FPGA module receives the low-speed signal and UART serial signal from the HDMI signal, and combines them into an HDMI-SO composite signal before transmitting it through the optical transmitting module. The optical receiving module connected to the FPGA module converts the received HDMI-SO composite signal into an HDMI-SI signal and transmits the signal into the FPGA module. The FPGA module demodulates the HDMI-SI composite signal into the low-speed signal and USB serial signal from the HDMI signal.

[0016] The level conversion circuit at the receiving end converts the level output by the FPGA module into a level that the HDMI interface module can recognize. The HDMI interface module at the receiving end reassembles the HDMI signal and outputs it to the display device. The USB keyboard and mouse interface module at the receiving end converts the USB serial signal into a USB keyboard and mouse signal and connects it to the host or keyboard and mouse device.

[0017] As a preferred embodiment, the FPGA module combines the low-speed signal and the UART serial signal in the HDMI signal into an HDMI-SO composite signal through time-division multiplexing or protocol-aware scheduling.

[0018] As a preferred embodiment, the optical fiber link uses a single six-core OM3 multimode optical fiber, wherein cores 2-5 are dedicated to the unidirectional transmission of TMDS signals in HDMI signals, and cores 1 and 6 are used for bidirectional transmission of the composite signal HDMI-SO formed by low-speed signals and USB serial signals in HDMI signals.

[0019] As a preferred embodiment, the optical emitting module includes a VCSEL driving circuit and a VCSEL laser, and the optical receiving module includes a photodiode and a transimpedance amplifier. The emitting end includes a correspondingly configured four-channel laser driver and a four-array VCSEL, a photodiode and a transimpedance amplifier, a VCSEL driving circuit and a VCSEL; the receiving end includes a correspondingly configured four-array photodiode and a four-channel transimpedance amplifier, a VCSEL driving circuit and a VCSEL, a photodiode and a transimpedance amplifier.

[0020] As a preferred embodiment, the receiving end is also equipped with an LVDS receiver, and the HDMI-SI composite signal output by the optical receiving module is converted into TTL level by the LVDS receiver.

[0021] As a preferred embodiment, the HDMI interface module at the transmitting end is an HDMI full signal encoding optical module, the USB keyboard and mouse interface module at the transmitting end is a USB keyboard and mouse signal modulation module, the HDMI interface module at the receiving end is an HDMI decoding output interface used to decode and output HDMI signals to the monitor; the USB keyboard and mouse interface module at the receiving end is a USB HID device identification module used to identify USB keyboard and mouse devices.

[0022] To achieve the second objective mentioned above, the present invention adopts the following technical solution:

[0023] The optical transmission method for multiplexing HDMI full signal and USB keyboard and mouse low-speed signal, using any of the above-mentioned systems, follows the HDMI signal power-on sequence and integrates USB keyboard and mouse signal transmission. The specific steps are as follows:

[0024] S1. Power-on and Initialization

[0025] Transmitter power-on: The source device (such as a computer) provides 5V power through the HDMI interface; the low-speed HDMI signal is input to the FPGA module after level conversion; the USB keyboard and mouse signal is converted into a serial signal by the USB keyboard and mouse interface module and input to the FPGA module; Receiver power-on: The receiver is independently powered, the FPGA module of the receiver is initialized, and it waits for the optical signal.

[0026] S2. Signal processing and multiplexing at the transmitting end

[0027] The FPGA module at the transmitter integrates low-speed signals with USB signals: The FPGA module at the transmitter receives HPD_33, SDA_33, SCL_33 and USB-TXD / USB-RXD signals, combines multiple signals into an HDMI-SO composite signal through a time-division multiplexing protocol, and converts it into an optical signal by the optical transmitter module; the high-speed TMDS signal in the HDMI signal does not pass through the FPGA module, but is directly converted into an optical signal by the optical transmitter module;

[0028] S3, Fiber Optic Transmission

[0029] Six-fiber synchronous optical signal transmission is adopted: fiber cores 2-5 are used to transmit high-speed TMDS signals in HDMI signals; fiber cores 1 and 6 are used to transmit low-speed signals in HDMI signals and HDMI-SO composite signals formed by USB keyboard and mouse signals.

