KR101654720B1 - A method for controlling can by can coordinator - Google Patents
A method for controlling can by can coordinator Download PDFInfo
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- KR101654720B1 KR101654720B1 KR1020150126745A KR20150126745A KR101654720B1 KR 101654720 B1 KR101654720 B1 KR 101654720B1 KR 1020150126745 A KR1020150126745 A KR 1020150126745A KR 20150126745 A KR20150126745 A KR 20150126745A KR 101654720 B1 KR101654720 B1 KR 101654720B1
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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
- H04L2012/40208—Bus networks characterized by the use of a particular bus standard
- H04L2012/40215—Controller Area Network CAN
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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
- H04L2012/40267—Bus for use in transportation systems
- H04L2012/40273—Bus for use in transportation systems the transportation system being a vehicle
Abstract
Description
The present invention relates to a method for controlling a CAN (Controller Area Network), and more particularly, to a CAN control method performed by a CAN coordinator.
The automobile that appeared for the purpose of convenient transportation has developed a lot of technology related to the vehicle from now to the present. The vehicle combines the latest electric, electronic and information communication technologies to provide the driver with higher safety and convenience, It is evolving into a place where people who can not live their own lives can play the role of space for work and rest.
In order for the vehicle to evolve, a large number of electronic control devices will be mounted, and the number of electronic control devices will rapidly increase as the level of vehicle-related technology increases. In particular, the proportion of electronic control equipment in the cost of manufacturing automobiles is increasing. In addition, experts predict that 80% of future innovative technologies will be related to electronic technology (see Non-Patent Document 1). In order to control more electronic control devices, wiring is increased. The increase of such wiring is difficult in vehicle design, increases the weight of the vehicle, which makes performance and fuel efficiency less efficient, and also increases manufacturing cost Non-patent document 2). Therefore, a network-based communication system that enables organic control between electronic control devices and solve various problems has become necessary. By this request, CAN (Controller Area Network) system has been developed (see Non-Patent Document 3). The fact that such a communication network is applied to a vehicle means that the system of the mechanical system is electronically controlled, which allows more precise control and reduces the weight of the vehicle by reducing the wiring of the vehicle, thereby improving the performance of the vehicle, It has several advantages.
However, this network system is more important than reliability guarantee. Reliability must be secured in many ways, but reliability in network systems must be guaranteed for transmission and reception so that devices connected to the network can be properly controlled without errors. Even if the reliability of the components constituting the network is ensured, the reliability of the communication, which is the main function, can not be secured. If the necessary information can not be properly transmitted, errors will occur and the network system will become unsuitable.
The CAN system, which guarantees the reliability of such transmission, is equipped with various mechanisms for communication, and has various complementary functions such as transmission-related stability and error handling for data, and is designated as ISO 11898 and ISO 11519-1 standard , And its reliability has been applied to almost all kinds of vehicles currently mass-produced. The CAN system, which has many advantages, has been widely used in many industrial fields such as machinery and medical care.
When analyzing the messages of the CAN (Controller Area Network) system, which is most commonly applied as a vehicle network system, it consists of periodic signals informing regular messages periodically and a large amount of event messages occurring according to the moments. When these data messages are communicated and a message is sent from several nodes connected to the CAN bus at the same time in a system where the traffic on the bus is relatively low, the CAN system is relatively efficient You can arbitrate for conflicts. However, in a system where the traffic on the bus is relatively high, when the message collides, the arbitration is performed through the arbitration process. At this time, since the traffic of the bus is high, there are many data messages having higher priority than the identifier of the data message to be transmitted A transmission delay may occur and data may not be transmitted within a desired time or a transmission opportunity may be missed. That is, the average transmission delay increases as the bus traffic increases (see Non-Patent Document 4).
SUMMARY OF THE INVENTION Accordingly, it is a first object of the present invention to solve the above-mentioned problems, and it is an object of the present invention to provide a method and system for managing CAN messages, , CAN control method performed by CAN (Controller Area Network) coordinator that can implement Plug and Play function that can be connected to CAN system without upgrading existing CAN device and can operate organically .
It should be understood, however, that the present invention is not limited to the above-described embodiments, but may be variously modified without departing from the spirit and scope of the invention.
A CAN control method performed by a CAN (Controller Area Network) coordinator according to an embodiment of the present invention includes: transmitting a registration mode start message to a plurality of nodes in the CAN in response to entry of a registration mode; Receiving, from at least one of the plurality of nodes, a response message indicating completion of the registration mode and including the number of control data for each function of the node; Counting the number of responding nodes among the plurality of nodes and the number of function-specific control data of each of the responding nodes based on the response message; Transmitting a function-specific control data transmission right message based on the counting result to a responding node among the plurality of nodes; Receiving a function-specific control data information message including request information related to a function and an operation condition of the corresponding node from a responding node among the plurality of nodes; And transmitting a node setup message to a responding node of the plurality of nodes by setting a function and an operation condition of each of the plurality of nodes, based on the function-specific control data information message, have.
According to one embodiment, the request information on the function and the operation condition of the corresponding node includes an ID allocation request, the response message has an ID belonging to a registration mode data section, and the node setup message includes a function An ID belonging to the general message data section can be assigned to the message data section.
According to one embodiment, the request information on the function and the operation condition of the corresponding node further includes an urgent message transmission permission request, and the node setup message further includes an ID belonging to the urgent message data interval And the ID of the emergency message data section may have a priority over the ID of the general message data section.
According to one embodiment, the request information regarding the function and the operation condition of the corresponding node includes a request for at least one of data function, transmission or reception availability, control method of function, and data acquisition position in normal mode operation can do.
According to one embodiment, the identity placement request may be a request for any of automatic placement, priority placement, placement in front of a particular feature, and placement after a particular feature.
According to one embodiment, the function-specific control data transmission right message may include a node number to be authorized.
According to an exemplary embodiment, the function-specific control data transmission right message may set an authorization time based on the number of function-specific control data of the responding node among the plurality of nodes.
According to an exemplary embodiment, the function-specific control data transmission right message may allow the plurality of responding nodes to sequentially transmit function-specific control data transmission rights when there are a plurality of nodes responding to the plurality of nodes .
According to an embodiment, when the step of receiving the response message fails to receive a response message from the plurality of nodes, the step of terminating the registration mode may further include terminating the registration mode.
According to an exemplary embodiment, the method may further include terminating the registration mode when receiving a response message from any one of nodes previously registered in the CAN coordinator fails.
Receiving a registration mode complete message from the responding node indicating that the setting of the function and operating condition of the corresponding node according to the node setting message is completed; And terminating the registration mode in response to the registration mode complete message.
According to one embodiment, the termination of the registration mode may indicate an error occurrence for the CAN. Alternatively, according to one embodiment, in response to the end of the registration mode, the CAN coordinator may be deactivated, and the plurality of nodes may operate in normal travel mode.
According to the CAN control method according to the embodiment of the present invention described above, transmission delay, which is a weak point of the existing CAN system, can be improved through use of the CAN coordinator, and even when a new node capable of both transmission and reception is applied , It is possible to implement a plug and play function that can be run on the system without upgrading existing nodes.
In addition, the CAN coordinator operates only in the registration mode and stops the function of the CAN coordinator after the end of the registration mode, so that it does not affect the existing CAN system which is settled as a stable system through a lot of trial and error . Therefore, other CAN devices can be maintained in the same way as existing CAN systems to provide a system with stability.
1 is a conceptual diagram of CAN communication of a vehicle.
Figure 2 is a comparative drawing of the CAN application.
Figure 3 shows the CAN standard.
Fig. 4 shows a CAN applied to a vehicle.
5 shows the communication network of the CAN system.
6 shows the CAN bus signal.
Figure 7 shows the process of arbitration on the CAN 2.0A bus.
Figure 8 shows the hierarchical structure of the CAN protocol.
9 shows data exchange by the CAN layer.
10 shows a data frame structure of CAN.
11 shows the transmission / reception relationship between CAN 2.0A and CAN 2.0B.
12 is a block diagram showing a configuration of a coordinator.
13 is a flowchart of a CAN control method performed by a CAN (Controller Area Network) coordinator according to an embodiment of the present invention.
14 is a flow chart of the operation of the CAN device controlled by the CAN coordinator.
15 shows a basic format of CAN data.
16 shows the
17 shows a
18 shows a
FIG. 19 shows a node
20 shows a node
FIG. 21 shows a node
22 is a configuration diagram of the CAN test module.
23 shows a CAN test node.
24 shows the CAN data message measurement equipment.
25 shows the experimental environment configuration.
26 shows the CAN data transmission delay.
