A multi-device serial bus communication system

Abstract

The present application discloses a multi-device serial bus communication system, which relates to the field of serial communication technology and includes a communication host, at least two communication slaves, and a signal isolator. The communication slaves are connected to the main line of the serial bus through corresponding branch lines in the serial bus, and are connected to the communication host through the main line. The signal isolator is arranged on the branch line corresponding to at least one communication slave, and is used to isolate the signal transmitted on the corresponding branch line when the communication slave connected to itself is not selected. The present invention can avoid problems such as signal reflection, impedance discontinuity and capacitive load superposition caused by excessively long branch lines, thereby improving the quality of high-frequency signals transmitted by the serial bus.

Description

Technical Field

[0001] The present application relates to the field of serial communication technology, and in particular to a multi-device serial bus communication system. Background Art

[0002] Communication technology is crucial in modern electronic devices and systems. Its efficiency, stability, and flexibility improve device performance and facilitate functional expansion. Serial communication interfaces are widely used due to their simple wiring, low cost, and adaptability.

[0003] In device connections based on serial bus communication, multiple slave devices under the same master share the same serial bus, including clock and data signals. Chip select signals determine which slave device is valid for the data currently being transmitted on the bus. When multiple slave devices cannot adopt an ideal daisy-chain topology due to physical layout constraints, such as limited printed circuit board (PCB) routing space or dispersed device layout, long branch lines can cause signal reflections, impedance discontinuities, and capacitive load stacking, resulting in degraded serial bus signal quality. Summary of the Invention

[0004] The present application provides a multi-device serial bus communication system to at least solve the problem in the related art of signal quality degradation caused by excessively long branch lines.

[0005] The present application provides a multi-device serial bus communication system, including: a communication host; at least two communication slaves, the communication slaves are connected to the main line of the serial bus through corresponding branch lines in the serial bus, and are connected to the communication host through the main line; a signal isolator is provided on the branch line corresponding to at least one communication slave, and the signal isolator is used to isolate the signal transmitted on the corresponding branch line when the communication slave connected to itself is not selected.

[0006] In the present application, a signal isolator is provided on a branch line corresponding to at least one communication slave. The signal isolator isolates the signal transmitted on the corresponding branch line when the communication slave connected to itself is not selected, and the unselected communication slave is physically disconnected from the main line of the serial bus, thereby avoiding problems such as signal reflection, impedance discontinuity and capacitive load superposition caused by the excessive length of the branch line, improving the quality of high-frequency signals transmitted by the serial bus, and ensuring the timing stability and communication reliability of the serial bus transmission signal in multi-device scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In order to more clearly illustrate the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0008] Figure 1 Schematic diagram of the structure of a multi-device serial bus communication system in the related art;

[0009] Figure 2 Schematic diagram of another multi-device serial bus communication system in the related art;

[0010] Figure 3 This is a structural diagram of a multi-device serial bus communication system in an embodiment of the present application;

[0011] Figure 4 This is a schematic structural diagram of another multi-device serial bus communication system according to an embodiment of the present application;

[0012] Figure 5 This is a structural diagram of another multi-device serial bus communication system according to an embodiment of the present application;

[0013] Figure 6 This is a structural diagram of another multi-device serial bus communication system in an embodiment of the present application. DETAILED DESCRIPTION

[0014] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0015] It should be noted that, in the description of this application, the terms "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. The terms "first," "second," etc., in this application are used to distinguish similar objects, and are not used to describe a particular order or sequence.

[0016] In related technologies, when multiple communication slaves are dispersed on a PCB or connected across boards, a multi-device serial bus communication solution may encounter problems such as signal reflection, impedance discontinuity, and capacitive load superposition due to the excessive length of the branch lines. It is necessary to ensure signal integrity by reducing the bus rate, etc., which will greatly affect the bus communication efficiency.

[0017] Serial bus communication solutions include those based on the Enhanced Serial Peripheral Interface (eSPI) and the Serial Peripheral Interface (SPI).

