CN111314190A - Data transmission system and method with arbitration interface having reset function - Google Patents
Data transmission system and method with arbitration interface having reset function Download PDFInfo
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- CN111314190A CN111314190A CN202010293899.6A CN202010293899A CN111314190A CN 111314190 A CN111314190 A CN 111314190A CN 202010293899 A CN202010293899 A CN 202010293899A CN 111314190 A CN111314190 A CN 111314190A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/40—Bus networks
- H04L12/40006—Architecture of a communication node
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/40—Bus networks
- H04L12/40169—Flexible bus arrangements
- H04L12/40176—Flexible bus arrangements involving redundancy
- H04L12/40182—Flexible bus arrangements involving redundancy by using a plurality of communication lines
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/40—Bus networks
- H04L2012/40208—Bus networks characterized by the use of a particular bus standard
- H04L2012/40215—Controller Area Network CAN
Abstract
The invention provides a data transmission system and a method with a reset function for an arbitration interface, which comprises the following steps: at least two pairs of data buses, one pair of arbitration buses and a plurality of communication nodes; the arbitration bus is used for arbitrating the data bus and transmitting by taking an arbitration frame as a unit, each arbitration frame comprises at least two arbitration time periods, and each arbitration time period selects a winning communication node for obtaining the data transmission right; each communication node comprises a control module, a conduction control unit and a reset unit; when the control module of each communication node detects that the communication node has a data transmission requirement, the control conduction control unit is controlled to transmit each symbol of the identifier to the arbitration bus, and when the control conduction control unit detects that the symbol is successfully transmitted, the control reset unit resets the arbitration bus so as to avoid influencing the transmission of the next symbol. The invention can improve the reliability of the arbitration interface and meet the requirements of high-speed, reliable and real-time communication among a plurality of communication nodes.
Description
Technical Field
The present invention relates to the field of data transmission, and in particular, to a data transmission system and method with an arbitration interface having a reset function.
Background
A CAN (Controller Area Network) bus has been widely used in the fields of automobile application, industrial automation, and the like because of its advantages of high reliability, real-time performance, and the like.
The CAN bus only comprises a pair of differential signal lines, adopts serial data transmission and has simple structure; the method supports multi-master communication, namely each node device can actively initiate data communication to other node devices on the network at any time, and the communication sequence is determined according to the priority of the identifier of each node device; when a plurality of node devices simultaneously initiate communication, the avoidance priority with low priority is high. However, the bus rate is limited, and is up to 1Mbps (the communication distance is less than 40 meters), and the data frame of the CAN bus CAN transmit at most 8 bytes of effective data each time, which cannot meet the design requirement of large data volume high-speed communication among a plurality of node devices. In addition, when there are many node devices hanging on the bus, communication conflicts easily occur, only one node device is allowed to acquire the ownership of the bus for data transmission by arbitration each time, and other node devices have to wait, which also limits the bus rate.
Disclosure of Invention
The invention aims to provide a data transmission system and a data transmission method with a reset function for an arbitration interface, which can improve the reliability of the arbitration interface in the multipoint interconnection application occasion, realize the high-speed and real-time communication requirements among a plurality of communication nodes by utilizing a high-speed bus, and have high transmission efficiency and high reliability.
The technical scheme provided by the invention is as follows:
a data transmission system with reset function for arbitration interface, comprising: at least two pairs of data buses, wherein all the data buses transmit by taking a data frame as a unit; the arbitration buses transmit by taking arbitration frames as units, the transmission time of the arbitration frames is the same as that of the data frames, each arbitration frame comprises at least two arbitration time periods, and each arbitration time period arbitrates a winner communication node of the time period; the communication nodes are respectively connected in parallel and hung on the data buses and the arbitration bus; each communication node includes: the arbitration interface module comprises a conduction control unit and a reset unit; the conduction control unit is used for sending each symbol of the identifier of the conduction control unit to the arbitration bus; the reset unit is used for resetting the arbitration bus; the data sending module is used for sending own data to a target data bus; the control module is used for controlling the conduction control unit to send each symbol of the identifier of the conduction control unit to the arbitration bus in the current arbitration time period of the current arbitration frame when the self data sending requirement is detected; and when the symbol is detected to be successfully sent, controlling the reset unit to reset the arbitration bus and then continuously sending the next symbol; when detecting that the identifier is successfully sent, the communication node is a winning communication node in the time period, and controls the data sending module to send own data to a target data bus in the next data frame, and meanwhile, the identifier is not sent in the current arbitration frame; when the identifier transmission failure is detected and the current arbitration time period is not the last arbitration time period of the current arbitration frame, controlling the conduction control unit to retransmit the identifier to the arbitration bus in the next arbitration time period of the current arbitration frame until the identifier transmission is successful or the last arbitration time period of the current arbitration frame is reached.
It is further preferred that the number of arbitration periods per arbitration frame is equal to the number of data buses.