[0030] S4. Receiver signal demultiplexing and output

[0031] Optical signal reception and conversion: The optical signals of fiber cores 2-5 are converted into TMDS electrical signals by the optical receiving module and directly output to the HDMI interface; the optical signals of fiber cores 1 and 6 are converted into HDMI-SI composite signals by the optical receiving module and LVDS receiver and then input to the FPGA module.

[0032] FPGA module demodulation: The FPGA module parses the HDMI-SI serial data stream and separates the HPD_33, SDA_33, SCL_33 and USB-RXD / USB-TXD signals;

[0033] Level conversion and output: The low-speed signal output by the FPGA module is converted to 5V by the level conversion module and sent to the HDMI interface; the USB serial signal is converted back to USB D+ / D- by the USB keyboard and mouse interface module and output to the host.

[0034] Power supply simulation and HPD processing: After the receiving FPGA module detects the signal from the transmitting end, it controls the MOSFET to turn on, providing 5V power to the HDMI interface and pulling the HPD signal high to simulate the display connection status; after the source detects the HPD high level, it starts DDC communication, completes the handshake, and sends the high-speed video signal.

[0035] S5, USB keyboard and mouse data transfer

[0036] Two-way communication: USB keyboard and mouse signals are converted into serial signals at the transmitting end, transmitted to the receiving end through optical fiber, and then converted back into USB signals. Data from the USB device at the receiving end is also transmitted back to the transmitting end through fiber cores 1 and 6.

[0037] As a preferred option, the time slice allocation of the FPGA module at the transmitting end in step S2 is as follows: priority is given to transmitting HPD state changes, followed by transmitting I2C data when the SCL signal is active, and finally transmitting USB data in the idle time slot; at the same time, the FPGA module detects the I2C bus status and USB activity and dynamically schedules the signals.

[0038] As a preferred option, step S5 uses dynamic time-division multiplexing and error correction codes to ensure timely data transmission from the USB device and ensure that the operation delay of the USB device is ≤3ms.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] The system of this invention perfectly integrates the functions that originally required two separate systems (HDMI optical transceiver and USB optical transceiver) into a single system. Users only need to deploy one set of equipment and one composite optical cable to simultaneously complete audio and video transmission and remote interactive control, greatly simplifying the system structure.

[0041] The method of this invention can optimize signal paths while ensuring performance: it adopts a differentiated strategy of "high-speed signal pass-through and low-speed signal processing".

[0042] TMDS signal pass-through: Three pairs of TMDS data signals and one pair of TMDS clock signals are transmitted directly by a dedicated optical transmitter module without FPGA processing. This avoids the data processing delays and bandwidth bottlenecks that FPGA may introduce, ensuring the real-time performance and high fidelity of high-definition video signal transmission (especially 4K / 8K high-bandwidth video), with no image delay and no compression loss.

[0043] Intelligent fusion of low-speed signals: The low-speed signals (HPD, SCL, SDA) of HDMI and USB signals are merged and transmitted via FPGA. This takes full advantage of the intermittent operation of low-speed signals and avoids the waste of laying a large amount of fiber optic cable for them separately.

[0044] The method of this invention also ensures system handshake and stability: by accurately reproducing the low-speed HDMI signal, especially the HPD (Hot-Plug Detection) and DDC (I2C) signals, at the receiving end using an FPGA, it can perfectly simulate a handshake between a "display" and the source device. This fundamentally guarantees the reliability and stability of HDMI link establishment, avoiding recognition failures caused by timing or signal mismatches.

[0045] The method of this invention achieves true bidirectional control: the architecture explicitly supports bidirectional transmission of USB signals. This not only allows users to control the transmitting computer using a keyboard and mouse at the receiving end, but also allows status information from USB devices (such as keyboards with indicator lights) to be transmitted back from the receiving end to the transmitting end, realizing complete bidirectional interaction. Attached Figure Description

[0046] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute a limitation thereof.

