CN115037571B

CN115037571B - Hub applied to star-shaped TTP network and implementation method thereof

Info

Publication number: CN115037571B
Application number: CN202210629084.XA
Authority: CN
Inventors: 牛萌; 蹇红; 刘坤; 谢军; 张超; 涂晓东
Original assignee: University of Electronic Science and Technology of China; Xian Flight Automatic Control Research Institute of AVIC
Current assignee: University of Electronic Science and Technology of China; Xian Flight Automatic Control Research Institute of AVIC
Priority date: 2022-06-06
Filing date: 2022-06-06
Publication date: 2024-05-17
Anticipated expiration: 2042-06-06
Also published as: CN115037571A

Abstract

The invention relates to the technical field of communication buses of aircraft management systems, and discloses a hub applied to a star TTP network. The invention provides a starting scheme based on Bigbang mechanisms based on the starting principle of a hub, and meanwhile, the starting scheme of the invention comprises three starting paths and is suitable for various starting scenes.

Description

Hub applied to star-shaped TTP network and implementation method thereof

Technical Field

The invention relates to the technical field of communication buses of aircraft management systems, in particular to a hub applied to a star-shaped TTP network and an implementation method thereof.

Background

In recent years, computer systems having high reliability, safety, and criticality are widely used in the safety-critical fields of aerospace, automotive fields, industrial control, and the like. Such computer systems essentially require a distributed solution such that a portion of the system is damaged without causing the entire system to fail. However, spatial distribution implies implementation of the communication infrastructure such that participants in the system are able to exchange information. For economic reasons, the communication infrastructure typically needs to be implemented as a shared resource, and a dedicated communication protocol must be implemented to coordinate its use. The communication protocol can be based on the synchronization of local clocks of participants, and a Bus Guardian (BG) is adopted to protect and coordinate the use of shared resources. Such a network for protecting and coordinating shared resources may employ a bus time triggered network for protection and coordination, as shown in fig. 7; however, with a bus-type time triggered network, it is costly to use 2n bus protectors because of the dual redundancy system. In order to realize the function of protecting and coordinating shared resources, fewer hubs can be used in a star time trigger network to realize the function of bus protection and coordinating TTP node shared resources, researches on hubs of star time trigger networks TTP are currently fresh in China, and therefore, a hub applied to the star TTP network and having better instantaneity, certainty and better fault tolerance performance is designed.

Disclosure of Invention

The invention provides a hub applied to a star TTP network and an implementation method thereof, wherein the star time trigger network is based on a time division multiplexing technology, and the design of the hub enables the star time trigger network to have better fault tolerance and lower cost than a bus time trigger network.

The invention is realized by the following technical scheme:

A hub for star TTP network is composed of gate control module and transceiver module, start control module, synchronous control module, clock generation and synchronization module, MEDL analysis module, frame analysis module, cluster mode switching module, shaping module, frame length calculation module and on-line configuration module,

The input end of the receiving and transmitting module is respectively connected with the shaping module, the gating module and the frame length calculating module, and the output end of the receiving and transmitting module is respectively connected with the gating module, the frame analyzing module and the online configuration module;

the input end of the time generation and synchronization module is respectively connected with the frame analysis module, the shaping module and the MEDL analysis module, and the output end of the time generation and synchronization module is respectively connected with the starting control module and the synchronization control module;

the input end of the MEDL analysis module is respectively connected with the starting control module, the synchronous control module, the cluster mode switching module and the online configuration module, and the output end of the MEDL analysis module is also respectively connected with the frame length calculation module, the starting control module and the synchronous control module;

the output end of the frame analysis module is also connected with the cluster mode switching module;

the output end of the starting control module is also connected with the gating module and the synchronous control module respectively;

The output end of the synchronous control module is also connected with the gate control module.

As optimization, the start control module is used for realizing the transition of the hub from the asynchronous state to the synchronous state in the start stage of the hub, enabling the hub to generate a start input enabling signal and a start output enabling signal in the start stage according to the Sender Membershp Flag signal provided by the MEDL analysis module and the system time provided by the clock generation submodule, controlling the input and output of an external node connected with the hub by the start input enabling signal and the start output enabling signal, and simultaneously transmitting a PSP start time point, a TP start time point, a PRP start time point, a time slot end time point and the current time slot number in a time slot when the start is completed to the synchronous control module after the start is completed;

The synchronous control module is used for generating a synchronous input enabling signal and a synchronous output enabling signal of the control gating module after the hub enters the synchronous state according to each time point when the hub enters the synchronous state and the time slot information provided by the MEDL analyzing module, and dividing each time slot of the hub in the synchronous stage, wherein each time slot comprises an IDLE stage, namely an IDLE stage; PSP stage, i.e. stage before transmission; a TP stage, namely a data sending stage; PRP stage, namely stage after transmission; the hub performs state skipping according to the time of each stage;

The clock generation and synchronization module comprises a clock generation sub-module and a clock synchronization sub-module, wherein the clock generation sub-module works in the starting stage of the hub, and obtains the initial time of the hub according to Global time/start time and frame analysis time obtained from the frame analysis module and the transmission delay and propagation delay provided by the MEDL analysis module, and forms the local time of the hub through the initial time; the clock synchronization sub-module works when the hub is in a synchronization stage, acquires a time difference value transmitted by the shaping module, calculates a correction term and corrects a local clock (local time) of the hub according to the correction term so as to realize at least one time synchronization in one TDMA Round, wherein the correction is divided into single-step correction and multiple correction, and the correction rule is determined by a schedule in the MEDL analysis module;

The MEDL analysis module comprises a global entry table, a protocol parameter table, a MEDL identification table, a time slot parameter table and 7 cluster mode tables; after the hub is started, the on-line configuration module transmits loading configuration data to a storage unit RAM of the MEDL analysis module, after the hub self-checking is finished, the starting control module or the synchronous control module sends a time slot request signal or a global protocol parameter acquisition request signal to the MEDL analysis module at the beginning stage of each time slot, the MEDL analysis module receives the time slot request signal or the global protocol parameter acquisition request signal, and according to the starting address and the length of each table configured by the global item, the corresponding information in the scheduling table is sent to the starting control module or the synchronous control module by combining the request signal type;

The frame analysis module is used for analyzing an input frame to obtain a Global Time/Startup Time field, a DMC field and a Cluster position field of a control state field in the frame, transmitting the Global Time/Startup Time field of the control state field in the frame to the clock generation and synchronization module, and transmitting the DMC field and the Cluster position field to the Cluster mode switching module to trigger the Cluster mode switching module to send a Cluster switching signal to the MEDL analysis module;

The cluster mode switching module is used for checking whether a mode change request is allowed or not in a PRP stage of a hub, setting the content of the mode change request as the content of delay mode change if the mode change request is allowed, assigning a subsequent mode corresponding to the content of delay mode change to the cluster mode when a field EOC representing the last time slot in the cluster mode in a schedule is detected to be effective and the current time slot is about to end, transmitting the changed cluster mode to the MEDL analysis module, and entering a new cluster mode in the next time slot;

the receiving and transmitting module is used for receiving and transmitting data by the hub and comprises a baud rate generating sub-module, a receiving sub-module, a transmitting sub-module, a registering sub-module and a CRC checking sub-module;

the shaping module isolates the time domain SOS fault, adds shaping delay at the tail of a receiving window in the TP stage, and generates a shaping output enabling signal to the transceiver module when the system time of the hub is up to the completion of the shaping delay;

The gate control module inputs and outputs data according to the start input enabling signal and the start output enabling signal in a hub starting stage, and opens and closes each port corresponding to the node according to the synchronous input enabling signal and the synchronous output enabling signal transmitted by the synchronous control module in a hub synchronous stage, wherein the gate control module comprises a start gate control sub-module, a synchronous gate control sub-module and an output selection sub-module;

the frame length generation module is used for calculating the frame length of each transmission according to the data length, the frame type and the frame length overhead fixed by each frame type provided by the MEDL analysis module, and outputting the calculated frame length to the receiving and transmitting module and the gate control module;

The on-line configuration module is used for configuring data for a node or a hub, when the configuration host computer downloads the configuration data, a section of destination field for identifying a destination is added at the front end of the configuration data, the destination field of the hub and the destination field of the node are unique and different, so that the hub firstly judges the identification field, if the field is judged to be the configuration data sent to the hub, the global entry table in the configuration data is checked to be correct, if the configuration data is checked to be correct, the data is configured to the RAM of the MEDL analysis module, and meanwhile, the hub also forwards the configuration data; if the field is determined to be the sending node, the data is forwarded to the corresponding node.

