Data transmission system and method for LED display control

Abstract

The invention provides a data transmission system and method for LED display control, and relates to the technical field of LED display, and the system comprises a daisy chain topology structure formed by directly connecting a transmitting device and a multi-stage receiving device through a DP cable; auxiliary signal interface circuits are arranged in the sending device and each receiving device, and a direct current coupling connection structure is adopted between the auxiliary signal interface circuits and the auxiliary channel differential line pairs; an impedance matching circuit is arranged on a signal input path of the auxiliary signal interface circuit and comprises a damping resistor connected in series on a differential signal path and a terminating resistor bridged between the differential signal paths; the system is configured to carry out auxiliary signal transmission by utilizing the auxiliary channel differential line pair, and a Manchester encoding mode or an encoding mode combining reverse non-return-to-zero encoding with bit filling is adopted when the auxiliary signal is transmitted. By implementing the technical scheme provided by the invention, the effect of improving the transmission stability is achieved.

Description

Technical Field

[0001] This application relates to the field of LED display technology, and specifically to a data transmission system and method for LED display control. Background Technology

[0002] In existing LED display control systems, gigabit Ethernet cables are commonly used for cascaded transmission. However, at ultra-large resolutions, the effective bandwidth of a single Ethernet cable (approximately 950Mbps) is limited. When driving high-resolution displays such as 4K / 8K, the transmitting device needs to extend a large number of Ethernet cables, resulting in complex wiring and high costs. Currently, some systems attempt to use the standard DisplayPort (DP) interface for connection, but significant technical bottlenecks exist in practical applications. The AUX auxiliary channel in the standard DP protocol is designed for low-speed configuration communication, and the current transmission rate based on the DP auxiliary channel is typically only around 1Mbps. When applied to long-distance or multi-level cascaded LED control scenarios, the massive amounts of real-time status monitoring, point-by-point correction, and firmware update data of the LED screen cause high data transmission latency, slow refresh rates, and even communication timeout failures due to this low bandwidth. This severely limits the transmission distance and signal integrity, making the auxiliary channel unable to carry high-speed data, resulting in poor stability during long-distance transmission. Summary of the Invention

[0003] To address the aforementioned technical problems, this application provides a data transmission system and method for LED display control.

[0004] In a first aspect, this application provides a data transmission system for LED display control, comprising: a transmitting device and a multi-level receiving device; the transmitting device and the first-level receiving device, as well as two adjacent receiving devices, are directly connected via DP cables to form a daisy-chain topology; each DP cable includes a main link differential pair for transmitting display data and an auxiliary channel differential pair for transmitting auxiliary signals; each transmitting device and each receiving device is internally provided with an auxiliary signal interface circuit, and the auxiliary signal interface circuit and the auxiliary channel differential pair are connected by a DC coupling structure; an impedance matching circuit is provided on the signal input path of the auxiliary signal interface circuit, the impedance matching circuit including a damping resistor connected in series on the differential signal path and a termination resistor connected across the differential signal paths; the system is configured to use the auxiliary channel differential pairs for auxiliary signal transmission, and when transmitting auxiliary signals, Manchester encoding or a non-return-to-zero encoding combined with bit-filling encoding is used to support a transmission rate greater than or equal to 100 megabits per second.

[0005] By adopting the above technical solution, the transmitting device and the first-level receiving device, as well as two adjacent receiving devices, are directly connected via DP cables to form a daisy-chain topology, which simplifies wiring and reduces costs. The DC-coupled connection structure and the absence of AC DC blocking capacitors can maintain stable signal level transmission and avoid baseline drift and charge accumulation. The damping resistor in the impedance matching circuit suppresses signal reflection fluctuations, limits surge current protection ports, and the termination resistor matches the characteristic impedance of the cable. The specific encoding method can achieve a transmission rate of auxiliary signals greater than or equal to 100 megabits per second, improving data transmission efficiency and long-distance transmission stability.

[0006] Optionally, the DC-coupled connection structure is a direct electrical connection structure. The direct electrical connection structure removes the AC coupling capacitor and pull-up / pull-down resistors in the standard DP interface configuration, and maintains stable signal level transmission through the DC electrical path, avoiding baseline drift and charge accumulation caused by continuous transmission of the same level in AC coupling.

[0007] By adopting the above technical solution, the AC coupling capacitor and pull-up / pull-down resistors in the standard DP interface configuration are removed by using a direct electrical connection structure, and a pure DC path interface circuit structure is constructed. The AC coupling energy storage mechanism that is prone to baseline drift is abandoned, and a direct resistive connection that can maintain the stability of the DC component of the signal is adopted instead. The DC electrical path can maintain the stable transmission of the signal level and avoid the baseline drift and charge accumulation caused by AC coupling when transmitting the same level continuously. This allows the AUX channel to reliably carry high-speed digital signals on the order of 100Mbps, and the transmission distance is extended to meet the needs of large LED display cascading.

[0008] Optionally, the auxiliary signal interface circuit includes a signal transmitting unit, a signal receiving unit, a damping resistor, and a termination resistor. The damping resistor includes a first resistor and a second resistor. The first resistor is connected in series between the first differential input terminal of the signal receiving unit and the first signal line of the corresponding auxiliary channel differential pair in the DP cable. The second resistor is connected in series between the second differential input terminal of the signal receiving unit and the second signal line of the corresponding auxiliary channel differential pair in the DP cable. The first differential output terminal of the signal transmitting unit is connected to the first signal line of the corresponding auxiliary channel differential pair in the DP cable, and the second differential output terminal of the signal transmitting unit is connected to the second signal line of the corresponding auxiliary channel differential pair in the DP cable. The connection is as follows: a terminating resistor is connected between the two differential input terminals of the signal receiving unit; or, a first resistor is connected in series between the first differential output terminal of the signal transmitting unit and the first signal line of the corresponding auxiliary channel differential pair in the DP cable, and a second resistor is connected in series between the second differential output terminal of the signal transmitting unit and the second signal line of the corresponding auxiliary channel differential pair in the DP cable; the first differential input terminal of the signal receiving unit is connected to the first signal line of the corresponding auxiliary channel differential pair in the DP cable, and the second differential input terminal of the signal receiving unit is connected to the second signal line of the corresponding auxiliary channel differential pair in the DP cable; a terminating resistor is connected between the two differential input terminals of the signal receiving unit.

[0009] By adopting the above technical solution, the specific composition and connection method of the auxiliary signal interface circuit are clarified. The damping resistor and the termination resistor are connected in a specific way, which can better achieve impedance matching and ensure stable transmission of the auxiliary signal in the differential pair of the auxiliary channel of the DP cable. Combined with the encoding method adopted by the system, it helps to achieve high-speed and stable transmission of the auxiliary signal in the daisy-chain topology.

[0010] Optionally, the damping resistor has a resistance range of 10Ω-22Ω. The damping resistor is used to suppress reflection fluctuations generated during signal transmission and to limit surge current to protect the input and output ports of the auxiliary signal interface circuit. The termination resistor has a resistance range of 80Ω-120Ω and is used to match the characteristic impedance of the differential pairs of the auxiliary channel in the DP cable.

[0011] By adopting the above technical solution, in a data transmission system consisting of a transmitting device and a receiving device connected by a DP cable to form a daisy-chain topology, and utilizing auxiliary channel differential pairs to transmit auxiliary signals and employing a specific encoding method to achieve high-speed transmission, a damping resistor with a resistance range of 10Ω-22Ω (including the first resistor and the second resistor) can suppress reflection fluctuations in signal transmission and limit surge current to protect the input and output ports of the auxiliary signal interface circuit. A termination resistor with a resistance range of 80Ω-120Ω can match the characteristic impedance of the auxiliary channel differential pairs in the DP cable.