[0018] eSPI was designed to replace the existing LPC bus in the x86 architecture. While fully compatible with the LPC bus's functionality, it also further expands data transmission capabilities and communication scope. For example, eSPI converts out-of-band (OOB) System Management Bus (SMBus) and sideband GPIO signals into in-band messages that can be transmitted over eSPI, significantly expanding the types of signals it can transmit and the functional implementation options. Furthermore, eSPI allows a single master device to connect to multiple slave devices, selecting each slave device through the Chip Select (CS) signal. This feature provides the foundation for building multi-device collaborative systems. Furthermore, eSPI supports multiple virtual channels, allowing different channels to handle different types of data transmission, making eSPI more adaptable to complex data exchange scenarios.

[0019] Taking the multi-device eSPI communication solution as an example, the related art connects a single communication master (Master) to multiple communication slaves (Targets). The eSPI communication bus primarily consists of clock (CLK) and data (DATA) lines. The master and all slaves share clock and data signals, and each slave requires its own chip select signal. When the master pulls down the chip select signal of a slave, the corresponding slave interprets the clock and data signals sent by the master. Other slaves whose chip select signals have not been pulled down will not respond to the clock and data signals on the eSPI communication bus.

[0020] However, current eSPI communication technology still faces a series of challenges and limitations in practical applications. In terms of device connection, in order to reduce the number of bus signals, multiple communication slaves share the same clock and data signals under the same communication, and only a separate chip select signal is used to determine which communication slave the data currently transmitted on the bus is valid for. This limits the system's flexibility in expanding the number of devices. When building large-scale, complex multi-device communication systems, it is necessary to consider the mutual influence of signal integrity between multiple devices and optimize the PCB wiring to ensure that all communication slaves can receive correct data. However, when multiple communication slaves are distributed more dispersedly on the PCB or connected across boards, it is necessary to strictly control the daisy chain topology or reduce the bus rate to ensure the integrity of the eSPI signal, which will greatly affect the efficiency of bus communication.

[0021] like Figure 1 As shown, the related technology directly connects the communication master Master to three communication slaves Target0, Target1, and Target2 via clock and data lines. This requires a daisy-chain topology during PCB layout and routing. Specifically, the three communication slaves must be as close together as possible, with the main line from the communication master Master to the farthest communication slave Target2. The branch lines from the main line to communication slaves Target0 and Target1 are as short as possible to minimize the impact of signal reflections on the integrity of the eSPI communication signal. Transmission line theory shows that in this topology, the signal reaching communication slave Target0 is affected by the extra transmission line from Target0 to Target2, resulting in poor signal quality. In this case, strict control of the daisy-chain topology can optimize the signal quality of communication slave Target0.

[0022] When the layout of the communication slaves is relatively scattered, such as Figure 2 As shown in the figure, if the communication slave Target2 and the communication master Master are located on two different boards and require a long cable connection, the layout of the communication slaves Target0 and Target1 cannot be close to the communication slave Target2, thus failing to form a daisy-chain topology. In this case, only the communication master and the communication slave Target2 are unaffected due to the short extra branch cable. The communication between the communication master and the communication slaves Target0 and Target1 will be affected by the long branch cable of the communication slave Target2, which will reflect the normal transmission signal, reducing the signal transmission quality and affecting the normal eSPI communication.

[0023] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0024] The embodiment of the present application provides a multi-device serial bus communication system, such as Figure 3 As shown, the system includes:

[0025] Communication host;

[0026] At least two communication slaves, each of which is connected to a main line of the serial bus via a corresponding branch line in the serial bus and is connected to a communication master via the main line;

[0027] A signal isolator is provided on a branch line corresponding to at least one communication slave, and the signal isolator is used to isolate the signal transmitted on the corresponding branch line when the communication slave connected to the signal is not selected.

[0028] Specifically, the multi-device serial bus communication system of the embodiment of the present application is applicable to various electronic systems that require multiple devices to work together, such as industrial control, smart home, Internet of Things devices, etc.

[0029] Multi-device serial bus communication refers to a system in which a master device exchanges data with multiple slave devices via a serial bus. The master device controls and coordinates the communication process, while the slave devices receive commands from the master and provide feedback on data or status. Multi-device serial bus communication solutions include those based on eSPI and SPI.