[0047] Figure 1 This is a schematic diagram of the HDMI protocol transmitted by the system of this invention;

[0048] Figure 2 This is a power-on timing diagram of the HDMI signal transmitted by the system of this invention;

[0049] Figure 3 This is a schematic diagram of the power-on timing of the modules in the system of this invention;

[0050] Figure 4 This is a schematic diagram of data transmission in the system of the present invention;

[0051] Figure 5 This is a schematic diagram of the connection structure between the transmitter and the host of the system of the present invention;

[0052] Figure 6 This is a schematic diagram of the connection structure between the receiving end of the system of the present invention and the display and keyboard and mouse devices;

[0053] Figure 7 This is a schematic diagram of the level conversion chip in the system of the present invention;

[0054] Figure 8 This is a schematic diagram of the level conversion circuit of the system of the present invention;

[0055] Figure 9 This is a schematic diagram of the structure of the USB keyboard and mouse interface module of the present invention;

[0056] Figure 10 This is a schematic diagram of the FPGA module of the present invention;

[0057] Figure 11 This is a schematic diagram of the single-channel drive circuit of the present invention;

[0058] Figure 12 This is a schematic diagram of the single-channel drive circuit of the present invention. Detailed Implementation

[0059] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0060] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0061] Furthermore, in the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0062] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more, unless explicitly defined otherwise.

[0063] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0064] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0065] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0066] The principle of HDMI communication protocol is as follows Figure 1 As shown, the functions of each signal channel are as follows:

[0067] TMDS 0: Transmits B signal, HSYNC signal, and VSYNC signal;

[0068] TMDS 1: Transmits G signals, CTL0, CTL1, and audio signals;

[0069] TMDS 2: Transmits R signals, CTL2, CTL3, and audio signals;

[0070] TMDS C: Transmits clock signal;

[0071] CEC: Consumer Electronics Control Channel, through which audiovisual equipment can be controlled;

[0072] HEAC: Preservation or Audio Return Channel;

[0073] DDC (SCL, SDA): The data bus for communication between the monitor and the computer host. Its main function is to send basic information of the monitor to the computer host, such as sending EDID information to the host.

[0074] HPD: The detection signal sent by the monitor to the source, including two states: connected and disconnected. When the source detects that the HPD pin is greater than 2V, the monitor and the host are connected. When the source detects that the HPD pin is less than 0.8V, the monitor and the host are disconnected.

[0075] POWER: The +5V voltage signal provided by the host to the monitor, with a magnitude of 4.8V-5.3V;

[0076] GND: Power ground and signal ground.

[0077] The power-on sequence of HDMI is as follows Figure 2As shown, the HDMI communication protocol can be simply divided into three parts: power supply (5V, GND), low-speed identification signals (HPD, DDC [SCL, SDA]), and high-speed audio and video transmission signals (TMDS 0, TMDS 1, TMDS 2, TMDS C). (In addition, there are two other auxiliary function signals, CEC and HEAC, which are not covered in this invention.)

[0078] The high-speed audio and video transmission will only begin after the low-speed identification signal is successfully connected. If the low-speed identification signal is not connected, has an incorrect connection, or fails, the high-speed audio and video signal will not be transmitted, resulting in a black screen. If noise is present in the low-speed identification signal and reaches the device's recognition range, the video will flicker or fail to transmit.

[0079] The power-on negotiation process between the HDM source and display ends is as follows: a) The source end provides 5V power to the display end; b) The display end detects the power supply and pulls HPD up to above 2V; c) The source end detects that HPD has been pulled high and starts DDC communication; d) The DDC communication handshake between the two parties is successful, and the display end provides 3.3V voltage to the TMDS channel; e) The source end sends a high-speed video signal, and the display end screen lights up.

[0080] The optoelectronic module is divided into two modules: TX (source end) and RX (display end). The signal is transmitted through 6 optical fibers (12 optical fibers for dual-channel modules) and each end is powered by an independent 5V power supply.

[0081] Low-speed identification signals (HPD, DDC [SCL, SDA]) are sampled according to the serial encoding / decoding protocol initially planned. Because DDC has bidirectional signals, it is transmitted using two optical fibers. High-speed audio and video transmission signals (TMDS 0, TMDS 1, TMDS 2, TMDS C) undergo photoelectric conversion by a four-channel high-speed chip and laser, and are transmitted from the TX end to the RX end via four optical fibers. The module power-on timing principle is as follows: Figure 3 As shown.

[0082] like Figures 4 to 12 As shown, the HDMI full signal and USB keyboard and mouse low-speed signal multiplexing optical transmission system includes a transmitter and a receiver connected by an optical fiber link. Both the transmitter and receiver include an optical transmitter module, an optical receiver module, an HDMI interface module, a level conversion circuit, a USB keyboard and mouse interface module, an FPGA module, and a power supply circuit. The power supply circuit supplies power to the transmitter or the receiver.

