KR100747760B1 - Time division scheduling method on can and the can system thereof - Google Patents

Abstract

A time division scheduling method in a CAN(Controller Area Network) and a CAN system thereof are provided to decide the time when a particular message will be transmitted according to the intention of a designer, and to ensure transmission time for an emergency message. A master node(10) includes a cycle generation module(12) which generates a cycle message at certain time intervals. More than one of slave nodes(30,50) attempts to transmit the message at a predetermined time according to the cycle message. The master node(10) is a gateway. The slave nodes(30,50) include message scheduling modules(32) for recognizing the predetermined time.

Description

Time division scheduling method on CAN and its CAN system

1 is a configuration diagram schematically showing a CAN system for providing a time division scheduling method according to an embodiment of the present invention.

2 illustrates a time structure of one cycle according to a preferred embodiment of the present invention.

3 is a flowchart illustrating a process of generating and transmitting a cycle message by a master node of a CAN system according to an exemplary embodiment of the present invention.

4 is a flowchart illustrating a message processing procedure using a time division scheduling scheme of a node of a CAN system according to an exemplary embodiment of the present invention.

5 is a flowchart illustrating a time division scheduling process according to an event trigger according to a preferred embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

100: CAN system

10: master node

12: cycle generation module

30: Critical Node

32: message scheduling module

50: noncritical node

The present invention relates to a controller area network (CAN), and more particularly, to a time division scheduling method in a CAN and a CAN system thereof.

In the automotive sector, the CAN (controller area network), which is used to exchange information between on-board electronic control units (ECUs) such as engine management systems, transmission control, instrument packs, and body electronics, is a control application system. Refers to a microcontroller that connects the sensors, starting devices, etc. within each other.

Conventional CAN uses an event trigger method, which results in message delay due to non-preemptive characteristics and arbitration mechanism, thereby restricting its application to various systems for increasing vehicle stability and convenience. . In other words, in the transmission of messages with priority, the mediation mechanism causes some delay in the higher priority messages, and the lower priority messages are delayed in transmission due to the CAN-specific arbitration mechanism. This happens.

Accordingly, time trigger protocols have been proposed as an in-vehicle CAN technology. However, a conventional time triggered CAN (TTCAN: Time Triggered CAN) must be additionally equipped with a hardware device different from the CAN, and thus a problem such as an additional cost occurs.

Accordingly, an object of the present invention is to provide a time division scheduling method in CAN and a CAN system that can solve a message transmission time delay.

Another object of the present invention is to provide a time division scheduling method and a CAN system in CAN that can guarantee message transmission time using a time trigger-based protocol without additional hardware.

Another object of the present invention is to provide a time division scheduling method and a CAN system in CAN that can determine a transmission time of a specific message according to a designer's intention and can guarantee a transmission time for an emergency message.

Still other objects of the present invention will become more apparent through the preferred embodiments described below.

According to an aspect of the present invention for achieving the above object, a controller area network (CAN) system, the master node including a cycle generation module for generating a cycle message at a predetermined time period; And one or more slave nodes attempting to transmit the message at a predetermined time corresponding to the cycle message.

More preferably, the master node may be a network gateway.

In addition, the slave node may include a message scheduling module for recognizing the designated time.

In addition, one cycle according to the cycle message is divided into a plurality of time slots, and one node may transmit a message for each time slot.

In addition, the slave node is divided into a critical node and a non-critical node, and the cycle may include a critical slot for transmitting a message by a critical node and a non-critical slot for transmitting a message by a plurality of non-critical nodes. Can be.

In addition, the time slot may be set equal to or greater than the sum of the message transmission time and the processing time.

In addition, the slave node may transmit an emergency message according to the generated event by reserving a specific time slot of a cycle according to a cycle message received next.

According to another aspect of the present invention for achieving the above object, a time division scheduling method in a controller area network (CAN) system, comprising: generating a cycle message at the master node and sending it over a bus; And at least one slave node receiving the cycle message recognizes a global time according to the cycle message, recognizes a predetermined time to send a message, and attempts to send a message at the specified time. A time division scheduling method is provided.