[0030] As the control center of the entire multi-device serial bus communication system, the communication host possesses powerful data processing and communication management capabilities. It coordinates the operations of the various communication slaves, including sending commands, receiving data, allocating communication resources, and managing communication timing. Its design requires high-speed data processing capabilities to meet the data flow requirements of multi-device communication, and it must also exhibit excellent stability and reliability to ensure the normal operation of the entire system.

[0031] For example, the communication host may adopt various common processors or controllers, such as a central processing unit (CPU), a microcontroller unit (MCU), a digital signal processor (DSP), or a field-programmable gate array (FPGA).

[0032] There are multiple communication slaves, devices that communicate with the master. These slaves connect to the main serial bus line via corresponding branch lines, and are then connected to the master. These slaves can be various devices with data acquisition, processing, or execution capabilities, such as sensor nodes, actuator controllers, and data acquisition modules. Each slave has an independent communication interface for exchanging data with the master.

[0033] It should be understood that, depending on the actual application, the communication host and the communication slaves can be set on the same board, or the communication host and the communication slaves can be set on two boards respectively, or the communication host and some of the communication slaves can be set on the same board, and the other part of the communication slaves can be set on another board.

[0034] In a serial bus communication system, the main line serves as the core signal transmission channel, directly connecting to the communication host and fulfilling the critical task of transmitting signals between the communication host and the various branch lines. Each communication slave, in turn, connects to the main line via its own branch line and, in turn, establishes a connection with the communication host. When the communication host needs to communicate data with a specific communication slave, it selects that slave using a chip select signal. Once a communication slave is selected, the communication host can perform normal serial data transmission with it, including sending commands, writing data, and reading data. Communication slaves that are not selected do not need to receive or respond to data transmitted on the serial bus and remain in a standby state, awaiting possible subsequent communication instructions.

[0035] The core function of a signal isolator is to physically isolate signal transmission on branch lines. Specifically, when a communication slave is not selected, the signal isolator effectively blocks the signal on that branch line, preventing it from interfering with the signal on the main line. This interference is primarily caused by signal reflections, impedance mismatches, or other electrical characteristics on the branch line. By isolating the branch line signals from unselected communication slaves, the signal isolator significantly improves the communication reliability and signal quality of the entire system, ensuring the accuracy and stability of data transmission between the communication master and the selected slaves.

[0036] Signal isolators can be implemented in a variety of ways, with the most common ones being analog switches and buffers. Analog switches achieve signal isolation and transmission by controlling their on and off states. When the analog switch is on, the signal passes normally; when it is off, the signal transmission path is blocked, achieving isolation. Buffers, by providing functions such as signal amplification and impedance matching, not only achieve signal isolation but also provide a certain degree of signal shaping and amplification, thereby improving signal transmission quality.

[0037] Depending on the actual application scenario and requirements, the placement of signal isolators offers a degree of flexibility. In some simple systems, a single signal isolator might be installed on a single branch line of a communication slave to meet basic signal isolation requirements. In more complex systems, to more effectively control the potential interference of each branch line on the main line, signal isolators can be installed on the branch lines of multiple communication slaves. Generally speaking, to minimize the impact of branch lines on the overall signal, signal isolators are preferably placed on longer branch lines. This is because long branch lines are more prone to signal reflections and impedance mismatches, which have a more significant impact on the main line signal. By installing signal isolators on these long branch lines, signal interference can be more effectively suppressed, improving overall system performance.

[0038] In one example, during actual operation, the signal isolator is controlled by the communication host. When the communication slave connected to the signal isolator is enabled, the communication host sends a corresponding control signal to open the signal isolator. At this point, the signal can be transmitted normally from the main line to the branch line, and then to the communication slave, enabling data exchange. Conversely, when the communication slave connected to the signal isolator is not enabled, the communication host controls the signal isolator to be in an isolated state. In this case, the signal is reflected at the signal isolator and does not continue to transmit along the subsequent branch line and generate reflections. As a result, the signal received by the remaining communication slaves is greatly reduced in the presence of reflections, and the signal quality is significantly improved. Specifically, the signal reflection on the branch line of the unenabled communication slave is limited to before the isolator, and does not interfere with the signal propagation on the main line, thereby ensuring the purity and integrity of the main line signal.