[0083] The HDMI interface module at the transmitting end receives the HDMI signal from the source device. The TMDS signal in the HDMI signal is directly transmitted through a set of optical transmitting modules. The optical receiving module at the transmitting end transmits the TMDS signal to the HDMI interface module at the receiving end.

[0084] The level conversion circuit at the transmitting end converts the low-speed signal level in the HDMI signal into a level that the FPGA module can recognize; the USB keyboard and mouse interface module at the transmitting end converts the USB keyboard and mouse signals into UART serial signals.

[0085] The FPGA module connects to one set of optical receiving modules and another set of optical transmitting modules, enabling bidirectional communication between the FPGA module at the transmitting end and the FPGA module at the receiving end. The FPGA module receives the low-speed signal and UART serial signal from the HDMI signal, and combines them into an HDMI-SO composite signal before transmitting it through the optical transmitting module. The optical receiving module connected to the FPGA module converts the received HDMI-SO composite signal into an HDMI-SI signal and transmits the signal into the FPGA module. The FPGA module demodulates the HDMI-SI composite signal into the low-speed signal and USB serial signal from the HDMI signal.

[0086] The level conversion circuit at the receiving end converts the level output by the FPGA module into a level that the HDMI interface module can recognize. The HDMI interface module at the receiving end reassembles the HDMI signal and outputs it to the display device. The USB keyboard and mouse interface module at the receiving end converts the USB serial signal into a USB keyboard and mouse signal and connects it to the host or keyboard and mouse device.

[0087] The FPGA module combines the low-speed signal and UART serial signal in the HDMI signal into an HDMI-SO composite signal through time-division multiplexing or protocol-aware scheduling.

[0088] This invention employs Time Division Multiplexing (TDM) to divide the time of a physical channel (fiber core 1 or 6) into non-overlapping time slots, which are then allocated to different signals in turn. This allows a single optical fiber to transmit multiple signals, significantly improving the utilization of fiber bandwidth. Simultaneously, the combination of protocol-aware scheduling introduces a dynamic priority mechanism, the effects of which are reflected in:

[0089] Ensuring HDMI link stability: Prioritizing the transmission of HPD status changes to ensure that the connection / disconnection status of the display device can be instantly sensed by the source device, which is the foundation for normal HDMI operation.

[0090] To ensure accurate EDID reading: I2C data (SDA) is transmitted first when SCL (I2C clock) is active, which ensures that the source device reads the display's EDID (Extended Display Identifier Data) smoothly and accurately, and avoids reading failures caused by data blocking.

[0091] Optimize user experience: When the HDMI low-speed signal is idle, it transmits USB data at full speed to minimize keyboard and mouse operation latency and provide a smooth interactive experience.

[0092] The fiber optic link uses a single six-core OM3 multimode fiber, where cores 2-5 are dedicated to the unidirectional transmission of TMDS signals in HDMI signals, and cores 1 and 6 are used for bidirectional transmission of the composite signal HDMI-SO formed by low-speed signals and USB serial signals in HDMI signals.

[0093] The optical emitting module includes a VCSEL driving circuit and a VCSEL laser, and the optical receiving module includes a photodiode and a transimpedance amplifier. The emitting end includes a correspondingly configured four-channel laser driver and a four-array VCSEL, a photodiode and a transimpedance amplifier, a VCSEL driving circuit and a VCSEL; the receiving end includes a correspondingly configured four-array photodiode and a four-channel transimpedance amplifier, a VCSEL driving circuit and a VCSEL, a photodiode and a transimpedance amplifier.

[0094] The receiving end is also equipped with an LVDS receiver, and the HDMI-SI composite signal output by the optical receiving module is converted into TTL level by the LVDS receiver.

[0095] The HDMI interface module on the transmitting end is an HDMI full signal encoding optical module, the USB keyboard and mouse interface module on the transmitting end is a USB keyboard and mouse signal modulation module, the HDMI interface module on the receiving end is an HDMI decoding output interface, used to decode HDMI signals and output them to the monitor; the USB keyboard and mouse interface module on the receiving end is a USB HID device identification module, used to identify USB keyboard and mouse devices.

[0096] The transmission signals HDMI-SCL, HDMI-SDA, and HDMI-HPD of this invention are connected to the HDMI connector. In the HDMI protocol, the standard level is 5V, but the IO withstand voltage of the FPGA chip is 3.3V. Therefore, a bidirectional level conversion chip is added to convert the 5V level to 3.3V and vice versa.

