JP5892391B2 - Communication control method - Google Patents

Description

  The present invention relates to a communication control method implemented in an electronic control device.

  Conventionally, an electronic control unit (ECU) mounted on a vehicle has a plurality of CAN controllers connected to the same communication bus inside one electronic control unit, and performs CAN communication. For example, the electronic control device described in Patent Document 1 has a single CAN controller in a normal mode and one or more CAN controllers in a reception-only mode, and prevents transmission / reception of ACK in the device. .

JP 2011-131713 A

  The electronic control device disclosed in Patent Document 1 intends to avoid a situation in which a bus abnormality cannot be detected by returning ACKs within the apparatus when an abnormality such as disconnection occurs in the bus. However, the CAN controller in the reception-only mode cannot transmit ACK, and a new problem arises that detection of bus abnormality using ACK reception does not function. Patent Document 1 makes no mention of such a problem when the bus is abnormal.

  The present invention was created in view of the above points, and its purpose is the only CAN module set in the normal mode (corresponding to the “CAN controller” in Patent Document 1), and reception only. An electronic control device having one or more CAN modules set in a mode is to provide a communication control method for performing appropriate processing when a bus abnormality occurs.

The communication control method of the present invention includes a CAN module A and a CAN module B connected to the same bus for CAN communication, the only CAN module A set in a normal mode capable of transmission and reception, and a reception-only mode. This is a method implemented in an electronic control device including a microcomputer having one or more CAN modules B set to, and a CAN transceiver that connects the CAN module A and the CAN module B to a bus.
In this communication control method, when an abnormality occurs in the bus, the CAN initialization process for determining an abnormality in the bus based on information detected by the CAN module A and then initializing all the CAN modules A and CAN modules B. It is characterized by implementing.

  In the present invention, when the bus abnormality occurs, the CAN module A in the normal mode can detect the bus abnormality by detecting the bus abnormality. Further, in the subsequent CAN initialization process, by synchronizing the initialization processes of all the CAN modules, a plurality of CAN modules can be controlled as “integrated single CAN module”.

Further, in the CAN initialization process, it is preferable to start the CAN communication when the initialization processes of all the CAN modules A and CAN modules B connected to the same bus are normally completed. In CAN communication, the CAN module A reception process and the CAN module B reception process are performed in random order, and finally the CAN module A transmission process is performed.
By detecting the abnormality of all the CAN modules before the transmission / reception process, a plurality of CAN modules can be controlled as “integrated single CAN module”.

Further, in this case, in the CAN initialization process, it is preferable to perform the initialization process of the CAN module B after the CAN module A is prioritized.
By not operating the CAN module B in the reception-only mode, which is the sub, until the main CAN module A in the main mode is operating normally, it is possible to prevent inconsistencies in the integrated control.

1 is a system schematic diagram of an electronic control device according to an embodiment of the present invention. 1 is a schematic configuration diagram of an electric power steering device to which an electronic control device according to an embodiment of the present invention is applied. The main flowchart of the "communication control process" by embodiment of this invention. 4 is a sub-flowchart of the first embodiment of “CAN initialization process” in FIG. 3. FIG. 6 is a sub-flowchart of a second embodiment of “CAN initialization process” in FIG. 3. FIG. 6 is a sub-flowchart of “CAN module initialization process” in FIGS. 4 and 5; FIG. 4 is a sub-flowchart of “CAN module reception processing” in FIG. 3; FIG. 4 is a sub-flowchart of “CAN module transmission processing” in FIG. 3.

DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of an electronic control device that implements a communication control method according to the present invention will be described with reference to the drawings.
An electronic control device (hereinafter referred to as “ECU”) according to an embodiment of the present invention is mounted on a vehicle and used to control an electric power steering device that assists steering torque. First, the overall configuration of the electric power steering apparatus will be described with reference to FIG.

  The electric power steering apparatus 1 includes a torque sensor 94 that is installed on a steering shaft 92 and detects a steering torque in the steering system 90. A pinion gear 96 is provided at the tip of the steering shaft 92, and the pinion gear 96 meshes with the rack shaft 97. A pair of wheels 98 are rotatably connected to both ends of the rack shaft 97 via tie rods or the like.

