JP2013082352A - Communication equipment for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correspond to the increase of communication data volume by using a previously set message buffer.SOLUTION: There are provided a plurality of message buffers (hereinafter called as MB) in which at least a message and CANID (hereinafter called as ID) showing a class of the message are stored, and a CAN controller 11 which extracts data stored in MBs to constitute a frame and transmits it, and when receiving a frame, stores an extracted message in the MB in which an ID matching an ID extracted from the frame is stored. When timing is approaching to transmit a frame in a data pattern (hereinafter called as DP)1 which is set up beforehand for each ID, data of DP1 and a sum value CSUM1 are stored in the MB in which an ID corresponding to the timing is stored, and when timing is approaching to transmit a frame by DP2, data of the DP2 and a sum value CSUM2 are stored in the MB in which the ID is stored.

Description

  The present invention relates to a vehicle communication apparatus that transmits and receives messages using a message buffer.

  In order to enhance control and enhance services in vehicles, in-vehicle devices such as electronic control units (ECUs) are connected to each other via a communication bus to form a local area network (so-called in-vehicle LAN). (See, for example, Patent Document 1), and a CAN (Controller Area Network) protocol, which is one of the CSMA / CD systems, is a communication protocol that is frequently used for in-vehicle LANs. Are known.

  In this CAN protocol, before a transmission message is framed and transmitted to a communication bus, the transmission message is stored in a message buffer in which an identification ID code (hereinafter referred to as CANID) indicating the type of the transmission message is set, and communication is performed. When a frame is received via the bus, it is defined that the received message extracted from the frame is stored in a message buffer in which the same CANID as the CANID assigned to the received message is stored.

JP 2001-265402 A

  In recent years, with the advancement of control and the like, the amount of communication data exchanged between in-vehicle devices in the in-vehicle LAN has increased. However, the upper limit of the number of message buffers provided in the communication device mounted on the in-vehicle device is determined in advance (for example, 32). For this reason, when the amount of communication data increases, there is a problem that a message buffer must be added.

  The present invention has been made in view of these problems, and an object of the present invention is to provide a technique that can cope with an increase in the amount of communication data using a message buffer provided in advance.

  In order to achieve the above-mentioned object, the invention according to claim 1 is characterized in that a message and a message identification code indicating a message type as a message type are stored at least in a plurality of message buffers, and stored in the message buffer. When the received data is extracted via the communication bus, the message identification code that matches the message identification code extracted from the received frame is stored. And a transmission / reception unit for storing a message extracted from the frame in a message buffer, wherein the first storage unit has a first timing when the first storage unit reaches a first timing preset for each message identification code. For messages with message identification codes corresponding to The data of the determined first data type and the first data type information indicating the first data type are stored in the message buffer in which the message identification code corresponding to the first timing is stored, and the second storage means However, when the second timing preset for each message identification code is different from the first timing, the message of the message identification code corresponding to the first timing is preset to be different from the first data type. Data of the data type and second data type information indicating the second data type are stored in a message buffer in which a message identification code corresponding to the second timing is stored.

  In the vehicle communication device configured as described above, first, at the first timing, the data of the first data type and the first data type information for the message of the message identification code corresponding to the first timing are It is stored in a message buffer in which a message identification code corresponding to one timing is stored. Thereby, a frame including the message identification code stored in the message buffer, the data of the first data type, and the first data type information is transmitted. Furthermore, at a second timing different from the first timing, for a message with a message identification code corresponding to the second timing, data of a second data type different from the first data type and second data type information are It is stored in a message buffer in which a message identification code corresponding to the timing is stored. Thereby, the frame including the message identification code stored in the message buffer, the data of the second data type, and the second data type information is transmitted. That is, two types of frames including the same message identification code and different data types are transmitted at different timings. Each of these two types of frames includes information indicating the data type.

  Therefore, the communication device that has received the frame transmitted immediately after the first timing stores the message (from the frame) in the message buffer in which the message identification code that matches the message identification code extracted from the received frame is stored. That is, the communication device that has received the frame transmitted immediately after the second timing, while storing the data of the first data type and the first data type information), matches the message identification code extracted from the received frame. The message extracted from the frame (that is, the data of the second data type and the second data type information) is stored in the message buffer in which the identification code is stored.

  Therefore, two types of data having different data types can be stored in a time-division manner in the message buffer storing the same message identification code, and stored in the message buffer storing the same message identification code. The data type of the received data can be recognized from the first data type information and the second data type information.