[0097] Additionally, in the HDMI protocol, the 5V power to the receiver is supplied by the transmitter. However, a pure optical module cannot transmit current, so a power control circuit is added. When the RX FPGA module receives a signal from the TX FPGA module, it controls the MOSFET to conduct, thereby supplying power to the HDMI connector (e.g., ...). Figure 8 (As shown).

[0098] like Figure 9As shown, the USB keyboard and mouse interface module of this invention uses the CH9350 chip, which is a USB keyboard and mouse to serial communication control chip. Combining the ease of use of asynchronous serial ports, it extends the USB communication between the USB keyboard, mouse, and USB host to an asynchronous serial port (UART) mode, facilitating data integration with audio, video, and other signals, or directly extending the signal via a 2-wire 485 signal. It is widely used in KVM extension, KVM switching, KM synchronization, and other applications. The USB D+ / D- signals are connected to the CH9350, which converts the USB keyboard and mouse signals into serial signals (TXD / RXD). Pin 45:SEL allows selection as a downstream module (connected to the mouse and keyboard) or an upstream module (connected to the host).

[0099] like Figure 10 As shown, in the receiver module: HPD_33, SDA_33, and USB-TXD are integrated into HDMI-SO by the FPGA module. The HDMI-SI signal is demodulated into SCL_33, SDA_33, and USB-RXD by the FPGA module. In the transmitter module: SCL_33, SDA_33, and USB-RXD are integrated into HDMI-SO by the FPGA module. The HDMI-SI signal is demodulated into HPD_33, SDA_33, and USB-TXD by the FPGA module.

[0100] like Figure 11 and Figure 12 As shown, the integrated HDMI-SO signal can directly drive the VCSEL laser to emit light through a single-channel driver circuit. The single-channel receiver circuit can output a differential SI signal through a photodiode (PD) and a single-channel transimpedance amplifier. Finally, it passes through an LVDS single-channel receiver to become an HDMI-SI signal (TTL), which can be directly transmitted into the FPGA module.

[0101] The optical transmission method for multiplexing HDMI full signal and USB keyboard and mouse low-speed signal, using any of the above-mentioned systems, follows the HDMI signal power-on sequence and integrates USB keyboard and mouse signal transmission. The specific steps are as follows:

[0102] S1. Power-on and Initialization

[0103] Transmitter power-on: The source device (such as a computer) provides 5V power through the HDMI interface; the low-speed HDMI signal is input to the FPGA module after level conversion; the USB keyboard and mouse signal is converted into a serial signal by the USB keyboard and mouse interface module and input to the FPGA module; Receiver power-on: The receiver is independently powered, the FPGA module of the receiver is initialized, and it waits for the optical signal.

[0104] S2. Signal processing and multiplexing at the transmitting end

[0105] The FPGA module at the transmitting end integrates low-speed signals with USB signals: The FPGA module at the transmitting end receives HPD_33, SDA_33, SCL_33 and USB-TXD / USB-RXD signals, and combines multiple signals into an HDMI-SO composite signal through a time-division multiplexing protocol, which is then converted into an optical signal by the optical transmitting module; the high-speed TMDS signal in the HDMI signal bypasses the FPGA module and is directly converted into an optical signal by the optical transmitting module; the time slice allocation of the FPGA module at the transmitting end is as follows: priority is given to transmitting HPD state changes, followed by I2C data transmission when the SCL signal is active, and finally USB data transmission in idle time slots; at the same time, the FPGA module detects the I2C bus status and USB activity and dynamically schedules signals.

[0106] S3, Fiber Optic Transmission

[0107] Six-fiber synchronous optical signal transmission is adopted: fiber cores 2-5 are used to transmit high-speed TMDS signals in HDMI signals; fiber cores 1 and 6 are used to transmit low-speed signals in HDMI signals and HDMI-SO composite signals formed by USB keyboard and mouse signals.

[0108] S4. Receiver signal demultiplexing and output

[0109] Optical signal reception and conversion: The optical signals of fiber cores 2-5 are converted into TMDS electrical signals by the optical receiving module and directly output to the HDMI interface; the optical signals of fiber cores 1 and 6 are converted into HDMI-SI composite signals by the optical receiving module and LVDS receiver and then input to the FPGA module.