Further preferably, the conduction control unit includes: the driving subunit is used for translating each symbol of the identifier of the driving subunit into a predefined level value to obtain a driving output voltage; the comparison subunit is used for comparing the driving output voltage with the arbitration bus voltage; the switch subunit is used for conducting the switch when the permission signal is effective and conducting the driving output voltage to the arbitration bus; the control module is further used for controlling the permission signal according to the comparison result of the driving output voltage and the arbitration bus voltage.
Further preferably, the control module is further configured to maintain the validity of the permission signal until a symbol clearing time when the driving output voltage is not lower than the arbitration bus voltage, and cancel the permission signal and control the reset unit to reset the arbitration bus when the symbol clearing time is reached; and when the driving output voltage is lower than the arbitration bus voltage, the permission signal is cancelled to be invalid.
Further preferably, the driving subunit includes a digital-to-analog converter and a buffer, the switching subunit is a first field effect transistor, and the comparing subunit includes a comparator and a resistor; the input end of the digital-to-analog converter inputs the symbol of the identifier, the output end of the digital-to-analog converter is electrically connected with the input end of the buffer, the output end of the buffer is electrically connected with the drain electrode of the first field effect transistor, the gate electrode of the first field effect transistor inputs the permission signal, and the source electrode of the first field effect transistor is connected to the arbitration bus; the positive input end of the comparator is electrically connected with the output end of the buffer, and the negative input end of the comparator is connected to the arbitration bus through a resistor.
Further preferably, the reset unit is a second field effect transistor, and a gate of the second field effect transistor inputs a reset signal.
The invention also provides a data transmission method, which comprises the following steps: in the current arbitration time period of the current arbitration frame, the communication node with the data transmission requirement transmits each symbol of the identifier of the communication node to an arbitration bus; when the symbol is detected to be successfully sent, the communication node resets the arbitration bus, continues to send the next symbol and repeats the steps until the symbol is the last symbol of the identifier; when the identifier is detected to be successfully sent, the communication node is a winner communication node of the time period, and sends own data to a target data bus in the next data frame, and meanwhile, the identifier is not sent in the current arbitration frame; when the identifier transmission failure is detected and the current arbitration period is not the last arbitration period of the current arbitration frame, the communication node retransmits the identifier onto the arbitration bus in the next arbitration period of the current arbitration frame until the identifier transmission is successful or the last arbitration period of the current arbitration frame has been reached.
It is further preferred that the number of arbitration periods per arbitration frame is equal to the number of data buses.
Further preferably, the sending, by the communication node having a data transmission demand, each symbol of its identifier onto the arbitration bus in the current arbitration period of the current arbitration frame includes: in the current arbitration time period of the current arbitration frame, the communication node with the data transmission requirement translates each symbol of the identifier of the communication node into a predefined level value to obtain a driving output voltage; controlling a permission signal according to a comparison result of the driving output voltage and an arbitration bus voltage; conducting the drive output voltage onto an arbitration bus when the grant signal is active.
Further preferably, the controlling the permission signal according to the comparison result of the driving output voltage and the arbitration bus voltage includes: when the driving output voltage is not lower than the arbitration bus voltage, maintaining the validity of the permission signal until the symbol clearing time, and when the symbol clearing time is reached, canceling the permission signal and controlling the reset unit to reset the arbitration bus; and when the driving output voltage is lower than the arbitration bus voltage, the permission signal is cancelled to be invalid.
The data transmission system and the method for the arbitration interface with the reset function provided by the invention can bring at least one of the following beneficial effects:
1. the arbitration bus is separated from the data bus, so that the transmission rate of the data bus can be improved, and the transmission rate of the arbitration bus is reduced on the premise of ensuring the transmission rate of the data bus, so that the reliability of the system is improved;
2. the invention can reduce the transmission delay caused by collision and improve the transmission efficiency of the bus by providing a plurality of pairs of data buses and a plurality of arbitration opportunities in 1 arbitration frame;
3. in each symbol sending stage of the identifier, the communication node which successfully sends the symbol resets the arbitration bus after the symbol is successfully sent, so that the mutual influence among the symbols on the arbitration bus is avoided, and the reliability of the arbitration interface is improved.
Drawings
The foregoing features, technical features, advantages and implementations of a data transmission system and method with an arbitration interface having a reset function will be further described in the following detailed description of preferred embodiments in a clearly understandable manner in conjunction with the accompanying drawings.
FIG. 1 is a schematic diagram of an embodiment of a data transmission system with a reset function for an arbitration interface according to the present invention;
FIG. 2 is a schematic diagram of a conduction control unit of another embodiment of a data transmission system with a reset function for an arbitration interface according to the present invention;
FIG. 3 is a circuit diagram of an arbitration interface module of another embodiment of a data transmission system with an arbitration interface having a reset function according to the present invention;
FIG. 4 is a schematic diagram of symbol output timing;
FIG. 5 is a flow chart of one embodiment of a data transmission method of the present invention;
fig. 6 is a flow chart of another embodiment of a data transmission method of the present invention.