FIG. 27 shows a transmission delay time according to an increase in a data message.
28 shows an improvement in transmission delay for an urgent message.
29 is a diagram related to the transmission of an urgent message of a specific identifier.
30 shows application of the emergency message transmission delay improvement system and comparison of the non-use.
31 shows a CAN node arrangement process of the CAN coordinator.
32 shows a CAN
33 shows a communication process for Plug and Play.
For the embodiments of the invention disclosed herein, specific structural and functional descriptions are set forth for the purpose of describing an embodiment of the invention only, and it is to be understood that the embodiments of the invention may be practiced in various forms, The present invention should not be construed as limited to the embodiments described in Figs.
The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprise", "having", and the like are intended to specify the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, , Steps, operations, components, parts, or combinations thereof, as a matter of principle.
Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be construed as meaning consistent with meaning in the context of the relevant art and are not to be construed as ideal or overly formal in meaning unless expressly defined in the present application .
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.
1. Overview
In the present invention, a new module called CAN coordinator that manages items and information about data of each node connected to the CAN system is added, and an improvement method by arranging a dual ID for a transmission delay part and a CAN This is a plug that can communicate with existing nodes by managing information by CAN coordinator only if it is connected to CAN network, unless hardware modification is needed when adding a new node (Node) I would like to suggest the Plug and Play function. A test board was fabricated to evaluate the performance of the proposed system. Experiments were conducted to verify the improvement of transmission delay for urgent messages and to implement plug - and - play functions.
The present invention will be described in detail below. In
2. CAN (Controller Area Network)
2.1. Overview of CAN
The CAN protocol is a real-time, serial, and broadcasting protocol with high level of security, and is an international standard defined in ISO11898 for high-speed transmission and ISO11519-2 for low-speed transmission. CAN is a serial network communication method originally designed to be applied to automobiles and has been widely applied to various industrial fields in recent years (see Non-Patent Document 5).
CAN is a vehicle network system developed by Bosch in Germany in 1933 at the request of the automobile company, Benz, in order to communicate between ECUs (Electronic Control Units) in the vehicle. In 1986, the Society of Automotive (SAE) Engineers, and it was established in 1993 as an international standard for ISO (see Non-Patent Document 6).
Fig. 1 is a conceptual diagram of a CAN communication of a vehicle, and Fig. 2 is a comparative diagram of a CAN application. In today's vehicles, as shown in FIG. 1, an increase in the number of control modules and sensor modules for controlling a vehicle increases the wiring harness, which causes problems in connection and weight. As shown in FIG. 2, as the number of control modules increases, wiring increases, manufacturing cost increases, reliability decreases, and control module additions become difficult.
Therefore, the CAN system uses two twisted wires to connect the control module and the sensor to solve the problems caused by the increase in the wiring, and it is superior in cost performance compared with other communication protocols and is strong against external electromagnetic waves and noise In the automotive industry, the CAN system has been introduced competitively. In addition, it is utilized in various fields such as industrial automation, building automation, medical equipment, trains, heavy equipment, etc. (refer to non-patent document 7).
Various network protocols are applied to vehicles, and classified into Class A, Class B, and Class C depending on data transmission speed. Class A is low speed of less than 10kbps, Class B is medium speed of less than 100kbps, Class C is high speed of more than 100kbps. Here, CAN communication is a typical high-speed communication network belonging to Class C, and is used as a network for precise control of power train, multimedia, and body electric field in real time. Fig. 3 shows the CAN standard (see Non-Patent Document 8).
CAN, which is used in the above-mentioned vehicles, is grouped into power train, multimedia, and body electric field depending on the speed and purpose of the CAN, though there are differences depending on the manufacturer.
Fig. 4 shows a CAN applied to a vehicle. Referring to FIG. 4, the chassis CAN responsible for the power train has a communication speed of 500 kbps and a vehicle such as ECU (Engine Controller Unit), MDPS (Motor Driven Power Steering) and ABS (Anti Lock Brake System) The body CAN, which is responsible for the body electric field, has a communication speed of 100kbps and is equipped with DDM (Driver Door Module), ADM (Assist Door Module), PSM (Power Seat Module ), And SWRC (Steering Wheel Remote Controller). The multimedia CAN, which is responsible for multimedia, is connected at the same speed as the body CAN at 100kbps , And is responsible for grouping such things as navigation and audio such as Monitor and HU (Head Unit).
Thus, the CAN system is grouped by application according to the application field or product.
2.2. Features of CAN
CAN is divided into ISO 11898-2 (High-speed: 50kbps to 1Mbps) and ISO 11898-3 (Low-speed: 50kbps to 125kbps) according to the hardware part and ISO standard. Non-Destructive Bitwise Arbitration, and all ECUs are capable of receiving all messages.
First, in terms of hardware features, a CAN system forms a communication network between CAN nodes, which are connected by twisted pair wires, and communication uses electrical differences, It is very strong against noise. Referring to FIG. 5, the CAN bus connects termination resistors to the ends of both ends, and terminating resistors connect to approximately 120Ω (see Non-Patent Document 9).
6 shows a CAN bus signal. Referring to FIG. 6, a CAN bus signal uses an electrical difference, that is, a difference between voltage levels on the bus indicates '0' and '1' 0 'is defined as dominant and a bit of' 1 'is defined as recessive (refer to non-patent document 10).
If the CAN high is 3.5V and the CAN low is 1.5V, this state is 'dominant', and if the CAN high and the CAN low are 2.5V, the state is '1'.
Figure 7 shows the process of arbitration on the CAN 2.0A bus. In this CAN system bus dominance and hysteresis are used to arbitrate the data on the bus. Fig. 7 is a process of arbitrating when three data simultaneously collide on the bus in the CAN 2.0A scheme having 11 bits of identifier.
7, the 11 bits of the identifier of CAN 2.0A are used.
Second, according to the ISO standard, ISO 11898-2 corresponding to CAN data bus Class C has a maximum speed of 1Mbps, the dominant CAN_H is 3.5V and the CAN_L is 1.5V. In the idle state, CAN_H and CAN_L 2.5V.
ISO 11898-3, which corresponds to the CAN data bus Class B, is called L-CAN with reduced Fault Tolerant Low Speed. It has a maximum speed of 125kbps. In the dominant state, CAN_H is 3.6V and CAN_L is 1.4V. Is 0V, and CAN_L is 5V (see Non-Patent Document 11).
Third, the non-destructive Bitwise Arbitration (CAN) has a message transmission mechanism called CSMA / CD-NDBA (Carrier Sense Multiple Access with Non-Destructive Bitwise Arbitration) As defined in the IEEE 802.3 standard. This means that the node that is trying to transmit data monitors whether another node is communicating on the network. It checks whether a signal is being transmitted to the bus, and then transmits the data if the bus is not being transmitted. CSMA / CD allows multiple nodes to be connected to the same network, reducing the bandwidth required to transmit conflicting packets. This method has a problem in that many nodes are connected to the bus, and load is generated and delay occurs when data is transmitted at a time. To avoid this delay, the CAN system uses a method of giving priority to one data when two or more nodes simultaneously transmit data on the bus. This is a non-destructive bitwise arbitration technique do.
Finally, broadcasting is possible because the CAN system has the feature of message oriented protocol. The CAN system does not communicate the data by the address of the node but the ID assigned by the message priority The data exchange is performed. Therefore, the node transmits data to the CAN bus, and the nodes connected to the CAN bus can receive all the data that the other node transmits to the bus. In this process, multicasting and broadcasting can be performed. Also, considering that this feature exists, it can be seen that a node that can simply receive data can be added to the existing CAN system without changing hardware or software.
With a few additional features of the CAN system, the CAN system provides electrical differential communication using twisted pair wires, which have very strong durability against electrical noise in electrically unstable systems such as vehicles and can be hardware compensated for errors Therefore, depending on how the receiving filter is set by hardware, it is possible to receive the desired ID and the data and the specific group and the entire receiving. Also. Because it provides hardware packet that transmits 8 data at a time, user can make packet format for packet communication like UART (RS232, RS485) communication, analyze how the other party sent data even when receiving data. Do.
However, since the CAN system carries hardware packet communication containing 8-byte data, it has a structure in which data can be inserted into the data buffer and transmitted or the received data buffer can be read, so that the hardware does all the processing without any special control. Based on these reasons, many manufacturers and various fields are used in various fields. In order to meet the demand, many semiconductor manufacturers such as microcontroller chip develop and sell various CAN controllers and transceivers. It is easy to supply and stable products, and the price is lowered under the competition of chip makers. Manufacturers who make products that can adopt CAN system are applying CAN system.
