Multi-device serial bus communication system

Abstract

The invention discloses a multi-device serial bus communication system, and relates to the technical field of serial communication, the multi-device serial bus communication system comprises a communication host, at least two communication slaves and a signal isolator, the communication slaves are accessed to a trunk line of a serial bus through corresponding branch lines in the serial bus and are connected with the communication host through the trunk line, and the signal isolator is connected with the communication host through a corresponding branch line in the serial bus. The signal isolator is arranged on the branch line corresponding to at least one communication slave machine and used for isolating signals transmitted on the corresponding branch line when the communication slave machine connected with the signal isolator is not gated, and the problems of signal reflection, discontinuous impedance, capacitive load superposition and the like caused by the fact that the branch line is too long can be avoided; and the quality of high-frequency signal transmission of the serial bus is improved.

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] In modern electronic devices and systems, communication technology is crucial. Its high efficiency, stability and flexibility can improve device performance and help expand functions. Serial communication interfaces are widely used due to their simple wiring, low cost and strong adaptability.

[0003] In the device connection based on serial bus communication, multiple communication slaves under the same communication host share the same serial bus, including clock and data signals, and the chip select signal is used to determine which communication slave the data transmitted on the current bus is valid for. When multiple slaves are limited by physical layout, such as limited wiring space on the printed circuit board (PCB) or scattered equipment, it is impossible to adopt the ideal daisy chain topology. If the branch line is too long, it will cause signal reflection, impedance discontinuity, capacitive load superposition and other problems, resulting in the degradation of the signal quality of the serial bus. 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 that signal quality is degraded due to 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 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] To more clearly illustrate the embodiments of the present application, the accompanying drawings required for the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0008] Figure 1 It is a schematic structural diagram of a multi-device serial bus communication system in the related art; Figure 2 It is a schematic structural diagram of another multi-device serial bus communication system in the related art; Figure 3 It is a schematic structural diagram of a multi-device serial bus communication system in an embodiment of the present application; Figure 4 It is a schematic structural diagram of another multi-device serial bus communication system in an embodiment of the present application; Figure 5 It is a schematic structural diagram of yet another multi-device serial bus communication system in an embodiment of the present application; Figure 6 It is a schematic structural diagram of still another multi-device serial bus communication system in an embodiment of the present application. Detailed implementation manners

[0009] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present application.

[0010] It should be noted that in the description of the present application, the terms "including", "comprising" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. The terms "first", "second", etc. in the present application are used to distinguish similar objects and are not used to describe a specific order or sequence.

[0011] In the related art, in the multi-device serial bus communication solution, when multiple communication slaves are relatively dispersed on the PCB or connected across boards, due to the excessively long branch lines, problems such as signal reflection, impedance discontinuity, and capacitive load superposition will occur. It is necessary to ensure signal integrity by means such as reducing the bus rate, which will greatly affect the bus communication efficiency.

[0012] Serial bus communication solutions include communication solutions based on the Enhanced Serial Peripheral Interface (eSPI) and the Serial Peripheral Interface (SPI), etc.

[0013] Among them, eSPI is designed to replace the original LPC bus under the x86 architecture. It not only fully compatible with the functions of the LPC bus, but also further expands the data transmission capacity and communication scope. For example, eSPI converts the Out-of-Band (OOB) System Management Bus (SMBus) and the Side-Band GPIO into In-Band messages that can be transmitted on eSPI, greatly enriching the types of signals it can transmit and the ways to implement functions. At the same time, eSPI allows a master device to connect to multiple slave devices and uses the Chip Select (CS) signal to select each slave device. This feature provides basic support for building a system where multiple devices work together. In addition, eSPI also supports multiple virtual channels, and different channels can be responsible for different types of data transmission tasks respectively, making eSPI more adaptable in complex data interaction scenarios.

[0014] Taking the eSPI communication solution for multiple devices as an example, in related technologies, a communication host is connected to multiple communication targets. The eSPI communication bus mainly includes a Clock (CLK) line and a DATA line. The clock signal and data signal are shared by the communication host and all communication targets, and each communication target requires an independent chip select signal. When the chip select signal of a communication target is pulled low by the communication host, the corresponding communication target will parse the clock signal and data signal sent by the communication host, and other communication targets whose chip select signals are not pulled low will not respond to the clock signal and data signal on the eSPI communication bus.