[0039] Furthermore, this signal isolation mechanism provides a degree of system protection. In exceptional circumstances, such as when a slave communication device experiences a fault or abnormality, the signal isolator effectively prevents the fault signal from propagating to the main line, thereby preventing a chain reaction across the entire system. This facilitates system maintenance and troubleshooting, while also enhancing system reliability and stability.

[0040] The multi-device serial bus communication system of an embodiment of the present invention is provided with a signal isolator on a branch line corresponding to at least one communication slave. The signal isolator isolates the signal transmitted on the corresponding branch line when the communication slave connected to itself is not selected, and physically disconnects the unselected communication slave from the main line of the serial bus, thereby avoiding problems such as signal reflection, impedance discontinuity and capacitive load superposition caused by excessively long branch lines, improving the quality of high-frequency signals transmitted by the serial bus, and ensuring the timing stability and communication reliability of serial bus transmission signals in multi-device scenarios.

[0041] In some embodiments, the signal isolator is an analog switch. The analog switch is provided on a branch line corresponding to the communication slave device farthest from the communication host. The communication host is configured to control whether the communication slave device is enabled through a chip select signal. When the communication slave device isolated by the analog switch is enabled, the analog switch is controlled to open.

[0042] Specifically, the analog switch may be a high-bandwidth, low-on-resistance metal-oxide-semiconductor (CMOS) analog switch, a metal-oxide-semiconductor field-effect transistor (MOSFET) switch, a mechanical contact switch, or an optically coupled switch.

[0043] Analog switches offer fast response times, rapidly switching between signal isolation and conduction. This rapid response ensures timely communication systems, enabling signals to be transmitted quickly when needed without lengthy waits or delays. Furthermore, the control logic for analog switches is relatively simple, typically controlled by simple high- and low-level signals to open and close them. This simple control approach not only reduces system complexity but also improves reliability and stability, reducing the risk of failures that can arise from complex control logic.

[0044] Place the analog switch on the branch line of the communication slave device farthest from the communication master, and control the opening of the analog switch through the control master. When the system is limited by physical layout, such as the large distance between devices cannot adopt the daisy chain topology, this layout can effectively reduce the impact of the long-distance communication slave device on the bus signal quality, reducing signal attenuation and interference.

[0045] At the same time, the communication host achieves efficient management of the entire communication process by synchronously controlling the selection status of the communication slave and the on / off status of the analog switch. When data communication with a communication slave is required, the communication host sends a chip select signal to select the slave and simultaneously controls the corresponding analog switch to open, allowing signal transmission to the slave. When the slave is not selected, the communication host controls the analog switch to an isolated state, blocking signal transmission on the branch line and preventing interference with the bus signal. This synchronous control method eliminates the need for an additional control unit, reducing system size and cost, and improving system integration and cost-effectiveness.

[0046] In some embodiments, the enable end of the analog switch and the select end of the corresponding communication slave are both connected to the same chip select pin on the communication host. The communication host is used to control whether the communication slave is enabled and whether the corresponding analog switch is turned on or off through the chip select signal.

[0047] Specifically, the on-off logic of the analog switch corresponds to the selection logic of the communication slave. Taking the enhanced serial peripheral interface bus as an example, the selection logic of the communication slave is low-level selection, and the analog switch is low-level open, so that the communication host can control the corresponding analog switch to open when the communication slave is selected, and control the corresponding analog switch to turn off when the communication slave is not selected.

[0048] In one example, the serial bus is an eSPI bus, with three communication slaves. A communication master connects to the three communication slaves sequentially from left to right via the CLK and DATA lines of the eSPI bus. An analog switch is provided on the branch line from the farthest communication slave, the rightmost communication slave. The three communication slaves are arranged from left to right, with the strobe pins of the first, second, and third communication slaves connected to the first, second, and third chip select pins CS0, CS1, and CS2 of the communication master, respectively. The third chip select pin CS2 is also connected to the analog switch, meaning that the analog switch is controlled by the chip select signal output by the third chip select pin CS2.