The reference numbers illustrate:
100. the device comprises an arbitration interface module, a 110 conduction control unit, a 120 reset unit, a 111 driving subunit, a 112 switching subunit, a 113 comparison subunit, a 200 control module and a 300 data sending module.
Detailed Description
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description will be made with reference to the accompanying drawings. It is obvious that the drawings in the following description are only some examples of the invention, and that for a person skilled in the art, other drawings and embodiments can be derived from them without inventive effort.
For the sake of simplicity, the drawings only schematically show the parts relevant to the present invention, and they do not represent the actual structure as a product. In addition, in order to make the drawings concise and understandable, components having the same structure or function in some of the drawings are only schematically illustrated or only labeled. In this document, "one" means not only "only one" but also a case of "more than one".
In one embodiment of the present invention, as shown in fig. 1, a data transmission system with an arbitration interface having a reset function includes: at least two pairs of data buses, wherein all the data buses transmit by taking a data frame as a unit; the arbitration buses transmit by taking arbitration frames as units, the transmission time of the arbitration frames is the same as that of the data frames, each arbitration frame comprises at least two arbitration time periods, and each arbitration time period arbitrates a winner communication node of the time period; and the communication nodes are respectively connected in parallel and hung on the data buses and the arbitration bus.
Specifically, an arbitration frame and a data frame on the CAN bus are multiplexed on the same bus in a time-sharing manner, and the arbitration frame limits the transmission rate of the data frame. In order to increase the transmission rate of the data bus, the arbitration bus is separated from the data bus in the present invention. Arbitration information is sent on an arbitration bus, data information is sent on a data bus, the data bus can adopt a completely different high-speed channel coding transmission scheme from the arbitration bus, the data bus has a higher symbol modulation rate to meet the high-speed transmission requirement, and the arbitration bus has a lower symbol modulation rate to ensure the arbitration reliability.
The bus structure shown in fig. 1 includes two pairs of data buses and one pair of arbitration buses, where the data bus 1 is formed by one pair of conductors, the data bus 2 is formed by the other pair of conductors, and the arbitration bus is formed by one pair of conductors. Fig. 1 is only an example of a bus structure, and the bus structure according to the present invention may also include three or more pairs of data buses, and increasing the number of data buses may improve the bus transmission rate and efficiency, and reduce the transmission delay due to collision; however, too many pairs of data buses increase the manufacturing cost, and in practical applications, a compromise between transmission efficiency and manufacturing cost is required.
The arbitration bus is transmitted according to arbitration frames, one arbitration frame comprises a plurality of arbitration time periods, each arbitration time period is the identifier sending time of each communication node, the communication nodes are arbitrated according to the priority of the identifiers when colliding, the arbitration bus arbitrates the identifiers of the communication nodes participating in data sending right competition in the arbitration time period, only the identifiers with high priority are presented on the arbitration bus, and the communication node corresponding to the identifier with high priority is the winner communication node of the arbitration time period.
The data bus is transmitted according to data frames, the transmission time of one data frame is the same as that of one arbitration frame, but the data volume transmitted in the same time is different, and the data volume of the data frame is larger than that of the arbitration frame, so that the transmission rate of the data bus is high. The arbitration frame with the same frame number may have the same start time as the data frame, or may have a fixed time offset, for example, the frame header of the data frame is delayed by a fixed time offset relative to the frame header of the arbitration frame with the same frame number.
Since there are at least 2 pairs of data buses, an arbitration frame contains at least 2 arbitration time periods for at least the 2-bit winning communication node to decide on data transmission for the next data frame. The number of arbitration periods contained in each arbitration frame is not less than the number of data buses, and may be equal to or greater than, if less than, the data buses are easily wasted.
During each arbitration period of each arbitration frame, the winning communication node will obtain the transmission right of the next data frame for transmitting one frame of data. The data frame comprises an identifier of the receiving equipment, so that the receiving equipment can identify whether the data is sent to the receiving equipment, and if so, the data is received; otherwise, the process is abandoned.
Each communication node includes:
an arbitration interface module 100 including a conduction control unit 110 and a reset unit 120;
the turn-on control unit 110 is configured to send each symbol of its own identifier to the arbitration bus;
the reset unit 120 is configured to reset the arbitration bus;
a data sending module 200, configured to send data of itself to a target data bus;
a control module 300, configured to control the conduction control unit to send each symbol of its identifier to the arbitration bus in the current arbitration period of the current arbitration frame when it is detected that there is a data sending need of itself; and when the symbol is detected to be successfully sent, controlling the reset unit to reset the arbitration bus and then continuously sending the next symbol; when detecting that the identifier is successfully sent, the communication node is a winning communication node in the time period, and controls the data sending module to send own data to a target data bus in the next data frame, and meanwhile, the identifier is not sent in the current arbitration frame; when the identifier transmission failure is detected and the current arbitration time period is not the last arbitration time period of the current arbitration frame, controlling the conduction control unit to retransmit the identifier to the arbitration bus in the next arbitration time period of the current arbitration frame until the identifier transmission is successful or the last arbitration time period of the current arbitration frame is reached.