[0012] Optionally, the transmitting device is configured with a link adaptation module, which performs link quality assessment and dynamically selects transmission parameters during the system initialization phase. The link adaptation module measures the total signal attenuation and initial bit error rate of the current entire link by sending a probe sequence to the end of the daisy chain and receiving feedback signals from the last-stage receiving device. If the total signal attenuation is less than a preset loss threshold and the initial bit error rate is lower than the preset bit error rate threshold, the current link is determined to be in a low-loss state, and the control system enters the first transmission mode, using a reverse non-return-to-zero encoding combined with bit-filling encoding, and sets the transmission rate to the first rate value. If the total signal attenuation is greater than or equal to the preset loss threshold, or the initial bit error rate is higher than or equal to the preset bit error rate threshold, the current link is determined to be in a high-loss long-distance state, and the control system enters the second transmission mode, using a Manchester encoding method with self-clock recovery characteristics, and sets the transmission rate to the second rate value, wherein the first rate value is greater than the second rate value.

[0013] By adopting the above technical solution, the link adaptive module can perform link quality assessment and dynamically select transmission parameters during the system initialization phase. By sending probe sequences and receiving feedback signals, it measures the total signal attenuation and calculates the initial bit error rate. Then, based on the link status determination results, it selects an appropriate transmission mode and rate. In the low-loss state, it adopts an inverse non-return-to-zero coding combined with bit-filling coding and sets a higher first rate value to improve transmission efficiency. In the high-loss long-distance state, it adopts Manchester coding with self-clock recovery characteristics and sets a lower second rate value to ensure the stability and reliability of signal transmission.

[0014] Optionally, the DP cable is a cable compliant with the DisplayPort physical layer standard, the transmitting device is a video transmitting card with a DP output interface, and the receiving device is a receiving card integrated into the LED display module with both DP input and DP output interfaces.

[0015] By adopting the above technical solutions and using DP cables that conform to the DisplayPort physical layer standard, the compatibility and standardization of data transmission can be guaranteed. Using a video transmitting card with a DP output interface as the transmitting device can adapt to the DP interface for data transmission. Using a receiving card integrated into the LED display module with DP input and DP output interfaces as the receiving device facilitates the reception and further transmission of data in the LED display control system. Combined with the daisy-chain topology, DC coupling connection, impedance matching circuit and specific encoding method of the entire system, high-speed and stable transmission of auxiliary signals can be achieved.

[0016] Optionally, the receiving device also includes a relay processing module, which is configured to decode the encoded auxiliary signal received from the downstream device through the auxiliary channel differential line, extract the downstream return data, integrate the monitoring data or correction parameters generated by the local device and re-encode them, and then forward them to the upstream device through the auxiliary signal interface circuit of the local device. Finally, all return data is converged to the transmitting device.

[0017] By adopting the above technical solution, the relay processing module of the receiving equipment can decode the encoded auxiliary signals of the downstream equipment to extract the returned data, integrate the monitoring data or correction parameters of this level, re-encode and forward it to the upstream equipment, so that all returned data can be converged to the transmitting equipment, facilitating status monitoring and parameter correction of each level of receiving equipment. At the same time, combined with the daisy-chain topology, DC-coupled connection structure, impedance matching circuit and specific encoding method adopted by the system, the transmission rate of auxiliary signals can be greater than or equal to 100 megabits per second, improving the stability and efficiency of long-distance transmission.

[0018] Optionally, the auxiliary signal is transmitted bidirectionally, including downlink control commands, firmware update data or correction parameters transmitted from the transmitting device to each level of receiving device, and uplink status monitoring data transmitted back from each level of receiving device to the transmitting device.

[0019] By adopting the above technical solution, bidirectional transmission of auxiliary signals between the transmitting device and the receiving devices at all levels is realized. This enables the transmitting device to transmit downlink control commands, firmware update data, or correction parameters to the receiving devices at all levels. At the same time, the receiving devices at all levels can transmit uplink status monitoring data back to the transmitting device, which facilitates comprehensive control and real-time status monitoring of the LED display system.

[0020] Optionally, the monitoring data may include at least one of the following: the temperature of the receiving device, its operating voltage, the LED brightness status, and fault codes.

[0021] By adopting the above technical solution, it is possible to monitor at least one of the following states of the receiving device: temperature, operating voltage, LED brightness status, fault code, etc., providing more comprehensive status information for the stable operation of the LED display control system and facilitating timely detection and handling of equipment abnormalities.

[0022] In a second aspect of this application, a data transmission method for LED display control is also provided, applied to any of the preceding data transmission systems for LED display control, comprising: directly connecting a transmitting device to a primary receiving device and adjacent receiving devices sequentially via DP cables to form a daisy-chain topology, wherein each DP cable includes a main link differential pair for transmitting display data and an auxiliary channel differential pair for transmitting auxiliary signals; configuring auxiliary signal interface circuits inside the transmitting and receiving devices to form a DC coupling path between the auxiliary signal interface circuits and the auxiliary channel differential pairs. An impedance matching circuit is set on the signal input path of the auxiliary signal interface circuit. The impedance matching circuit includes a damping resistor connected in series on the differential signal path and a termination resistor connected across the differential signal paths. Display data is transmitted in a daisy-chain topology using the main link differential pairs in the DP cable, and auxiliary signals are transmitted in a daisy-chain topology using the auxiliary channel differential pairs in the DP cable. When transmitting auxiliary signals, Manchester encoding or inverse non-return-to-zero encoding combined with bit-filling encoding is used to achieve a transmission rate of greater than or equal to 100 megabits per second in the daisy-chain topology.

[0023] In summary, one or more technical solutions provided in this application have at least the following technical effects or advantages: 1. A daisy-chain topology is used to connect the transmitting and receiving devices via DP cables, reducing wiring complexity and lowering costs; 2. The auxiliary signal interface circuit and the auxiliary channel differential line pair adopt a DC coupling connection structure and have no AC DC blocking capacitor. Combined with the impedance matching circuit, it ensures stable transmission of auxiliary signals. 3. The auxiliary signal is transmitted using a specific encoding method to achieve a transmission rate of 100 megabits per second or higher, solving the problems of high data transmission latency and slow refresh, and improving the stability of long-distance transmission. Attached Figure Description

[0024] Figure 1 This is a data transmission system framework diagram for LED display control provided in an embodiment of this application; Figure 2 This is a schematic diagram of a standard DP AUX circuit in related technologies; Figure 3 This is a schematic diagram of the DP AUX circuit provided in an embodiment of this application; Figure 4 This is a flowchart of a data transmission method for LED display control provided in an embodiment of this application. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0026] In the description of the embodiments of this application, the words "for example" or "for instance" are used to indicate examples, illustrations, or explanations. Any embodiment or design that is described as "for example" or "for instance" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design options. Rather, the use of the words "for example" or "for instance" is intended to present the relevant concepts in a specific manner.

[0027] In the description of the embodiments of this application, the term "multiple" means two or more. 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 indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. The terms "comprising," "including," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0028] The following is in conjunction with the appendix Figure 1 -Appendix Figure 4 The embodiments of this application will be described in detail.

[0029] In related technologies, traditional LED display control systems suffer from bandwidth bottlenecks. Using gigabit Ethernet cables (1000Mbps) for interconnection, at ultra-large resolutions, transmitting devices require a large number of Ethernet cables, leading to extremely complex wiring. While some solutions use DisplayPort (DP) cables, the AUX bus in the standard DP protocol only supports 1Mbps. In systems with dozens or even hundreds of cascaded receiver cards, the return speed of monitoring data and correction parameters is extremely slow. Adding extra Ethernet cables for high-speed return significantly increases cable costs, interface size, and PCB material costs, while also increasing wiring complexity and causing system redundancy. Furthermore, when using AC coupling circuits in the DP standard for high-speed transmission, the inability to achieve perfect DC balance results in baseline drift caused by AC coupling, severely degrading signal quality. This application aims to address the above-mentioned problems in related technologies.