2.3. Hierarchical structure of CAN
8 shows a hierarchical structure of the CAN protocol. The data exchange method of the CAN communication protocol is compared with the
First, the physical layer is the lowest layer involved in establishing, maintaining, and disconnecting a physical link for data transmission. The physical layer is a type of signal indicating '0' and '1', a standard of a connector to be connected, Tolerance values, names and roles of various control signals, and the like, and substantially transmits electrical signals through the medium to be transmitted. Next, the data link layer is the most important part to implement the CAN protocol. Encoding that makes two signals of 0 and 1, which are made in the physical layer, Framing to construct a frame with data created through the error detection, error detection to prevent error generation, and flow control to correct the speed difference between nodes and nodes (See Non-Patent Document 12).
9 shows data exchange by the CAN layer. As shown in FIG. 9, in the physical layer, the message transmission and reception structure according to the layer of the CAN system is transferred to the voltage level (data dominance and hysteresis) of the CAN bus, and the data link layer Data Link Layer), the CAN controller converts the received voltage level into a logic level of '0' and '1' and recognizes the data by dividing it into an identifier (Identifier) and data (Data). In the application layer, data information is classified according to the system of each node (see Non-Patent Document 13).
In addition, since the CAN protocol is multi-master communication, CAN nodes connected to the CAN bus can all be masters and can be used whenever you want to use the bus.
2.4. Frame structure of CAN
The CAN frame is composed of four types of data frames, a remote frame, an error frame, and an overload frame. The CAN frame includes an Inter Frame, It is classified into five types, and their types and functions are described in [Table 2-1].
[Table 2-1] CAN Frame Types and Functions
Since the system proposed in the present invention proceeds by utilizing a data frame, the related art will be focused on.
10 shows a data frame structure of CAN. As shown in FIG. 10, there are two types of data frames of the CAN system: CAN 2.0A (Standard Format) and CAN 2.0B (Extended Format). In the data frame, a SoF (Start of Frame), an Arbitration Field, a RTR ), A control field, a data field, a CRC field, an ACK field, and an end of frame (EoF), and data fields can transmit data of 64 bits at maximum (refer to non-patent document 14) .
As mentioned above, there are two versions of the CAN protocol: CAN 2.0A (Standard Format) and CAN 2.0B (Extended Format). The biggest difference is in the Arbitration Field. CAN 2.0A consists of 11 bits, and CAN 2.0B consists of 29 bits including
11, which shows the transmission / reception relationship between CAN 2.0A and CAN 2.0B, it is possible to receive a message transmitted in CAN 2.0B from CAN 2.0A but from CAN 2.0B, The message can not be received at CAN 2.0A (see non-patent document 15).
In the data field based on CAN 2.0A, a Start of Frame (SoF) indicates the beginning of a message frame, an Arbitration Field indicates an 11-bit identifier and a Remote Transmission Request (RTR) bit When the RTR bit is '0', it means remote transmission when the data frame is '1'. The control field is composed of 6 bits, and is composed of a 2-bit spare field and a 4-bit data length code. The data field contains data to be transmitted and is composed of 64 bits. The Cyclic Redundancy Check (CRC) field is composed of a CRC code for periodically checking duplication of 15 bits and a 1-bit delimiter to check whether there is an error in the message. The ACK field consists of 2 bits and consists of a 1-bit ACK slot and a 1-bit ACK delimiter. The End of Frame (EoF) consists of 7 bits, all of which have a value of '1' indicating the end of the message.
The control field consists of 6 bits, and consists of 2 bits of spare bits and 4 bits of data length code, and the data field can transmit 0 to 8 bits of data to be transmitted. That is, up to 64 bits can be transmitted. The CRC field is composed of a CRC code for periodically checking duplication of 15 bits and a delimiter of 1 bit. The ACK field consists of 2 bits and consists of a 1-bit ACK slot and a 1-bit ACK delimiter. Finally, EoF consists of 7 bits, all of which have a value of 1.
3. Related Studies
3.1. A study on existing CAN real-time guarantee (improvement of transmission delay)
In order to control among many electronic control devices constituting the product system, it is necessary to control the transmission and reception control signals of each electronic control device at appropriate timing, that is, how to send signals in real time for communication It has become an issue. In other words, if multiple data signals are transmitted and received through a network composed of buses, a collision will occur for the data transmission occurring at the same time, and transmission delay and transmission loss will occur due to the arbitration process for the collision. Such transmission delay and transmission loss may cause errors such as malfunction or inoperability of the apparatus.
Particularly, in the case of CAN (Controller Area Network) system to be dealt with in the present invention, tens of thousands of vehicles have started communication for controlling between electronic control devices, and since applied fields are widely used in vehicles, It is more important to transmit and receive signals in conjunction with human safety.
For example, in the case of a vehicle, when the collision of the vehicle occurs, the airbag is not electrified, or when the brake is applied, information related to the airbag is not transmitted at an appropriate time The transmission delay causes various devices to not operate organically, resulting in a failure to function, which leads to a great loss.
As described in
In order to solve these problems, various researches related to the transmission delay occurring in the CAN system have been preceded. In order to improve the transmission delay by appropriately scheduling the order of transmission of data messages, Can be seen.
The scheduling method for improving the transmission delay is classified into static or dynamic scheduling, preemptive or non-preemptive scheduling (see Non-Patent Document 19).
Static scheduling is a scheduling method that is applied to existing CAN systems. It allocates priorities according to the importance of data messages and arranges IDs according to their importance. This means that the data message is transmitted according to the ID thus arranged. Dynamic scheduling, on the other hand, means that there is a change in the priority of the data message transmitted, depending on the situation or need while the system is operating normally.
Preemptive scheduling means that if any message on the bus preempts the bus and transmits a data message, the preemptive scheduling means waiting until the transmission of the data message is completed. Non-preemptive scheduling Refers to allowing a message to be transmitted by priority even if any message is on the bus. Here, the CAN system has a preemptive scheduling property that, if any message is on the bus, other nodes do not send data messages and wait for any messages to complete their transmission.
In this paper, we propose a dynamic scheduling scheme based on static scheduling. In this paper, we propose a dynamic scheduling scheme based on static scheduling. EDF (Earliest Deadline First) is a typical case. In addition, there is a distributed message allocation method among methods related to improvement of transmission delay. In the present invention, a scheduling technique and a distributed message allocation method are introduced in the prior art for improving transmission delay.
3.1.1. Scheduling technique
Deadline Monotonic Scheduling (DMS), which is a representative method of static scheduling, is a scheduling scheme that changes RMS (Rate Monotonic Scheduling) to a suitable form for application to CAN systems. In RMS, which is known as an optimal static scheduling technique, the priority is determined by the length of a cycle. A message having a short period precedes a message having a long period in priority. Messages in the order of priority given in this way are sequentially placed on the synchronized time line and transmitted. RMS generally assumes that the transmission period is the same as the deadline, but this is not always the case. Thus, the DMS is changed to give a higher priority to a data message having a shorter deadline time until the transmission of the data message is completed. These fixed scheduling schemes are advantageous in that they are simple to implement. However, there is a problem in that synchronization between the nodes constituting the network is required for this, and when a large amount of data messages collide and high traffic occurs, May not be able to transmit or delay transmission.
The EDF (Earliest Deadline First) method is a dynamic scheduling method. In this scheduling method, a deadline transmits a message close to the deadline first. This method does not determine the priority of a data message. Instead, once a data message has been transmitted, all nodes immediately acknowledge the deadline of their own data message and transmit the remaining message to the deadline first. Dynamic EDF techniques can improve problems that can occur in static DMS and can increase bus utilization.
Dynamic scheduling techniques such as EDF are based on many real-time prose scheduling algorithms, but they are not widely used as scheduling methods for messages in communication systems. The reason for this is that excessive overhead occurs in the process of occupying the bus for communication, and all the nodes must be synchronized in order to perform the EDF. Also, all nodes connected to the network are hard to implement because they have to continuously monitor how close their data messages are to the deadline and how they differ from other data messages, And also a large load is applied to the processor (see
The study of existing scheduling techniques shows that although there are advantages and disadvantages to both static scheduling and dynamic scheduling, static scheduling techniques are less efficient than dynamic scheduling techniques (see Non-Patent Document 19).
3.1.2. Distributed message allocation technique
The distributed message allocation scheme is a method to guarantee the real-time quality-of-service performance of the data message by increasing the network transmission capacity of the CAN system. It is a microcontroller having two or more CAN controllers It is a system that can operate dual channels by using two CAN transceivers. However, when a message is transmitted using two channels, if the channel is not appropriately selected, the network traffic may be rapidly tilted to one side.