[0110] FPGA module demodulation: The FPGA module parses the HDMI-SI serial data stream and separates the HPD_33, SDA_33, SCL_33 and USB-RXD / USB-TXD signals;

[0111] Level conversion and output: The low-speed signal output by the FPGA module is converted to 5V by the level conversion module and sent to the HDMI interface; the USB serial signal is converted back to USB D+ / D- by the USB keyboard and mouse interface module and output to the host.

[0112] Power supply simulation and HPD processing: After the receiving FPGA module detects the signal from the transmitting end, it controls the MOSFET to turn on, providing 5V power to the HDMI interface and pulling the HPD signal high to simulate the display connection status; after the source detects the HPD high level, it starts DDC communication, completes the handshake, and sends the high-speed video signal.

[0113] S5, USB keyboard and mouse data transfer

[0114] Two-way communication: USB keyboard and mouse signals are converted into serial signals at the transmitting end, transmitted to the receiving end through optical fiber, and then converted back into USB signals. Data from the USB device at the receiving end is also transmitted back to the transmitting end through fiber cores 1 and 6.

[0115] In step S5, dynamic time-division multiplexing and error correction codes are used to ensure timely data transmission from the USB device and to ensure that the operation delay of the USB device is ≤3ms.

[0116] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0117] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. An optical transmission system that multiplexes HDMI full-signal and USB keyboard / mouse low-speed signals, characterized in that: It includes a transmitter and a receiver connected via an optical fiber link. Each transmitter and receiver includes an optical transmitter module, an optical receiver module, an HDMI interface module, a level conversion circuit, a USB keyboard and mouse interface module, an FPGA module, and a power supply circuit. The power supply circuit supplies power to the transmitter or the receiver. The HDMI interface module at the transmitting end receives the HDMI signal from the source device. The TMDS signal in the HDMI signal is directly transmitted through a set of optical transmitting modules. The optical receiving module at the transmitting end transmits the TMDS signal to the HDMI interface module at the receiving end. The level conversion circuit at the transmitting end converts the low-speed signal level in the HDMI signal into a level that the FPGA module can recognize; the USB keyboard and mouse interface module at the transmitting end converts the USB keyboard and mouse signals into UART serial signals. The FPGA module connects to one set of optical receiving modules and another set of optical transmitting modules, enabling bidirectional communication between the FPGA module at the transmitting end and the FPGA module at the receiving end. The FPGA module receives the low-speed signal and UART serial signal from the HDMI signal, and combines them into an HDMI-SO composite signal before transmitting it through the optical transmitting module. The optical receiving module connected to the FPGA module converts the received HDMI-SO composite signal into an HDMI-SI signal and transmits the signal into the FPGA module. The FPGA module demodulates the HDMI-SI composite signal into the low-speed signal and USB serial signal from the HDMI signal. The level conversion circuit at the receiving end converts the level output by the FPGA module into a level that the HDMI interface module can recognize. The HDMI interface module at the receiving end reassembles the HDMI signal and outputs it to the display device. The USB keyboard and mouse interface module at the receiving end converts the USB serial signal into a USB keyboard and mouse signal and connects it to the host or keyboard and mouse device.

2. The dual-redundant optical link system based on HDMI optoelectronic transmission according to claim 1, characterized in that, The FPGA module combines the low-speed signal and UART serial signal in the HDMI signal into an HDMI-SO composite signal through time-division multiplexing or protocol-aware scheduling.

3. The dual-redundant optical link system based on HDMI optoelectronic transmission according to claim 1, characterized in that, The fiber optic link uses a single six-core OM3 multimode fiber, where cores 2-5 are dedicated to the unidirectional transmission of TMDS signals in HDMI signals, and cores 1 and 6 are used for bidirectional transmission of the composite signal HDMI-SO formed by low-speed signals and USB serial signals in HDMI signals.

4. The dual-redundant optical link system based on HDMI optoelectronic transmission according to claim 1, characterized in that, The optical emitting module includes a VCSEL driving circuit and a VCSEL laser, and the optical receiving module includes a photodiode and a transimpedance amplifier. The emitting end includes a correspondingly configured four-channel laser driver and a four-array VCSEL, a photodiode and a transimpedance amplifier, a VCSEL driving circuit and a VCSEL; the receiving end includes a correspondingly configured four-array photodiode and a four-channel transimpedance amplifier, a VCSEL driving circuit and a VCSEL, a photodiode and a transimpedance amplifier.