[0030] This application provides a data transmission system for LED display control. Figure 1This application provides a data transmission system framework diagram for LED display control. The system includes: a transmitting device and multiple receiving devices; the transmitting device and the first-level receiving device, as well as two adjacent receiving devices, are directly connected via DP cables to form a daisy-chain topology; each DP cable includes a main link differential pair for transmitting display data and an auxiliary channel differential pair for transmitting auxiliary signals; each transmitting device and each receiving device has an auxiliary signal interface circuit, and the auxiliary signal interface circuit and the auxiliary channel differential pair are connected by DC coupling; an impedance matching circuit is provided on the signal input path of the auxiliary signal interface circuit, the impedance matching circuit including a damping resistor connected in series in the differential signal path and a termination resistor connected across the differential signal paths; the system is configured to use the auxiliary channel differential pairs for auxiliary signal transmission, and when transmitting auxiliary signals, Manchester encoding or inverse non-return-to-zero encoding combined with bit-filling encoding is used to support a transmission rate greater than or equal to 100 megabits per second.

[0031] In the above embodiments, the transmitting device and the first-level receiving device, as well as two adjacent receiving devices, are directly connected via DP cables to form a daisy-chain topology, which simplifies wiring and reduces costs. The DC-coupled connection structure and the absence of AC DC blocking capacitors maintain stable signal level transmission, avoiding baseline drift and charge accumulation. The damping resistor in the impedance matching circuit suppresses signal reflection fluctuations, limits surge current protection ports, and the termination resistor matches the characteristic impedance of the cable. The specific encoding method can achieve a transmission rate of auxiliary signals greater than or equal to 100 megabits per second, improving data transmission efficiency and long-distance transmission stability.

[0032] This embodiment utilizes a DisplayPort (DP) physical link and deeply modifies its auxiliary channel (AUX) to achieve high-speed, long-distance, and reliable bidirectional data communication. The transmitting device typically refers to a video transmitting card, responsible for receiving and processing video source signals before transmitting them. The receiving device refers to an LED receiving card, responsible for driving LED beads for display; these are the basic components of the system. All devices (transmitting card + multi-level receiving cards) are connected end-to-end via DP cables, like a chain. This structure provides extremely simple physical cabling, connecting all devices with a single cable, fundamentally solving the complexity of parallel cabling with multiple network cables. Data (whether downstream video or upstream control signals) is transmitted sequentially along this "chain." The main link differential pairs are high-speed data channels within the DP cable (usually four pairs), with extremely high bandwidth (e.g., DP1.4 up to 32.4Gbps). This system uses DP cables to transmit display data (video streams). Due to its high bandwidth, a single DP cable can carry high-resolution video such as 4K / 8K, replacing multiple gigabit network cables and solving the downstream bandwidth bottleneck. The auxiliary channel differential pair is a pair of low-speed, bidirectional communication lines within the DP cable. In the standard DP protocol, it is only used for low-speed control such as initial handshake between devices and reading display information, with a rate of approximately 1 Mbps. The core of this embodiment is to modify and reuse this channel to undertake high-speed data return tasks. Standard DP uses AC coupling capacitors at the interface to isolate DC components and prevent potential differences between devices. However, in high-speed, long-distance transmission, if the number of "0"s and "1"s in the transmitted data stream is unbalanced for a long time (non-DC balance), the capacitors will repeatedly charge and discharge, causing baseline drift in the signal voltage reference. The receiving end cannot correctly judge the signal, and the bit error rate surges. The auxiliary signal interface circuit of this embodiment adopts a DC-coupled connection structure, removing these AC coupling capacitors and using DC coupling (direct electrical connection), fundamentally eliminating the baseline drift problem caused by capacitor charging and discharging, laying the physical foundation for high-speed, long-distance transmission. The impedance matching circuit in the auxiliary signal interface circuit is a specific circuit added to the signal input path after DC coupling to protect the chip interface and ensure signal quality. A damping resistor is connected in series in the differential signal path. Its functions are twofold: first, to limit potential surge current and protect the sensitive input stage of the receiver chip; and second, in long-distance transmission, to absorb signal reflections in conjunction with the cable's characteristic impedance, preventing signal overshoot, ringing, or jitter caused by superimposed reflected waves, thus improving signal integrity. A termination resistor is connected across the differential pairs, matching the characteristic impedance of the AUX differential pairs in the DP cable. Its function is to absorb signal energy at the receiving end, preventing signal reflection at the terminal and further stabilizing the signal. After the physical layer modification, a new data encoding protocol needs to be matched to achieve high speeds.Manchester encoding is a self-synchronizing, DC-balanced encoding method. Each bit has a level transition in the middle, with the direction of the transition representing "0" or "1". The advantages of Manchester encoding are that clock information is directly embedded in the data stream, making synchronization at the receiver extremely easy; and the high and low levels each account for 50%, achieving perfect DC balance, making it a perfect match for DC-coupled circuits. The disadvantage is its low bandwidth efficiency (100Mbps data requires a 200MHz signal bandwidth). NRZI (Non-Return-to-Zero) + Bit-stuffing encoding: NRZI encoding uses "level flip" to represent 0 and "level hold" to represent 1. To avoid long strings of "1"s (i.e., no level transition for a long time) causing the receiver to lose synchronization, "0"s are forcibly inserted (i.e., a transition is created), this is "bit stuffing". The advantage of combining NRZI with bit-stuffing encoding is high bandwidth efficiency, approaching 100%, but slightly poorer DC balance.

[0033] Taking a large stadium's circular LED canopy as an example, it consists of 200 cabinets (receiver cards) connected in a ring. Related technologies use network cables for connection, requiring dozens or even hundreds of cables to converge from various parts of the canopy to the control room, creating a "forest of cables." Transmitting the status of all cabinets (temperature, brightness, voltage) takes tens of seconds, making real-time monitoring impossible. The solution in this embodiment places a transmitting card in the control room, connected to the receiving card of the first cabinet at the starting point of the canopy via a DP cable. This receiving card is then connected to the second cabinet via a second DP cable, and so on, in a "daisy-chain" manner, connecting all 200 cabinets. The physical wiring consists of only one cable running along the canopy, making it extremely simple. The 4K event signal is transmitted in high-bandwidth streaming mode through the main link of the DP cable, flowing in real-time from the transmitting card through each level of receiving card to drive the LED display with zero latency. The monitoring data generated by each cabinet is modulated into a high-speed differential signal via its internal DC-coupled auxiliary signal interface circuit (the AC coupling capacitors that could cause baseline drift have been removed, and damping resistors and termination resistors have been added to protect the chip and suppress reflections), following Manchester encoding (due to its superior synchronization robustness in venues with strong electromagnetic interference). The data from cabinet 200 is transmitted forward along the AUX channel to cabinet 199; the auxiliary signal interface circuit of cabinet 199 receives and decodes the signal, extracts the data from cabinet 200, integrates its own monitoring data, re-encodes it, and continues to transmit it forward to cabinet 198… This relay process continues cascading, until the monitoring data from all 200 cabinets converges to the transmitting card within sub-seconds, allowing the control room software to view the health status of each cabinet in the entire canopy in real time.

[0034] This embodiment uses a single high-bandwidth DP line in a "daisy chain" to replace multiple network cables, solving the problem of complex cabling and high cost caused by dozens of network cables required in related technologies. It utilizes the high bandwidth of the DP main link to carry ultra-high-definition video on a single line. The AUX channel undergoes dual modifications at the physical layer (DC coupling + impedance matching) and protocol layer (high-speed encoding), increasing the rate to the 100Mbps level. DC coupling eliminates baseline drift; damping resistors and termination resistors suppress reflections and match impedance; Manchester encoding provides strong synchronization and DC balance, jointly ensuring stable transmission over cables longer than 50 meters.