Among the methods that have been studied to improve it, a message allocation method has been proposed in which a CAN node determines a channel to which a message is to be transmitted when two channels are used (see Non-Patent Document 20). However, this method has a disadvantage in that a data message can not be appropriately allocated when an error occurs in a traffic prediction mode for monitoring traffic.
In another study on the distributed message allocation technique, a distributed message allocation method has been proposed in which all nodes can predict traffic and appropriately allocate a message (see Non-Patent Document 21).
In the case of such a distributed message allocation technique, a microcontroller having two CAN controllers and two transceivers should be used as described above. This feature is applicable to the implementation of distributed message allocation There are some advantages, but the cost of creating CAN devices can add up. In fact, in terms of the price provided by the manufacturer of the chip, the microcontroller with the added CAN controller, even though it is a chip of the same specification, can be confirmed that it is formed at twice the price or more, Also, two per module should be used.
Although there have been many studies on the improvement of the transmission delay of the CAN system, two representative research results are introduced and the advantages and disadvantages of each improvement method are referred to based on the results of these studies.
In the present invention, a new node called a CAN coordinator can be added to the improvement of the CAN system. The CAN system has been officially announced at the Society of Automotive Engineers (SAE) in Detroit, USA in 1986 and has been improved since 1993 when it was established as an ISO International Standard. The current CAN has been applied to most production vehicles Which is a stable system. This modification of the stable system in normal operation may result in a decrease in the reliability of the system again in actual mass production products, and it may take time to prove the reliability of the system. Therefore, by adding a module called CAN coordinator, In this registration mode, when the CAN coordinator adds a new CAN device which can improve the transmission delay for the urgent message and transmit and receive, The plug-and-play function that can be connected to the CAN system without any upgrade of the existing CAN device and can operate organically is implemented. When the registration mode is finished, the same operation as the general CAN system is performed, To implement the proposed function It can guarantee to stability.
4. Suggested System
4.1. Outline of the proposed system
Most communication-related systems, including CAN systems, must be able to transmit and receive data in a reliable and timely manner in order to process requests. In particular, CAN systems that are applied to precision instruments, vehicles, It is more important that the data is transmitted without being delayed when the data is transmitted. Also, in the existing CAN system, multicasting and broadcasting can be performed because the data is exchanged on the bus by the ID assigned according to the priority of the data message, not by the address of the node. Do. In the case of a node that can only receive, it can be added without changing the hardware or software of the existing nodes connected to the CAN bus. However, in the case of a node that must perform transmission and reception other than the node As the existing nodes were upgraded, new nodes could be added.
In order to improve these points, in this chapter, a new device type called CAN coordinator is newly defined, and based on this, an improvement measure against the transmission delay, which is a weak point of the existing CAN system, Since the CAN system was officially announced by the Society of Automotive Engineers (SAE) in 1986, it has been through a lot of trial and error and changes since the introduction of the plug and play function, Since the system is stable, the proposed system aims to not affect the existing CAN system. Therefore, the proposed system newly introduces the concept of registration mode, and the CAN coordinator operates only in the registration mode. After the registration mode is finished, the CAN coordinator is stopped and other CAN devices are kept same as the existing CAN system We propose a system that guarantees stability.
4.1.1. System configuration
12 is a block diagram showing a configuration of a coordinator. As shown in FIG. 12, the coordinator H / W is largely composed of a microcontroller including a CAN module and a CAN transceiver. The H / W is the same as the other node configuration and basic part because the CAN coordinator is the same concept as one node in the CAN system.
In CAN ID application part, 11 bit of CAN 2.0A and 29 bits of CAN 2.0B can be applied to this system. However, hereafter, the 11 bit ID of CAN 2.0A which is most applied to the present vehicle is applied. do. In addition, the exemplary operation speed may be based on 100 kbps, which is frequently used in a body electric system of a vehicle.
4.1.1.1. Suggested system device Type Definition
4.1.1.1 defines the CAN coordinator, node, and transmission data message type, which are components of the proposed system.
A) CAN Coordinator
13 is a flowchart of a CAN control method performed by a CAN (Controller Area Network) coordinator according to an embodiment of the present invention. Hereinafter, a CAN control method according to an embodiment of the present invention will be described in more detail with reference to FIG. When the CAN coordinator is first powered on, it enters the registration mode and, in response to entry of the registration mode, sends a registration mode start message to the plurality of nodes in the CAN. Here, the CAN coordinator can send a registration mode start message to the CAN bus to which the nodes are connected.
The CAN coordinator that sends the registration mode setup message waits for a response from each node connected to the CAN bus for a certain period of time, where each node has a registration mode data interval, for example, between 701 and 7FF The CAN coordinator can monitor a data message having an ID of, for example, 701 to 7FF when the CAN coordinator enters the registration mode. If there is no response from the node due to a problem or an error, the CAN coordinator exits the registration mode and informs the node that there is no response to help the system check. That is, if a failure to receive a response message from a plurality of nodes fails, the registration mode can be terminated and the end of the registration mode can indicate an error occurrence for the CAN.
As a result of the monitoring, from the at least one of the plurality of nodes, it is possible to indicate that the registration mode is ready and receive a response message including the number of control data for each function of the node. That is, when each node responds to the registration mode start message of the CAN coordinator in a normal manner in accordance with the node order, the number of nodes connected to the CAN bus is counted by the CAN coordinator, It also counts how many functional control data the node has. In other words, the CAN coordinator can count the number of responding nodes among the plurality of nodes and the number of function-specific control data of each of the responding nodes based on the received response message.
If it is not the first time to operate the system, the CAN coordinator has the existing CAN node information. If there is a node that is not registered in the CAN coordinator, And informs the CAN coordinator that an error has occurred so that the system can be inspected.
If there is no abnormality in the first message sent from the node, the CAN coordinator completes the operation, and sends a message granting data transmission right to the node so that the control of the function of each node and the data indicating the status can be received To the node. That is, a function-specific control data transmission right message based on the above-described counting result can be transmitted to the responding node among the plurality of nodes.
The function-specific control data transmission right message may include the node number of the node to which the authorization is granted and may set the authorization time based on the number of function-specific control data of the responding node among the plurality of nodes. In addition, when there are a plurality of nodes responding to the plurality of nodes, it is possible that the nodes responding to the plurality of nodes have sequential access rights to control data by function. For example, if there are three nodes, the message is given to the first node, and if the CAN coordinator receives information about the data as much as the number of data the first node has, Granting the transmission right to the
According to the above authorization, the CAN coordinator can receive a function-specific control data information message including request information on the function and operation condition of the corresponding node from the responding node among the plurality of nodes. The request information regarding the function and operation condition of the corresponding node may include a request for at least one of a function of data, transmission or reception availability, a control method of the function, and a data acquisition position in a normal mode operation.
In this way, the CAN coordinator, receiving the second message containing the function-specific data information from each node, analyzes and stores the related roles, operations, operation method, location for the operation, whether there is an urgent message, The function and operating condition of each of the plurality of nodes can be set.
In accordance with the ID placement request in the data among the analyzed information, the CAN coordinator determines whether the ID of the data message is automatically placed in the general message data section, for example, between 100 and 6FF, The ID of the data message should be assigned according to the analysis of whether or not to place the ID of the function before or after the ID. Also, among the data in which the existing normal IDs are arranged, it is checked whether there is an ID relocation request in order to improve or improve the performance of the product. At this time, if there is an ID relocation request, the CAN coordinator can rearrange the IDs according to the request of the data.
The request information regarding the function and operation condition of the corresponding node may further include an urgent message transmission permission request, so that it is further checked whether or not there is an urgent message transmission permission request in addition to the ID allocation. If there is an urgent message transmission permission request, the CAN coordinator selects an empty ID in the urgent message data section, for example, between 000 and 0FF, in accordance with the emergency degree, and the urgent message An ID is further allocated to the user. That is, in case of a data message related to a function that urgently needs to be sent when an event situation occurs, an ID between 100 and 6FF for transmitting information such as a normal state, and an urgent message urgently required to be transmitted to an urgent situation, An ID between 000 and 0FF having a priority higher than an ID between 100 and 6FF may be disposed and two IDs may be placed in the data for one function.
When the role and operation of the data and the ID placement are finished, the CAN coordinator completes the setting of the functions and operating conditions of each node, and transmits a node setup message including the information about the settings to the response Can be transmitted to one node. That is, the CAN coordinator sends a setup message, which informs the order of the predefined functions in order, including the operation information on the function of the data message, the data ID that can be transmitted and received in the normal mode, . When the setup message is transmitted for each function, the CAN coordinator finally transmits the setup message transmission completion message and the registration mode end message. Because of the nature of the CAN system, the nodes that are controlled by the data and nodes that need to use the function select the data part of the function, set the information about the data message according to the setup message, To avoid losing information about it.