[0015] However, the current eSPI communication technology still faces a series of challenges and limitations in practical applications. In terms of device connection, to reduce the number of bus signals, multiple communication slaves share the same clock and data signals under the same communication, and only determine which communication slave the data transmitted on the current bus is valid through a separate chip select signal. This limits the flexibility of the system in terms of expanding the number of devices. When building a large-scale and complex multi-device communication system, it is necessary to consider the mutual influence of signal integrity among multiple devices and optimize the PCB wiring to ensure that all communication slaves can receive correct data. However, when multiple communication slaves are relatively dispersed on the PCB or connected across boards, it is necessary to strictly control the daisy chain topology or reduce the bus speed and other means to ensure the integrity of eSPI signals, which will greatly affect the bus communication efficiency.

[0016] As Figure 1 shown, the related technology directly connects the communication host Master to three communication slaves Target0, Target1, and Target2 through the clock line and data line. It is necessary to adopt the daisy chain topology in the PCB layout and wiring, that is, pay attention to the fact that the three communication slaves are as close as possible, and the trace from the communication host Master to the farthest communication slave Target2 is the main trunk line, and the branch lines from the main trunk line to the communication slave Target0 and the communication slave Target1 are as short as possible to reduce the impact of signal reflection on the integrity of eSPI communication signals. According to the transmission line theory, in this topology, the signal reaching the communication slave Target0 is affected by an extra transmission line section from the communication slave Target0 to the communication slave Target2, and the signal quality is poor. At this time, the signal quality of the communication slave Target0 can be optimized by strictly controlling the daisy chain topology.

[0017] When the layout of the communication slaves is relatively dispersed, as Figure 2 shown, the communication slave Target2 and the communication host Master are located on two different boards respectively, and when the two boards need to be connected by a long cable, the layouts of the communication slave Target0 and the communication slave Target1 cannot be close to the communication slave Target2, so the daisy chain topology cannot be satisfied. At this time, only the communication between the communication host Master and the communication slave Target2 is not affected because the extra branch line is short. The communication between the communication host Master and the communication slave Target0 and the communication slave Target1 will reflect the signals transmitted normally due to the too long branch line of the communication slave Target2, reducing the signal transmission quality and affecting the normal communication of eSPI.

[0018] To enable those skilled in the art of this technology to better understand the solution of this application, the following further elaborates on this application in combination with the accompanying drawings and specific embodiments.

[0019] Embodiments of the present application provide a multi-device serial bus communication system, such as Figure 3 shown. The system includes: 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. 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.

[0020] Specifically, the multi-device serial bus communication system of the embodiments of the present application is applicable to various electronic systems that require multi-device collaborative work, such as industrial control, smart home, Internet of Things devices, etc.

[0021] Multi-device serial bus communication refers to a solution in which a communication host and multiple communication slaves perform data interaction through a serial bus in a communication system. The communication host is responsible for controlling and coordinating the entire communication process, while the communication slave is a device that receives the host instruction and feeds back corresponding data or status information. The multi-device serial bus communication solution includes communication solutions based on eSPI and SPI, etc.

[0022] As the control center of the entire multi-device serial bus communication system, the communication host has powerful data processing and communication management capabilities. The communication host is responsible for coordinating the work among the communication slaves, including sending instructions, receiving data, allocating communication resources, and managing communication timing, etc. Its design needs to have high-speed data processing capabilities to meet the data traffic requirements during multi-device communication, and should have good stability and reliability to ensure the normal operation of the entire system.

[0023] Exemplarily, the communication host can 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), etc.

[0024] There are multiple communication slaves, which are devices that communicate with the host. The communication slaves are connected to the main line of the serial bus through corresponding branch lines in the serial bus and are thus connected to the communication host. The communication slave can be various devices with data acquisition, processing, or execution functions, such as sensor nodes, actuator controllers, data acquisition modules, etc. Each communication slave has an independent communication interface for data interaction with the communication host.

[0025] It should be understood that according to the actual application scenario, the communication host and the communication slave can be set on the same board, or the communication host and the communication slave are respectively set on two boards, or the communication host and a part of the communication slaves are set on the same board, and the other part of the communication slaves are set on another board.