[0035] In an optional embodiment, the DC-coupled connection structure is a direct electrical connection structure. The direct electrical connection structure removes the AC coupling capacitor and pull-up / pull-down resistors in the standard DP interface configuration, and maintains stable signal level transmission through the DC electrical path, avoiding baseline drift and charge accumulation caused by continuous transmission of the same level in AC coupling.

[0036] In the above embodiment, a direct electrical connection structure is adopted to remove the AC coupling capacitors and pull-up / pull-down resistors in the standard DP interface configuration, constructing a pure DC path interface circuit structure. This eliminates the AC coupling energy storage mechanism, which is prone to baseline drift, and instead employs a direct resistive connection that maintains the stability of the DC component of the signal. This ensures stable signal level transmission through the DC electrical path, avoiding baseline drift and charge accumulation caused by continuous transmission at the same level during AC coupling. This allows the AUX channel to reliably carry high-speed digital signals in the 100Mbps range, extending the transmission distance to 20-50 meters or more, meeting the requirements of large LED display cascading. This removes physical layer obstacles for subsequent high-speed (e.g., 100Mbps), long-distance (e.g., 20-50 meters) data transmission on the AUX channel. This embodiment, by adopting DC coupling, actively breaks the conventional constraints of the DP standard protocol and creatively solves the inherent baseline drift problem of AC coupling in high-speed, long-distance application scenarios.

[0037] In the standard DisplayPort (DP) protocol definition, the auxiliary channel (AUXCH) must employ AC coupling, meaning a DC blocking capacitor is connected in series between the transmitting end (TX) or receiving end (RX) and the DP cable, linked in series on the differential signal line. This isolates the DC potential difference between devices and prevents current caused by ground loops. This embodiment uses a direct electrical connection structure, forming a purer resistive connection through the cable. This allows lossless transmission of the DC component in the signal, completely eliminating baseline drift caused by capacitor charging and discharging. The standard DP pull-up and pull-down resistor network is designed to facilitate level reset after AC coupling. In DC coupling mode, these resistors are not only redundant but may also cause additional load or level conflicts. Removing them allows the logic state to be directly determined by the output level of the driver chip and the input threshold of the receiving end, simplifying the circuit path. In long-distance or multi-stage cascading, AC coupling capacitors accumulate charge like a "bucket," causing the overall signal waveform to rise or fall. DC coupling acts like a "smooth water channel," where charge flows instantly with the signal without accumulation, thus ensuring absolute stability of the receiver's decision level when transmitting long strings of consecutive "0"s or "1"s. Standard DP AUX channels, due to series capacitors, experience severe baseline drift when transmitting long strings of codes or through multiple cascaded stages, limiting communication distance to a very short range and making them unsuitable for long-distance LED control. This embodiment completely eliminates baseline drift, supports long string code transmission, extends the effective communication distance from a few meters to tens of meters or more, and supports cascading of dozens or even hundreds of devices.

[0038] In an optional embodiment, the auxiliary signal interface circuit includes a signal transmitting unit, a signal receiving unit, a damping resistor, and a termination resistor. The damping resistor includes a first resistor and a second resistor. The first resistor is connected in series between the first differential input terminal of the signal receiving unit and the first signal line of the corresponding auxiliary channel differential pair in the DP cable. The second resistor is connected in series between the second differential input terminal of the signal receiving unit and the second signal line of the corresponding auxiliary channel differential pair in the DP cable. The first differential output terminal of the signal transmitting unit is connected to the first signal line of the corresponding auxiliary channel differential pair in the DP cable, and the second differential output terminal of the signal transmitting unit is connected to the second signal line of the corresponding auxiliary channel differential pair in the DP cable. Two signal lines are connected; a terminating resistor is connected between the two differential input terminals of the signal receiving unit; or, a first resistor is connected in series between the first differential output terminal of the signal transmitting unit and the first signal line of the corresponding auxiliary channel differential pair in the DP cable, and a second resistor is connected in series between the second differential output terminal of the signal transmitting unit and the second signal line of the corresponding auxiliary channel differential pair in the DP cable; the first differential input terminal of the signal receiving unit is connected to the first signal line of the corresponding auxiliary channel differential pair in the DP cable, and the second differential input terminal of the signal receiving unit is connected to the second signal line of the corresponding auxiliary channel differential pair in the DP cable; a terminating resistor is connected between the two differential input terminals of the signal receiving unit.

[0039] In the above embodiments, the specific composition and connection method of the auxiliary signal interface circuit are clarified. The damping resistor and the termination resistor are connected in a specific way to better achieve impedance matching and ensure stable transmission of the auxiliary signal in the differential pair of the auxiliary channel of the DP cable. Combined with the encoding method adopted by the system, it helps to achieve high-speed and stable transmission of the auxiliary signal in the daisy-chain topology.

[0040] The auxiliary signal interface circuit is the physical layer interface between the auxiliary channel differential pairs and the internal logic, undertaking the functions of bidirectional signal transmission, reception, impedance matching, surge suppression, and reflection absorption. The signal transmitting unit converts the encoded digital signal into differential levels to drive the DP cable for transmission; the signal receiving unit picks up the differential signal from the DP cable and restores it to digital logic levels; a damping resistor is connected in series in the differential path to dampen oscillations, limit current, and suppress reflections; a termination resistor is connected in parallel at the differential input to match the cable's characteristic impedance and absorb end reflections. The auxiliary signal interface circuit in this embodiment includes two connection topologies: the first is a series damping resistor at the receiving unit end plus a parallel termination resistor at the receiving unit end; the second is a series damping resistor at the transmitting unit end plus a parallel termination resistor at the receiving unit end. Both schemes aim to eliminate impedance mismatch problems caused by multiple daisy-chain nodes, ensuring waveform quality of high-speed signals during long-distance transmission. Taking the first scheme as an example, the damping resistor is placed immediately before the input pins of the receiver chip. Its main function is to limit transient large currents (such as ESD and surges) that may surge into the input stage of the receiver chip from the cable, thus providing protection. Simultaneously, it works in conjunction with the characteristic impedance of the cable, the input capacitance of the receiver, and the output impedance of the transmitter to dampen (suppress) signal reflections caused by impedance mismatch, preventing reflected waves from superimposing at the receiver and causing signal overshoot, ringing, or additional jitter. The termination resistor is connected between the input terminals of the receiver units. The resistance value of the termination resistor matches the characteristic impedance of the differential pair, forming a parallel termination. When the signal comes from the cable, its energy is absorbed by this resistor, greatly reducing signal reflection at the receiver and ensuring a clean signal waveform. Placing the termination resistor at the input terminal of the receiver unit (after the damping resistor) ensures that the termination network directly acts on the input node of the receiver chip, which is the most effective signal integrity processing method. The transmitter unit directly drives the cable, providing the strongest driving capability. The DP standard interface circuit in related technologies does not adequately consider surge protection and overvoltage protection. In complex industrial and outdoor environments, cables may introduce interference or surge voltages, which can easily damage the device by directly impacting the chip pins. The auxiliary signal interface circuit in this embodiment significantly improves signal integrity and ensures the stability of high-speed data transmission. The series damping resistor, as a simple passive protection component, can effectively improve the interface's ability to resist electrical overstress and electrostatic discharge, reducing the risk of equipment failure in the field. By simply adding a few low-cost standard resistors and combining them with an optimized layout, the key problem of high-speed long-distance transmission is solved, achieving extremely high cost-effectiveness.

[0041] In one optional embodiment, the damping resistor has a resistance range of 10Ω-22Ω. The damping resistor is used to suppress reflection fluctuations generated during signal transmission and to limit surge current to protect the input and output ports of the auxiliary signal interface circuit. The termination resistor has a resistance range of 80Ω-120Ω and is used to match the characteristic impedance of the differential pairs of the auxiliary channel in the DP cable.