Specifically, each communication node has a unique identifier for identifying itself, and the identifier is composed of one or more multilevel symbols. Before sending data, each communication node must first send its own identifier on the arbitration bus, and after the own identifier is successfully sent on the arbitration bus, the communication node obtains the use authority of the target data bus, and then can send data on the next frame of the target data bus. The arbitration bus is transmitted according to arbitration frames, one arbitration frame at least comprises 2 arbitration time periods, and the arbitration time periods are used for the communication nodes to send identifiers. During the current arbitration period, the communication node having a data transmission requirement can transmit each symbol of its own identifier to the arbitration bus in bit to participate in data transmission right competition.
After each bit of symbol of the identifier is sent by the communication node, detecting the symbol on the arbitration bus; when the symbol on the arbitration bus is different from the symbol sent by the communication node, the sending of the identifier is considered to be failed, and the sending of the subsequent symbol of the identifier is stopped; when the symbol on the arbitration bus is the same as the symbol sent by the communication node, the symbol is sent successfully, after the symbol is sent successfully, the arbitration bus is reset, the condition that the existing voltage on the arbitration bus influences the sending of the next symbol is avoided, and then the next symbol of the identifier is sent continuously; when the communication node successfully transmits all the symbols of the identifier, the transmission of the identifier is considered successful. In each symbol sending stage of the identifier, the communication node with successfully sent symbols resets the arbitration bus after detecting that the symbols are successfully sent, so that mutual influence among the symbols on the arbitration bus is avoided, and the reliability of the arbitration interface is improved.
When a plurality of communication nodes send identifiers simultaneously, the communication nodes which can correctly send the identifiers to the arbitration bus obtain the wins of the arbitration at this time, become the wining communication nodes, obtain the use right of the next data frame of the target data bus, and stop sending own identifiers in the arbitration frame.
If the identifier transmission failure is detected and the current arbitration time period is not the last arbitration time period of the current arbitration frame, the communication node can continue to participate in subsequent arbitration, and continues to transmit the identifier to participate in data transmission right competition when the next arbitration time period of the current arbitration frame arrives, namely continues to transmit the identifier to obtain the use right of the target data bus when the next arbitration time period becomes the current arbitration time period.
Example (c): the bus structure comprises 1 pair of arbitration buses and 3 pairs of data buses, each arbitration frame comprises 3 arbitration time periods, the winning communication node of each arbitration time period obtains the data transmission right of the target data bus corresponding to the arbitration time period, for example, the target data bus of the 1 st arbitration time period is the 1 st pair of data bus, the target data bus of the 2 nd arbitration time period is the 2 nd pair of data bus, the target data bus of the 3 rd arbitration time period is the 3 rd pair of data bus, the winning communication node of the 1 st arbitration period of the current arbitration frame obtains the transmission of the 1 st data frame to the data bus, the winning communication node of the 2 nd arbitration period obtains the transmission of the 2 nd data frame to the data bus, and the winning communication node of the 3 rd arbitration period obtains the transmission of the 3 rd data frame to the data bus.
If the communication node obtains arbitration success in the 1 st arbitration time period of the current arbitration frame, the communication node is the winning communication node of the arbitration time period, and obtains data transmission of the next data frame of the data bus in the 1 st arbitration time period, and meanwhile, the communication node stops continuously transmitting the identifier of the communication node in the current arbitration frame, namely, the communication node does not participate in arbitration of the 2 nd and 3 rd arbitration time periods of the current arbitration frame. In the arbitration frame, the communication node obtains the data sending opportunity and does not participate in the subsequent competition of the data bus, so that the opportunity can be given to other equipment, and the fairness is increased.
If the communication node does not obtain arbitration wins in the 1 st arbitration period of the current arbitration frame, the communication node can continue to participate in the 2 nd arbitration of the current arbitration frame, and resend its own identifier in the 2 nd arbitration period. If the 2 nd arbitration fails, the 3 rd arbitration of the current arbitration frame can also be participated. If the 2 nd arbitration is successful, the communication node obtains to send data in the 2 nd data frame of the data bus while not participating in the 3 rd arbitration.
Devices that do not contend successfully have multiple arbitration opportunities in one arbitration frame and can continue to transmit identifiers, and once contention succeeds, no identifiers are transmitted in the current arbitration frame for the purpose of giving other devices opportunities. At the next arbitration frame, all devices are again participating in arbitration.
Due to the fact that multiple pairs of data buses exist, multiple communication nodes can compete out to obtain the use right of the data buses in each arbitration frame, and therefore the transmission rate of the data buses is improved.