The invention also discloses a realization method of the hub applied to the star TTP network, which uses the hub applied to the star TTP network and comprises the following steps:

s1, connecting two hubs with a plurality of nodes, wherein the two hubs and the plurality of nodes form a star network;

S2, powering up the hub and the nodes, and entering a starting stage after the hub is initialized;

S3, in a starting stage, the clock generation and synchronization module obtains the initial time of the hub by combining the Global time/start time and the frame analysis time obtained by the frame analysis module with the transmission delay and the propagation delay provided by the MEDL analysis module, meanwhile, the frame length calculation module calculates the frame length of the current time slot according to the data length and the IF field of the current time slot obtained by the MEDL analysis module so as to judge whether frame transmission is finished, schedule information of the MEDL analysis module and the initial time of the hub are transmitted to the starting control module, the starting control module enables the hub to generate a starting input enabling signal and a starting output enabling signal in the starting stage according to the information provided by the MEDL analysis module and the system time provided by the clock generation submodule, meanwhile, the starting control module checks the schedule information, the hub enters a frame listening state after the checking is passed, and the corresponding time is transmitted to the synchronization control module according to the transition of the frame running state received in a specified time range when the hub is started, and the hub enters the synchronization stage;

S4, the synchronous control module outputs a synchronous input enabling signal and a synchronous output enabling signal of the control gating module, and divides each time slot of the hub in a synchronous stage, and the hub performs state jump according to IDLE, PSP, TP and a PRP stage of each time slot; the clock generation and synchronization module performs time synchronization at least once in each TDMA Round, each port of the gating module is turned on/off according to the input output enabling control signal, the receiving and transmitting module outputs data to the gating module through the output enabling signal given by the shaping module, and whether transmission is finished is judged according to the frame length of the data obtained by the frame length calculation module.

As optimization, the starting control module of the hub comprises a validity checking state, a frame listening state, a cold starting state, an integration state, a synchronization state, a waiting integration state and a waiting synchronization state; s3, the starting control module checks the schedule information, and the specific steps of checking that the hub enters a frame listening state after passing through and performing state transition according to the received frames within a specified time range are as follows:

starting a control module to perform validity check: after the hub is started and initialized, performing crc test on the MEDL identification table, the protocol parameter table and the global entry table transmitted by the MEDL analysis module, and jumping the hub to a frame listening state after the crc test is completed;

when the concentrator is in a frame listening state, the concentrator is used for carrying out frame identification, when the concentrator is in the frame listening state, the concentrator continues to receive frames, if no frame is detected in 2 TDMA Round time ranges, the concentrator jumps to a cold starting state, if a valid cold starting frame (sent by a cold starting node) is detected in 2 TDMA Round time ranges, the concentrator jumps to a standby integrating state, and if a valid synchronous frame is detected in 2 TDMA Round time ranges, the concentrator jumps to a standby synchronizing state;

the hub is in a cold start state and comprises a first cold start stage and a second cold start stage, when the hub is in the cold start state, the hub continues to receive frames, the hub is in the first cold start stage first, the hub executes Bigbang mechanism when in the first cold start stage, if a valid cold start frame is detected within 1 TDMA Round range and CRC check is successful, the hub jumps to the second cold start stage, otherwise, the hub still stays in the first cold start stage;

If the hub is in the second cold start stage, executing frame identification, if a valid cold start frame is detected within 1 TDMA Round range, the hub jumps to an integrated state, otherwise, the hub jumps back to the first cold start stage;

if the hub is in the state of waiting for integration, if the CRC check is correct before the end of the current time slot, the hub is changed into the state of integration, otherwise, the hub is changed into the frame listening state again;

If the hub is in an integrated state, if no valid frame or no frame exists in a TDMA Round range, the hub is changed into a frame listening state again, and if a valid frame sent in from another node which is different from the last sending node is detected in the TDMA Round range, the hub jumps to a synchronous state;

If the hub is in a waiting synchronous state, if a valid frame is detected before the end of the current time slot, the hub is in a synchronous state, otherwise, the hub is in a frame listening state again;

When the hub enters a synchronous state, a PSP start time point, a TP start time point, a PRP start time point, a time slot end time point and the current time slot number in the time slot when the startup is completed are transmitted to the synchronous control module.

As an optimization, in S4, the specific steps of the synchronization control module outputting the input/output enabling control signal of the control gating module and dividing each time slot of the hub in the synchronization stage, and the hub performing the state jump according to each time slot are as follows:

s4.1, in the synchronization stage, when each time slot starts, the hub enters an S_Init state, judges whether the current system is active or not and whether the cluster mode is switched or not, then enters an IDLE stage of each time slot in the synchronization stage, and the hub jumps to the S_IDLE state, namely an IDLE state;

S4.2, the synchronous control module continuously acquires MEDL the current time slot information in the analysis module, and after the current time slot information is updated, the step 4.3 is carried out,

S4.3, the time slot information stored in the online configuration module is assigned to a register in the synchronous control module, and the synchronous control module calculates the ending time, PSP stage starting time, TP stage starting time, PRP stage starting time, the starting time and ending time of a receiving window in the TP stage according to the acquired time slot information;

and S4.4, judging whether any time calculated in the step S4.3 exceeds a maximum threshold, if so, subtracting the maximum threshold from the local time of the hub to serve as system time, otherwise, directly using the local time of the hub as the system time.

In the code design, there is a ma counter bit width of 16 bits specifying the node and hub, the ma counter is a time counter, and the 16 bit width means a maximum of 65535. But the local clock (local time) of the hub is running in mi, the ratio ma-ma/mi needs to be converted into a clock in mi. The ratio ma/mi is not fixed, so the bit width of the mi counter is defined as 28, that is, the maximum value of the mi counter is much larger than the ma counter, which is usually larger than the maximum value ma/mi of the ma counter. Thus if the local clock counter mi of the hub is made to always increment by 1, the clocks of the hub and the nodes will be out of sync if the maximum threshold is exceeded without subtracting the maximum threshold, which is a fatal error for the time triggered network.