[0026] In a serial bus communication system, the main line serves as the core signal transmission channel, directly connecting to the communication host and undertaking the key task of transmitting signals between the communication host and each branch line. Each communication slave is connected to the main line through its respective branch line, and then establishes a connection with the communication host. When the communication host needs to conduct data communication with a specific communication slave, it selects the communication slave through a chip select signal. Once the communication slave is selected, the communication host can perform normal serial data transmission with it, including various operations such as sending instructions, writing data, or reading data. The communication slaves that are not selected do not need to receive or respond to the data transmitted on the serial bus and are in a standby state, waiting for possible subsequent communication instructions.

[0027] The core function of the signal isolator is to physically isolate the signal transmission on the branch line. Specifically, when a certain communication slave is not selected, the signal isolator can effectively block the signal on that branch line, preventing it from interfering with the signal on the main line. This interference is mainly caused by signal reflection, impedance mismatch, or other electrical characteristic problems on the branch line. By isolating the branch line signal of the unselected communication slave, 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 host and the selected slave.

[0028] There are various ways to implement the signal isolator. Common ones include analog switches (analog switch) and buffers (buffer), etc. The analog switch realizes signal isolation and transmission by controlling its on and off states. When the analog switch is in the on state, the signal can pass through normally; when it is off, it blocks the signal transmission path to achieve the purpose of isolation. The buffer, while realizing signal isolation, can also perform a certain degree of signal shaping and enhancement by providing functions such as signal amplification and impedance matching to improve the signal transmission quality.

[0029] According to the actual application scenarios and requirements, the setting method of the signal isolator also has a certain degree of flexibility. In some simple systems, only one signal isolator may be set on the branch line of a communication slave to meet the basic signal isolation requirements. In more complex systems, in order to more effectively control the potential interference of each branch line on the main line, signal isolators can be set on the branch lines of multiple communication slaves. Generally speaking, in order to minimize the impact of the branch line on the overall signal, the signal isolator is preferably set on the longer branch line. This is because long branch lines are more likely to cause problems such as signal reflection and impedance mismatch, and the impact on the main line signal is also more significant. By setting signal isolators on these long branch lines, signal interference can be more effectively suppressed and the overall performance of the system can be improved.

[0030] In one example, during the 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 turn on the signal isolator. At this time, the signal can be normally transmitted from the main line to the branch line, and then reach the communication slave to achieve data interaction. On the contrary, 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 will be reflected at the signal isolator, and will not continue to be transmitted along the subsequent branch line and generate reflections. In this way, the signal received at the remaining communication slaves is greatly reduced by the reflection, and the signal quality is significantly improved. Specifically, the signal reflection on the branch line of the communication slave that has not been enabled will be limited before the isolator, and will not interfere with the signal propagation on the main line, thereby ensuring the purity and integrity of the main line signal.

[0031] Furthermore, this signal isolation mechanism also has a certain system protection function. In some special cases, such as when the communication slave fails or is in an abnormal state, the signal isolator can effectively prevent the fault signal from propagating to the main line, avoiding a chain reaction to the entire system. This facilitates system maintenance and troubleshooting, and also enhances the reliability and stability of the system.

[0032] The multi-device serial bus communication system of the embodiment of the present invention is provided with a signal isolator on the 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.

[0033] In some embodiments, the signal isolator is an analog switch. The analog switch is disposed on the branch line corresponding to the communication slave that is farthest from the communication host. The communication host is configured to control whether the communication slave is selected through a chip select signal, and when the communication slave isolated by the analog switch is selected, the analog switch is controlled to turn on.

[0034] Specifically, the analog switch can be a complementary metal-oxide-semiconductor (CMOS) analog switch with high bandwidth and low on-resistance, a metal-oxide-semiconductor field-effect transistor (MOSFET) switch, a mechanical contact switch, an opto-coupler switch, or the like.

[0035] The analog switch has a fast response speed and can quickly switch between the signal isolation and conduction states. This fast response ability ensures the timeliness of the communication system, enabling signals to be transmitted quickly when needed without long waiting or delays. Moreover, the control logic of the analog switch is relatively simple and can usually be controlled to turn on and off through simple high and low level signals. This simple control method not only reduces the control complexity of the system but also improves the reliability and stability of the system, reducing the risk of failures that may occur due to complex control logic.

[0036] Placing the analog switch on the branch line of the communication slave farthest from the communication host and controlling the analog switch to turn on through the control host, when the system is limited by the physical layout, such as when the device spacing is too large to use a daisy chain topology, this layout can effectively reduce the impact of the long-distance communication slave on the bus signal quality and reduce signal attenuation and interference.