[0049] When the communication master selects the third communication slave, the analog switch is open. When the communication master is idle or selects the first communication slave or the second communication slave, the analog switch is closed.

[0050] When the communication host communicates with the first or second communication slave, the analog switch is turned off. The signal will be reflected at the analog switch and will no longer be reflected again after being transmitted to the subsequent long-distance branch line. Therefore, the reflection effect of the eSPI CLK signal and DATA signal received at the first communication slave and the selected second communication slave is greatly reduced, and the signal quality is significantly improved, achieving normal eSPI communication.

[0051] When the communication host selects the third communication slave, the analog switch is opened. At this time, the actual signal receiving end is the third communication slave. Although the quality of the CLK signal and DATA signal received by the first and second communication slaves will deteriorate, the bus data at this time does not require the response of the first and second communication slaves, so it will not affect the communication.

[0052] The multi-device serial bus communication system of the embodiment of the present application not only reduces the impact of excessively long branch lines on signal transmission by setting analog switches, but also simultaneously controls the communication slave selection and analog switches through the chip select pin of the communication host, thereby simplifying the control logic.

[0053] Furthermore, the chip select signal of each communication slave directly controls the enable terminal of the corresponding analog switch. The on / off action of the analog switch is strictly synchronized with whether the communication slave is strobed. Due to the certain delay in strobing, it can ensure that the channel connection is completed before the communication slave is strobed. At the same time, when the communication slave is not strobed, the analog switch remains closed, isolating the communication slave from the physical connection of the bus, thereby improving the stability and reliability of the multi-device serial bus communication system.

[0054] In some embodiments, as Figure 4 As shown, the communication slave isolated by the analog switch is arranged on the second circuit board, the communication host, the analog switch and the remaining communication slaves are arranged on the first circuit board, and the communication slave isolated by the analog switch is connected to the analog switch via a connecting line.

[0055] Specifically, the communication slave isolated by the analog switch is placed on the second circuit board, and the analog switch and the communication host are arranged on the first circuit board, so as to realize a flexible layout of the communication slave.

[0056] When the communication slave on the second circuit board is deselected, the analog switch is turned off, and the signal is reflected back from the analog switch. Compared to traditional designs, this eliminates the need for the signal to traverse a long transmission line before reflection, significantly shortening the signal reflection path. Even in complex scenarios where the communication slaves are distributed across different circuit boards, high signal transmission quality is effectively maintained, significantly improving the overall performance and stability of the communication system.

[0057] Furthermore, a first connecting terminal is provided on the first circuit board, and a second connecting terminal is provided on the second circuit board. The first connecting terminal is connected to the second connecting terminal through a connecting wire, the analog switch is connected to the first connecting terminal, and the communication slave isolated by the analog switch is connected to the second connecting terminal.

[0058] Specifically, the first connection terminal and the second connection terminal are precisely connected through the connection line, so that the analog switch is closely connected to the first connection terminal, and the communication slave isolated by the analog switch is reliably connected to the second connection terminal.

[0059] It should be understood that the first connection terminal and the second connection terminal are equipped with at least three pin headers, which are responsible for transmitting the chip select signal, CLK signal and DATA signal in turn. During the actual connection process, the pin headers of the first connection terminal and the second connection terminal are connected to each other, and accurate signal transmission is achieved through the connecting wire. This terminal connection method can avoid messy wiring methods, make the connection between circuit boards more orderly, greatly improve the standardization of the connection, and also provide great convenience for installation and maintenance personnel. In actual operation, the installer can easily insert the connecting wire into the corresponding pin header to achieve quick connection; and when disassembly or maintenance is required, the connecting wire can also be quickly unplugged to perform independent inspection and maintenance of the circuit board, saving time and labor costs and improving work efficiency.

[0060] In some embodiments, as Figure 5 As shown, the number of analog switches is the same as the number of communication slaves. Any analog switch is set on the branch line of the corresponding communication slave. The enable end of any communication slave is connected to different chip select pins on the communication host. The communication host is used to control whether the communication slave is enabled through the chip select signal. When the communication slave is enabled, the corresponding analog switch is controlled to open.