  When the driver operates the handle 91, the steering shaft 92 connected to the handle 91 rotates, and the rotational motion of the steering shaft 92 is converted into the linear motion of the rack shaft 97 by the pinion gear 96. The pair of wheels 98 are steered at an angle corresponding to the displacement.

The electric power steering apparatus 1 includes a motor 80 that generates steering assist torque, a reduction gear 89 that reduces the rotation of the motor 80 and transmits the rotation to the steering shaft 92, and the motor driving apparatus 2. The motor 80 is a three-phase brushless motor, and rotates the reduction gear 89 forward and backward. The motor drive device 2 includes an ECU 10 that is a control device, a rotation angle sensor 85 that detects a rotation angle of the motor 80, the above-described torque sensor 94, a vehicle speed sensor 95 that detects a vehicle speed, and the like.
With this configuration, the electric power steering apparatus 1 generates a steering assist torque for assisting the steering of the handle 91 and transmits the steering assist torque to the steering shaft 92.

Next, the configuration of the ECU 10 will be described with reference to the system schematic diagram of FIG.
The ECU 10 is connected to a CAN communication bus 18 together with an ECU that controls other in-vehicle devices, and exchanges data used for control by performing data communication with other ECUs via the bus 18 using the CAN protocol. The bus 18 is constituted by a two-wire communication line including a CAN-H line and a CAN-L line used in the CAN protocol.

The ECU 10 includes a microcomputer 11 and a CAN transceiver 17.
The microcomputer 11 includes a CPU (central processing unit) 12 that executes programs, a RAM 13 that stores calculation results and the like by the CPU 12, a ROM 14 that stores programs executed by the CPU 12, a CAN module A15 that is a controller for CAN communication, and a CAN Module B16 and the like are incorporated. The RAM 13 and the ROM 14 are connected to the CPU 12 so that they can communicate with each other. The CAN module A15 and the CAN module B16 are also connected to the CPU 12 so that they can communicate with each other.

  The CAN module A15 is set in a normal mode in which CAN communication can be transmitted and received, and returns ACK as a confirmation response when data is received. On the other hand, the CAN module B16 is set to a reception-only mode in which ACK is not returned when data is received. This configuration is the same as the configuration described in Patent Document 1, and prevents the two CAN modules from returning ACKs by establishing a transmission / reception pair within the microcomputer 11.

The CAN module A15 is the only “main CAN module” for one microcomputer 11. On the other hand, an example in which one CAN module B16 is provided in the microcomputer 11 in FIG. 1 is shown, but two or more CAN modules B16 may be provided in the microcomputer 11.
In the following description, when CAN module A15 and CAN module B16 are not distinguished, they are collectively described as “CAN modules 15 and 16”.

  The CAN modules 15 and 16 each have a transmission terminal Tx and a reception terminal Rx, and each transmission terminal Tx and reception terminal Rx are connected to a CAN transceiver 17. The CAN transceiver 17 is connected to the bus 18 and inputs / outputs signals to / from the bus 18. Thus, the CAN module A15 and the CAN module B16 are connected to the same bus 18 via the CAN transceiver 17.

  Each of the CAN modules 15 and 16 has 32 message frame transmission / reception buffer mailboxes, and this number limits the number of messages that can be transmitted and received by one CAN module. Thus, with the above configuration, the number of receivable messages can be increased to 64 messages by combining the two CAN modules 15 and 16 while preventing the transmission and reception of ACK within the microcomputer 11. Moreover, the number of receivable messages can be further increased by providing two or more CAN modules B16.

  Incidentally, there may be a case where an abnormality occurs in the CAN communication bus 18. For example, there is an abnormality such as communication failure or disconnection due to excessive data or a mismatch in setting speed between the transmission side and the reception side. Japanese Patent Application Laid-Open No. H10-228667, which is a conventional technology, does not mention any processing when such a bus abnormality occurs. Therefore, the communication control method of the present invention is characterized by an original process executed by the ECU 10 when a bus abnormality occurs.