More preferably, one cycle according to the cycle message is divided into a plurality of time slots, and one node may transmit a message for each time slot.

In addition, the slave node is divided into a critical node and a non-critical node, and the cycle includes a critical slot in which the critical node transmits a message and a non-critical slot in which a plurality of the non-critical nodes compete and transmit a message. It may include.

In addition, the time slot may be set equal to or greater than the sum of the message transmission time and the processing time.

The method may further include a step in which a slave node having an emergency event is reserved for a specific time slot of a next cycle, wherein the master node transmits a next cycle message at a predetermined time interval; And transmitting, by the slave node that reserved the specific time slot, an emergency message according to the emergency event in the reserved specific time slot.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms including ordinal numbers such as first and second may be used to describe various components, but the components are not limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term and / or includes a combination of a plurality of related items or any item of a plurality of related items.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, and in describing the present invention with reference to the accompanying drawings, the same or corresponding components are given the same reference numerals regardless of the reference numerals. Duplicate explanations will be omitted.

In addition, a CAN system for performing time division scheduling according to an embodiment of the present invention will be described by using a vehicle system as an example for convenience of description, but the present invention is not limited thereto.

1 is a block diagram schematically illustrating a CAN system for providing a time division scheduling method according to an exemplary embodiment of the present invention, and FIG. 2 is a diagram illustrating a time configuration of one cycle according to an exemplary embodiment of the present invention. to be.

The CAN system 100 according to the present invention predefines a communication pattern of a bus such as TTCAN (Time Triggered CAN) to ensure high priority message transmission and reduce message transmission delay from nodes having low priority. Can be. The CAN system 100 may control a bus division of time division multiple access (TDMA) scheme using regular repetition of a cycle.

Referring to FIG. 1, the CAN system 100 for time division scheduling according to an embodiment of the present invention includes a plurality of nodes, and one of the nodes controls a cycle of a cycle. Perform the function of 10). Here, not only general nodes such as anti-lock breaking system (ABS) and electronic control power steering (ESP), but also all nodes such as a main control node (not shown) and a network gateway for combining with other networks are mastered. Naturally, the node 10 may be configured as a node, but a general node such as ABS or ESP may fail to perform its function. Thus, a gateway node may be used for a more secure function of the master node 10. It is more preferable to perform the function of the master node 10.

The master node 10 is a cycle message every predetermined period of time (i.e., at each cycle start time) so that other nodes (hereinafter referred to as 'slave nodes') can recognize the time to send the message (i.e., CAN data). Create and send a cycle message. Accordingly, slave nodes that receive a cycle message every cycle recognize the start time of one cycle (hereinafter referred to as 'global time') according to the cycle message, and specify a predetermined time (a corresponding time slot). ), See FIG. 2).

The master node 10 includes a cycle generation module 12 for generating a cycle message as described above. The master node 10 transmits a cycle message at a predetermined predetermined time (should be set larger than one cycle time, see FIG. 2). Each node that receives the cycle message may transmit the message at a preset time for one cycle time.

Referring to FIG. 2, one cycle time may be divided into a plurality of time slots. In the present embodiment, as shown in the drawing has been shown that there are five time slots in one cycle time, but this is only one embodiment and is not limited thereto. In addition, it is obvious that the quantity or / and order of critical and non-critical messages is not limited to the illustrated configuration.

According to an embodiment of the present invention, a time slot for a cycle message (Cycle Msg. 210), which is a reference message indicating that one cycle starts in one cycle, and a critical message (that is, the critical node 30 is transmitted) Message, a critical slot that is a time slot for transmitting 220 and 240, and a non-critical slot that is a time slot for transmitting a noncritical message (a message transmitted by the non-critical node 50, 230 and 250). Can be.

A time slot according to a preferred embodiment of the present invention may be set to be equal to or more than a time obtained by adding a message transmitting time (MTT), which is a time for transmitting a message, and a message processing time (MPT), which is a time for processing a message at a node. . MTT is a value obtained by dividing the CAN data frame, which is the size of the data format used in the CAN system 100, by the CAN bus rate.