S4.5, detecting whether the system time reaches the start time of the PSP stage, if so, jumping to the PSP stage by the hub, entering an S_PSP state, setting the IDLE_flg to 0 and setting the PSP_flg to 1; otherwise, the synchronous control module stays in an S_IDLE state, IDLE_flg is set to be 1, PSP_flg is set to be 0, IDLE_flg indicates that the synchronous control module is in an IDLE stage of the current time slot, and PSP_flg indicates that the synchronous control module is in a PSP stage of the current time slot;

S4.6, detecting whether the system time reaches the starting time of the TP stage, jumping to the TP stage if the system time reaches the starting time of the TP stage, entering the S_TP state, setting TP_flg to be 1, setting PSP_flg to be 0, and transmitting and receiving data by a transceiver module in the stage; otherwise, staying in an S_PSP state and setting TP_flg to 0, wherein PSP_flg is set to 1, the TP_flg represents that the synchronous control module is in a TP stage of a current time slot, and the PSP_flg represents that the hub is in a PSP stage of the current time slot;

S4.7, detecting whether the system time reaches the PRP stage starting time, jumping to the PRP stage if the system time reaches the PRP stage starting time, entering an S_PRP state, setting PRP_flg to be 1, and setting TP_flg to be 0; otherwise, stay in the s_tp state and set tp_flg to 1 and prp_flg to 0, where prp_flg indicates that the hub is in the PRP phase of the current slot;

S4.8, when the system time is equal to the current time slot ending time, the state of the synchronous control module is changed into the S_Init state described in S4.1, the next_slot_flg is set to 1, and the PRP_flg is set to 0; otherwise, stay in the s_prp state, prp_flg is 1, and next_slot_flg is 0.

As optimization, in S4.6, the TP stage includes a pre-receive window stage, a receive window stage, and a post-receive window end stage, and the specific process in the TP stage includes:

s4.6.1, in the pre-receive window stage, when the system time is equal to the receive window start time point, jumping to the receive window stage, setting receve _window_phase_flg to 1, setting before_window_phase_flg to 0, and setting the input enable unconditional to a corresponding value, namely enable_in [ sender_ membership _flg ] =0, namely the input enable is valid low; otherwise, stay at the current pre-receiving window stage and set enable_in to an invalid value, wherein receve _window_phase_flg represents that the current pre-receiving window stage is in receiving window; before window_phase_flg indicates the stage before receiving the window; enable_in [ sender_ membership _flg ] =0, enable_in represents input enable, sender_ membership _flg represents node identification currently transmitted;

S4.6.2, in the receiving window stage, when the system time is equal to the receiving window ending time point, jumping to the receiving window ending post stage; otherwise, staying in a receiving window stage, detecting whether a corresponding node of the current time slot has data input, if so, setting a corresponding flg to be 1, otherwise, setting the flg to be 0;

S4.6.3, after the receiving window ends, when the system time is equal to the time point of the PRP start, jumping to the PRP stage, entering a state S_PRP, otherwise, staying in the S_TP state, judging the flg in S4.6.2 in the S_TP state, if the flg is 1, continuously keeping the enable_in [ sender_ membership _flg ] =0, otherwise, setting the enable_in [ sender_ membership _flg ] =1 to be invalid.

As an optimization, the specific process of the clock generation and synchronization module performing at least one time of time synchronization in each TDMA Round is as follows:

a1, acquiring the actual acquired time and the theoretical acquired time difference diff of the data in a shaping module, and storing the time difference diff in a time synchronization module;

a2, calculating a correction term according to a fault-tolerant median algorithm;

A3, if the Clksyn field of the current time slot is analyzed to be 1 in the MEDL analysis module, clock correction is executed in the PRP stage of the current time slot, if the MEDL analysis module analyzes that the free_running_ MAcroticks _t0 field of the current time slot is 1, single-step correction is executed, otherwise multi-step correction is executed.

As optimization, the receiving and transmitting module is used for receiving and transmitting data in the synchronous stage of the concentrator and comprises a baud rate generating sub-module, a receiving sub-module, a transmitting sub-module, a registering sub-module and a CRC checking sub-module,

The baud rate generation submodule is used for generating baud rates;

The receiving submodule is arranged to receive the falling edge to consider that the data transmission starts, and the frame length provided by the frame length calculation module is used for judging whether the data transmission ends or not after the data transmission ends;

The transmission start of the sending sub-module is determined by an enabling signal provided by the shaping module, and the transmission end of the sending sub-module is judged by the frame length;

The registering sub-module is matched with the shaping module and used for registering the input data for a period of shaping time;

The CRC checking sub-module is used for carrying out CRC checking on input data, and the CRC checking mode is that the input data is checked at the same time.

As optimization, the shaping module adds a shaping delay at the end of the receiving window stage of the TP stage, waits until the system time reaches the shaping delay completion time, and then generates output enabling, and the output enabling control transceiver module forwards the data buffered in the register sub-module.

As optimization, the gating module comprises a starting gating sub-module, a synchronous gating sub-module and an output selection sub-module, wherein the starting gating sub-module is used for receiving or outputting data in a starting stage of the hub, the synchronous gating sub-module is used for receiving or outputting data according to synchronous input enabling signals and synchronous output enabling signals in a synchronous stage of the hub, and the output selection sub-module is used for selecting and outputting output data of the starting gating sub-module or data of the synchronous gating sub-module according to a starting state or a synchronous state of the hub.

Compared with the prior art, the invention has the following advantages and beneficial effects:

1. The invention provides a complete hub design scheme, only two hubs are needed for bus protection by one star time trigger network, and compared with a bus TTP network, the invention greatly reduces the cost and has better fault tolerance performance of the system.

2. The hub of the invention can avoid the language disorder fault and the time domain SOS fault, thereby having higher fault tolerance than a bus type time triggering network.

3. The invention provides a starting scheme based on Bigbang mechanisms based on the starting principle of a hub, and meanwhile, the starting scheme of the invention comprises three starting paths and is suitable for various starting scenes.

Drawings

In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings that are needed in the examples will be briefly described below, it being understood that the following drawings only illustrate some examples of the present invention and therefore should not be considered as limiting the scope, and that other related drawings may be obtained from these drawings without inventive effort for a person skilled in the art. In the drawings:

FIG. 1 is a block diagram of a hub for a star TTP network;

FIG. 2 is a schematic diagram of a system architecture of a star time triggered network;

FIG. 3 is a startup control state diagram of the startup control module;

FIG. 4 is a synchronous control flow diagram of the start control module;

Fig. 5 is a slot diagram;

FIG. 6 is a schematic diagram of SOS shaping by the shaping module in the time domain;

Fig. 7 is a schematic diagram of a system architecture of a bus type time triggered network.

Detailed Description

For the purpose of making apparent the objects, technical solutions and advantages of the present invention, the present invention will be further described in detail with reference to the following examples and the accompanying drawings, wherein the exemplary embodiments of the present invention and the descriptions thereof are for illustrating the present invention only and are not to be construed as limiting the present invention.

Examples

As shown in fig. 1, a hub applied to a star TTP network includes a gating module 9 and a transceiver module 7 that are disposed at a physical link layer, and a start control module 1, a synchronization control module 2, a clock generation and synchronization module 3, MEDL analysis module 4, a frame analysis module 5, a cluster mode switching module 6, a shaping module 8, a frame length calculation module 10 and an online configuration module 11 that are disposed at a protocol layer, wherein an input end of the transceiver module 7 is respectively connected with the shaping module 8, the gating module 9 and the frame length calculation module 10, and an output end of the transceiver module 7 is respectively connected with the gating module 9, the frame analysis module 5 and the online configuration module 11; the input end of the time generation and synchronization module 3 is respectively connected with the frame analysis module 5 and the shaping module 8 and MEDL analysis module 4, and the output end of the time generation and synchronization module 3 is respectively connected with the starting control module 1 and the synchronization control module 2; the input end of the MEDL analysis module 4 is respectively connected with the starting control module 1, the synchronous control module 2, the cluster mode switching module 6 and the online configuration module 11, and the output end of the MEDL analysis module 4 is also respectively connected with the frame length calculation module 10, the starting control module 1 and the synchronous control module 2; the output end of the frame analysis module 5 is also connected with the cluster mode switching module 6; the output end of the starting control module 1 is also connected with the gating module 9 and the synchronous control module 2 respectively; the output end of the synchronous control module 2 is also connected with the gating module 9.

MEDL refers to THE MESSAGE descriptor list, which is understood herein as a schedule.