  Thereby, the data amount of each of the data of the first data type and the data of the second data type does not exceed the data amount that can be stored in one message buffer, and the data of the first data type and the second data When the total data amount with the type data exceeds the data amount that can be stored in one message buffer, the message buffer for storing the data of the first data type and the data of the second data type are stored. It is no longer necessary to provide a separate message buffer for this purpose, and it is possible to cope with an increase in the amount of communication data using a message buffer provided in advance.

  Further, it is necessary to receive a vehicle communication device (hereinafter referred to as first and second data required communication device) that requires reception of data of the first data type and data of the second data type, and data of the first data type. And a vehicle communication device that does not require reception of data of the second data type (hereinafter referred to as a second data unnecessary communication device). When a frame including data of a type is transmitted, the first and second data-needed communication devices need a function for determining whether the received frame includes the second data type information. The two-data unnecessary communication apparatus does not need a function for determining whether or not the second data type information is included in the received frame. Of the plurality of vehicle communication devices constituting the vehicle communication system, the second data type information is provided only to the vehicle communication device (first and second data required communication devices) that require data of the second data type. Can be added to the second data unnecessary communication device without adding any function to the second data type communication device. It is possible to construct a vehicle communication system.

  In the vehicle communication device according to claim 1, as described in claim 2, the first data type information is based on a first checksum calculation formula set in advance for data of the first data type. And the second data type information is based on a second checksum calculation formula that is set in advance differently from the first checksum calculation formula for the data of the second data type. The calculated second checksum value may be used, or the first data type information may be a data length of data of the first data type, and the second data type may be the second data type. The information is the data length of the data of the second data type, and the data length may be different between the data of the first data type and the data of the second data type.

  The checksum value and the data length are conventionally widely used as information included in the frame. In the vehicle communication system configured to transmit and receive a frame including the checksum value or the data length, It is possible to distinguish between data of the first data type and data of the second data type without adding new information. Specifically, in a communication system that transmits and receives data including a checksum for error detection of transmission and reception data, a checksum value may be used as the first and second data type information, and communication that transmits and receives data including a data length. In the system, the data length may be used as the first and second data type information.

It is a block diagram which shows the structure of the vehicle communication system 1 and a message buffer. It is a flowchart which shows the transmission message storage process of 1st Embodiment. It is a figure which shows the data pattern of message buffer MB of 1st Embodiment. It is a flowchart which shows the received message storage process of 1st Embodiment. It is a flowchart which shows the received message storage process of 1st Embodiment which does not require the data pattern 2. FIG. It is a flowchart which shows the transmission message storage process of 2nd Embodiment. It is a figure which shows the data pattern of message buffer MB of 2nd Embodiment. It is a flowchart which shows the received message storage process of 2nd Embodiment.

(First embodiment)
A first embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a vehicle communication system 1 to which the present invention is applied.

  A vehicle communication system 1 is mounted on a vehicle and communicates with each other via a common communication bus BS between a plurality of electronic control units (hereinafter referred to as ECUs) 10a, 10b, 10c,. These ECUs 10a, 10b, 10c,... Are configured so as to function as nodes. In this vehicle communication system 1, CAN (CAN: Controller Area Network) is adopted as a communication protocol. Hereinafter, when any one of ECUs 10a, 10b, 10c,.

  Specifically, the ECUs 10a, 10b, 10c,... Control the engine ECU that controls the engine, the brake ECU that controls the brake control, the steering ECU that controls the steering control, the suspension ECU that controls the suspension control, and the light on / off control. Various electronic control devices such as an ECU can be listed. In FIG. 1, five ECUs 10 are illustrated, but it goes without saying that the number of ECUs 10 constituting the communication system 1 is not limited to this.

  The ECU 10 includes a CAN controller 11 that controls communication with other ECUs according to the CAN protocol, a CAN transceiver 12 that transmits and receives data between the CAN controller 11 and the communication bus BS, and other CAN controllers 11 through the CAN controller 11. By exchanging messages with the ECU, a control unit 13 that executes various processes in cooperation with other ECUs is provided.

The CAN transceiver 12 is configured to reliably transmit and receive a signal that satisfies a predetermined electrical condition of the communication bus.
The CAN controller 11 includes a data storage unit 21 provided with a plurality of message buffers MB (32 in this embodiment) for storing messages transmitted and received between ECUs, and a message based on the stored value of the message buffer MB. Transmission control that is framed and transmitted to the communication bus BS via the CAN transceiver 12, reception control that receives a frame via the CAN transceiver 12 and extracts a message, and the bus right when a frame collides on the bus A protocol core unit 22 that executes communication control according to the CAN protocol, such as arbitration control, and an access control unit 23 that controls access to the data storage unit 21 during transmission control and reception control of the protocol core unit 22 are provided. Yes.