In another embodiment of the present invention, as shown in fig. 1 and fig. 2, a data transmission system with an arbitration interface having a reset function includes:
on the basis of the previous embodiment, add:
the conduction control unit of each communication node comprises a driving subunit, a switching subunit and a comparison subunit. The driving subunit is used for translating each symbol of the identifier of the communication node into a predefined level value to obtain a driving output voltage; the switch subunit is used for conducting a switch when the permission signal is effective and conducting the driving output voltage to an arbitration bus; the comparison subunit is used for comparing the driving output voltage with the arbitration bus voltage.
The control module is further used for controlling a permission signal according to the comparison result of the driving output voltage and the arbitration bus voltage.
Specifically, when each symbol of the identifier is transmitted, the control module of the communication node inputs the symbol into the driving subunit, and inputs a permission signal into the switching subunit, and the initial value of the permission signal is valid. The sign is changed into a corresponding driving output voltage by the driving subunit, and the driving output voltage is simultaneously input to the switching subunit and the comparing subunit. The comparison subunit compares the driving output voltage corresponding to the symbol with the arbitration bus voltage, and if the symbol is superior to symbols sent by other communication nodes participating in arbitration at present, a positive feedback result is output; the control module controls the permission signal to continue to remain valid according to the positive feedback result. If the symbol is lower than the symbols sent by other communication nodes participating in arbitration at present, the comparison subunit outputs a negative feedback result; the control module controls the grant signal to be invalid according to the negative feedback result. When the permission signal is continuously effective, the switch is continuously conducted, and the driving output voltage corresponding to the symbol is stably conducted to the arbitration bus, namely the symbol is successfully sent. When the grant signal is invalid, the switch is turned off, and the driving output voltage corresponding to the symbol is not conducted to the arbitration bus, so that the symbol fails to be sent.
In another embodiment of the present invention, as shown in fig. 1, fig. 2, and fig. 3, a data transmission system with an arbitration interface having a reset function includes:
on the basis of the previous embodiment, add:
the driving subunit comprises a digital-to-analog converter and a buffer, the switching subunit is a first field effect transistor, and the comparing subunit comprises a comparator and a resistor. The input end of the digital-to-analog converter inputs the symbol of the identifier, the output end of the digital-to-analog converter is electrically connected with the input end of the buffer, the output end of the buffer is electrically connected with the drain electrode of the first field-effect tube, the grid electrode of the first field-effect tube inputs the permission signal, and the source electrode of the first field-effect tube is connected to the arbitration bus; the positive input end of the comparator is electrically connected with the output end of the buffer, and the negative input end of the comparator is connected to the arbitration bus through a resistor.
The reset unit is a second field effect transistor, and a reset signal is input to the grid electrode of the second field effect transistor.
The control module is further used for maintaining the validity of the permission signal until the symbol clearing time when the driving output voltage is not lower than the arbitration bus voltage, and revoking the permission signal and controlling the reset unit to reset the arbitration bus when the symbol clearing time is reached; when the driving output voltage is lower than the arbitration bus voltage, the permission signal is cancelled to be invalid.
Specifically, the present embodiment provides a specific arbitration interface circuit, as shown in FIG. 3, wherein VoIs a symbol of an identifier, VGFor the permission signal, VCFor reset signal, VRFor feedback signals, VLTo arbitrate bus voltages.
Upon transmitting each symbol of the identifier, the control module of the communication node will VoInputting the voltage into a digital-to-analog converter D1, converting the sign of the voltage into a predefined voltage by the digital-to-analog converter D1, outputting a stable driving output voltage after being driven by a buffer A1, reaching the drain of the first FET MP1 and the positive input terminal of the comparator C1, and receiving a permission signal VGIs output to the source of the first fet MP1 and conducted to the arbitration bus. The negative input end of the comparator C1 is connected to the arbitration bus through a resistor R, and the comparator C1 compares the voltages of the positive input end and the negative input end and outputs a feedback signal VR. The source of the second fet MP2 is grounded, the drain of the second fet MP2 is connected to the negative input terminal of the comparator C1 and one end of the resistor R, and the gate of the second fet MP2 inputs the reset signal VC. The control module is used for controlling the output according to the feedback signal VRAnd a reset signal VCControl permission signal VG。
For example, as shown in fig. 4, assume that a communication node outputs symbol 1, and when symbol 1 is output, VoAnd a permission signal VGAre simultaneously output, sign 1 has a higher priority, comparator C1 outputs VRAt a high level, the control module is at the high level VRUnder the action of (1) maintaining an allowable voltage VGHigh until the symbol clear time begins. When the allowable voltage VGAt high, the first fet MP1 is conducting and the symbol 1 is conducted to the arbitration bus. Before the clock period is over half and the symbol clearing time begins, the control module detects the feedback signal VRAnd according to VRAnd judging whether the communication node obtains the control right. After the symbol is cleared, the control module of the communication node that has acquired the control right (i.e., the communication node that has successfully transmitted the symbol) first cancels the permission voltage VGThen controls the reset signal VCThe output is high level, the second field effect transistor MP2 is conducted to make VLAnd falls to a low level.