Next, an implementation method of a hub applied to a star TTP network according to another embodiment of the present invention will be described.

The invention relates to a realization method of a hub applied to a star TTP network, which uses the hub applied to the star TTP network and comprises the following steps:

S1, connecting two hubs and a plurality of nodes, wherein the two hubs and the plurality of nodes form a star network, as shown in FIG. 2, the number of the hubs in the invention is 2, and the number of the nodes is 10;

S3, in a starting stage, the clock generation and synchronization module obtains the initial time of the hub through the Global time/start time and the frame analysis time obtained from the frame analysis module and the transmission delay and the propagation delay provided by the MEDL analysis module, meanwhile, the frame length calculation module obtains the data length and the IF field of the current time slot according to the MEDL analysis module to calculate the frame length of the current time slot so as to judge whether frame transmission is finished, schedule information of the MEDL analysis module and the initial time of the hub are transmitted to the starting control module, the starting control module enables the hub to generate a starting input enabling signal and a starting output enabling signal according to the information (a transmission delay field, a TP duration time, a PSP duration field, a time slot duration field, a ma and mi ratio field and the time slot number field contained in the current round) provided by the frame analysis module, and the system time provided by the clock generation submodule, meanwhile, the starting control module checks the schedule information, enters a frame listening state after the checking is passed, and when the frame is converted into a frame listening state in a specified time range, and the corresponding transmission time is completed to the hub module when the transmission is completed to the synchronous control module;

In this embodiment, the start control module 1 is configured to implement a transition from an unsynchronized state to a synchronized state of the hub during a start phase of the hub, and enable the hub to generate a start input enable signal and a start output enable signal during the start phase according to the Sender Membershp Flag signal provided by the MEDL parsing module and the system time provided by the clock generation submodule, where the start input enable signal and the start output enable signal control input and output of an external node connected to the hub, and simultaneously, after the start is completed, transmit a PSP start time point, a TP start time point, a PRP start time point, a time slot end time point, and a current time slot number in a time slot when the start is completed to the synchronization control module.

The start control module generates a start input enabling signal and a start output enabling signal according to Sender Membershp Flag signals provided by the MEDL analysis module, local time provided by the clock generation submodule and the like, and the enabling signals control the input and the output of each port of the hub gating module. In the starting stage, the starting module of the hub can give input enabling to 10 ports at the same time, the gating module opens corresponding ports according to the enabling signals, when a certain correct node is detected to input data and no speaking and disorder nodes are detected, after the shaping time arrives, the starting module gives output enabling signals to ports corresponding to other nodes except the sending node, the receiving and transmitting module outputs the data to the gating module, and the gating module forwards the data to other nodes according to the output enabling signals. After the start-up process is completed, each time point (PSP start time point, TP start time point, PRP start time point and time slot end time point) and the current time slot number in the time slot when the start-up is completed are transmitted to the synchronous control module.

As shown in fig. 3, the startup control module of the hub includes a validity check state, a frame listening state, a cold startup state, an integration state, a synchronization state, a wait for integration state, and a wait for synchronization state; s3, the starting control module checks the schedule information, and the specific steps of checking that the hub enters a frame listening state after passing through and performing state transition according to the received frames within a specified time range are as follows:

starting a control module to perform validity check: after the hub is started and initialized, performing crc test on three tables, namely a global entry table (Global entry table), a protocol parameter table (Schedule/Protocol parameter) and a MEDL identification table (MEDL IDENTIFIER table), transmitted by the MEDL analysis module, and jumping the hub to a frame listening state listen after the crc test is completed;

When the hub is in the frame listening state, frame identification is carried out according to the frame type identified by the frame analysis module, the hub continues to receive frames when the hub is in the frame listening state, if no frame (no valid frame or no frame) is detected in 2 TDMA Round time ranges (determined by the system time provided by the clock generation submodule), the hub jumps to a cold start state Co l d_start, if a valid cold start frame (cold start frame sent by the cold start node) is detected in 2 TDMA Round time ranges, the hub jumps to a standby integration state, and if a valid synchronous frame (I frame) is detected in 2 TDMA Round time ranges, the hub jumps to a standby synchronous state. TDMA round is explained in detail in fig. 5.

If the hub is in a cold start state, the hub needs to execute the actions of two stages (first executing the first cold start stage and then executing the second cold start stage), when the hub is in the cold start state, the hub continues to receive the frame, and when the hub is in the first cold start stage, the hub executes Bigbang mechanism, namely, the received frame is directly forwarded without being integrated on the frame, frame type judgment and CRC check are carried out while forwarding, if an effective cold start frame is detected within 1 TDMA Round range and the CRC check on the cold start frame is successful, the hub jumps to the second cold start stage, otherwise, the hub still stays in the first cold start stage;

When the hub enters the synchronous state, the PSP stage starting time point, the TP stage starting time point, the PRP stage starting time point and the current time slot ending time point of the time slot where the starting state ends are transmitted to the synchronous control module.

The starting control module is provided with three starting paths, wherein the first starting path is as follows: the node is powered on earlier than the hub, after the node performs communication activity, the hub is powered on and started up again, the hub can receive a cold start frame once the hub is started up, and the hub can be directly integrated on the received cold start frame, namely a path 2-7-5-6 in fig. 3; the second startup path: when the hub is started but no node is started, the hub needs to wait until the node starts to perform communication activities and then integrate the communication activities on the corresponding cold start node to finish starting, on a second starting path, the hub needs to execute bigbang mechanisms, the Bigbang mechanism of the hub is different from the mechanism that the node directly refuses to receive frames, but directly forwards the first received cold start frame to ensure that the node can normally receive the frame of the time, and the direct forwarding also means that the hub cannot integrate the cold start frame, namely, cannot update the local C state according to the C state of the first received cold start frame, and the corresponding path is 2-3-4-5-6; the third starting path is a running synchronization cluster, and when a node wants to join the cluster, the third starting path can be integrated on a synchronization frame (I frame) sent by the synchronization node, so that starting is completed, and the corresponding path is 2-8-6.

The synchronization control module is configured to generate a synchronization input enable signal and a synchronization output enable signal for controlling the gating module 9 after the hub enters the synchronization state according to an initial time point when the hub enters the synchronization state and the time information provided by the MEDL parsing module, and divide each time slot of the hub in the synchronization stage, as shown in fig. 5, where each time slot includes an IDLE stage, that is, an IDLE stage; PSP stage, i.e. stage before transmission; a TP stage, namely a data sending stage; the PRP stage, namely the stage after transmission, the synchronous control module generates corresponding IDLE_flg, PSP_flg, TP_flg and PRP_flg identifiers; the hub makes state jumps according to the time of each phase.

FIG. 5 shows a 4-node time triggered system, a TDMA round comprising 4 nodes; the cluster cycle contains 2 TDMA rounds, which may be more, as judged by the actual situation. One slot consists of IDLE, PSP, TP, PRP four phases. IDLE represents an IDLE phase; PSP represents pre-SEND PHASE, the stage before transmission; TP represents transmission phase, representing a data transmission stage; PRP represents post-RECEIVE PHASE, the phase after transmission.

Next, the implementation of the synchronization control module is specifically described in connection with the implementation method, as shown in fig. 4.