Next, communication control processing executed by the ECU 10 will be described with reference to the flowcharts of FIGS. FIG. 3 is a main flowchart of the entire communication control process, and FIGS. 4 to 8 are sub-flowcharts describing the steps in FIG. 3 in detail.
Among them, two embodiments of “CAN initialization processing” are shown in FIGS. 4 and 5, and “CAN module reception processing and transmission processing” are shown in FIGS. 7 and 8, respectively. Details of the “CAN module initialization process” step in the “CAN initialization process” of FIGS. 4 and 5 are further shown in FIG.

  In the following description of the flowchart, the symbol S indicates “step”. The symbol A at the end indicates a step related to the CAN module A15, and the symbol B at the end indicates a step related to the CAN module B16. In FIG. 4 and FIG. 5, the same step numbers are assigned to substantially the same steps.

The main routine of the communication control process shown in FIG. 3 is executed at regular intervals, and periodically performs CAN transmission / reception processing.
Here, a situation where an abnormality has occurred in the bus 18 is assumed. When a bus abnormality occurs, the CAN module B16 in the reception-only mode cannot detect a bus abnormality, so the CAN module A15 in the normal mode detects a bus abnormality in S01. If a bus abnormality is detected (S01: YES), the process proceeds to the CAN initialization process of S10, and both the CAN module A15 and the CAN module B16 are initialized.

When the initialization process of all the CAN modules 15 and 16 is normally completed, or when no bus abnormality is detected in S01 (NO), the CAN communication is started. In CAN communication, the reception process (S30A) of the CAN module A15 and the reception process (S30B) of the CAN module B16 are performed in random order, and finally the transmission process (S40A) of the CAN module A15 is performed.
As will be described later, when there is no reception message or transmission message in each of the CAN modules 15 and 16, substantial processing may not be performed in the reception processing S30A, S30B or transmission processing S40A.

Next, two embodiments of the sub-flow of the CAN initialization processing step (S10) are shown in FIGS.
In the CAN initialization process of the first embodiment shown in FIG. 4, first, the initialization process of the main CAN module A15 is prioritized (S20A), and then it is determined whether or not the CAN module A15 is normal. (S11). When the CAN module A15 is abnormal (S11: NO), both the CAN module A15 and the CAN module B16 are stopped without performing the initialization process of the CAN module B16 (S14).

  If the CAN module A15 is normal (S11: YES), the CAN module B16 is initialized (S20B), and then it is determined whether the CAN module B16 is normal (S12). When the CAN module B16 is abnormal (S12: NO), both the CAN module A15 and the CAN module B16 are stopped (S14). When the CAN module B16 is normal (S12: YES), the initialization process is set to “normal completion”.

  In the CAN initialization process of the second embodiment shown in FIG. 5, the initialization process S20A of the CAN module A15 and the initialization process S20B of the CAN module B16 are performed without assigning priorities, and then the CAN module A15 and the CAN module are processed. It is determined whether both B16 are normal (S13). If any of the CAN modules 15 and 16 is abnormal, both the CAN module A15 and the CAN module B16 are stopped (S14), and the initialization process is “normally completed” only when all the CAN modules 15 and 16 are normal. And

FIG. 6 shows a subflow of the initialization processing steps (S20A, S20B) of the CAN modules 15 and 16 in the CAN initialization processing of the first and second embodiments.
In the initialization process of the CAN module, the mode shifts to a configuration mode in which various settings of the CAN modules 15 and 16 can be changed (S21), and it is checked that the registers of the CAN modules 15 and 16 are not fixed (S22). ). Subsequently, after setting the transmission / reception of each mailbox (MailBox) (S23) and setting the communication baud rate (S24), the system shifts to a normal mode in which communication control is possible (S25).

Finally, FIG. 7 and FIG. 8 show subflows of the reception processing steps (S30A, S30B) of the CAN modules 15 and 16, and the transmission processing step (S40A) of the CAN module A15.
In the reception process shown in FIG. 7, the presence / absence of a received message in each mailbox (MailBox) is checked in S31. If there is a received message (S31: YES), after acquiring message data from the mailbox (S32), the status of the mailbox is set to no received message (S33). If there is no received message (NO) in S31, the process ends.