Referring back to FIG. 1, the slave node may be divided into a critical node 30 and a non-critical node 50. The critical node 30 may transmit a message by occupying the data bus BUS in a predetermined time slot (ie, the critical slot of FIG. 2) during one cycle. That is, each critical node 30 has a predetermined time slot for transmitting a message among corresponding cycle times. In contrast, the non-critical node 50 has no predetermined time slot, and the plurality of non-critical nodes 50 compete with each other in the non-critical slot of one cycle, and the selected non-critical node 50 The message can be transmitted in the corresponding time slot. It is obvious to those skilled in the art because each node competing to use the bus is a technique also used in current CAN.

Therefore, each slave node 30, 50 must know the time it sends a message, and therefore each includes a message scheduling module 32. The message scheduling module 32 functions to recognize the time (time slot) for the node to transmit the message by using the received cycle message and the previously stored scheduling data.

In this case, the period generation module 12 of the master node 10 and the message scheduling module 32 of the slave node need not be implemented in hardware. More preferably implemented.

Hereinafter, a process of transmitting a cycle message by the master node 10 and a process of performing a corresponding operation when each slave node receives a message will be described.

3 is a flowchart illustrating a process of generating and transmitting a cycle message by a master node of a CAN system according to an exemplary embodiment of the present invention, and FIG. 4 is a time division of a node of a CAN system according to an exemplary embodiment of the present invention. A flowchart illustrating a message processing process using a scheduling method.

Referring to FIG. 3, the master node 10 generates a cycle message (step 310) and transmits the generated cycle message to other nodes via the bus BUS (step 320).

The master node 10 waits for a predetermined time (set not to be less than one cycle time) (step 330), and then proceeds to step 310.

Therefore, the master node 10 repeatedly transmits a cycle message at a predetermined time period, so that each node, that is, slave nodes, recognizes a time to send a message and, if there is a message to be transmitted, transmits a message in a corresponding time slot. have.

Referring to FIG. 4, when a message is received (step 410), the slave node determines whether the message is a cycle message (step 420).

If the determination result is a cycle message, the slave node determines whether the current cycle is a cycle period preset to transmit the message (step 430). That is, the critical node 30 among the slave nodes has information on a specific cycle in which it can send a message among the plurality of cycles, and information on a corresponding time slot of the cycle. Therefore, each slave node that receives the cycle message determines and recognizes whether or not the current cycle is a cycle previously designated to transmit the message. Of course, non-critical nodes 50 may compete to transmit messages in every cycle since they transmit messages in non-critical slots, and more preferably one or more non-critical nodes 50 may also transmit messages. Specific cycles may be specified. If the non-critical nodes 50 do not have a predetermined cycle, step 430 does not need to be executed and may proceed directly to step 440.

Here, the slave node may use the identification information included in the cycle message to determine whether the current cycle is a cycle designated in advance so that the message can be transmitted.

As a result of the determination in step 430, if the current cycle according to the cycle message is a predetermined cycle to transmit the message, the slave node transmits the message in a predetermined time slot of the cycle (step 440). Of course, the non-critical nodes 50 compete with other non-critical nodes 50 in a predetermined non-critical slot to transmit a message.

5 is a flowchart illustrating a time division scheduling process according to an event trigger according to a preferred embodiment of the present invention.

The CAN system according to a preferred embodiment of the present invention uses TDMA time division scheduling as described above, and if a specific node needs to transmit an urgent message, it may transmit a message in an event trigger method. .

For example, a node such as an anti-lock breaking system (ABS) may not necessarily send a message periodically, but may also send an emergency message only when an urgent event such as a brake operation occurs.

Therefore, when a specific event of the CAN system according to the preferred embodiment of the present invention has to send an emergency message due to an urgent event occurs, the specific time slot of the next cycle (as shown in Figure 2, the first time slot of one cycle) Is occupied by a cycle message and uses one of the second and subsequent time slots (e.g., the second time slot) to send the corresponding emergency message. Of course, there may be a node previously designated to send a message in that particular time slot, but since the transmission of an emergency message may be prioritized, the node is preferably implemented to send a message in the next cycle.