S4.1, in the synchronous stage, when each time slot starts, the hub enters an S_Init state, judges whether the current system is active (whether nodes send data or not) or not and whether the cluster mode is switched or not, then enters an IDLE stage of each time slot in the synchronous stage, and the hub jumps to the S_IDLE state, namely an IDLE state;

S4.2, continuously acquiring current time slot information in the MEDL analysis module by the synchronous control module, and entering a step 4.3 after the current time slot information is updated;

In the code design, there is a ma counter bit width of 16 bits specifying the node and hub, the ma counter is a time counter, and the 16 bit width means a maximum of 65535. But the local clock (local time) of the hub is running in mi, the ratio ma-ma/mi needs to be converted into a clock in mi. The ratio ma/mi is not fixed, so the bit width of the mi counter is defined as 28, that is, the maximum value of the mi counter is much larger than the ma counter, and is usually larger than the maximum value of the ma counter multiplied by the ratio ma/mi. Thus if the local clock counter mi of the hub is made to always increment by 1, the clocks of the hub and the nodes will be out of sync if the maximum threshold is exceeded without subtracting the maximum threshold, which is a fatal error for the time triggered network.

S4.5, detecting whether the system time reaches the start time of the PSP stage, if the system time reaches the start time of the PSP stage (PSP_start_T_mi is calculated by a synchronous control module through acquiring time slot information in a schedule, the hub jumps to the PSP stage, enters an S_PSP state, and sets IDLE_flg to 0 and PSP_flg to 1; otherwise, the synchronous control module stays in an S_IDLE state, IDLE_flg is set to be 1, PSP_flg is set to be 0, IDLE_flg indicates that the synchronous control module is in an IDLE stage of the current time slot, and PSP_flg indicates that the synchronous control module is in a PSP stage of the current time slot;

s4.6, detecting whether the system time reaches the TP stage starting time (TP_start_T_mi, the unit is mi, and the synchronization control module is used for calculating by acquiring time slot information in a schedule), if so, jumping to the TP stage, entering into an S_TP state, setting TP_flg to be 1, setting PSP_flg to be 0, and carrying out data transmission in the TP stage by the transceiver module; otherwise, staying in an S_PSP state and setting TP_flg to 0, wherein PSP_flg is set to 1, the TP_flg represents that the synchronous control module is in a TP stage of a current time slot, and the PSP_flg represents that the hub is in a PSP stage of the current time slot;

S4.7, detecting whether the system time reaches PRP stage starting time (PRP_start_T_mi: the unit is mi, which is calculated by a synchronous control module through acquiring time slot information in a schedule), and jumping to the PRP stage if the system time reaches the PRP stage, entering into an S_PRP state, setting PRP_flg to be 1, and setting TP_flg to be 0; otherwise, stay in the s_tp state and set tp_flg to 1 and prp_flg to 0, where prp_flg indicates that the hub is in the PRP phase of the current slot;

s4.8, when the system time is equal to the current time Slot ending time (slot_end_T_mi, the unit is mi, and the control module calculates by acquiring time Slot information in a scheduling table), the state of the synchronous control module is changed into S4.1, the next_slot_flg is set to be 1, and the PRP_flg is set to be 0; otherwise, stay in the s_prp state, prp_flg is 1, and next_slot_flg is 0.

After entering the synchronization phase, the PRP phase of each time slot is used for judging whether cluster mode switching is carried out. If mode change request parsed by the frame parsing module is 001, it is determined whether M1 in the schedule table in the MEDL parsing module is 1, if yes, it indicates that the current time slot allows the cluster mode to be switched to the subsequent mode 1, and when the last time slot of the current cluster mode is finished, a new cluster mode is output to the MEDL parsing module for subsequent MEDL parsing.

Specifically, in S4.6, the TP stage includes a pre-receive window stage, a receive window stage, and a post-receive window end stage, and the specific process in the TP stage includes:

S4.6.1, in the pre-Receive window stage, when the system time is equal to the Receive window start time (received_window_s_t_mi, the unit is mi, and the synchronization control module calculates by acquiring the time slot information in the schedule), the process jumps to the Receive window stage, sets receve _window_phase_flg to 1, sets before_window_phase_flg to 0, and sets the input enable unconditional to a corresponding value, namely enable_in [ sender_ membership _flg ] =0, namely the input enable is valid low; otherwise, stay at the current pre-receiving window stage and set enable_in to an invalid value, wherein receve _window_phase_flg represents that the current pre-receiving window stage is in receiving window; before window_phase_flg indicates the stage before receiving the window; enable_in [ sender_ membership _flg ] =0, enable_in represents input enable, sender_ membership _flg represents node identification currently transmitted;

S4.6.2, in the Receive window stage, when the system time is equal to the Receive window end time (received_window_e_t_mi, the unit is mi, and is calculated by the synchronous control module through obtaining the time slot information in the schedule), jumping to the Receive window end post stage; otherwise, staying in a receiving window stage, detecting whether a corresponding node of the current time slot has data input, if so, setting a corresponding flg to be 1, otherwise, setting the flg to be 0;

S4.6.3, after the receiving window ends, when the system time is equal to the time (prp_start_t_mi, the unit is mi, and the control module calculates by acquiring the time slot information in the schedule), the control module jumps to the PRP stage, enters a state s_prp, otherwise, stays in the s_tp state, determines the flg in S4.6.2 in the s_tp state, if the flg is 1, then continuously keeps the enable_in [ sender_ membership _flg ] =0, otherwise, the enable_in [ sender_ membership _flg ] =1, and sets to be invalid.

In the synchronous stage, the hub acquires the information of the current time slot in the IDLE stage of each time slot, namely, acquires a time slot entry table of the current time slot from the MEDL analysis module, a Sender Membership Flag signal in the time slot entry table represents a sending node mark of the current time slot, the synchronous control module generates a synchronous input enabling signal of a node represented by Sender Membership Flag according to the signal at the beginning time of a receiving window in the TP stage, and the gating module opens a port of the node represented by Sender Membership Flag after detecting the synchronous input enabling signal. If the correct node is detected to have data input in the receiving window stage, the synchronous control module continues to synchronously input enabling signals to the corresponding ports and generate synchronous output enabling signals to other ports in the TP stage after the receiving window stage is finished, and the gating module forwards data to the other ports according to the synchronous input enabling signals and the synchronous output enabling signals.

The clock generation and synchronization module 3 comprises a clock generation sub-module and a clock synchronization sub-module, wherein the clock generation sub-module works in the starting stage of the hub, obtains the initial time of the hub according to the Global time/start time and the frame analysis time obtained by the frame analysis module 5 and the transmission delay and the propagation delay provided by the MEDL analysis module 4, and forms the local time (the unit is mi, and one mi is equal to one system clock period) of the hub through the initial time; the synchronization stage of the clock synchronization sub-module hub works, acquires the time difference value transmitted by the shaping module 8, calculates and corrects the correction term to realize at least one time of time synchronization in one TDMA Round, wherein the correction is divided into single-step correction and multiple correction, and the rule of the correction is determined by the schedule in the MEDL parsing module 4.

According to protocol AS6003, the clock generation and synchronization module performs at least one time synchronization in each TDMA Round, requiring three steps to be performed:

The MEDL parsing module 4 includes a global entry table (Global entry table), a protocol parameter table (Schedule/Protocol parameter), a MEDL identification table (MEDL IDENTIFIER table), a slot parameter table (slot table), and 7 cluster mode tables; each cluster mode table comprises a mode control table and a plurality of time slot entries, after the hub is started, the online loading configuration module transmits loading configuration data to a storage unit RAM of the MEDL analysis module 4, after the hub self-checking is completed, at the beginning stage of each time slot, the starting control module 1 or the synchronous control module 2 sends a time slot request signal or a global protocol parameter acquisition request signal to the MEDL analysis module 4, and after the MEDL analysis module 4 receives the time slot request signal or the global protocol parameter acquisition request signal, the starting address and the length of each table configured by the global entries are combined with the type of the request signal to send corresponding information in the scheduling table to the starting control module or the synchronous control module.