[0037] At the same time, the communication host synchronously controls the selection state of the communication slave and the on / off state of the analog switch to achieve efficient management of the entire communication process. When data communication needs to be performed with a certain communication slave, the communication host sends a chip select signal to select the slave, and at the same time controls the corresponding analog switch to turn on so that the signal can be normally transmitted to the slave. When the slave is not selected, the communication host controls the analog switch to be in an isolated state, blocking the signal transmission on this branch line and preventing it from interfering with the bus signal. This synchronous control method does not require the introduction of an additional control unit, thereby reducing the volume and cost of the system and improving the integration and economy of the system.

[0038] In some embodiments, the enable terminal of the analog switch and the select terminal of the corresponding communication slave are both connected to the same chip select pin on the communication host. The communication host is configured to control whether the communication slave is selected through a chip select signal and control whether the corresponding analog switch is turned on or off.

[0039] Specifically, the on-off logic of the analog switch corresponds to the strobe logic of the communication slave. Taking the enhanced serial peripheral interface bus as an example, if the strobe logic of the communication slave is strobed by a low level, then the analog switch is opened by a low level. Thus, the communication host can control the corresponding analog switch to open when the communication slave is strobed and control the corresponding analog switch to turn off when the communication slave is not strobed.

[0040] In one example, the serial bus is an eSPI bus, and there are three communication slaves. The communication host is connected to the three communication slaves in sequence from left to right through the CLK line and DATA line of the eSPI bus. An analog switch is set on the branch line of the outermost communication slave, i.e., the communication slave on the right end. The three communication slaves are sorted from left to right. The strobe terminals of the first communication slave, the second communication slave, and the third communication slave are respectively connected to the first chip select pin CS0, the second chip select pin CS1, and the third chip select pin CS2 on the communication host. The third chip select pin CS2 is also connected to the analog switch at the same time, that is, the analog switch is controlled by the chip select signal output by the third chip select pin CS2.

[0041] When the communication host strobes the third communication slave, the analog switch is opened. When the communication host is idle or strobes the first communication slave or the second communication slave, the analog switch is turned off.

[0042] When the communication host communicates with the first communication slave or the second communication slave, the analog switch is turned off. The signal will be reflected at the analog switch and will no longer be transmitted through the subsequent long-distance branch line and then reflected. Therefore, the reflection influence on the CLK signal and DATA signal of the eSPI received at the first communication slave and when the second communication slave is strobed is greatly reduced, and the signal quality will be significantly improved, realizing normal communication of the eSPI.

[0043] When the communication host strobes 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 communication slave and the second communication slave will deteriorate at this time, the bus data at this time does not require the response of the first communication slave and the second communication slave, so it will not affect the communication.

[0044] The multi-device serial bus communication system of the embodiment of the present application not only reduces the influence of too long branch lines on signal transmission by setting an analog switch, but also simplifies the control logic by controlling the strobe of the communication slave and the analog switch simultaneously through the chip select pins of the communication host.

[0045] Moreover, 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 selected. Due to the existence of a certain delay in selection, it can ensure that the channel connection has been completed before the communication slave is selected. At the same time, it is ensured that in the non-selected state of the communication slave, the analog switch maintains the off state, isolating the physical connection between the communication slave and the bus, thus improving the stability and reliability of the multi-device serial bus communication system.

[0046] In some embodiments, as Figure 4 shown, the communication slave isolated by the analog switch is arranged on the second circuit board, and the communication host, the analog switch and the remaining communication slaves are arranged on the first circuit board. The communication slave isolated by the analog switch is connected to the analog switch through a connecting wire.

[0047] Specifically, placing the communication slave isolated by the analog switch on the second circuit board and the analog switch and the communication host on the first circuit board can achieve a flexible layout of the communication slaves.

[0048] When the communication slave on the second circuit board is in the non-selected state, the analog switch will turn off, and at this time the signal is reflected back at the analog switch. Compared with the traditional design, there is no need to let the signal travel a long transmission line before reflection, greatly shortening the signal reflection path. Even in the complex scenario where the communication slaves are scattered and distributed on different circuit boards, it can still effectively ensure the high quality of signal transmission, greatly improving the overall performance and stability of the communication system.

[0049] Furthermore, a first connection terminal is also provided on the first circuit board, and a second connection terminal is also provided on the second circuit board. The first connection terminal is connected to the second connection terminal through a connecting wire. The analog switch is connected to the first connection terminal, and the communication slave isolated by the analog switch is connected to the second connection terminal.