[0061] Exemplarily, the serial bus is an eSPI bus, and there are three communication slaves. The communication host is connected to the three communication slaves from left to right in sequence through the CLK line and DATA line of the eSPI bus. The three communication slaves are arranged from left to right, and a corresponding analog switch is provided on the branch line of each communication slave.

[0062] Specifically, the strobe pins of the first, second, and third communication slaves, along with their corresponding analog switches, are connected to the first, second, and third chip select pins (CS0, CS1, and CS2) on the communication master, respectively. Each analog switch is controlled by the chip select signal from its respective communication slave. When the communication master needs to exchange data with a specific communication slave, it sends a strobe signal to the corresponding chip select pin, simultaneously controlling the conduction of the corresponding analog switch, thus establishing a signal transmission path between the communication master and the target communication slave.

[0063] With the above setup, the impact of extraneous branch lines can be ignored by simply ensuring that the three analog switches are routed close enough on the circuit board. The layout of the three communication slaves is largely unaffected by their relative positions, which provides greater flexibility and convenience for the overall circuit board layout design. Designers can focus more on arranging the positions of the communication slaves from the perspective of overall system architecture and functional implementation, without worrying too much about the adverse effects of their relative positions on signal transmission quality. They only need to ensure that the trace length from each communication slave to the communication master meets the maximum trace distance requirements to ensure that the signal can be transmitted with sufficient strength and integrity.

[0064] Since the chip select signal only selects one analog switch at a time and the three analog switches are close enough, the multi-device serial bus communication system of the embodiment of the present invention can be considered as a point-to-point topology with the communication host connecting to three communication slaves respectively. This point-to-point communication method completely eliminates the adverse effects such as signal reflection and interference that may be caused by the branch lines of other communication slaves, thereby maximizing the signal quality of the eSPI bus, providing a solid foundation for the system to transmit data stably and efficiently, and effectively ensuring the reliable operation and high performance of the entire communication system in various complex working environments.

[0065] In addition, the embodiment of the present invention eliminates the impedance mutation caused by the branch line of the unselected communication slave by turning off the analog switch, shortening the equivalent length of the branch line to the level of the switch package parasitic parameters, and when the analog switch is in the off state, the equivalent capacitance of the corresponding communication slave to the bus is reduced to the off capacitance range of the analog switch, effectively ensuring the integrity of the signal.

[0066] In some embodiments, as Figure 6 As shown, the communication slave includes a first communication slave and a second communication slave, the analog switch is set on the branch line corresponding to the second communication slave, the selection end of the first communication slave and the selection end of the second communication slave are both connected to the same chip select pin on the communication host, the enable end of the analog switch is connected to the first communication slave, the first communication slave monitors the working status of the second communication slave, when the second communication slave is working normally, the first communication slave controls the analog switch to open, and receives the information on the serial bus parsed by the second communication slave, when the second communication slave is hung, the first communication slave controls the analog switch to turn off, the first communication slave parses the information on the serial bus and outputs response information to the serial bus.

[0067] Furthermore, the first communication slave is also connected to the second communication slave via a preset bus. The first communication slave sends a monitoring signal to the second communication slave via the preset bus and receives information on the serial bus parsed by the second communication slave.

[0068] In one example, the I2C bus is a simple, bidirectional, two-wire synchronous serial bus commonly used to connect microcontrollers and peripheral devices. The monitoring signal uses a watchdog signal. The watchdog signal is a signaling mechanism used to monitor system operation and is widely used in embedded systems for fault detection and recovery.

[0069] Specifically, the first communication slave sends a watchdog signal to the second communication slave via the I2C bus. When the second communication slave receives the signal, it processes it accordingly based on its current operating status and returns a signal to the first communication slave. By monitoring the signal returned by the second communication slave, the first communication slave can determine whether the second communication slave is operating normally.

[0070] When the second communication slave is operating normally, the watchdog signal it returns is a pulse-width modulated (PWM) wave. PWM is a coding method that modulates the width of a series of pulses to transmit various forms of information. In this example, a normal PWM wave indicates that the second communication slave is operating normally. However, if the second communication slave experiences a fault such as a hang-up, the PWM wave signal stops jumping, remaining stable and no longer exhibiting PWM characteristics. By detecting this change, the first communication slave can quickly identify abnormal conditions in the second communication slave, effectively monitoring its operating status.