After completing the setup message, the nodes will send a message to end the setup and registration mode. When this procedure is completed, the registration mode will be terminated. That is, the CAN coordinator can receive a registration mode completion message indicating that the setting of the function and the operation condition of the corresponding node according to the node setup message has been completed from the node that responded to the plurality of nodes, The registration mode can be ended.
When the registration mode is terminated, the CAN coordinator is not involved in the normal CAN system until it is powered on again after power-off, and each node is assigned a CAN coordinator The data can be communicated through the ID, the role, and the operation method.
B) CAN Device
14 is a flow chart of the operation of the CAN device controlled by the CAN coordinator. Hereinafter, the operation of the CAN device (node) will be described in more detail with reference to Fig. At the first power-on, each node enters the registration mode and waits for a certain time to receive a registration mode setup start message from the CAN coordinator. At this time, if the CAN coordinator fails to receive the registration mode setting start message from the CAN coordinator due to a trouble or various problems, the normal mode of operation is performed in order to prevent the system stop.
Upon receipt of the registration mode setting start message from the CAN coordinator within a predetermined time, each node transmits information on the existence of the node and the number of control data by function, which can control the function of the node, And receives a function-specific control data transmission right message that can control the function of the node with the CAN coordinator, and waits to be granted the function-specific control data transmission right.
When the CAN coordinator completes the processing after receiving the first message, it sends a second message to the node to grant the transmission right for the number of data in order to receive the information about the function-specific data sent from the node.
In the second message, the node receiving the transmission right transmits the function-specific control data including the ID of the function data held in each node and the request information about the function and the operation condition of each node including the role and operation to the CAN coordinator in sequence send.
The CAN coordinator processes the second message transmitted from the node according to the contents requested by the node, and after the process is completed, the CAN coordinator transmits the node setup message to the node with information according to the data format. Each node receiving the message, as specified by the CAN coordinator, checks the identity of the data originating from the node, the ID to receive the necessary data, and the ID to which the output should be sent, Is completed and stored. Nodes that do not correspond to the setting are excluded from the setting.
After completing the setting, each node sends the setup completion and registration mode completion message and enters the normal operation mode, and operates in the same manner as the existing CAN system with the information of the function ID assigned by the CAN coordinator.
C) Data format
In the present invention, the system configuration is based on CAN 2.0A as an example. This is because the characteristics of the system proposed in the present invention should specify and arrange the area of the CAN identifier. Since the CAN 2.0A has the 11-bit identifier, the total identifier range can be up to 000-7FF.
The identifier may be divided into a section for placing emergency message data, a section for placing general message data, and a section for sending and receiving a data message between the CAN coordinator and the nodes in the registration mode.
If more CAN data is needed, CAN 2.0B, which is an extension of CAN 2.0A, will have a larger range than CAN 2.0A with an 11-bit identifier because CAN 2.0B has a 29-bit identifier can do.
[Table 4-1] ID area according to data classification
1) Urgent message data: Urgent message data should have precedence over any message in case of urgent message, and should be free about transmission delay due to this priority acquisition.
In the case of a vehicle, for example, when a collision occurs, the impact of the accident is large, and when the deployment of an air bag is required, the values of the sensors are pushed by the priority of other messages, Unfolded or improperly deployed can not only play an essential role in the airbag, but can also lead to secondary accidents, leading to greater risk.
An example situation can be an extreme case, but it can be a real situation, which means that untimely situations can arise if the communication system does not guarantee timeliness. Therefore, data which should be transmitted urgently, that is, data whose timeliness should be guaranteed among others, should be arranged in an urgent message data period (for example, 000-0FF) to improve a portion where transmission delay due to identifier priority may occur .
2) Normal message data: A normal data message is used during operation of a normal CAN system. The message data can be arranged with an ID of, for example, 100-6FF.
3) Registration mode data: When the first CAN system is powered on, it enters the registration mode. At this time, the CAN coordinator can send a data message to the node with an ID of 700, Each node may communicate an information message of the node, e.g. with an ID between 701-7FF.
15 shows a basic format of CAN data. Hereinafter, the basic format of the CAN data transmitted to the CAN bus, that is, the data format related to the communication between the CAN coordinator and the nodes will be described in more detail with reference to FIG.
According to the CAN 2.0A standard used in the present invention, the identifier (ID) has 11 bits, the data section is composed of 8 bits from D0 to D7, and Dn is composed of 8 bits, so that D0 to D7 Lt; / RTI > bytes.
First, the message transmitted from the CAN coordinator to the node includes a registration mode start message, a data transmission right related message for each function of the node, a second message of the node, a setup message to be sent after setting the request according to the request, There are four types of end messages. However, since the registration mode start message and the registration mode end message have the same format, the messages can be divided into three groups. In the following, the present invention will be described in more detail with reference to the accompanying drawings and tables.
1) Coordinator message transmission format 1 (Start registration mode, end registration mode)
16 shows the
[Table 4-2] Coordinator
[Table 4-2] Coordinator Message Transmission Format Looking at the data contents of D0 in 1, the bits from 7 to 4 are the sender identification part indicating who is to send this message. The division method is 7- 5 is 0, and the fourth bit is 1, it means a message that the CAN coordinator transmits to the node.
The bits from 3 to 0 indicate a message to be transmitted at present, and four messages are separately expressed in the present invention. In this way, messages having the same format can be transmitted through the bits of 3 to 0 of D0, and since the registration mode start and registration mode end messages are simply meaningful or meaningful, the data of D1-D7 All can be transmitted by putting a null value ('0').
2) Coordinator message transmission format 2 (function message transmission right of node)
The coordinator
[Table 4-3] Coordinator
3) Coordinator message transmission format 3 (node setup message)
The coordinator
Bit 7-4 of D0 data is the sender identification part, and bit 3-0 is the message identification part, which is the same as the
[Table 4-4] Coordinator message transmission format Three D1 data
D1 data represents the function of the data as shown in [Table 4-4]. Since the function definition of the data uses 8 bits, a total of 256 functions can be defined. Based on the function of this data, the data transmitted from the CAN coordinator is recognized, and each node sets an ID And a transmission and reception method for controlling the function can be acquired and the setting can be performed.
[Table 4-5] Coordinator message transmission format Three D2 data
D2 shows whether a data message can be transmitted and received and how to control its function. The contents of the second message received at the node are sent to another node to be transmitted to another node.
6-0 bit refers to the control method, and the control method is presented in a number of ways depending on the application that the user wants to use. Therefore, the contents in [Table 4-5] For example, if On is used as '1', Off is used as '0', On is used as '0', Off is used as '1' Whether to provide '1' and '0' when providing, or whether to use counter information such as engine RPM.
[Table 4-6] Coordinator message transmission format Three D3 data
The D3 data define where the transmitted / received data should be acquired and controlled in D0-D7 when the apparatus is operated in CAN normal mode.
The 7th to 4th bits of data in D3 set the initial position, and the 3-0th bit defines the end position. For example, if the data control position is D0, the first position of the 7th bit is set to '0', the 3-0th bit is set to '0', and the D0 position .
When the control position of the data is widened to D0-D2, the first position of the 7th bit is set to '0', and the 3-0th bit is set to '2' to set the range.
That is, because of this promise, the 7-4th bit set value can not be larger than the 3-0th bit set value, and if it breaks, the wrong setting occurs.
Finally, the data for D4-D7 has a total range of 32 bits, which is defined so that the identifier of CAN 2.0B can also support 29 bits. Among them, the 7th bit of D4 area refers to the use of CAN 2.0A or CAN 2.0B. When using CAN 2.0A, '1' and when using CAN 2.0B, '0' is set to follow each identifier format. Since the present invention uses the 11-bit identifier format of CAN 2.0A, the 5-0th bit of D4 is marked as disabled in [Table 4-7].
The 6th bit is an urgent message with no urgent message if it is '1' and an emergency message if it is '0'.
[Table 4-7] Coordinator message transmission format Three D4-D7 data
The D4-D7 data is an area for informing the ID allocated to the data corresponding to the second message data request sent from the node, and the data message for control between the nodes in the normal mode It can be used as an identifier.
Next, the message transmitted from the node to the CAN coordinator includes a first message related to the start of the registration mode, a second message having information of function-specific data for controlling each node, a message indicating that the setting is completed in the CAN coordinator, There are three types of registration mode termination messages. The format is divided into three types because each message to be transmitted is different. I will explain the details with the figures and tables.