  In the transmission process shown in FIG. 8, the presence / absence of a transmission message in each mailbox (MailBox) is checked in S41. If there is a transmission message (S41: YES), after sending the message data of the mailbox (S42), the state of the mailbox is set to no transmission message (S43). If there is no transmission message (NO) in S41, the process ends.

The effect by ECU10 of the said embodiment is demonstrated.
(1) In the above embodiment, the microcomputer 11 has the CAN module A15 in the normal mode and the CAN module B16 in the reception-only mode connected to the same bus, thereby preventing the transmission and reception of ACK in the microcomputer 11. The two CAN modules 15 and 16 can be combined. As a result, the number of messages that can be received by the ECU 10 can be increased.

  For example, the electric power steering apparatus 1 to which the ECU 10 of the above embodiment is applied is characterized in that the amount of information received from the rotation angle sensor 85, the torque sensor 94, the vehicle speed sensor 95, etc. is larger than the amount of information to be transmitted. Furthermore, when an automatic steering assist system and an automatic parking assist system, which are new technologies, are used, image information from a camera that captures the surroundings of the vehicle is received, and the ECU 10 of the electric power steering apparatus 1 The information received is expected to increase more and more. Therefore, the effect that the amount of received information can be increased is exhibited particularly effectively.

  (2) In the above-described embodiment, when a bus abnormality occurs, the CAN module A15 in the normal mode can detect the bus abnormality by detecting the bus abnormality. Further, in the subsequent CAN initialization process, by synchronizing the initialization process of all the CAN modules 15 and 16, a plurality of CAN modules 15 and 16 are controlled as "integrated single CAN module". Can do.

  (3) In the CAN initialization process, when the initialization process of all the CAN modules A15 and CAN module B16 connected to the same bus is normally completed, the CAN communication is started. By detecting the abnormality of all the CAN modules 15 and 16 before the transmission / reception processing, the plurality of CAN modules 15 and 16 can be controlled as “integrated single CAN module”.

  (4) When the first embodiment of FIG. 4 is adopted in the CAN initialization process and the initialization process of the CAN module A15 is prioritized and then the initialization process of the CAN module B16 is performed, By preventing the CAN module B16 in the reception-only mode from operating until the normal-mode CAN module A15 operates normally, inconsistency in the integrated control can be prevented.

(Other embodiments)
As described above, two or more CAN modules B16 may be provided. In that case, the order of execution of the reception processing in FIG. 3 may be any order including the CAN module A15. Further, in S20B of “CAN module B initialization process” in FIGS. 4 and 5, initialization processes of all CAN modules B16 are performed.

The electronic control device that implements the communication control method of the present invention is not limited to an ECU for an electric power steering device, and may be any electronic control device. For example, this is particularly effective for electronic control devices that receive a large amount of information, such as a meter ECU and a brake ECU.
As mentioned above, this invention is not limited to such embodiment, In the range which does not deviate from the meaning of invention, it can implement with a various form.

10 ... ECU (electronic control unit),
11 ... Microcomputer,
15 ... CAN module A,
16: CAN module B,
17 ... CAN transceiver,
18 ... Bus.

Claims (3)

CAN module A (15) and CAN module B (16) connected to the same bus (18) for CAN communication, the only CAN module A set in the normal mode capable of transmission and reception, and reception only A microcomputer (11) having one or more CAN modules B set in a mode;
A CAN transceiver (17) for connecting the CAN module A and the CAN module B to the bus;
A communication control method implemented in an electronic control device (10) comprising:
When an abnormality occurs in the bus, an abnormality in the bus is determined based on information detected by the CAN module A (S01), and then all CAN modules A and CAN modules B are initialized. A communication control method characterized in that the processing (S10) is performed.   2. The CAN communication is started when the initialization processing of all the CAN modules A and CAN modules B connected to the same bus is normally completed in the CAN initialization processing. Communication control method.   3. The CAN initialization process (S20B) is performed after the CAN module A initialization process (S20A) is prioritized and then the CAN module B initialization process (S20B) is performed. Communication control method.

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