[0042] In the above embodiments, the data transmission system consists of a transmitting device and a receiving device, which are connected by a DP cable to form a daisy-chain topology. Based on the use of auxiliary channel differential pairs to transmit auxiliary signals and the adoption of a specific encoding method to achieve high-speed transmission, a damping resistor (including a first resistor and a second resistor) with a resistance range of 10Ω-22Ω can suppress reflection fluctuations in signal transmission and limit surge current to protect the input and output ports of the auxiliary signal interface circuit. A termination resistor with a resistance range of 80Ω-120Ω can match the characteristic impedance of the auxiliary channel differential pairs in the DP cable.

[0043] In high-speed digital signal transmission (especially at rates >100Mbps in this solution), resistors are no longer simple current-limiting components, but rather regulators of signal integrity. The damping resistor (10Ω-22Ω) is a precisely calculated value; it must be large enough to absorb reflected energy and limit surges, but not so large as to excessively attenuate the signal amplitude, making it unrecognizable at the receiver. The termination resistor (80Ω-120Ω) is used to match the characteristic impedance of the DP cable's auxiliary channel (AUX). The damping resistor not only suppresses reflections at the signal level but also acts as a surge current limiter at the physical level, preventing the large currents from hot-plugging or electrostatic discharge from damaging the fragile nanoscale chip ports. This embodiment, by using damping and termination resistors within a preferred resistance range, maximizes the suppression of signal reflections and ringing, ensuring extreme stability and low bit error rate in high-speed data transmission, and significantly improving the system's robustness and lifespan in harsh electrical environments.

[0044] In an optional embodiment, the transmitting device is configured with a link adaptation module for performing link quality assessment and dynamically selecting transmission parameters during the system initialization phase. The link adaptation module measures the total signal attenuation and initial bit error rate of the current entire link by sending a probe sequence to the end of the daisy chain and receiving feedback signals from the last-stage receiving device. If the total signal attenuation is less than a preset loss threshold and the initial bit error rate is lower than the preset bit error rate threshold, the current link is determined to be in a low-loss state, and the control system enters a first transmission mode, using a non-return-to-zero encoding combined with bit-filling encoding, and setting the transmission rate to a first rate value. If the total signal attenuation is greater than or equal to the preset loss threshold, or the initial bit error rate is higher than or equal to the preset bit error rate threshold, the current link is determined to be in a high-loss long-distance state, and the control system enters a second transmission mode, using a Manchester encoding method with self-clock recovery characteristics, and setting the transmission rate to a second rate value, wherein the first rate value is greater than the second rate value.

[0045] In the above embodiments, the link adaptive module can perform link quality assessment and dynamically select transmission parameters during the system initialization phase. By sending probe sequences and receiving feedback signals, it measures the total signal attenuation and calculates the initial bit error rate. Then, based on the link status determination results, it selects an appropriate transmission mode and rate. In the low-loss state, it adopts an inverse non-return-to-zero coding combined with bit-filling coding and sets a higher first rate value to improve transmission efficiency. In the high-loss long-distance state, it adopts Manchester coding with self-clock recovery characteristics and sets a lower second rate value to ensure the stability and reliability of signal transmission.

[0046] During system power-on initialization in this embodiment, instead of directly transmitting service data, a specific probe sequence is sent. This is a test bitstream of a known pattern (such as a pseudo-random binary sequence, PRBS) for "testing the path." The probe sequence signal travels through the entire daisy chain to the end device, which detects the signal quality (attenuation or bit error rate, BER) and feeds the result back to the transmitting end. This allows for the assessment of the weakest link in the entire chain. When the link quality is good, the system enters the first transmission mode, enabling non-return-to-zero (NRZI) encoding with bit stuffing. NRZI encoding is highly efficient (1 symbol = 1 bit), and combined with bit stuffing, it solves the problem of long consecutive codes, allowing full utilization of the physical bandwidth. A first rate value is set, such as 200 Mbps (or other values). Due to the good link quality, a higher rate can be used to pursue maximum data throughput. When the link quality is poor, the system enters the second transmission mode, switching to Manchester encoding. Although the efficiency is halved (1 symbol = 0.5 bits), each bit has a transition, providing strong self-clock recovery capability and DC balance, and can tolerate significant signal attenuation and jitter (second rate value, such as 100 Mbps, or other values). In this embodiment, the actual carrying capacity (attenuation, bit error rate) of the physical link is actively detected before communication begins. Then, based on the detection results, the system intelligently switches between two coding schemes (efficient NRZI combined with bit stuffing and robust Manchester) and their corresponding rates. The goal is that in any actual deployment environment (regardless of cable length or environmental interference), the system can automatically find the optimal "performance-reliability" balance point under the current conditions to achieve globally optimal communication.

[0047] In an optional embodiment, the DP cable is a cable compliant with the DisplayPort physical layer standard, the transmitting device is a video transmitting card with a DP output interface, and the receiving device is a receiving card integrated into the LED display module and having both a DP input interface and a DP output interface.

[0048] In the above embodiments, DP cables conforming to the DisplayPort physical layer standard are used to ensure the compatibility and standardization of data transmission; a video transmitting card with a DP output interface is used as the transmitting device, which can be adapted to the DP interface for data transmission; a receiving card integrated into the LED display module and having DP input and DP output interfaces is used as the receiving device, which facilitates the reception and further transmission of data in the LED display control system. Combined with the daisy-chain topology, DC coupling connection, impedance matching circuit and specific encoding method of the entire system, high-speed and stable transmission of auxiliary signals can be achieved.

[0049] This embodiment utilizes high-bandwidth, highly shielded cables conforming to the DP physical layer standard as the physical medium for long-distance signal transmission. DP cables typically contain multiple pairs of high-speed differential lines (Main Link) and a pair of low-speed bidirectional auxiliary lines (AUX CH). This system focuses on reconstructing the physical characteristics of the AUX channel or reusing the Main Link channel, breaking through its original protocol limitations. Each module has both DP input and DP output interfaces, making the module itself an active relay node in the signal link. Signals are no longer transmitted directly point-to-point from the transmitting card to each receiving card (requiring numerous independent cables), but rather, like "threading a needle," all modules are connected in series through a continuous DP cable. This architecture greatly simplifies wiring complexity and enables station-by-station signal regeneration and forwarding. The transmitting device is a video transmitting card with a DP output interface. In the LED display industry, this is a dedicated device responsible for receiving video signals from signal sources such as computers, cameras, and media players, performing format conversion, image processing, data segmentation and packaging, and then driving downstream receiving cards through the output interface. The receiver card has a DP input interface and a DP output interface. The DP input interface is used to receive signals (including main link video data and AUX channel data) from the front-end device (sending card or the previous level receiver card). The DP output interface is used to send the processed signals (continuously transmitted video data and integrated AUX return data) to the next level receiver card. The dual DP interfaces enable a single receiver card to become a "relay node" in a daisy chain. It not only processes the data that this module needs to display, but also is responsible for passing the data stream (downlink and uplink) to the next node without loss or after processing according to rules (such as relay integration of AUX data).

[0050] In an optional embodiment, the receiving device further includes a relay processing module, which is configured to decode the encoded auxiliary signal received from the downstream device via the auxiliary channel differential line, extract the downstream return data, integrate the monitoring data or correction parameters generated by the local device and re-encode them, and then forward them to the upstream device through the auxiliary signal interface circuit of the local device. Finally, all return data is converged to the transmitting device.

[0051] In the above embodiments, the relay processing module of the receiving device can decode the encoded auxiliary signal from the downstream device to extract the returned data, integrate the monitoring data or correction parameters of this level, re-encode it, and forward it to the upstream device, so that all returned data can be converged to the transmitting device, facilitating status monitoring and parameter correction of each level of receiving device. Simultaneously, combined with the daisy-chain topology, DC-coupled connection structure, impedance matching circuit, and specific encoding method adopted by the system, a transmission rate of auxiliary signals greater than or equal to 100 megabits per second can be achieved, improving the stability and efficiency of long-distance transmission.