1) Node message transmission format 1 (registration mode start message)
Node
FIG. 19 shows a node
[Table 4-8] Node
In the data contents of D0 in [Table 4-8], the bits from 7 to 4 are the sender identification part indicating who is to send this message, and the dividing method is the fifth bit Is '1' and the remaining bits are set to '0', it means the message that the node sends to the CAN coordinator.
The bits up to 3-0 are a part of the message that is currently being sent, and they represent three different messages. Thus, the format according to each message can be divided and transmitted through bits of 3-0 to D0.
[Table 4-9] Node
D1 in [Table 4-8] defines the number of the node operating by the actual control signal. The number of nodes can be set up to 256. If the predefined data is transmitted in D1 according to the display format of the corresponding node number, the CAN coordinator determines which node is connected to the CAN bus, When the system is powered on again, the system can be informed of the system response according to whether the node responds or not.
D2 data refers to the number of data that can be controlled with respect to the function of the node. Assuming that the data to be controlled by the function of the node is different, the number of functions and the number of the control signals are equivalent to each other.
[Table 4-10] Node
The number of these control data is displayed as [Table 4-10]. The reason for informing the CAN coordinator at the beginning is that when transmitting the data message corresponding to the
2) Node message transmission format 2 (data information message per function)
20 shows a node
[Table 4-11] Node message transmission format Double D2 data
D2 data represents the function of the data as shown in [Table 4-11]. Since the function definition of the data uses 8 bits, a total of 256 functions can be defined. Based on the function of this data, the CAN coordinator recognizes the function-specific data, performs various functions such as ID arrangement and the like.
[Table 4-12] Node message transmission format Double D3 data
D3 in [Table 4-12] shows whether the data message can be transmitted and received and how to control its function.
Bit 6-0 refers to the control method. When the CAN codec writes this control criterion and sends the node setup message, which is the third message, the other nodes that want to use the function are also checked It is used as a control method in normal mode. The control method can be defined in a number of ways depending on the method of constructing each system and the intended use.
D4 data defines when to receive and control the transmitted / received data from D0 to D7 when operating in CAN normal mode.
[Table 4-13] Node's message transmission format Double D4 data
Among the data in D4 in [Table 4-13], the 7th to 4th bits set the initial position, and the 3-0th bit defines the end position. For example, in Table 4-11, if the data control position is D0, set the first position of bit 7-4 to '0', and set the D0 position with bit 3-0 being '0' give.
When the control position of the data is widened to D0-D2, the first position of the 7th bit is set to '0', and the 3-0th bit is set to '2' to set the range.
That is, because of this promise, the 7-4th bit set value can not be larger than the 3-0th bit set value, and if it breaks, the wrong setting occurs.
[Table 4-14] Node's message transmission format Double D5 data
The message D5 is related to the urgent message transmission permission request. In the normal case, the ID of 100-6FF is used. In addition, the ID of 000-0FF is further added to the message whose timeliness should be further guaranteed by various urgent situations.
The reason for not giving a message between 000-0FF from the beginning is that when there is really urgent message to be transmitted, if there is data that uses the ID between 000-0FF as usual ID for communication, The IDs between 000-0FF may be used only in an urgent case, thereby reducing the burden on the transmission delay, and in order to ensure more timeliness, the urgent message is to be additionally arranged separately from the message normally communicated .
In [Table 4-14], it is defined that there is no urgent message if '0x00' in D5 and 'urgent message addition batch request' if '0x01'. The reason why the 8-bit case is given to the urgent message request part is to provide further enhanced function support without changing the transmission protocol in the post-system.
[Table 4-15] Node's message transmission format Double D6 data
D6 in [Table 4-15] places the ID of the data between 100-6FF, and it is a section requesting how to arrange it. That is, if '0x00' is set to 'D6', ID arrangement is performed in order to transmit the node presence message to the CAN coordinator.
When '0x01' is set, the corresponding data is assigned the ID 100 - 6FF, which is the topmost ID in the ID section used for normal operation.
If the data is set to '0x02', the corresponding data is placed in front of the specific function. For example, if the data is related to the vehicle horn and the specific data is the part responsible for the headlight of the vehicle, The CAN coordinator places the ID of the relevant CAN device in front of the specific data position in the production, and the CAN coordinator places the ID in accordance with the request.
If you are asked to place an ID in front of data that is specific to the function, if another ID is placed in front of it, the data ID that performs the specified function is lowered to the next ID, and the ID is assigned to the requested ID.
[Table 4-16] Node's message transmission format Double D7 data
D7 in [Table 4-16] is set when '0x02' or '0x03' function is used in D6. If you refer to the function of data defined in D2, This is the message that the coordinator will refer to.
If you do not use '0x02' or '0x03' function in D6, D7 will transmit null value ('0').
3) Node message transmission format 3 (Setup complete message)
FIG. 21 shows a node
The node
Since the contents of D0 and D1 are the same as
4.2. Real-time guarantee (improved transmission delay)
In the CAN system, there will be no data irrelevant to timely transmission of data at the right time among the data messages that provide function control and information, but there will be differences in how much timeliness should be assured.
That is, among the various data, there is data that needs more timeliness. For example, in the case of vehicles, information signals about important accelerator pedal and brake pedal when driving a car, There is a data signal such as an AIR-BAG for which there is a general signal such as a window or a door which is slightly lower in priority than such data.
In general, IDs are allocated to 100-6FF in general and urgent messages. In case of urgent messages, IDs between 000-0FF are further allocated to improve transmission delay.
That is, in the case of a status message such as a module status or abnormality, normally, communication is performed with an ID of 100-6FF, and when an urgent situation such as an accident occurs, the data is transmitted with an ID of 000-0FF.
In the registration mode of the system proposed by the present invention, the emergency message ID arrangement informs the information in the second message transmitted from the node to the CAN coordinator, and the contents of the second message (data information message per function) .1.1. The CAN coordinator is set by the data format specified in the D5 data area of the second message sent from the node to the CAN coordinator, An ID capable of normally communicating with the function defined in the data of D2 is allocated between 100 and 6FF, and an ID capable of further transmitting an urgent message is assigned between 000-0FF.
In addition, the CAN coordinator informs all nodes of the function of the CAN data used in the present system, the normal ID and the ID in case of emergency in the third message, the node setup message, If it is not the initial system setting, it compares it with the value set in itself, and if there is an additional message about the urgent message transmission case by the upgrade procedure such as product improvement, If not, the setup is complete and a registration mode exit message is sent to the CAN coordinator.
In the CAN normal mode, all data will be communicated at regular intervals with IDs between 100-6FF. If an emergency occurs due to various situations, the additional data 000-0FF from the CAN coordinator And transmits the urgent message through the ID between them. This makes it possible to improve the transmission delay since it has priority over the CAN BUS as compared with the data which is normally communicated. Practical improvements and improvements are discussed in
4.3. Plug and Play
In the conventional CAN system, considering all the situations from planning of the product to post-production, the ID and operation related to each node's data transmission have been fixedly considered.
This means that once a CAN system is applied to a single product, there is no change in the CAN system until the product is discontinued, and for certain companies, new products with improved performance are introduced , It will depend on the position of which one is more efficient. However, for these reasons, the idea of adding a module to the CAN system is not likely to occur.
Therefore, it is possible to add any number of nodes that can receive only one of the characteristics of the CAN system. This is possible because of the fixed concept as mentioned above. It is possible to simply receive only nodes that are connected to the existing CAN bus because of broadcasting, which is one of the characteristics of the CAN system. It is possible.
If a change in the law related to the product necessitates retrospective application of existing products, and new CAN devices, which can be both transmitted and received, are added to the CAN system, manufacturers must correct and improve the transmission and reception of new CAN In order to apply the data requested to be received from the device or the data requested to be transmitted, the parts of the nodes connected to the existing CAN bus must be individually upgraded. As the number of existing nodes related to the new node increases, Losses on costs are bound to grow.
Accordingly, even if a new node requesting both transmission and reception is added, it is possible to manage by the CAN coordinator. Therefore, even if a new node requesting transmission and reception without further upgrade is connected to the CAN bus, And plug-and-play functionality in a CAN system capable of organically communicating with the CAN system.
The plug-and-play function in the CAN system can be implemented in the registration mode, which is an operating period of the system proposed by the present invention. The technical content of the second message (control data information message for each function) transmitted from the node to the CAN coordinator is its technical content.