  Each message buffer MB provided in the data storage unit 21 is given a box number (an integer value of 0 to 31 in this embodiment) for identifying the message buffer.

  Each message buffer MB stores a CANID register R1 for storing an identification code (hereinafter referred to as CANID) indicating the type and priority of the message, and a DLC (Data Length Code) indicating the data length of the message. A DLC register R2 and a message register R3 for storing a message transmitted in a frame or a message extracted from a received frame are provided. The message register R3 has eight 1-byte data storage areas, and the message register R3 can store a maximum of eight bytes of data. Each 1-byte data storage area is assigned a data number (an integer value of 1 to 8 in this embodiment) for identifying the storage area. Hereinafter, the data storage area where the assigned data number is n is referred to as the nth data storage area (n is an integer value of 1 to 8), and the assigned data numbers are 1, 2, 3, 4, 5, 6 , 7 and 8 are represented as data1, data2, data3, data4, data5, data6, data7, and data8, respectively.

  The control unit 13 includes a CPU 31, a ROM 32, and a RAM 33, and executes various processes when the CPU 31 executes processes based on programs stored in the ROM 32. For example, when there is a message to be transmitted to another ECU (hereinafter referred to as a transmission message), the CANID corresponding to the message is identified from the message content, and the message in the message buffer MB in which the identified CANID is set A message is stored in the register R3.

  Further, when receiving a notification that the frame has been received from the CAN controller 11, the control unit 13 receives a message from another ECU by reading the contents of the message register R3 of the message buffer MB.

  In the ECU 10 configured as described above, the control unit 13 executes a transmission message storage process for storing the transmission message in the message buffer MB, and a reception message storage process for storing the reception message stored in the message buffer MB in the RAM 33. .

  First, the procedure of the transmission message storage process executed by the control unit 13 will be described with reference to FIGS. FIG. 2 is a flowchart showing the transmission message storage process. FIG. 3 is a diagram showing a data pattern of the message buffer MB. This transmission message storage process is a process repeatedly executed while the ECU 10 is activated.

  When this transmission message storage process is executed, the CPU 31 of the control unit 13 first determines in S10 whether there is a CANID approaching the timing for transmitting a frame. Here, if there is no CANID approaching the timing for transmitting a frame (S10: NO), the transmission message storage process is temporarily terminated. On the other hand, if there is a CANID approaching the timing for transmitting a frame (S10: YES), it is determined in S20 whether or not it is the timing for transmitting data pattern 1.

  In the data pattern 1, the sum value CSUM1 calculated by the following equation (1) is stored in the eighth data storage area of the message buffer MB (see FIG. 3A).

  In the data pattern 2, the sum value CSUM2 calculated by the following equation (2) is stored in the eighth data storage area of the message buffer MB (see FIG. 3B).

The timing for executing frame transmission with data pattern 1 and the timing for executing frame transmission with data pattern 2 are set in advance for each CANID.
If the transmission timing is the data pattern 1 at S20 (S20: YES), the sum value CSUM1 is calculated by the above equation (1) for the data (ie, data 1 to 7) to be transmitted this time at S30. Then, the process proceeds to S50.

  On the other hand, if it is not the timing to transmit with data pattern 1 at S20 (S20: NO), it is determined that it is the timing to transmit with data pattern 2, and the data to be transmitted this time (ie, data1 to data1) is determined at S40. 7) The sum value CSUM2 is calculated by the above equation (2), and the process proceeds to S50.

  In S50, the data (data 1 to 7) to be transmitted this time are stored in the first to seventh data storage areas of the message buffer MB in which the CANID determined in S10 is approaching the frame transmission timing. At the same time, the sum value CSUM1 or sum value CSUM2 calculated in S30 or S40 is stored in the eighth data storage area. Thereafter, in S60, the CAN controller 11 is caused to execute a process of framing and transmitting the message stored in the message buffer MB in the process of S50, and the transmission message storage process is temporarily ended.

  Next, the procedure of the received message storage process executed by the control unit 13 will be described with reference to FIG. FIG. 4 is a flowchart showing received message storage processing. This received message storage process is a process repeatedly executed while the ECU 10 is activated.