The frame parsing module 5 parses an input frame to obtain Global Time/Startup Time (Global Time/initial Time) fields, DMC (delay mode change) fields and Cluster position (Cluster position) fields of a control status field (C-state) in the frame, and transmits Global Time/Startup Time (Global Time/Startup Time) fields of the control status field in the frame to the clock generating and synchronizing module 3, and transmits DMC (delay mode change) fields and Cluster position (Cluster position) fields to the Cluster mode switching module 6 to trigger the Cluster mode switching module 6 to send a Cluster switching signal to the MEDL parsing module 4.

In the starting process, the frame analysis module analyzes the time, cluster position (containing DMC, cluster Mode and Round slot field) and frame header (containing Mode Change Request and Type) in the C state of the frame while receiving the input frame; transmitting start time in the cold start frame to a time generation module for generating a local clock; and judging whether the frame is an I frame, an N frame or a cold start frame according to fields such as DMC, cluster Mode and Type, and outputting a frame Type mark to a start control module and a synchronous control module for state jump judgment.

The cluster mode switching module 6 is configured to check mode change request (mode change request) whether the content of the hub is allowed or not in the PRP stage, set mode change request (mode change request) to DMC (delay mode change) if the content is allowed, assign a subsequent mode corresponding to DMC to a cluster mode when it is detected that the EOC field of the last slot in the present cluster mode is valid and the current slot is about to end, and transmit the changed cluster mode to the MEDL parsing module, where the next slot represents a new cluster mode to start running.

The receiving and transmitting module 7 is used for receiving and transmitting data in the synchronous stage of the hub and comprises a baud rate generating sub-module, a receiving sub-module, a transmitting sub-module, a registering sub-module and a CRC checking sub-module;

The baud rate generation submodule is used for generating baud rates; in the present invention, the baud rate is set to 5M;

The receiving sub-module is configured to determine whether the data transmission is started (because the input enable is valid at low level) when the data transmission is finished by receiving the falling edge, and determine whether the data transmission is finished by the frame length provided by the frame length calculation module;

The transmission start of the sending sub-module is determined by the shaping enabling signal provided by the shaping module, and the transmission end of the sending sub-module is judged by the frame length;

The register sub-module is matched with the shaping module and is used for caching the input data for shaping time;

The shaping module 8 is configured to isolate a time domain SOS fault, add a shaping delay at the end of a receiving window in the TP stage, and generate a shaping output enable signal to the transceiver module 7 when the shaping delay is completed after the system time of the hub is reached.

The shaping module of the invention performs shaping in the time domain, mainly to avoid SOS faults in the time domain. Because the hub and the node both have an ideal reception time point, when the frame arrives earlier than the ideal reception time point, the hub can wait until the system time is the ideal reception time point and forward the data, but when the frame arrives later than the ideal reception time point, the hub has no way to buffer the frame until the system time is equal to the ideal reception time point. Besides, the clock error between the nodes can be reduced by adjusting the ratio of Ma to Mi, but the ratio of Ma to Mi is a fixed value after each configuration is completed, and if the configuration data is to be modified, the configuration data needs to be modified, so that the operation is inconvenient.

Specifically, the shaping module adds a shaping delay at the end of the receiving window stage of the TP stage, waits until the system time reaches the shaping delay completion time, and then generates a shaping output enable signal, the shaping output enable signal controls the transceiver module to forward the data buffered in the register sub-module, and the node takes the shaping delay as propagation delay. In this way, regardless of whether the data input to the hub is within any time period (whether earlier or later) within the hub receiving window, it is ensured that all receiving nodes receive the completed data without a portion of the nodes receiving the correct frame and a portion of the nodes not receiving the correct frame, and the shaping module effectively avoids a time domain SOS failure between the nodes (slightly-off-specifiacation). As shown in fig. 6, the artificial delay at the optimal reception time point is set to a period hub_delay (at least half a reception window), and then the delay of the hub is calculated into the propagation delay of the node, that is, the propagation delay between the node 0 and the node 1 needs to be set to be the sum of the node 0 propagation delay corr0, the hub delay hub_delay and the hub propagation delay corr_h. When the input data is not shaped, as shown by the red line segment in the time domain SOS shaping schematic diagram, when the data of the node 0 arrives at the hub receiving window earlier, the data cannot arrive in the range of the receiving window of the node 1 after being forwarded by the hub.

The gating module 9 inputs and outputs data according to the start input enabling signal and the start output enabling signal in a hub starting stage, and opens and closes each port corresponding to the node according to the synchronous input enabling signal and the synchronous output enabling signal transmitted by the synchronous control module in a hub synchronous stage, wherein the gating module comprises a start gating sub-module, a synchronous gating sub-module and an output selecting sub-module;

the gating module comprises a starting gating sub-module, a synchronous gating sub-module and an output selection sub-module, wherein the starting gating sub-module is used for receiving or outputting data in a starting stage of the hub, the synchronous gating sub-module is used for receiving or outputting data according to synchronous input enabling signals and synchronous output enabling signals in a synchronous stage of the hub, and the output selection sub-module is used for selecting and outputting output data of the starting gating sub-module or data of the synchronous gating sub-module according to a starting state or a synchronous state of the hub.

In the starting stage, data conflict can exist at first, and in the second starting path, a Bigbang mechanism is adopted, so that the hub randomly selects data forwarding of one port; the second hub can also correctly select the input data during the first and third startup paths because the first hub that is running will give the second hub current time slot information to startup. After the second hub is successfully integrated, correct data selection can be performed according to the time slot information provided by the schedule, and according to the idea of time division multiplexing, the input enabling of at most one port in one time slot is effective, namely, only the data corresponding to the node of the current time slot specified by the schedule is allowed to be input, and after the data is shaped, the data is sent to the gating module through the receiving and transmitting module. The receiving and transmitting module is a physical layer interface of the invention, and the invention adopts a half duplex method for receiving and transmitting, so the gate control module can forward data to all ports except the input data port.

After the synchronization stage is entered, the data is transmitted and received by the synchronous gating sub-module, the data transmitted by the correct node of the current time slot is transferred to the receiving sub-module in the transmitting and receiving module, and the data transmitted by the node which should not transmit the data in the time slot is shielded. The receiving sub-module detects the falling edge to judge whether the data starts to be transmitted or not, and then judges whether the data of the current time slot is transmitted or not according to the frame length provided by the frame length calculating module. The data in the synchronous stage is not directly forwarded, but enters fifo in the register sub-module, and the data in the register sub-module is output to the sending sub-module after the shaping module gives out the shaping enabling signal, and the sending sub-module judges whether the transmission is finished or not by judging the frame length. The sending sub-module forwards the data to the gating module, and the gating module forwards the data to other nodes according to the synchronous output enabling signals output by the synchronous control module.

The gating function of the start-up phase and the gating function of the synchronization phase are designed separately, so that an output selection module is also required. The output selection module selects the output data of the start gating and the synchronous gating, outputs the output data of the start gating sub-module in the start stage, and outputs the output data of the synchronous gating sub-module in the synchronous stage.

The frame length generating module 10 is configured to calculate a frame length of each transmission according to the data length and the frame type provided by the MEDL parsing module and the frame length overhead fixed by each frame type, and output the calculated frame length to the transceiver module 7 and the gate control module 9.

The frame length calculation module obtains the data length APPDATA LENGTHE of the current time slot and the IF field according to the MEDL analysis module to determine whether the data input by the current time slot is a display frame or an implicit frame, IF the data is the implicit frame, the data has no C state, and IF the data is the display frame, the data has the C state. The display frame and the implicit frame have fixed frame cost, and after the frame type is judged, the frame length of the current time slot transmitting node can be calculated by using the fixed frame cost and the data length so as to judge whether the frame transmission is finished or not.