The contents of the function-specific control data information message, which is the second message sent from the node to the CAN coordinator, include information about the function and operation of the data (data only to be received or data which can be transmitted and received) And the data of 8-byte data is used to acquire and drive the information of the corresponding data. This is an indicator of how to use the function when a new node accesses an existing CAN system, so that the CAN coordinator can learn the effect of connecting to the CAN system by learning it with own message.
In the first message interval, the new node sends a signal to the CAN coordinator to inform its existence, and the CAN coordinator detects that there is a change in the number of nodes compared with the existing number of nodes.
That is, the CAN coordinator recognizes the addition and function of the new module, and the CAN coordinator grants transmission permission to obtain data information on the function of the new node. The new node that has been granted the transmission right sends the second message, the function-specific data information message, and the CAN coordinator that receives the information sends the data in the order of 100-6FF according to the request. , And also grasps another request such as whether it is an urgent message, and sets and stores the request.
The CAN coordinator transmits the data on the basis of the existing function and data of the function of the new node, the control method, the control position, the control ID, etc. through the CAN bus in the node setup message section. The nodes connected to the system will be able to see all the data.
The nodes receiving these messages will be reset according to their roles and needs, and will be able to operate organically with existing CAN nodes without any special upgrades due to the addition of new modules. This can be easily applied even if a new module is added due to the existence of a CAN coordinator that has a function and a control method for each node and manages the data.
5. Experiment And performance evaluation
5.1. Configure your experiment
The CAN coordinator and the CAN nodes were fabricated to implement the performance evaluation and plug-and-play function of the improvement of the transmission delay of the CAN system proposed in the present invention.
22 is a configuration diagram of the CAN test module. The CAN coordinator and the CAN node for the performance evaluation and the implementation are the same in the hardware, and only the software part is applied differently according to the role of each. This is because the CAN coordinator proposed in the present invention belongs to one of the nodes in the CAN system and thus has the same configuration as each node without any special hardware device. The software is related to the CAN coordinator that enables the nodes connected to the CAN system to be managed, and the on-off operation control and status information notification to each node through data communication suitable for the CAN system. And a node related to the node. Also, each of the nodes is subjected to different software depending on its role in the operation.
First, the configuration of the hardware is as follows. A microcontroller including a CAN controller and a transceiver for transmitting and receiving a CAN data signal to and from the bus are connected to the nodes connected to the CAN system. A plurality of switches for transmitting a control signal, and an LED and a buzzer for receiving a control signal and confirming driving. The microcontroller uses Microchip's 18F66K80, and the function of the chip's CAN bus module is shown in [Table 5-1] (see non-patent document 22).
[Table 5-1] CAN Bus Module Features of 18F66K80
First, the relatively important functions of the CAN module of the 18F66K80 are described briefly. The CAN 2.0B specification is supported in the CAN system. Including CAN 2.0A, and the message bit rate is up to 1Mbps. The CAN transceiver uses Microchip's MCP2551, which is the same manufacturer as the microcontroller. The functions are shown in [Table 5-2] (see Non-Patent Document 9).
[Table 5-2] Features of the MCP2551
The CAN transceiver needs to be aware of the supported operating speed and whether it can support CAN 2.0A or CAN 2.0B. For example, if the microcontroller's CAN module has a performance of 1 Mbps and the CAN transceiver does not support 1 Mbps performance (for example, SW CAN transceivers up to a maximum of 83.3 kbps), care must be taken when designing hardware related to the CAN system.
The CAN test module manufactured in this manner is shown in FIG. 23, and a total of six CAN test node modules except for the test module to be used as the CAN coordinator are manufactured. 23 shows a CAN test node.
Also, in order to implement CAN test nodes that can perform on-off operation using the CAN coordinator for CAN data message management and the CAN data message, we programmed them according to the algorithm of the proposed system in
24 shows the CAN data message measurement equipment. That is, the equipment used for the CAN data message measurement is as shown in FIG. 24, and if the data message is communicating on the CAN bus, the equipment displays the communication time, the identifier, and the data of 8 bytes in the message This device can monitor whether the data that is responsible for the function of each node is operating normally on the bus.
By using this monitoring function, it is possible to confirm the transmission delay by measuring the communication time of the CAN messages on the bus, and the CAN coordinator monitors the transmission and reception of data in order by the algorithm to each node connected to the system , It is confirmed that the function control data is normally transmitted by using the switches of the respective nodes after the registration mode is ended, and the plug and play function is implemented.
25 shows the experimental environment configuration. As shown in FIG. 25, six test nodes to be utilized as the CAN module except for the test node to be utilized as the CAN coordinator described above are utilized in total, and seven CAN modules are connected in sequence to the CAN bus. And a power supply line for applying a 5V power supply.
First, in order to test the transmission delay, each connected CAN test node must transmit a CAN data message at the same time. Therefore, in the transmission delay test procedure, it is set to transmit only one message for each node at the same time, and a node having a priority higher than the data of the experiment node is added to the CAN bus and the transmission delay time is checked through the CAN data message measuring device Respectively. In addition, the part of the emergency message is transmitted when an input is made to the microcontroller through a designated switch input, which is further configured in the node, and it is also measured whether the urgent message has priority over other data messages and can improve the transmission delay .
In addition, the part of the plug-and-play function, which is one of the additional functions of the CAN coordinator, connects the CAN test nodes sequentially one by one. The part where the data message is normally transmitted and received according to the algorithm of the proposed system, The CAN coordinator is able to perform normal communication using the identifiers placed by the CAN coordinator. For detailed experimental methods and performance improvement, see section 5.2. Section of this chapter.
5.2. Performance evaluation
In this section, we show the improvement of the transmission delay for emergency messages in the system using the CAN coordinator, and the plug-in that works together with the existing connected CAN nodes without upgrading the new module addition part to other nodes when adding the new node. We will implement Plug and Play function and evaluate performance of improvement and operation according to the proposed algorithm.
First, we experimented on improvement of transmission delay for urgent messages. In order to check whether the transmission delay actually occurs in the CAN system, the environment where the transmission delay may occur is reproduced through the actually manufactured CAN test node. The reproduction method is set so that only one message is transmitted to each CAN test node at the same time, and a different CAN identifier is assigned to each data, and a data message therefor is also different. Identifier and data are given according to node order as in [Table 5-3].
[Table 5-3] Test node-specific data messages to reproduce transmission delay
The CAN data message assigned to each node according to the sequence number is similarly set to be transmitted every about 1 second. Since the nodes send CAN data messages to the CAN bus once a second at the same time, several data messages collide with each other. In the process of arbitrating this collision, it is assumed that data delayed in priority will cause transmission delay. In addition, the number of CAN test nodes was sequentially increased from one node to six, and how much the transmission delay time increased was measured by a measuring device.
26 shows the CAN data transmission delay. That is, FIG. 26 is a measurement result of a CAN data message measuring device that a total of four CAN test nodes transmit one data at a speed of 100 kbps according to the format of [Table 5-3]. In the measured result, it is possible to see the part where the data is transmitted with the identifier of 100 in the first 1 and the data of 01 00 00 00 00 00 00, and the data message of 2-4 is transmitted every 1 sec The data message pushed in the priority order can be seen to have a transmission delay of about 1.2-1.7 ms compared to the data message having the priority in the immediately preceding order. That is, assuming that the priority of the data identifiers is sequentially set in the order of 1 to 4, and the transmission delay is about 1.5 ms compared to the priority data immediately before the data to be transmitted, The data message No. 4 having the lowest priority has a transmission delay of about 4.5 ms. [Table 5-4] is based on Fig. 26.
[Table 5-4] Transmission delay result of CAN data message
FIG. 27 shows a transmission delay time according to an increase in a data message. Experiments were performed more than 100 times in total, but only the portion of the transmission delay, which is changed by 1-3 shifts, is recorded in Table 5-4.
In FIG. 27, two test nodes are further added based on the test recording [Table 5-4], and the same transmission delay experiment is performed, and the average value is obtained, and the number of data messages having higher priority than the data transmitted from the
The X axis represents the number of times each node transmits one data at a time on the CAN bus, and the Y axis represents the time at which each data is transmitted. As mentioned above, as the number of data to be transmitted at one time increases, transmission delay of low-ranking data is longer than that of the highest-priority data. Therefore, applying the part of the improvement of the transmission delay for the urgent message proposed in the present invention, the result as shown in FIG. 28 can be obtained. FIG. 28 shows an improvement in transmission delay for an urgent message.