[0052] This embodiment incorporates a relay processing module in the receiving device to decode the coded auxiliary signals uploaded from downstream devices, extract data, integrate them with the local monitoring data, re-encode the signals, and forward them to the upstream device. This allows the return data to be relayed step-by-step in a daisy-chain topology and ultimately converge to the transmitting device. Specifically, the coded auxiliary signals from downstream devices are first decoded to remove physical layer noise and extract the downstream return data. Then, the monitoring data or correction parameters collected at this level are integrated with the downstream data at the protocol level to form an aggregated data frame. Finally, the integrated data is re-encoded and forwarded to the upstream device through the local interface, allowing all return data to converge to the transmitting device step-by-step along the daisy chain. This embodiment solves the technical problems of easy attenuation of auxiliary return signals, inability to penetrate long distances, and difficulty in unified data aggregation in multi-level cascaded scenarios, avoiding signal distortion and interruptions caused by long-distance multi-level transmission. Through relay regeneration and data integration, transmission stability can be effectively improved, enabling efficient aggregation of data from dozens to hundreds of receiving cards, ensuring the reliability and real-time performance of high-speed return transmission.

[0053] The relay processing module is electrically connected to the receiving device via dual DP interfaces. Either DP interface is bidirectional. For example, when transmitting display data downstream, the first DP interface is used as the input interface and the second DP interface is used as the output interface; when transmitting data upstream (auxiliary signals, such as monitoring data), the second DP interface is used as the input interface and the first DP interface is used as the output interface.

[0054] In an optional embodiment, the transmission direction of the auxiliary signal is bidirectional, including downlink control commands, firmware update data or correction parameters transmitted from the transmitting device to each level of receiving device, and uplink status monitoring data transmitted back from each level of receiving device to the transmitting device.

[0055] In the above embodiments, bidirectional transmission of auxiliary signals between the transmitting device and the receiving devices at all levels is realized. This enables the transmitting device to transmit downlink control commands, firmware update data, or correction parameters to the receiving devices at all levels. At the same time, the receiving devices at all levels can transmit uplink status monitoring data back to the transmitting device, which facilitates comprehensive control and real-time status monitoring of the LED display system.

[0056] In this embodiment, the auxiliary channel differential pair is configured as a bidirectional transmission structure, enabling downlink transmission from the transmitting device to the receiving device and uplink return transmission from the receiving device to the transmitting device within the same physical link. Downlink transmission is used to transmit control commands, firmware update data, and calibration parameters, while uplink transmission is used to return status monitoring data from each level of the receiving device. In related technologies, LED display control systems often require the additional deployment of a separate monitoring bus (such as RS485) for status return, resulting in complex wiring and high costs. This solution solves the problems of existing LED control systems where the auxiliary channel only supports low-speed unidirectional communication, requiring additional dedicated control and return lines, leading to complex wiring and high system redundancy. It also overcomes the shortcomings of standard DP AUX channels, which have insufficient bandwidth and cannot simultaneously carry large volumes of downlink configuration data and uplink monitoring data. Through single-link bidirectional high-speed transmission, no additional hardware interfaces or transmission cables are needed. This fully utilizes the physical channel resources of DP cables, effectively reducing system structural complexity and material costs, improving the transmission efficiency and versatility of the auxiliary channel, meeting the needs of remote control, online upgrades, batch calibration, and real-time status monitoring in large-scale cascading scenarios, and significantly improving system maintenance convenience and operational reliability.

[0057] In one optional embodiment, the monitoring data includes at least one of the following: the temperature of the receiving device, operating voltage, LED brightness status, and fault codes.

[0058] This embodiment enables monitoring of at least one status of the receiving device, such as temperature, operating voltage, LED brightness status, and fault codes. This provides more comprehensive status information for the stable operation of the LED display control system, facilitating timely detection and handling of equipment anomalies. The monitoring data transmitted back by the receiving device through the auxiliary channel can include one or more of the following: temperature, operating voltage, LED brightness status, and fault codes. This allows each level of receiving device to upload its key operating parameters and status to the transmitting device in real time via the high-speed auxiliary channel, forming a full-link visualized monitoring system. This technical solution solves the problems of traditional LED display control systems, which suffer from insufficient backhaul bandwidth and a single communication channel, making it impossible to obtain the real-time operating status of the receiving card and detect overheating, undervoltage, abnormal brightness, and communication failures in advance. It also avoids the drawbacks of traditional solutions, such as cumbersome wiring, high cost, and poor scalability due to the need for additional monitoring circuitry. By standardizing the acquisition and high-speed transmission of core status parameters, the system can achieve real-time monitoring, anomaly warning, and rapid fault location of multi-level receiving devices, thereby improving the operational safety and stability of the LED display system, reducing the difficulty of on-site maintenance, and ensuring the real-time performance and accuracy of monitoring data through a 100Mbps high-speed transmission channel, providing reliable data support for remote operation and maintenance, intelligent correction, and system protection.

[0059] The following description is based on specific embodiments. This application provides a high-speed, long-distance transmission system and method for a DP AUX bus in an LED display control system, specifically proposing a customized DP link protocol architecture, including the following: 1. AUX bus physical layer circuit modification Circuit architecture: The AC coupling capacitor in the standard DP protocol is removed, and a DC coupling architecture is adopted; Hardware reinforcement: Connect a 10Ω-22Ω damping current-limiting resistor in series on the differential line at the receiving end, and connect a 100Ω matching resistor across the end; Anti-interference and protection mechanism: Utilizing the common ground characteristics within the system, in conjunction with current-limiting resistors, it suppresses reflections, improves EMI, and protects I / O over long distances of 20m-50m.

[0060] 2. Optimization of auxiliary encoding protocol The modified AUX physical channel uses Manchester encoding or NRZI+ bit-stuffing encoding.

[0061] Technical benefits: It increases the original 1Mbps AUX bandwidth to 100Mbps, enabling real-time high-speed backhaul of dozens or even hundreds of levels of data from receiving cards without the need for additional cables; when using the NRZI+ bit-stuffing encoding method, it can further increase the bandwidth, or significantly improve transmission stability and reduce the bit error rate while maintaining a 100Mbps rate.

[0062] The transmission system (or LED cascade system) for LED display control in this embodiment uses DP cables as the data transmission carrier, and the transmitting end (corresponding to the aforementioned transmitting device) and the receiving end (corresponding to the aforementioned receiving device), as well as the receiving ends, are directly connected via DP interfaces. The auxiliary channel (AUX) in the DP cable uses DC coupling for data return. Protective resistors ranging from 10Ω to 22Ω are connected in series on the AUX differential pairs (AUX+ / AUX-) at the receiving end to limit inrush current and match long-line impedance. As an optional approach, the physical layer transmission uses Manchester encoding to ensure DC balance and self-synchronizing clock extraction; as another optional approach, the physical layer transmission uses NRZI+ bit-stuffing encoding to suppress DC components and ensure clock synchronization, further improving the transmission bandwidth based on the aforementioned hardware. The AUX channel supports high-speed transmission, with a return rate of no less than 100Mbps.

[0063] Table 1 compares the advantages and disadvantages of Manchester coding and NRZI+bit stuffing coding. When using Manchester coding to achieve an effective throughput of 100Mbps, its flip frequency reaches as high as 200MHz. This not only doubles the bandwidth requirements of the transmission link but also poses a severe challenge to signal integrity at high frequencies, easily inducing serious bit errors in long-distance transmission. Therefore, without upgrading the link hardware cost, the NRZI combined with bit stuffing scheme is a better choice: it effectively mitigates channel loss and electromagnetic interference by significantly reducing the cutoff frequency of the physical signal, ensuring link robustness in long-distance transmission. Although Manchester coding is not suitable for high-performance data links due to its double bandwidth requirement, in environments with extremely high synchronization robustness requirements or strong interference environments where the physical layer uses transformer isolation, Manchester coding still has unparalleled reliability advantages due to its natural DC balance and self-clocking characteristics. Therefore, the choice of coding scheme should be based on the actual usage environment.