[0050] Specifically, the first connection terminal and the second connection terminal are accurately connected through a connecting wire, 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.

[0051] It should be understood that the first connection terminal and the second connection terminal are at least equipped with three pin headers, which are responsible for transmitting the chip select signal, the CLK signal, and the DATA signal in sequence. During the actual connection process, the pin headers of the first connection terminal and the second connection terminal are correspondingly connected, and the accurate transmission of signals is achieved through the connection wires. This terminal connection method can avoid the messy wiring method, make the connection between circuit boards more orderly, greatly improve the connection standardization, and also provide great convenience for installers and maintainers. In actual operation, installers can easily insert the connection wires into the corresponding pin headers to achieve quick connection; when disassembly or maintenance is required, the connection wires can also be quickly pulled out to independently check and maintain the circuit board, saving time and labor costs and improving work efficiency.

[0052] In some embodiments, as Figure 5 shown, the number of analog switches is the same as the number of communication slaves, and any one of the analog switches is respectively arranged on the branch line of the corresponding communication slave. The strobe terminals of any one of the communication slaves are respectively connected to different chip select pins on the communication master. The communication master is used to control whether the communication slave is strobed through the chip select signal. When the communication slave is strobed, the corresponding analog switch is controlled to be turned on.

[0053] Exemplarily, the serial bus is an eSPI bus, there are three communication slaves, the communication master is connected to the three communication slaves in sequence from left to right through the CLK line and the DATA line of the eSPI bus. The three communication slaves are sorted from left to right, and corresponding analog switches are arranged on the branch lines of each communication slave.

[0054] Specifically, the strobe terminals of the first communication slave, the second communication slave, and the third communication slave, as well as their respective corresponding analog switches, are respectively connected to the first chip select pin CS0, the second chip select pin CS1, and the third chip select pin CS2 on the communication master. Each analog switch is controlled by the chip select signal of its respective communication slave. When the communication master needs to perform data interaction with a specific communication slave, a strobe signal is sent to the corresponding chip select pin, and at the same time, the conduction of the corresponding analog switch is controlled to establish a signal transmission path between the communication master and the target communication slave.

[0055] According to the above settings, it is only necessary to ensure that the wiring of the three analog switches on the circuit board is close enough, so that the influence of the redundant branch lines can be ignored. The layout of the three communication slaves is not significantly affected by their relative positions, which provides greater flexibility and convenience for the overall layout design of the circuit board. Designers can focus more on arranging the positions of the communication slaves from the perspective of the overall system architecture and function implementation, without having to worry too much about the adverse effects of their relative positions on the signal transmission quality. They only need to ensure that the wire lengths from each communication slave to the communication master meet the requirements of the longest wire length, so as to ensure that the signal can be transmitted with sufficient strength and integrity.

[0056] 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 according to the embodiment of the present invention can be considered as a point-to-point topology from the communication master to the three communication slaves. This point-to-point communication method completely eliminates the adverse effects such as signal reflection and interference that may be brought by the branch lines of other communication slaves, thus maximizing the signal quality of the eSPI bus, providing a solid foundation for the stable and efficient data transmission of the system, and effectively ensuring the reliable operation and high-performance performance of the entire communication system in various complex working environments.

[0057] In addition, the embodiment of the present invention eliminates the impedance mutation caused by the branch lines of the unselected communication slaves by turning off the analog switch, shortens the equivalent length of the branch lines to the level of the parasitic parameters of the switch package, 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 signal integrity.

[0058] In some embodiments, as Figure 6 shown, the communication slaves include a first communication slave and a second communication slave. The analog switch is arranged on the branch line corresponding to the second communication slave. The select terminals of the first communication slave and the second communication slave are both connected to the same chip select pin on the communication master. The enable terminal of the analog switch is connected to the first communication slave. The first communication slave monitors the working state 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 hangs, the first communication slave controls the analog switch to turn off, parses the information on the serial bus and outputs a response message to the serial bus.

[0059] Furthermore, the first communication slave is also connected to the second communication slave through a preset bus. The first communication slave sends a monitoring signal to the second communication slave through the preset bus and receives the information on the serial bus parsed by the second communication slave.