[0071] Exemplarily, the serial bus is an eSPI bus, and there are three communication slaves. The communication master is connected to the three communication slaves from left to right via the CLK line and DATA line of the eSPI bus. The three communication slaves are, from left to right, the third communication slave, the first communication slave, and the second communication slave. The communication master, the third communication slave, the first communication slave, and the analog switch are provided on one circuit board, and the second communication slave is provided on another circuit board. The third communication slave and its corresponding analog switch are respectively connected to the first chip select pin CS0 of the communication master, and the first and second communication slaves are both connected to the third chip select pin CS2. The analog switch is provided on a branch line of the second communication slave, and the enable terminal of the analog switch is connected to and controlled by the first communication slave.

[0072] The first communication slave and the second communication slave share the third chip select pin CS2. When the second communication slave is working normally, the first communication slave only acts as a receiver, synchronously parsing part of the eSPI information sent by the communication host to the second communication slave, and will not respond to the serial bus, so there will be no conflict in the shared chip select pin.

[0073] The multi-device serial bus communication system of an embodiment of the present invention operates as follows: a first communication slave monitors the normal operation of a second communication slave. If the second communication slave is operating normally, the analog switch is opened, and the first communication slave does not parse the corresponding information. Instead, the second communication slave receives the information and transmits it to the first communication slave via another path, such as the I2C bus. If the first communication slave detects that the second communication slave is dead, the second communication slave is unable to synchronize the corresponding information with the first communication slave. The first communication slave actively turns off the analog switch, responds to the eSPI information sent by the communication master on behalf of the second communication slave, and parses the corresponding content.

[0074] In a multi-device serial bus communication system according to an embodiment of the present invention, a first communication slave monitors the operating status of a second communication slave. During normal operation, the first communication slave controls an analog switch to open and receive parsed information from the second communication slave. In the event of a hang-up, the analog switch is turned off, and the first communication slave independently parses and outputs a response. This design allows the first and second communication slaves to share a chip select signal without affecting the normal operation of the two communication slaves. This allows the communication host to connect to more communication slaves, increasing the scalability of the multi-device serial bus communication system.

[0075] It should be understood that the number of three communication slaves described in any of the above embodiments of the present invention is only an example. In different usage scenarios, the number of communication slaves can be two, four, six, or other different numbers to meet usage requirements.

[0076] In addition, based on the addition of analog switches in the above embodiment, those skilled in the art may also combine other means to improve signal transmission quality, such as terminal impedance matching (such as series termination resistors) and trace length optimization, to improve the integrity of eSPI high-frequency signals above 66 MHz, reduce the bit error rate, and ensure the timing stability and communication reliability of eSPI signals in multi-device scenarios.

[0077] In some embodiments, the signal isolator employs a buffer.

[0078] When a signal isolator uses a buffer, its function is to re-drive the received signal, so the input and output are effectively isolated at all times. Using a buffer eliminates the need for chip select signals to dynamically turn the buffer on and off. Simply place three buffers on the circuit board in a daisy-chain topology that meets the requirements. Each buffer's output connects to the communication slave in a point-to-point topology, unaffected by the input.

[0079] However, this advantage of buffers also comes with significant limitations. Because buffers must first identify the input signal and then re-drive the output, this process inevitably introduces significant latency. Typically, buffer latency can reach 8ns, compared to the typical 0.5ns latency of an analog switch. This makes the buffer's latency 40 times greater. Considering the complete link from a communication host sending a signal and ultimately receiving a response, after two buffer delays, the overall link latency increases by 15ns compared to a solution using analog switches. This significant delay increase can negatively impact the communication host's timing judgment, potentially leading to data parsing anomalies and compromising the reliability and stability of the entire communication system.