[0064] Table 1 Feature Dimension Manchester encoding Inverse Non-Return-to-Zero (NRZI) coding Basic principles Level transitions are used to represent bits (e.g., down transition = 1, up transition = 0); a transition is forced at the center of each bit cycle. Level flipping represents "0", and level holding represents "1" (or vice versa); the transition only occurs at specific points. Synchronization principle Physical layer enforces synchronization; every bit must have a transition, and clock information is directly embedded in the data stream. Logic layer auxiliary synchronization; synchronization using level flipping; forced transitions by inserting redundant bits (bit stuffing) Bandwidth efficiency 50% (extremely low); the effective rate is twice the data rate (100Mbps requires a 200MHz waveform). High (close to 100%); except for a very few fill bits, the waveform frequency is highly matched to the bit rate. Self-synchronization capability Perfect, never loses its clock, no need to worry about long 0s or long 1s. Strong (algorithm-dependent), triggering a flip by forcibly inserting a 0 after a series of consecutive 1s. DC balance Natural balance, with a strict 50 / 50 ratio of positive and negative voltage levels. Imbalance, even with position filling, may still result in DC offset. Physical layer advantages of NRZI in long-distance DC links (1) Eliminate baseline drift and charge accumulation In traditional AC-coupling long-line transmission, unbalanced bit streams (such as consecutive 0s or 1s) can cause voltage shifts across capacitors, resulting in baseline drift.

[0065] This application employs DC-coupling combined with Manchester or NRZI+ bit-stuffing encoding: DC path stability: Under the DC-coupled architecture, since there is no charging and discharging process of the coupling capacitor, the high-frequency phase distortion caused by the equivalent series resistance (ESR) and inductance (ESL) of the capacitor is eliminated, so that the signal still maintains strict waveform symmetry under a 50-meter long line.

[0066] (2) Anti-shake capability Low-frequency suppression: With the 22Ω damping resistor in this application, the high-frequency components of Manchester encoding are effectively preserved, while the low-frequency (50Hz / 100Hz) power frequency noise picked up by the cable is efficiently filtered out by the digital filter because it does not conform to the transition characteristics of Manchester encoding, thus achieving zero bit error rate in tens of thousands of tests in the complex electromagnetic environment of three-phase power.

[0067] (3) Control of reflected waves by impedance damping At a speed of 100Mbps, the propagation delay of a 50-meter DP cable is much greater than the signal rise time.

[0068] End absorption: This application incorporates a 22-ohm series resistor and a 100-ohm bridging resistor at the pin of the receiving chip. This topology forms a miniature damping attenuation network that effectively absorbs weak reflected waves caused by cable impedance discontinuities, preventing jitter at signal zero-crossing points and ensuring a stringent margin for logic level determination.

[0069] The physical layer of this application solves the problem of speeding up high-speed, long-distance AUX channels by using a specific combination of "DC coupling + 22Ω protection + Manchester encoding or NRZI + bit stuffing".

[0070] Figure 2 This is a schematic diagram of a standard DP AUX circuit in related technologies, such as... Figure 2 As shown, the configuration circuit of the DP interface includes an AC coupling capacitor (such as...). Figure 2 (C_AUX), pull-up and pull-down resistors, and bias resistors, etc. Pull-up and pull-down resistors include those connected to the power supply terminal (e.g., C_AUX), pull-up and pull-down resistors, etc. Figure 2 The pull-up resistors (DP_PWR, 2.5-3.3V) and the pull-down resistors connected to ground are included. Figure 2 Vbias_Tx and Vbias_Rx are the bias power supply terminals, and the bias resistor is 50Ω; Figure 2 The area between the two dashed lines represents a DP cable, which connects adjacent receiving devices on both sides, or connects a transmitting device and a first-level receiving device on both sides. Each device's DP interface includes a transmitting unit (or transmitting chip Tx) and a receiving unit (or receiving chip Rx).

[0071] Figure 3 This is a schematic diagram of the DP AUX circuit provided in the embodiments of this application, as shown below. Figure 3 In the diagram above, a damping resistor (e.g., 22Ω) is connected in series between the receiving unit (or receiving chip, Rx in the diagram) of the DP interface and the DP cable, and a resistor (e.g., 100Ω) is connected in parallel at the differential input terminal of the receiving unit, while the differential output terminal of the transmitting unit (or transmitting chip) is directly connected to the DP cable; or, as shown... Figure 3 The lower diagram shows a damping resistor connected in series between the differential output of the transmitting unit and the DP cable, and a terminating resistor connected in parallel at the differential input of the receiving unit. The main features of the DP AUX circuit provided in this application are: 1) Direct DC connection, eliminating the bias circuit; 2) A 22-ohm resistor connected in series with the damping resistor at the front end of the receiving chip; 3) A 100-ohm matching resistor connected in parallel across the pin.

[0072] The embodiments of this application have at least the following advantages: High-performance backhaul: Further improves the backhaul bandwidth of the LED cascade system, supporting large-scale real-time monitoring and data backhaul; High reliability: Zero bit error rate in 10,000 tests on a 50-meter cable, far exceeding the stability of traditional industrial long-distance transmission. Low cost: No expensive fiber optic cables or additional Ethernet PHY chips are required; high-speed data links can be achieved with simple resistor matching.

[0073] This application also provides a data transmission method for LED display control, applicable to the data transmission system for LED display control in any of the foregoing embodiments, such as... Figure 4 As shown, the process includes: Step S401: The transmitting device is directly connected to the primary receiving device and the adjacent receiving device in sequence through DP cables to form a daisy-chain topology. Each DP cable contains a main link differential pair for transmitting display data and an auxiliary channel differential pair for transmitting auxiliary signals. The DP cables used here must conform to the DisplayPort physical layer standard to ensure stable signal transmission. During connection, ensure the cables are securely connected to avoid loosening or poor contact. Professional cable connectors, such as pluggable or soldered connectors, can be used to connect the cables to the interfaces of the transmitting and receiving devices. For pluggable connectors, ensure the plug and socket fit tightly to prevent signal leakage. For soldered connectors, pay attention to the soldering process, ensuring the quality of the solder joints and avoiding problems such as cold solder joints.

[0074] Step S402: Configure the auxiliary signal interface circuit inside the transmitting and receiving devices to form a DC coupling path between the auxiliary signal interface circuit and the differential line pair of the auxiliary channel, and set an impedance matching circuit on the signal input path of the auxiliary signal interface circuit. The impedance matching circuit includes a damping resistor connected in series on the differential signal path and a termination resistor connected across the differential signal paths. In practice, the auxiliary signal interface circuit needs to remove the AC coupling capacitor and pull-up / pull-down resistors in the standard DP interface configuration to achieve a direct electrical connection and maintain stable signal level transmission. The selection of damping resistors and termination resistors should be based on the actual circuit design and the characteristic impedance of the DP cable to determine the appropriate resistance range. Multimeters and other testing equipment can be used to measure and verify the resistance values ​​to ensure they meet the requirements.

[0075] Step S403: Use the main link differential pairs in the DP cable to transmit display data in the daisy-chain topology, and use the auxiliary channel differential pairs in the DP cable to transmit auxiliary signals in the daisy-chain topology. When transmitting auxiliary signals, Manchester encoding or inverse non-return-to-zero encoding combined with bit-filling encoding is used to achieve a transmission rate of greater than or equal to 100 megabits per second in the daisy-chain topology.