When symbol 2 is output, VoAnd a permission signal VGAre simultaneously output. It is assumed that symbol 2 does not have a high priority among all communication nodes participating in the data transmission right election, i.e., the driving output voltage is lower than the voltage output by other communication nodes on the arbitration bus. Because the output voltages of other communication nodes reach the communication node after a transmission time delay, the comparator of the communication node reaches the communication node after a period of time tdRear output voltage VRWhen the level is changed to low level, the control module of the communication node immediately cancels the permission signal VGMeanwhile, the output of the reset signal V is not needed at the clearing momentC. From the failure of competition transmission to the end of the identifier transmission window, the equipment does not send symbols to participate in data transmission right competition selection.
Fig. 3 is only an example, in which the first fet and the second fet are PMOS transistors, and may be replaced by equivalent NMOS transistor circuits. The drain and the source of the first fet may also be used interchangeably, that is, the output terminal of the buffer is electrically connected to the source of the first fet, and the drain of the first fet is connected to the arbitration bus, which is not limited herein. FIG. 3 is a high priority arbitration circuit that can be changed to a low priority arbitration circuit if the negative input of the comparator is electrically coupled to the output of the buffer and the positive input of the comparator is coupled to the arbitration bus through a resistor.
In an embodiment of the present invention, as shown in fig. 5, a data transmission method based on the data transmission system with the arbitration interface having the reset function described in any of the foregoing embodiments includes:
step S100, in the current arbitration time period of the current arbitration frame, a communication node with a data transmission requirement transmits each symbol of the identifier of the communication node to an arbitration bus;
step S190, when it is detected that the symbol is successfully transmitted, the communication node resets the arbitration bus, and continues to transmit the next symbol, and repeats the above steps until the symbol is the last symbol of the identifier.
Step S200, the communication node detects whether the identifier of the communication node is successfully transmitted.
Specifically, each communication node has a unique identifier for identifying itself, and the identifier is composed of one or more symbols. Before sending data, each communication node must first send its own identifier on the arbitration bus, and after the own identifier is successfully sent on the arbitration bus, the communication node obtains the use authority of the target data bus, and then can send data on the next frame of the target data bus. The arbitration bus is transmitted according to arbitration frames, one arbitration frame at least comprises 2 arbitration time periods, and the arbitration time periods are used for the communication nodes to send identifiers. During the current arbitration period, the communication node having the data transmission requirement can transmit the identifier of the communication node to the arbitration bus in a bit mode so as to participate in data transmission right competition.
After the communication node sends a bit symbol of the identifier, monitoring the symbol on the arbitration bus; when the symbol on the arbitration bus is different from the symbol sent by the communication node, the sending of the identifier is considered to be failed, and the sending of the subsequent symbol of the identifier is stopped; when the symbol on the arbitration bus is the same as the symbol sent by the communication node, the communication node is indicated to successfully send the symbol with one bit of the identifier, and the next bit of the symbol with the identifier is continuously sent; when the communication node successfully transmits all symbols of the identifier, the transmission of the identifier is considered successful.
Step S300, when detecting that the identifier is successfully transmitted, the communication node is the winning communication node in the time period, and transmits its own data to the target data bus in the next data frame, while no longer transmitting the identifier in the current arbitration frame.
Step S400, when the identifier is detected to be failed to be sent, judging whether the current arbitration time period is the last arbitration time period of the current arbitration frame;
step S500 waits for the next arbitration period of the current arbitration frame to arrive when the current arbitration period is not the last arbitration period of the current arbitration frame, and then goes to step S100 until the identifier is successfully transmitted or the current arbitration period is the last arbitration period of the current arbitration frame.
Specifically, when a plurality of communication nodes simultaneously transmit identifiers, the communication node capable of correctly transmitting the identifiers to the arbitration bus obtains arbitration wins of the current arbitration time period, becomes a wining communication node, obtains the use right of the next data frame of the target data bus, and stops transmitting the identifier of the communication node in the arbitration frame.
If the identifier transmission failure is detected and the current arbitration time period is not the last arbitration time period of the current arbitration frame, the communication node can continue to participate in subsequent arbitration, and continues to transmit the identifier to participate in data transmission right competition when the next arbitration time period of the current arbitration frame arrives, namely continues to transmit the identifier to obtain the use right of the target data bus when the next arbitration time period becomes the current arbitration time period.
Example (c): the bus structure comprises 1 pair of arbitration buses and 3 pairs of data buses, each arbitration frame comprises 3 arbitration time periods, the winning communication node of each arbitration time period obtains the data transmission right of the target data bus corresponding to the arbitration time period, for example, the target data bus of the 1 st arbitration time period is the 1 st pair of data bus, the target data bus of the 2 nd arbitration time period is the 2 nd pair of data bus, the target data bus of the 3 rd arbitration time period is the 3 rd pair of data bus, the winning communication node of the 1 st arbitration period of the current arbitration frame obtains the transmission of the 1 st data frame to the data bus, the winning communication node of the 2 nd arbitration period obtains the transmission of the 2 nd data frame to the data bus, and the winning communication node of the 3 rd arbitration period obtains the transmission of the 3 rd data frame to the data bus.