  When this received message storage process is executed, the CPU 31 of the control unit 13 first determines in S110 whether or not a message has been stored in the message buffer MB. Here, if no message is stored in the message buffer MB (S110: NO), the received message storage process is temporarily terminated. On the other hand, when the message is stored in the message buffer MB (S110: YES), the message register R3 of the message buffer MB determined in S120 that the message is stored in S120 is expressed by the above equation (1). The sum value CSUM1 is calculated.

  Thereafter, in S130, it is determined whether or not the sum value CSUM1 calculated in S120 matches the data 8 of the message buffer MB determined in S110 that the message is stored. Here, when the sum value CSUM1 coincides with data8 (S130: YES), the process proceeds to S160.

  On the other hand, when the sum value CSUM1 does not coincide with data8 (S130: NO), the above equation (2) is applied to the message register R3 of the message buffer MB determined in S140 that the message is stored in S140. To calculate the sum value CSUM2.

  Thereafter, in S150, it is determined whether or not the sum value CSUM2 calculated in S140 matches the data 8 of the message buffer MB determined in S110 that the message is stored. If the sum value CSUM2 does not match data8 (S150: NO), the received message storage process is temporarily terminated. On the other hand, when the sum value CSUM2 matches data8 (S150: YES), the process proceeds to S160.

  In S160, the message stored in the message register R3 of the message buffer MB determined to have been stored in S110 is copied to the control RAM, and the received message storage process is temporarily terminated.

  The control RAM is a data storage area provided in the RAM 33, and is provided corresponding to each message buffer MB provided in the data storage unit 21. Thereby, CPU31 of the control part 13 can refer to the message copied to control RAM, and can perform a vehicle control process using the information which this message shows.

  The thus configured ECU 10 extracts a plurality of message buffers MB storing at least a message and a CANID indicating a message type, extracts data stored in the message buffer MB, forms a frame, and configures a communication bus BS. When the frame is received via the communication bus BS, the CAN that stores the message extracted from the frame in the message buffer MB in which the CANID that matches the CANID extracted from the received frame is stored. The controller 11 is provided, and when the timing of transmitting a frame with the data pattern 1 preset for each CANID approaches (S10: YES, S20: YES), the data of the data pattern 1 and the sum value CSUM1 are CANID corresponding to the timing When the data is stored in the stored message buffer MB (S30, S50) and the frame transmission timing approaches (S10: YES, S20: NO), the data of the data pattern 2 and the sum value CSUM2 Are stored in the message buffer MB in which the CANID corresponding to this timing is stored (S40, S50).

  Therefore, first, the data pattern 1 data and the sum value CSUM1 are stored in the message buffer MB, so that the CANID stored in the message buffer MB, the data of the data pattern 1, and the frame including the sum value CSUM1 are included. Is sent. Further, by storing the data pattern 2 data and the sum value CSUM2 in the message buffer MB, a frame including the CANID stored in the message buffer MB, the data pattern 2 data, and the sum value CSUM2 is transmitted. The That is, two types of frames including the same CANID and including different data types are transmitted at different timings. Each of the two types of frames includes information indicating the data type (that is, the sum value CSUM1, 2) (hereinafter, the frame including the data of the data pattern 1 and the sum value CSUM1 is referred to as the first frame, A frame including the data of data pattern 2 and the sum value CSUM2 is also referred to as a second frame).

  Therefore, the ECU 10 that has received the first frame stores the message extracted from the frame (that is, the data of the data pattern 1 and the sum value CSUM1) in the message buffer MB that stores the CANID that matches the CANID extracted from the received frame. ) Is received, the ECU 10 that has received the second frame stores the message extracted from the frame (that is, the data of the data pattern 2) in the message buffer MB in which the CANID that matches the CANID extracted from the received frame is stored. Sum value CSUM2) is stored.

  Therefore, two types of data having different data types can be stored in a time division manner in the message buffer MB in which the same CANID is stored, and the data stored in the message buffer MB in which the same CANID is stored. Can be recognized by the sum values CSUM1 and CSUM2.

  As a result, the data amount of each of the data pattern 1 and the data of the data pattern 2 does not exceed the amount of data that can be stored in one message buffer MB, and the data of the data pattern 1 and the data of the data pattern 2 When the total data amount exceeds the data amount that can be stored in one message buffer MB, the message buffer MB for storing data of data pattern 1 and the data for storing data of data pattern 2 There is no need to provide the message buffer MB separately, and it is possible to cope with an increase in the amount of communication data using the message buffer MB provided in advance.