The online configuration module 11 is configured to add a section of destination field for identifying a destination to the front end of the configuration data when the configuration data is downloaded by the configuration host, where the destination field of the hub and the destination field of the node are unique and different, so that the hub first determines the identification field, if the field is determined that the configuration data is sent to the hub, it checks whether the global entry table in the configuration data is correct, if the configuration data is checked to be correct, it configures the data to RAM Random access memory of the MEDL parsing module, and the random access memory), and at the same time, the hub forwards the configuration data; if the field is determined to be the sending node, the data is forwarded to the corresponding node.

The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.

Claims

1. The hub applied to the star-shaped TTP network is characterized by comprising a gating module (9) and a receiving and transmitting module (7) which are arranged on a physical link layer, a starting control module (1), a synchronous control module (2), a clock generation and synchronization module (3), a MEDL analysis module (4), a frame analysis module (5), a cluster mode switching module (6), a shaping module (8), a frame length calculation module (10) and an online configuration module (11), wherein the TTP network is a time triggered network, and the MEDL analysis module is a message description list analysis module;

The input end of the receiving and transmitting module (7) is respectively connected with the shaping module (8), the gating module (9) and the frame length calculating module (10), and the output end of the receiving and transmitting module (7) is respectively connected with the gating module (9), the frame analyzing module (5) and the online configuration module (11);

The input end of the clock generation and synchronization module (3) is respectively connected with the frame analysis module (5), the shaping module (8) and the MEDL analysis module (4), and the output end of the clock generation and synchronization module (3) is respectively connected with the starting control module (1) and the synchronization control module (2);

The input end of the MEDL analysis module (4) is respectively connected with the starting control module (1), the synchronous control module (2), the cluster mode switching module (6) and the online configuration module (11), and the output end of the MEDL analysis module (4) is also respectively connected with the frame length calculation module (10), the starting control module (1) and the synchronous control module (2);

the output end of the frame analysis module (5) is also connected with the cluster mode switching module (6);

the output end of the starting control module (1) is also respectively connected with the gating module (9) and the synchronous control module (2);

the output end of the synchronous control module (2) is also connected with the gate control module (9);

The starting control module (1) is used for realizing the transition of the hub from an asynchronous state to a synchronous state in the starting stage of the hub, enabling the hub to generate a starting input enabling signal and a starting output enabling signal in the starting stage according to the Sender Membership Flag signal provided by the MEDL analyzing module and the system time provided by the clock generating submodule, controlling the input and the output of an external node connected with the hub by the starting input enabling signal and the starting output enabling signal, and simultaneously transmitting a PSP starting time point, a TP starting time point, a PRP starting time point, a time slot ending time point and the current time slot number in a time slot when the starting is completed to the synchronous control module after the starting is completed; sender Membership Flag signals are transmitting end member variable sign signals;

The synchronous control module is used for generating synchronous input enabling signals and synchronous output enabling signals of the control gating module (9) after the hub enters the synchronous state according to each time point when the hub enters the synchronous state and the time slot information provided by the MEDL analysis module, and dividing each time slot of the hub in the synchronous stage, wherein each time slot comprises an IDLE stage, namely an IDLE stage; PSP stage, i.e. stage before transmission; a TP stage, namely a data sending stage; PRP stage, namely stage after transmission; the hub performs state skipping according to the time of each stage;

The clock generation and synchronization module (3) comprises a clock generation sub-module and a clock synchronization sub-module, the clock generation sub-module works in the starting stage of the hub, the initial time of the hub is obtained according to Global time/start time and frame analysis time obtained from the frame analysis module (5) and the transmission delay and propagation delay provided by the MEDL analysis module (4), and the local time of the hub is formed through the initial time; the clock synchronization sub-module works when the hub is in a synchronization stage, acquires a time difference value transmitted by the shaping module (8), calculates a correction term and corrects the local clock of the hub according to the correction term so as to realize at least one time synchronization in one TDMA Round, wherein the correction is divided into single-step correction and multiple correction, and the correction rule is determined by a schedule in the MEDL analysis module (4); global time/startup time is the Global time/startup time, and TDMA Round is the period arranged in a time division multiple access mode;

The MEDL analysis module (4) comprises a global entry table, a protocol parameter table, a MEDL identification table, a time slot parameter table and 7 cluster mode tables; each cluster mode table comprises a mode control table and a plurality of time slot entries, after a hub is started, an online configuration module transmits loading configuration data to a storage unit RAM of a MEDL analysis module (4), after hub self-checking is completed, a starting control module or a synchronous control module sends a time slot request signal or a global protocol parameter acquisition request signal to the MEDL analysis module (4) at the beginning of each time slot, and after the MEDL analysis module (4) receives the time slot request signal or the global protocol parameter acquisition request signal, corresponding information in a schedule is sent to the starting control module or the synchronous control module according to the starting address and the length of each table configured by the global entries and the type of the request signal;

The frame analysis module (5) is used for analyzing an input frame to acquire a Global Time/Startup Time field, a DMC field and a Cluster position field of a control state field in the frame, transmitting GlobalTime/Startup Time fields of the control state field in the frame to the clock generation and synchronization module (3), and transmitting the DMC field and the Cluster position field to the Cluster mode switching module (6) so as to trigger the Cluster mode switching module (6) to send a Cluster switching signal to the MEDL analysis module (4); the DMC field is a delay mode change field, and the Cluster position field is a Cluster position field;

the cluster mode switching module (6) is used for checking whether a mode change request is allowed or not in a PRP stage of a hub, setting the content of the mode change request as the content of delay mode change if the mode change request is allowed, assigning a subsequent mode corresponding to the content of delay mode change to the cluster mode when a field EOC representing the last time slot in the cluster mode in a schedule is detected to be valid and the current time slot is about to end, transmitting the changed cluster mode to the MEDL analysis module, and entering a new cluster mode in the next time slot; EOC, i.e. the end of the cluster period;

The receiving and transmitting module (7) is used for receiving and transmitting data by the hub and comprises a baud rate generating sub-module, a receiving sub-module, a transmitting sub-module, a registering sub-module and a CRC checking sub-module; the CRC sub-module is a cyclic redundancy check sub-module;

The shaping module (8) is used for isolating time domain SOS faults, shaping delay is added at the tail of a receiving window in the TP stage, and a shaping output enabling signal is generated to the transceiver module (7) when the shaping delay is completed after the system time of the hub is up to the completion of the shaping delay; SOS fault is a slight non-compliance fault in isolation time domain;

the gate control module (9) inputs and outputs data according to the start input enabling signal and the start output enabling signal in a hub starting stage, and opens and closes each port corresponding to the node according to the synchronous input enabling signal and the synchronous output enabling signal transmitted by the synchronous control module in a hub synchronous stage, wherein the gate control module (9) comprises a start gate control sub-module, a synchronous gate control sub-module and an output selection sub-module;

The frame length calculation module (10) is used for calculating the frame length of each transmission according to the data length, the frame type and the frame length overhead fixed by each frame type provided by the MEDL analysis module, and outputting the calculated frame length to the receiving and transmitting module (7) and the gate control module (9);

The online configuration module (11) is used for configuring data for a node or a hub, adding a section of field for identifying a destination at the front end of the configuration data when the configuration host downloads the configuration data, wherein the identification fields of the hub and the node are unique and different, if the field is judged that the configuration data is sent to the hub, checking whether a global entry table in the configuration data is correct, if the configuration data is checked to be correct, configuring the data to a RAM of the MEDL analysis module, and meanwhile, forwarding the configuration data by the hub; if the field is determined to be a node, the hub forwards the data.