If the communication node obtains arbitration success in the 1 st arbitration time period of the current arbitration frame, the communication node is the winning communication node of the arbitration time period, and obtains data transmission of the next data frame of the data bus in the 1 st arbitration time period, and meanwhile, the communication node stops continuously transmitting the identifier of the communication node in the current arbitration frame, namely, the communication node does not participate in arbitration of the 2 nd and 3 rd arbitration time periods of the current arbitration frame. In the arbitration frame, the communication node obtains the data sending opportunity and does not participate in the subsequent competition of the data bus, so that the opportunity can be given to other equipment, and the fairness is increased.
If the communication node does not obtain arbitration wins in the 1 st arbitration period of the current arbitration frame, the communication node can continue to participate in the 2 nd arbitration of the current arbitration frame, and resend its own identifier in the 2 nd arbitration period. If the 2 nd arbitration fails, the 3 rd arbitration of the current arbitration frame can also be participated. If the 2 nd arbitration is successful, the communication node obtains to send data in the 2 nd data frame of the data bus while not participating in the 3 rd arbitration.
Devices that do not contend successfully have multiple arbitration opportunities in one arbitration frame and can continue to transmit identifiers, and once contention succeeds, no identifiers are transmitted in the current arbitration frame for the purpose of giving other devices opportunities. At the next arbitration frame, all devices are again participating in arbitration.
Due to the fact that multiple pairs of data buses exist, multiple communication nodes can compete out to obtain the use right of the data buses in each arbitration frame, and therefore the transmission rate of the data buses is improved.
In another embodiment of the present invention, as shown in fig. 5 and fig. 6, a data transmission method includes:
on the basis of the previous embodiment, steps S110 to S170 in fig. 6 are used to replace steps S100 and S190 in fig. 5, and other steps are the same. For a communication node with a data transmission requirement, the process of transmitting the identifier each time is detailed as follows:
step S110, the communication node with data transmission requirement translates the symbol to be transmitted of the identifier into a predefined level value to obtain a driving output voltage;
step S120 determines whether the driving output voltage is lower than an arbitration bus voltage;
step S130, when the driving output voltage is not lower than the arbitration bus voltage, maintaining the validity of the permission signal until the symbol clearing time, and when the permission signal is valid, conducting the driving output voltage to the arbitration bus;
step S140, when the symbol clearing time arrives, revoking the permission signal, and controlling the reset unit to reset the arbitration bus;
step S150 determines whether the symbol to be transmitted is the last symbol of the identifier;
step S160, when the symbol to be sent is not the last symbol of the identifier, the next symbol of the identifier is taken as the symbol to be sent;
step S170, when the driving output voltage is lower than the arbitration bus voltage, the permission signal is cancelled to disable the driving output voltage.
Specifically, in each arbitration period, a communication node having a data transmission requirement can transmit its own identifier to the arbitration bus to participate in the data transmission right election, and the process of transmitting the identifier each time is the same. The identifier is usually made up of a number of symbols, the identifier being transmitted in sequence starting with the first symbol.
Each symbol of the identifier is transmitted by the communication node, which symbol is first translated into a predefined level value, resulting in a driving output voltage. The driving output voltage is output onto the arbitration bus under control of the grant signal. The driving output voltage corresponding to the symbol is compared with the arbitration bus voltage, and if the symbol is better than the symbols sent by other communication nodes currently participating in arbitration, the control permission signal continues to remain valid. The control grant signal is deactivated if the symbol is lower than the symbols sent by other communication nodes currently participating in the arbitration. When the grant signal is continuously asserted, the driving output voltage corresponding to the symbol is stably conducted to the arbitration bus, i.e., the symbol is successfully sent. When the grant signal is invalid, the driving output voltage corresponding to the symbol immediately stops conducting to the arbitration bus, so the symbol fails to be sent.