Referring to FIG. 5, as the event is generated (step 510), the node determines whether the generated event is an urgent event (step 520).

As a result of the determination, in case of the non-urgent general event, a message according to the corresponding event is transmitted through a time division scheduling process as shown in FIG. 4 (step 530).

If it is an urgent event as a result of the determination in step 520, a specific time slot of the next cycle is reserved (step 540). The reservation of time slots may be controlled by a main control node (not shown) controlling the CAN system 100, or may be controlled by a master node. When controlled by the master node, when the master node transmits a cycle message, the master node may include identification information in the cycle message so that the slave nodes can recognize that a specific node of the cycle is reserved.

Therefore, the node provides the main control node or the master node 10 with a reservation signal for reserving a specific time slot for the emergency message. According to another embodiment, without a separate reservation signal, the node may transmit a message using a specific time slot of the next cycle, in which case the node uses another identification information (for example, priority information). Can prevent them from using this particular time slot.

The node sends an emergency message at a specific time slot time of the reserved cycle as described above (step 550).

Therefore, the CAN system 100 according to the present invention can guarantee the transmission time for the emergency message of a specific node.

The method of the present invention as described above may be implemented in a program and stored in a computer-readable recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.).

The present invention is not limited to the above embodiments, and many variations are possible by those skilled in the art within the spirit of the present invention.

As described above, according to the present invention, there is an effect of providing a time division scheduling method and a CAN system in CAN that can eliminate a message transmission delay time.

In addition, the present invention has an effect that can be guaranteed for the message transmission time with a time trigger-based protocol without additional hardware.

In addition, the present invention can determine the transmission time of a specific message according to the intention of the designer, there is an effect that can ensure the transmission time for the emergency message.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art that various modifications of the present invention without departing from the spirit and scope of the invention described in the claims below And that it can be changed.

Claims (13)

In a controller area network (CAN) system, A master node including a period generating module for generating a cycle message at a predetermined time period; And Time division scheduling CAN system comprising one or more slave nodes attempting to transmit a message at a predetermined time corresponding to the cycle message. The method of claim 1, The master node is a time division scheduling CAN system, characterized in that the network gateway. The method of claim 1, And said slave node comprises a message scheduling module for recognizing said specified time. The method of claim 1, One cycle according to the cycle message is divided into a plurality of time slots, and time division scheduling CAN system, characterized in that one node transmits a message for each time slot. The method of claim 4, wherein The slave node is divided into a critical node and a non-critical node, and the cycle includes a critical slot for transmitting a message by a critical node and a non-critical slot for transmitting a message by a plurality of non-critical nodes. Time Division Scheduling CAN System. The method of claim 4, wherein And the time slot is set to be equal to or greater than the sum of the message transmission time and the processing time. The method of claim 1, And the slave node reserves and transmits an emergency message according to the generated event, and a specific time slot of a cycle according to a cycle message received next. In the time division scheduling method in a controller area network (CAN) system, Generating a cycle message at the master node and sending it over a bus; And At least one slave node receiving the cycle message recognizes a global time according to the cycle message, recognizes a predetermined time to send a message, and attempts to transmit a message at the specified time. Time division scheduling method. The method of claim 8, One cycle according to the cycle message is divided into a plurality of time slots, and one node transmits a message for each time slot. The method of claim 9, The slave node is divided into a critical node and a non-critical node, and the cycle includes a critical slot in which the critical node transmits a message and a non-critical slot in which a plurality of the non-critical nodes compete to transmit a message. Time division scheduling method, characterized in that. The method of claim 9, And the time slot is set equal to or greater than the sum of the message transmission time and the processing time. The method of claim 8, And scheduling, by the slave node where the emergency event has occurred, a specific time slot of a next cycle. The method of claim 9, The master node transmitting a next cycle message at regular time intervals; And And transmitting, by the slave node which reserved the specific time slot, an emergency message according to the emergency event in the reserved specific time slot.

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