[0060] In one example, the I2C bus is a simple, two-way, two-wire synchronous serial bus, commonly used to connect microcontrollers and peripheral devices. The monitoring signal uses a Watch Dog signal. The Watch Dog signal is a signal mechanism used to monitor whether the system is working properly, and is widely used in embedded systems to achieve fault detection and recovery.

[0061] Specifically, the first communication slave sends a Watch Dog signal to the second communication slave via the I2C bus. When the second communication slave receives this signal, it will perform corresponding processing according to its current working state and return 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 working properly.

[0062] When the second communication slave is working properly, the Watch Dog signal it returns is a Pulse Width Modulation (PWM) wave. PWM is a coding method that can transmit different forms of information by modulating the width of a series of pulses. In this example, a normal PWM wave signal indicates that the second communication slave is in a normal working state. When a fault such as a hang occurs in the second communication slave, the PWM wave signal will no longer change, that is, the signal remains in a stable state and no longer exhibits the characteristics of pulse width modulation. By detecting this change, the first communication slave can quickly identify the abnormal state of the second communication slave, thus achieving effective monitoring of the working state of the second communication slave.

[0063] Exemplarily, the serial bus is an eSPI bus, there are three communication slaves, and the communication master is connected to the three communication slaves in sequence from left to right through the CLK line and DATA line of the eSPI bus. The three communication slaves are the third communication slave, the first communication slave, and the second communication slave from left to right. The communication master, the third communication slave, the first communication slave, and the analog switch are arranged on one circuit board, and the second communication slave is arranged on another circuit board. The third communication slave and the corresponding analog switch are respectively connected to the first chip select pin CS0 on the communication master. The first communication slave and the second communication slave are both connected to the third chip select pin CS2. The analog switch is arranged on the branch line of the second communication slave, and the enable end of the analog switch is connected to the first communication slave and is controlled by the first communication slave.

[0064] The first communication slave and the second communication slave share the third chip select pin CS2. When the second communication slave is working properly, the first communication slave only acts as a receiver, synchronously parsing some of the eSPI information sent by the communication master to the second communication slave, and will not respond to the serial bus, so there will be no conflict in sharing the chip select pin.

[0065] The specific working process of the multi-device serial bus communication system according to the embodiment of the present invention is as follows: The first communication slave monitors whether the second communication slave is working properly. If the second communication slave is working properly, the analog switch is turned on, and the first communication slave does not parse the corresponding information. Instead, the second communication slave receives the information and then notifies the first communication slave through other paths, such as the I2C bus. When the first communication slave detects that the second communication slave has hung up, the second communication slave cannot synchronize the corresponding information to the first communication slave. The first communication slave actively turns off the analog switch and responds to the communication host to send eSPI information on behalf of the second communication slave and parses the corresponding content.

[0066] The multi-device serial bus communication system according to the embodiment of the present invention monitors the working state of the second communication slave through the first communication slave. When the second communication slave is working properly, the first communication slave controls the analog switch to turn on and receives the parsed information of the second communication slave. When the second communication slave has hung up, the analog switch is turned off, and the first communication slave parses and outputs the response by itself. This design can enable the first communication slave and the second communication slave to share a chip select signal without affecting the normal operation of the two communication slaves, enabling the communication host to connect more communication slaves and increasing the scalability of the multi-device serial bus communication system.

[0067] It should be understood that the number of communication slaves described in any of the above embodiments of the present invention is three only for illustration. In different usage scenarios, the number of communication slaves can be two, four, six, or other different numbers to meet the usage requirements.

[0068] In addition, on the basis of adding an analog switch in the above embodiments, those skilled in the art can also combine other means to improve the signal transmission quality. For example, terminal impedance matching (such as series termination resistors) and trace length optimization can be used to improve the integrity of eSPI signals at high frequencies above 66 MHz, reduce the bit error rate, and ensure the timing stability and communication reliability of eSPI signals in multi-device scenarios.

[0069] In some embodiments, the signal isolator uses a buffer.

[0070] When the signal isolator uses a buffer, because the function of the buffer is to re-drive the received signal, the input end and the output end are equivalent and isolated at any time. Using a buffer does not require a chip select signal to dynamically turn on and off the buffer. It only requires placing three buffers in a daisy chain topology that meets the requirements on the circuit board. The output end of each buffer to the communication slave is a point-to-point topology and will not be affected by the input end.