[Table 5-5] Improvement result of transmission delay of CAN data message
In Table 5-5, which is based on the result of FIG. 28, a transmission delay should occur due to identifier arbitration in the order of 110, 120, and 130 following the 100th identifier. When the 110th identifier is an emergency message event The switch input on the CAN test node is generated), the
In order to more clearly demonstrate the improvement of the urgent message transmission delay, the data transmitted at one time are sequentially increased and further experiments are performed. The results are shown in the graph of FIG. 29 is a diagram related to the transmission of an urgent message of a specific identifier.
Experimentally, the urgent message priority was given to the message sent from the
In the case where the system is not applied, it can be seen that as the TX data of the Y axis increases, the transmission time increases due to the increase of the transmission delay of the lower priority data. Compared with this, in the case of applying the urgent message transmission delay improvement system, even if the number of TX data to be transmitted on the bus increases, the message urgently transmitted has priority over the other identifiers. Therefore, It can be seen that the transmission time is almost constant.
Next, experimental methods and results are described for the implementation of the plug-and-play function. In this paper, we propose two CAN test nodes with CAN coordinator, which are used when the first system is configured and when a new module is added to the existing system. CAN data message measurement equipment.
31 shows a CAN node arrangement process of the CAN coordinator. 31 is an assumption that the first system is configured and that one node is connected to the CAN coordinator and that the communication in the registration mode between the CAN coordinator and the CAN node is recorded on the CAN data message measuring apparatus, Are listed in the table on the basis of [Table 5-6].
[Table 5-6] shows that the CAN coordinator communicates with 700 identifiers and the node with 701 identifiers. When the first CAN system is powered on, the CAN coordinator sends a registration mode start message with an identifier of 700 and a registration mode start message of 11 00 00 00 00 00 00 00, and the node receiving the registration mode start message from the coordinator is about 15 ms The first message is transmitted.
[Table 5-6] Result of CAN node arrangement process of CAN coordinator
In the first message, the node informs the number of the node through 00 of D1 to the registration mode preparation message of 21 00 02 00 00 00 00 00, and sends the number of function data held by the node through D2 to D2. The CAN coordinator that receives the data message of the node transmits the message of 12 00 00 00 00 00 00 00 to grant the data message transmission authority, and informs D1 of the node number of 00 to give the transmission right to the node. The node that previously informed the coordinator that it has two data messages has the right to occupy the CAN bus while sending two functional data formats from the coordinator. The authorized node transmits the format related to the two function data to the CAN coordinator. The CAN coordinator that receives the message transmits the setup message to the node after arranging the identifier according to the format, and the coordinator, Transmission complete and registration mode end messages are sent. The node that received the setup message completes the setup, and sends the setup completion and registration mode end message to the coordinator, and the registration mode ends. Next, the number of CAN nodes is gradually increased. When a new node is added, the CAN coordinator manages each node according to the proposed system, so that the plug-and-play function is applied, and the actual communication between the coordinator and the node And the results are shown in FIG. 32 shows a CAN
In order to operate the plug-and-play function in the CAN system, the CAN coordinator obtains the necessary information for managing the CAN nodes through communication with the CAN node. Based on the actually measured FIG. 32, Is represented by Fig. 33 shows a communication process for Plug and Play.
In the registration mode, the basic communication process between the CAN coordinator and the node is unified for stability, so no special addition process is required for the plug-and-play function to operate. That is, all basic processes such as the initial system, the existing system, and the addition of the new node operate in the same manner, and only the processing for entering the new node is added during the process. First, in order to enter the registration mode, the coordinator transmits a message indicating that the coordinator starts the registration mode to the existing node, and each node that receives this message sends the first message to the CAN coordinator. The CAN coordinator, which receives the first message sent by this node, can confirm that the new un-recorded node, other than the existing nodes being recorded, has entered the CAN bus and also has some functions. When the new node is detected, the CAN coordinator records the node number and the number of its functions, and grants authority to explain the functions of the existing nodes and the new node. The node that has been granted the transmission right sends a message to the CAN coordinator describing the functions it has, and the CAN coordinator sets the identifier for each function message sent by the node, Message. When the coordinator completes the setup message transmission, it sends a setup message transmission completion message and a registration mode end message. Each node receiving the setup message receives a data message for the related function and receives Or the transmission method, and sends a setting completion and registration mode end message.
In this way, several nodes provide data information about the function to the CAN coordinator, the CAN coordinator places an identifier (ID) according to the request of the function message, and a third message, A node that needs to acquire related function control and information can receive the setup message and set the configuration accordingly. Therefore, even if the new node is added to the existing CAN system, Plug-and-play functionality that runs in tandem with existing nodes without the hassle of upgrading.
6. Conclusion
We added an administrator-level module called CAN coordinator to the existing CAN system to complement the deficiencies on the CAN system and manage the data messages used more effectively. Among them, the CAN data message was upgraded to another related node connected to the existing CAN system when transmission delay improvement due to collision with another message during transmission and addition of a new node capable of transmission and reception to the CAN system , Plug and Play functionality that does not have to be.
First of all, when the transmission delay improvement part transmits several data messages at 100 kbps at the same time, the transmission delay of about 1.5 ms is delayed according to the message priority. In the event that there is a data message urgently to be transmitted in case of an event, the CAN coordinator can further arrange an ID for the urgent message transmission case so as to give priority to other messages and to transmit the data message at a proper time. However, in an environment in which all the nodes continuously transmit data messages at the same time as in the experimental environment of FIG. 5, other messages are shifted from the priority due to the urgent message transmission having priority, that is, And that the phenomenon of the occurrence of the phenomenon occurs. Of course, in case of the CAN system applied to the actual product, since all data transmission does not occur at the same time, but the CAN communication is performed with a time difference according to necessity, priority is given to the data message to be urgently transmitted It is very unlikely that all the messages will be collided with the transmission delay as in the experimental environment.
With regard to the Plug and Play function, since the CAN coordinator manages information such as data function, operation method, and data message location for operation, a new transmitting / receiving module enters the existing system The new module recognizes the information about the existing data and obtains the condition that can be operated organically with the existing nodes and the actual implemented result is obtained.
In this way, it is possible to improve the complement of CAN system by adding CAN coordinator to the existing CAN system, and it is possible to utilize it in various aspects. Through various studies in the future, CAN systems with CAN coordinators are expected to evolve further.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the following claims. It will be understood.
Claims (13)
Sending a registration mode start message to a plurality of nodes in the CAN in response to entry of a registration mode;
Receiving, from at least one of the plurality of nodes, a response message indicating completion of preparation of the registration mode and including the number of control data for each function of the prepared node in the registration mode;
Counting the number of responding nodes among the plurality of nodes and the number of function-specific control data of each of the responding nodes based on the response message;
Transmitting a function-specific control data transmission right message based on the counting result to a responding node among the plurality of nodes;
Receiving a function-specific control data information message including request information on the function and operating condition of the responding node from a responding node among the plurality of nodes; And
Setting a function and an operating condition of each of the responding nodes among the plurality of nodes based on the function-specific control data information message, and transmitting the node setting message to the responding node among the plurality of nodes, Control method.
Wherein the request information regarding the function and operating condition of the responding node includes an ID placement request,
Wherein the response message has an ID belonging to a registration mode data section,
Wherein the node setup message assigns an ID belonging to a general message data interval to the function of the responding node.
Wherein the request information regarding the function and operation condition of the responding node further includes an urgent message transmission permission request,
Wherein the node setup message further allocates an ID belonging to an emergency message data interval to the function of the responding node and the ID of the emergency message data interval has a priority over the ID of the general message data interval, .
Wherein the request information regarding the function and operating condition of the responding node includes a request for at least one of a function of data, transmission or reception availability, control method of function, and data acquisition position in normal mode operation, .
Wherein the request for ID placement is a request for either automatic placement, top priority placement, placement in front of a particular feature, and placement after a particular feature.
Wherein the function-specific control data transmission right message includes a node number to be authorized.
Wherein the function-specific control data transmission right message sets an authorization time based on the number of function-specific control data of the responding node among the plurality of nodes.
Wherein the function-specific control data transmission right message allows the plurality of responding nodes to sequentially transmit function-specific control data transmission rights when there are a plurality of nodes among the plurality of nodes.
And terminating the registration mode when receiving the response message fails to receive a response message from the plurality of nodes.
Further comprising the step of terminating the registration mode if a failure to receive a response message from any one of the nodes previously registered in the CAN coordinator fails.
Receiving a registration mode complete message from the responding node indicating that setting of the function and operating condition of the responding node according to the node setting message is completed; And
And terminating the registration mode in response to the registration mode complete message.
Wherein the end of the registration mode indicates an error occurrence for the CAN.
In response to the termination of the registration mode, the CAN coordinator stops operating, and the plurality of nodes operate in normal travel mode.
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