5. A dual-redundant optical link system based on HDMI optoelectronic transmission according to claim 1, characterized in that, The receiving end is also equipped with an LVDS receiver, and the HDMI-SI composite signal output by the optical receiving module is converted into TTL level by the LVDS receiver.

6. A dual-redundant optical link system based on HDMI optoelectronic transmission according to claim 1, characterized in that, The HDMI interface module on the transmitting end is an HDMI full signal encoding optical module, the USB keyboard and mouse interface module on the transmitting end is a USB keyboard and mouse signal modulation module, the HDMI interface module on the receiving end is an HDMI decoding output interface, used to decode HDMI signals and output them to the monitor; the USB keyboard and mouse interface module on the receiving end is a USB HID device identification module, used to identify USB keyboard and mouse devices.

7. A method for multiplexing HDMI full-signal and USB keyboard / mouse low-speed signal optical transmission, characterized in that, The system described in any one of claims 1 to 6 follows the HDMI signal power-on sequence and integrates USB keyboard and mouse signal transmission. The specific steps are as follows: S1. Power-on and Initialization Transmitter power-on: The source device (such as a computer) provides 5V power through the HDMI interface; the low-speed HDMI signal is input to the FPGA module after level conversion; the USB keyboard and mouse signal is converted into a serial signal by the USB keyboard and mouse interface module and input to the FPGA module; Receiver power-on: The receiver is independently powered, the FPGA module of the receiver is initialized, and it waits for the optical signal. S2. Signal processing and multiplexing at the transmitting end The FPGA module at the transmitter integrates low-speed signals with USB signals: The FPGA module at the transmitter receives HPD_33, SDA_33, SCL_33 and USB-TXD / USB-RXD signals, combines multiple signals into an HDMI-SO composite signal through a time-division multiplexing protocol, and converts it into an optical signal by the optical transmitter module; the high-speed TMDS signal in the HDMI signal does not pass through the FPGA module, but is directly converted into an optical signal by the optical transmitter module; S3, Fiber Optic Transmission Six-fiber synchronous optical signal transmission is adopted: fiber cores 2-5 are used to transmit high-speed TMDS signals in HDMI signals; fiber cores 1 and 6 are used to transmit low-speed signals in HDMI signals and HDMI-SO composite signals formed by USB keyboard and mouse signals. S4. Receiver signal demultiplexing and output Optical signal reception and conversion: The optical signals of fiber cores 2-5 are converted into TMDS electrical signals by the optical receiving module and directly output to the HDMI interface; the optical signals of fiber cores 1 and 6 are converted into HDMI-SI composite signals by the optical receiving module and LVDS receiver and then input to the FPGA module. FPGA module demodulation: The FPGA module parses the HDMI-SI serial data stream and separates the HPD_33, SDA_33, SCL_33 and USB-RXD / USB-TXD signals; Level conversion and output: The low-speed signal output by the FPGA module is converted to 5V by the level conversion module and sent to the HDMI interface; The USB serial signal is converted back to USB D+ / D- by the USB keyboard and mouse interface module and then output to the host. Power supply simulation and HPD processing: After the receiving FPGA module detects the signal from the transmitting end, it controls the MOSFET to turn on, providing 5V power to the HDMI interface and pulling the HPD signal high to simulate the display connection status; after the source detects the HPD high level, it starts DDC communication, completes the handshake, and sends the high-speed video signal. S5, USB keyboard and mouse data transfer Two-way communication: USB keyboard and mouse signals are converted into serial signals at the transmitting end, transmitted to the receiving end through optical fiber, and then converted back into USB signals. Data from the USB device at the receiving end is also transmitted back to the transmitting end through fiber cores 1 and 6.

8. The optical transmission method for multiplexing HDMI full signal and USB keyboard / mouse low-speed signal according to claim 7, characterized in that, In step S2, the time slice allocation of the FPGA module at the transmitting end is as follows: HPD state changes are transmitted first, followed by I2C data when the SCL signal is active, and finally USB data is transmitted in the idle time slot; at the same time, the FPGA module detects the I2C bus status and USB activity and dynamically schedules the signals.

9. The optical transmission method for multiplexing HDMI full signal and USB keyboard / mouse low-speed signal according to claim 7, characterized in that, In step S5, dynamic time-division multiplexing and error correction codes are used to ensure timely data transmission from the USB device and to ensure that the operation delay of the USB device is ≤3ms.

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