[0071] However, this advantage of the buffer is accompanied by obvious limitations. Since the buffer needs to first identify the input signal and then re-drive the output, this process inevitably introduces a relatively high delay. Typically, the delay of the buffer can reach 8 ns, while in contrast, the typical delay of the analog switch is only 0.5 ns. The delay of the buffer is 40 times that of the analog switch. Considering the complete link where the communication host sends a signal and finally receives a response, after two buffer delays, compared with the solution using an analog switch, the overall link delay will increase by 15 ns. Such a significant increase in delay will have an extremely adverse impact on the timing judgment of the communication host, possibly leading to abnormal data parsing, and thus affecting the reliability and stability of the entire communication system.

[0072] Therefore, in the above embodiments using an analog switch with a smaller delay, since the input and output cannot be isolated when the analog switch is turned on, it is proposed that the communication host precisely controls the analog switch through its chip select signal to achieve dynamic management of the signal path. When data interaction is required with a specific communication slave, the communication host sends the corresponding chip select signal to enable the corresponding analog switch, thereby establishing a signal path between the communication host and the target communication slave. This dynamic management method not only ensures the integrity quality during signal transmission but also minimizes the impact on the overall link timing, avoiding communication anomalies caused by excessive delay.

[0073] In addition, through the dynamic enabling control of the analog switch, it is also possible to effectively avoid communication quality problems that may be caused by complex factors such as signal reflection and interference. In practical applications, this optimized communication architecture design is of great significance for improving the performance and reliability of the system. Especially in high-speed communication scenarios with strict timing requirements, using an analog switch combined with chip select signal control can give full play to its low-delay advantage, ensuring the stable and efficient operation of the communication system and meeting the urgent needs of modern electronic devices for high-speed and reliable data transmission.

[0074] Those skilled in the art can further realize that the units and algorithm steps of each example described in combination with the embodiments disclosed in this article can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described according to functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Skilled professionals can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this application.

[0075] The above has introduced in detail a multi-device serial bus communication system provided by the present application. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present application, several improvements and modifications can still be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A multi-device serial bus communication system, characterized in that, Including: A communication host; At least two communication slaves, which 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 at least one of the branch lines corresponding to 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 itself is not selected.

2. The multi-device serial bus communication system according to claim 1, characterized in that, The signal isolator is an analog switch.

3. The multi-device serial bus communication system according to claim 2, wherein The analog switch is arranged on the branch line corresponding to the communication slave farthest from the communication host. The communication host is used to control whether the communication slave is selected through a chip select signal, and when the communication slave isolated by the analog switch is selected, the communication host controls the analog switch to open.

4. The multi-device serial bus communication system according to claim 3, wherein The communication slave isolated by the analog switch is arranged on the second circuit board, the communication host, the analog switch and the other communication slaves are arranged on the first circuit board, and the communication slave isolated by the analog switch is connected to the analog switch through a connecting line.

5. The multi-device serial bus communication system according to claim 4, characterized in that, A first connection terminal is further provided on the first circuit board, a second connection terminal is further provided on the second circuit board, the first connection terminal is connected to the second connection terminal through a connecting line, the analog switch is connected to the first connection terminal, and the communication slave isolated by the analog switch is connected to the second connection terminal.

6. The multi-device serial bus communication system according to claim 2, 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 corresponding to the corresponding communication slave. The selection terminals of any one of the communication slaves are respectively connected to different chip select pins on the communication host. The communication host is used to control whether the communication slave is selected through a chip select signal, and when the communication slave is selected, the corresponding analog switch is controlled to open.

7. The multi-device serial bus communication system according to claim 2, wherein The communication slaves include a first communication slave and a second communication slave. The analog switch is arranged on the branch line corresponding to the second communication slave. The selection terminals of the first communication slave and the second communication slave are both connected to the same chip select pin on the communication host. The enable terminal of the analog switch is connected to the first communication slave. The first communication slave monitors the working state of the second communication slave. When the second communication slave works 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 hangs, the first communication slave controls the analog switch to turn off, parses the information on the serial bus by the first communication slave and outputs a response message to the serial bus.

8. The multi-device serial bus communication system according to claim 7, wherein, The first communication slave is further connected to the second communication slave through a preset bus. The first communication slave sends a monitoring signal to the second communication slave through the preset bus and receives the information on the serial bus parsed by the second communication slave.

9. The multi-device serial bus communication system according to claim 1, characterized in that, The signal isolator is a buffer.

10. 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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