[0080] Therefore, in the aforementioned embodiment using analog switches with lower latency, since the analog switches cannot isolate the input and output when turned on, the communication host proposes to precisely control the analog switches through their chip select signals, achieving dynamic management of the signal path. When data exchange with a specific communication slave is required, the communication host sends the corresponding chip select signal, enabling the corresponding analog switch, thereby establishing a signal path between the communication host and the target communication slave. This dynamic management approach not only ensures the integrity of the signal transmission process, but also minimizes the impact on the overall link timing, avoiding communication anomalies caused by excessive latency.

[0081] Furthermore, dynamic enable control of analog switches can effectively avoid communication quality issues that may arise from complex factors such as signal reflections and interference. In practical applications, this optimized communication architecture design is crucial for improving system performance and reliability. In particular, in high-speed communication scenarios with strict timing requirements, the use of analog switches combined with chip select signal control can fully leverage their low-latency advantages, ensuring stable and efficient operation of the communication system and meeting the urgent need for high-speed, reliable data transmission in modern electronic devices.

[0082] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the components and steps of each example according to their functions. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0083] The above is a detailed introduction to a multi-device serial bus communication system provided by the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only intended to help understand the method and core concept of the present application. It should be noted that, for those skilled in the art, without departing from the principles of the present application, several improvements and modifications may be made to the present application, and such improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A multi-device serial bus communication system, characterized in that: include: Communication host; At least two communication slaves, each of which is connected to a main line of the serial bus via a corresponding branch line of the serial bus and is connected to the communication master via the main line; A signal isolator is provided on the branch line corresponding to at least one of the communication slaves, and the signal isolator is used to isolate the signal transmitted on the corresponding branch line when the communication slave connected to the signal is not selected. The signal isolator is an analog switch or a buffer, wherein the branch line and the trunk line both include an LCK line and a DATA line, and the analog switch is located on the LCK line and the DATA line. The enable end of the analog switch and the selection end of the corresponding communication slave are both connected to the same chip select pin on the communication host, and the communication host is used to control whether the communication slave is selected and whether the corresponding analog switch is turned on or off through the chip select signal; The analog switch is provided on the branch line corresponding to the communication slave farthest from the communication host, and the communication host is used to control whether the communication slave is enabled through a chip select signal, and when the communication slave isolated by the analog switch is enabled, the analog switch is controlled to be turned on, and when the communication slave is not enabled, the corresponding analog switch is controlled to be turned off; The communication slave isolated by the analog switch is arranged on a second circuit board, and the communication master, the analog switch, and the remaining communication slaves are arranged on a first circuit board. The communication slave isolated by the analog switch is connected to the analog switch via a connecting wire. A first connecting terminal is further provided on the first circuit board, and a second connecting terminal is further provided on the second circuit board. The first connecting terminal is connected to the second connecting terminal via a connecting wire. The analog switch is connected to the first connecting terminal, and the communication slave isolated by the analog switch is connected to the second connecting terminal. The communication slave includes a first communication slave and a second communication slave, the analog switch is set on the branch line corresponding to the second communication slave, the enable end of the first communication slave and the enable end of the second communication slave are both connected to the same chip select pin on the communication host, the enable end of the analog switch is connected to the first communication slave, the first communication slave monitors the working status of the second communication slave, when the second communication slave is working normally, the first communication slave controls the analog switch to open and receives information on the serial bus parsed by the second communication slave, when the second communication slave is hung, the first communication slave controls the analog switch to turn off, the first communication slave parses the information on the serial bus and outputs response information to the serial bus, the first communication slave is also connected to the second communication slave via a preset bus, the first communication slave sends a monitoring signal to the second communication slave via the preset bus and receives information on the serial bus parsed by the second communication slave.

2. The multi-device serial bus communication system according to claim 1, wherein: The number of the analog switches is the same as the number of the communication slaves. Any one of the analog switches is respectively arranged on the branch line of the corresponding communication slave. The enable end of any one of the communication slaves is respectively connected to different chip select pins on the communication host. The communication host is used to control whether the communication slave is enabled through a chip select signal. When the communication slave is enabled, the corresponding analog switch is controlled to open.

3. The multi-device serial bus communication system according to claim 1, wherein: The serial bus is an enhanced serial peripheral interface bus.

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