2. A method for implementing a hub for a star TTP network, using the hub for a star TTP network according to claim 1, comprising the steps of:

S3, in a starting stage, the clock generation and synchronization module obtains the initial time of the hub by combining the Global time/start time and the frame analysis time obtained by the frame analysis module with the transmission delay and the propagation delay provided by the MEDL analysis module, meanwhile, the frame length calculation module calculates the frame length of the current time slot according to the data length and the IF field of the current time slot obtained by the MEDL analysis module so as to judge whether frame transmission is finished, schedule information of the MEDL analysis module and the initial time of the hub are transmitted to the starting control module, the starting control module enables the hub to generate a starting input enabling signal and a starting output enabling signal in the starting stage according to the information provided by the MEDL analysis module and the system time provided by the clock generation submodule, meanwhile, the starting control module checks the schedule information, the hub enters a frame listening state after the checking is passed, and the corresponding time is transmitted to the synchronization control module according to the transition of the frame running state received in a specified time range when the hub is started, and the hub enters the synchronization stage; the IF field is a sync frame flag field;

S4, the synchronous control module outputs a synchronous input enabling signal and a synchronous output enabling signal of the control gating module, and divides each time slot of the hub in a synchronous stage, and the hub performs state jump according to IDLE, PSP, TP and a PRP stage of each time slot; the clock generation and synchronization module performs time synchronization at least once in each TDMARound, each port of the gating module is turned on/off according to the input/output enabling control signal, the receiving and transmitting module outputs data to the gating module through the output enabling signal given by the shaping module, and whether transmission is finished is judged according to the frame length of the data obtained by the frame length calculation module.

3. The method for implementing a hub for a star TTP network according to claim 2, wherein the start control module of the hub includes a validity check state, a frame listening state, a cold start state, an integration state, a synchronization state, a wait for integration state, and a wait for synchronization state; s3, the starting control module checks the schedule information, and the specific steps of checking that the hub enters a frame listening state after passing through and performing state transition according to the received frames within a specified time range are as follows:

When the concentrator is in a frame listening state, the concentrator is used for carrying out frame identification, when the concentrator is in the frame listening state, the concentrator continues to receive frames, if no frame is detected in 2 TDMA Round time ranges, the concentrator jumps to a cold starting state, if a valid cold starting frame is detected in 2 TDMA Round time ranges, the concentrator jumps to a waiting integration state, and if a valid synchronous frame is detected in 2 TDMA Round time ranges, the concentrator jumps to a waiting synchronization state;

The hub is in a cold start state and comprises a first cold start stage and a second cold start stage, when the hub is in the cold start state, the hub continues to receive frames, the hub is in the first cold start stage first, the hub executes Bigbang mechanism when in the first cold start stage, if a valid cold start frame is detected within 1 TDMA Round range and CRC check is successful, the hub jumps to the second cold start stage, otherwise, the hub still stays in the first cold start stage; bigbang mechanisms are collision avoidance mechanisms;

4. The method for implementing a hub for a star TTP network according to claim 2, wherein in S4, the synchronization control module outputs an input/output enable control signal for controlling the gating module and divides each time slot of the hub in a synchronization phase, and the specific steps of the hub performing state skipping according to each time slot are as follows:

S4.1, in the synchronous stage, when each time slot starts, the hub enters an S_Init state, judges whether the current system is active or not and whether the cluster mode is switched or not, then enters an IDLE stage of each time slot, and the hub jumps to the S_IDLE state, namely an IDLE state; the S_Init state is an initial state in a synchronous state;

S4.4, judging whether any time calculated in the step S4.3 exceeds a maximum threshold value, if so, subtracting the maximum threshold value from the local time of the hub to serve as system time, otherwise, directly using the local time of the hub as the system time;

S4.5, detecting whether the system time reaches the start time of the PSP stage, if so, jumping to the PSP stage by the hub, entering an S_PSP state, setting the IDLE_flg to 0 and setting the PSP_flg to 1; otherwise, the system stays in an S_IDLE state, IDLE_flg is set to be 1, PSP_flg is set to be 0, IDLE_flg indicates that the synchronous control module is in an IDLE stage of the current time slot, and PSP_flg indicates that the hub is in a PSP stage of the current time slot; the s_psp state is a pre-transmission stage state in the synchronous state;

S4.6, detecting whether the system time reaches the starting time of the TP stage, jumping to the TP stage if the system time reaches the starting time of the TP stage, entering the S_TP state, setting TP_flg to be 1, setting PSP_flg to be 0, and transmitting and receiving data by a transceiver module in the stage; otherwise, staying in an S_PSP state and setting TP_flg to 0, wherein PSP_flg is set to 1, the TP_flg represents that the synchronous control module is in a TP stage of a current time slot, and the PSP_flg represents that the hub is in a PSP stage of the current time slot; the s_tp state is a transmission phase state in the synchronous state;

S4.7, detecting whether the system time reaches the PRP stage starting time, jumping to the PRP stage if the system time reaches the PRP stage starting time, entering an S_PRP state, setting PRP_flg to be 1, and setting TP_flg to be 0; otherwise, stay in the s_tp state and set tp_flg to 1 and prp_flg to 0, where prp_flg indicates that the hub is in the PRP phase of the current slot; the s_prp state is a post-reception phase state in the synchronous state;

S4.8, when the system time is equal to the current time slot ending time, the state of the synchronous control module is changed into the S_Init state described in S4.1, the next_slot_flg is set to 1, and the PRP_flg is set to 0; otherwise, the method stays in the S_PRP state, PRP_flg is 1, next_slot_flg is 0, and next_slot_flg is the next time slot arrival sign.

5. The method of claim 4, wherein in S4.6, the TP stage includes a pre-receive window stage, a receive window stage, and a post-receive window stage, and the specific process in the TP stage includes:

s4.6.2, in the receiving window stage, when the system time is equal to the receiving window ending time point, jumping to the receiving window ending post stage; otherwise, staying in a receiving window stage, detecting whether a corresponding node of the current time slot has data input, if so, setting a corresponding flg to be 1, otherwise, setting the flg to be 0, namely a flag bit;

6. The method of claim 2, wherein the clock generation and synchronization module performs at least one time synchronization in each TDMARound as follows:

A1, acquiring the actual acquired time and the theoretical acquired time difference diff of the data in a shaping module, and storing the time difference diff in a time synchronization sub-module;

A3, if the Clksyn field of the current time slot is analyzed to be 1 in the MEDL analysis module, clock correction is executed in the PRP stage of the current time slot, if the MEDL analysis module analyzes that the free_running_ MAcroticks _t0 field of the current time slot is 1, single-step correction is executed, otherwise, multi-step correction is executed, and Clksyn field is a flag field for executing clock correction, and free_running_ MAcroticks _t0 is a macro scale Free running flag.

7. The method according to claim 2, wherein the transceiver module (7) is configured to perform data transmission and reception in a synchronization stage of the hub, and comprises a baud rate generating sub-module, a receiving sub-module, a transmitting sub-module, a registering sub-module and a CRC checking sub-module,

The baud rate generation submodule is used for generating baud rates;

8. The method according to claim 2 or 7, wherein the shaping module adds a shaping delay at the end of the receiving window stage of the TP stage, and generates an output enable when the system time reaches the shaping delay completion time, and the output enable control transceiver module forwards the data buffered in the register sub-module.

9. The method according to claim 2, wherein the gating module includes a start gating sub-module, a synchronization gating sub-module and an output selecting sub-module, the start gating sub-module is configured to receive or output data in a start stage of the hub, the synchronization gating sub-module is configured to receive or output data in a synchronization stage of the hub according to a synchronization input enable signal and a synchronization output enable signal, and the output selecting sub-module is configured to select and output data of the start gating sub-module or data of the synchronization gating sub-module according to a start state or a synchronization state in which the hub is located.