It should be noted that the above embodiments can be freely combined as necessary. The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A data transmission system with a reset function for an arbitration interface, comprising:
at least two pairs of data buses, wherein all the data buses transmit by taking a data frame as a unit;
a pair of arbitration buses for arbitration of the data buses; the arbitration bus takes arbitration frames as a unit for transmission, the transmission time of the arbitration frames is the same as that of the data frames, each arbitration frame comprises at least two arbitration time periods, and each arbitration time period arbitrates a winning communication node of the time period;
the communication nodes are respectively connected in parallel and hung on the data buses and the arbitration bus;
each communication node includes:
the arbitration interface module is used for sending the identifier of the arbitration interface module to the arbitration bus so as to participate in data sending right election of the data bus;
the arbitration interface module comprises a conduction control unit and a reset unit;
the conduction control unit is used for sending each symbol of the identifier of the conduction control unit to the arbitration bus;
the reset unit is used for resetting the arbitration bus;
the data sending module is used for sending own data to a target data bus;
the control module is used for controlling the conduction control unit to send each symbol of the identifier of the conduction control unit to the arbitration bus in the current arbitration time period of the current arbitration frame when the self data sending requirement is detected; and when the symbol is detected to be successfully sent, controlling the reset unit to reset the arbitration bus and then continuously sending the next symbol; when detecting that the identifier is successfully sent, the communication node is a winning communication node in the time period, and controls the data sending module to send own data to a target data bus in the next data frame, and meanwhile, the identifier is not sent in the current arbitration frame; when the identifier transmission failure is detected and the current arbitration time period is not the last arbitration time period of the current arbitration frame, controlling the conduction control unit to retransmit the identifier to the arbitration bus in the next arbitration time period of the current arbitration frame until the identifier transmission is successful or the last arbitration time period of the current arbitration frame is reached.
2. The data transmission system with reset function of arbitration interface of claim 1, wherein:
the number of arbitration periods per arbitration frame is equal to the number of data buses.
3. The data transmission system with arbitration interface and reset function according to claim 1 or 2, characterized in that:
the conduction control unit includes:
the driving subunit is used for translating each symbol of the identifier of the driving subunit into a predefined level value to obtain a driving output voltage;
the comparison subunit is used for comparing the driving output voltage with the arbitration bus voltage;
the switch subunit is used for conducting the switch when the permission signal is effective and conducting the driving output voltage to the arbitration bus;
the control module is further used for controlling the permission signal according to the comparison result of the driving output voltage and the arbitration bus voltage.
4. The data transmission system with reset function of arbitration interface of claim 3, wherein:
the control module is further configured to maintain the validity of the permission signal until a symbol clearing time when the driving output voltage is not lower than the arbitration bus voltage, cancel the permission signal when the symbol clearing time arrives, and control the reset unit to reset the arbitration bus; and when the driving output voltage is lower than the arbitration bus voltage, the permission signal is cancelled to be invalid.
5. The data transmission system with reset function of arbitration interface of claim 3, wherein:
the driving subunit comprises a digital-to-analog converter and a buffer, the switching subunit is a first field effect transistor, and the comparing subunit comprises a comparator and a resistor;
the input end of the digital-to-analog converter inputs the symbol of the identifier, the output end of the digital-to-analog converter is electrically connected with the input end of the buffer, the output end of the buffer is electrically connected with the drain electrode of the first field effect transistor, the gate electrode of the first field effect transistor inputs the permission signal, and the source electrode of the first field effect transistor is connected to the arbitration bus;
the positive input end of the comparator is electrically connected with the output end of the buffer, and the negative input end of the comparator is connected to the arbitration bus through a resistor.
6. The data transmission system with reset function of arbitration interface of claim 5, wherein:
the reset unit is a second field effect transistor, and a reset signal is input to a grid electrode of the second field effect transistor.
7. A data transmission method applied to the data transmission system with the arbitration interface having the reset function of claim 1, comprising:
in the current arbitration time period of the current arbitration frame, the communication node with the data transmission requirement transmits each symbol of the identifier of the communication node to an arbitration bus;
when the symbol is detected to be successfully sent, the communication node resets the arbitration bus, continues to send the next symbol and repeats the steps until the symbol is the last symbol of the identifier;
when the identifier is detected to be successfully sent, the communication node is a winner communication node of the time period, and sends own data to a target data bus in the next data frame, and meanwhile, the identifier is not sent in the current arbitration frame;
when the identifier transmission failure is detected and the current arbitration period is not the last arbitration period of the current arbitration frame, the communication node retransmits the identifier onto the arbitration bus in the next arbitration period of the current arbitration frame until the identifier transmission is successful or the last arbitration period of the current arbitration frame has been reached.
8. The method of claim 7, further comprising:
the number of arbitration periods per arbitration frame is equal to the number of data buses.
9. The method according to claim 7 or 8, wherein the transmitting each symbol of its identifier to the arbitration bus by the communication node having a data transmission requirement in the current arbitration period of the current arbitration frame comprises:
in the current arbitration time period of the current arbitration frame, the communication node with the data transmission requirement translates each symbol of the identifier of the communication node into a predefined level value to obtain a driving output voltage;
controlling a permission signal according to a comparison result of the driving output voltage and an arbitration bus voltage;
conducting the drive output voltage onto an arbitration bus when the grant signal is active.
10. The method of claim 9, wherein controlling the grant signal according to the comparison of the driving output voltage and the arbitration bus voltage comprises:
when the driving output voltage is not lower than the arbitration bus voltage, maintaining the validity of the permission signal until the symbol clearing time, and when the symbol clearing time is reached, canceling the permission signal and controlling the reset unit to reset the arbitration bus;
and when the driving output voltage is lower than the arbitration bus voltage, the permission signal is cancelled to be invalid.
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