[0076] During encoding, dedicated encoding chips or FPGAs (Field-Programmable Gate Arrays) can be used to implement the encoding function. For Manchester encoding, it is essential to ensure that the encoding chip or FPGA can correctly convert the raw data into Manchester encoded signals. For inverse non-return-to-zero encoding combined with bit stuffing, the correctness of the bit stuffing algorithm must be guaranteed to avoid consecutive identical voltage levels. Simultaneously, the signal transmission quality, such as signal strength and bit error rate, should be monitored in real time during transmission. Signal monitoring equipment can be used for this purpose, and any problems should be adjusted and addressed promptly.

[0077] This embodiment achieves efficient transmission of display data and auxiliary signals by constructing a daisy-chain topology and rationally configuring the auxiliary signal interface circuit. The specific encoding method improves the transmission rate of auxiliary signals, effectively solving problems such as complex wiring, low transmission rate, and poor stability in existing LED display control systems compared to traditional data transmission methods. In practical applications, strictly following the above steps ensures normal system operation, improves the overall performance and reliability of the LED display control system, and provides users with a better display experience.

[0078] It should be noted that the system and method embodiments provided in the above embodiments belong to the same concept. Other method embodiments correspond to the aforementioned system embodiments. Other technical features can be found in the previous embodiments and will not be repeated here.

[0079] The above description is merely an exemplary embodiment of this disclosure and should not be construed as limiting the scope of this disclosure. Any equivalent changes and modifications made in accordance with the teachings of this disclosure shall still fall within the scope of this disclosure. Other embodiments of this disclosure will be readily apparent to those skilled in the art upon consideration of the disclosure herein.

[0080] This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art that are not described in this disclosure.

Claims

1. A data transmission system for LED display control, characterized in that, include: Transmitting equipment and multi-level receiving equipment; The transmitting device and the first-level receiving device, as well as two adjacent receiving devices, are directly connected via DP cables to form a daisy-chain topology. Each of the DP cables includes a main link differential pair for transmitting display data and an auxiliary channel differential pair for transmitting auxiliary signals. Each of the transmitting devices and each of the receiving devices is provided with an auxiliary signal interface circuit. The auxiliary signal interface circuit and the auxiliary channel differential line pair are connected by a DC coupling structure. An impedance matching circuit is provided on the signal input path of the auxiliary signal interface circuit. The impedance matching circuit includes a damping resistor connected in series on the differential signal path and a termination resistor connected across the differential signal paths. The system is configured to use the auxiliary channel differential line pairs for auxiliary signal transmission, and employs Manchester encoding or inverse non-return-to-zero encoding combined with bit-filling encoding when transmitting auxiliary signals to support a transmission rate of 100 megabits per second or higher.

2. The system according to claim 1, characterized in that, The DC coupling connection structure is a direct electrical connection structure. This direct electrical connection structure removes the AC coupling capacitor and pull-up / pull-down resistors in the standard DP interface configuration. It maintains stable signal level transmission through the DC electrical path and avoids baseline drift and charge accumulation caused by continuous transmission of the same level in AC coupling.

3. The system according to claim 1, characterized in that, The auxiliary signal interface circuit includes a signal transmitting unit, a signal receiving unit, the damping resistor, and the termination resistor. The damping resistor includes a first resistor and a second resistor. The first resistor is connected in series between the first differential input terminal of the signal receiving unit and the first signal line of the auxiliary channel differential pair in the corresponding DP cable; the second resistor is connected in series between the second differential input terminal of the signal receiving unit and the second signal line of the auxiliary channel differential pair in the corresponding DP cable; the first differential output terminal of the signal transmitting unit is connected to the first signal line of the auxiliary channel differential pair in the corresponding DP cable; the second differential output terminal of the signal transmitting unit is connected to the second signal line of the auxiliary channel differential pair in the corresponding DP cable; the termination resistor is connected between the two differential input terminals of the signal receiving unit. or, The first resistor is connected in series between the first differential output terminal of the signal transmitting unit and the first signal line of the auxiliary channel differential pair in the corresponding DP cable; the second resistor is connected in series between the second differential output terminal of the signal transmitting unit and the second signal line of the auxiliary channel differential pair in the corresponding DP cable; the first differential input terminal of the signal receiving unit is connected to the first signal line of the auxiliary channel differential pair in the corresponding DP cable; the second differential input terminal of the signal receiving unit is connected to the second signal line of the auxiliary channel differential pair in the corresponding DP cable; the termination resistor is connected between the two differential input terminals of the signal receiving unit.

4. The system according to claim 3, characterized in that, The resistance value of the damping resistor is in the range of 10Ω-22Ω. The damping resistor is used to suppress reflection fluctuations generated during signal transmission and to limit surge current to protect the input and output ports of the auxiliary signal interface circuit. The termination resistor has a resistance of 80Ω-120Ω and is used to match the characteristic impedance of the auxiliary channel differential pairs in the DP cable.

5. The system according to claim 1, characterized in that, The transmitting device is equipped with a link adaptive module, which is used to perform link quality assessment and dynamically select transmission parameters during the system initialization phase; The link adaptive module measures the total signal attenuation and the initial bit error rate of the entire link by sending a probe sequence to the end of the daisy chain and receiving feedback signals from the last-stage receiving device. If the total signal attenuation is detected to be less than the preset loss threshold and the initial bit error rate is lower than the preset bit error threshold, then the current link is determined to be in a low-loss state, the control system enters the first transmission mode, adopts the encoding method of reverse non-return-to-zero coding combined with bit filling, and sets the transmission rate to the first rate value. If the total signal attenuation is detected to be greater than or equal to the preset loss threshold, or the initial bit error rate is higher than or equal to the preset bit error threshold, then the current link is determined to be in a high-loss long-distance state, the control system enters the second transmission mode, adopts the Manchester encoding method with self-clock recovery characteristics, and sets the transmission rate to the second rate value, wherein the first rate value is greater than the second rate value.

6. The system according to claim 1, characterized in that, The DP cable is a cable compliant with the DisplayPort physical layer standard, the transmitting device is a video transmitting card with a DP output interface, and the receiving device is a receiving card integrated into the LED display module and having both a DP input interface and a DP output interface.

7. The system according to claim 1, characterized in that, The receiving device further includes a relay processing module, which is configured to decode the encoded auxiliary signal received from the downstream device through the auxiliary channel differential line, extract the downstream return data, integrate the monitoring data or correction parameters generated by the local device and re-encode them, and then forward them to the upstream device through the auxiliary signal interface circuit of the local device. Finally, all return data is converged to the transmitting device.

8. The system according to claim 1, characterized in that, The auxiliary signal is transmitted bidirectionally, including downlink control commands, firmware update data or correction parameters transmitted from the transmitting device to each level of the receiving device, and uplink status monitoring data transmitted back from each level of the receiving device to the transmitting device.

9. The system according to claim 8, characterized in that, The monitoring data includes at least one of the following: the temperature, operating voltage, LED brightness status, and fault code of the receiving device.

10. A data transmission method for LED display control, characterized in that, The data transmission system for LED display control, as described in any one of claims 1 to 9, comprises: The transmitting device is directly connected to the primary receiving device and adjacent receiving devices in sequence through DP cables to form a daisy-chain topology. Each of the DP cables includes a main link differential pair for transmitting display data and an auxiliary channel differential pair for transmitting auxiliary signals. The auxiliary signal interface circuits inside the transmitting device and the receiving device are configured to form a DC coupling path between the auxiliary signal interface circuit and the differential line pair of the auxiliary channel, and an impedance matching circuit is set on the signal input path of the auxiliary signal interface circuit. The impedance matching circuit includes a damping resistor connected in series on the differential signal path and a termination resistor connected across the differential signal paths. Display data is transmitted in the daisy-chain topology using the main link differential pairs in the DP cable, and auxiliary signals are transmitted in the daisy-chain topology using the auxiliary channel differential pairs in the DP cable. When transmitting auxiliary signals, Manchester encoding or inverse non-return-to-zero encoding combined with bit-filling encoding is used to support a transmission rate of 100 megabits per second or higher in the daisy-chain topology.

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