  Furthermore, the ECU 10 that needs to receive the data of the data pattern 1 and the data of the data pattern 2 (hereinafter referred to as the first and second data required ECU 10), the data of the data pattern 1, and the data pattern 2 In a vehicle communication system in which there is a mixture of ECUs 10 that do not require data reception (hereinafter referred to as second data unnecessary ECUs 10), when a certain ECU 10 transmits a frame that includes data of data pattern 2, The data-required ECU 10 needs a function for determining whether or not the received frame includes the sum value CSUM2, while the second data-unnecessary ECU 10 determines whether or not the received frame includes the sum value CSUM2. The function for judging is unnecessary.

  That is, in the received message storage process in the ECU 10 (second data unnecessary ECU 10) that does not require the frame of the data pattern 2, as shown in FIG. 5, the processes of S140 and S150 are omitted, and in S130, the sum value CSUM1 is data8. Is the same as the received message storage process in the ECU 10 that requires the frame of the data pattern 2 except that the received message storage process is once ended (S130: NO). .

  That is, whether or not the sum value CSUM2 is included only in the vehicle communication device (first and second data necessity ECU 10) that requires data of the data pattern 2 among the plurality of ECUs 10 constituting the vehicle communication system 1. The vehicle communication system 1 capable of transmitting / receiving data of the data pattern 2 without adding any function to the second data unnecessary ECU 10 is constructed. It becomes possible.

  The checksum value has been widely used as information included in the frame. In the vehicle communication system 1 configured to transmit / receive a frame including the checksum value, a new frame is added to the checksum value. It is possible to distinguish between data of data pattern 1 and data of data pattern 2 without adding information.

  In the embodiment described above, the ECU 10 is the vehicle communication device according to the present invention, the CAN controller 11 is the transmission / reception means according to the present invention, the processes at S30 and S50 are the first storage means according to the present invention, and the processes at S40 and S50 are according to the present invention. Second storage means.

  CANID is the message identification code in the present invention, the timing determined as YES in S10 and S20 is the first timing in the present invention, the data of data pattern 1 is the data of the first data type in the present invention, and the sum value CSUM1 is the present The first data type information in the invention, the timing determined as YES in S10 and NO in S20 is the second timing in the present invention, the data of the data pattern 2 is the data of the second data type in the present invention, and the sum value CSUM2 is It is the 2nd data classification information in the present invention.

  Also, equation (1) is the first checksum calculation equation in the present invention, sum value CSUM1 is the first checksum value in the present invention, equation (2) is the second checksum calculation equation in the present invention, and sum value CSUM2 is the present one. It is a 2nd checksum value in invention.

(Second Embodiment)
A second embodiment of the present invention will be described below with reference to the drawings. In the second embodiment, only the parts different from the first embodiment will be described.

The vehicle communication system 1 in the second embodiment is the same as that in the first embodiment except that the transmission message storage process and the reception message storage process are changed.
First, the procedure of the transmission message storage process in the second embodiment will be described with reference to FIGS. FIG. 6 is a flowchart showing a transmission message storage process according to the second embodiment. FIG. 7 is a diagram illustrating a data pattern of the message buffer MB in the second embodiment.

  When this transmission message storage process is executed, the CPU 31 of the control unit 13 first determines in S210 whether there is a CANID approaching the timing for transmitting a frame. Here, if there is no CANID approaching the timing for transmitting a frame (S210: NO), the transmission message storage process is temporarily terminated. On the other hand, if there is a CANID that is approaching the timing for transmitting a frame (S210: YES), it is determined in S220 whether or not it is the timing for transmitting data pattern 1.

  In the data pattern 11, 8-byte data is stored in the message register R3 of the message buffer MB (see FIG. 7A). In the data pattern 12, 4 bytes of data are stored in the message register R3 of the message buffer MB (see FIG. 7B).

The timing for executing frame transmission with the data pattern 11 and the timing for executing frame transmission with the data pattern 12 are set in advance for each CANID.
If it is time to transmit the data pattern 11 in S220 (S220: YES), the message buffer MB storing the CANID determined in S210 that the frame is close to the timing to transmit in S230. The data (data 1 to 8) to be transmitted this time is stored in the message register R3, and the data length value DLC1 (8 in the present embodiment) indicating the data length in the data pattern 11 is stored in the DLC register R2, and S250 Migrate to

  On the other hand, if it is not the timing to transmit the data pattern 12 at S220 (S220: NO), it is determined that it is the timing to transmit the data pattern 12, and the timing to transmit the frame is approaching at S240. The data (data 1 to 4) to be transmitted this time are stored in the message register R3 of the message buffer MB in which the CANID determined in S210 is stored, and the data length value DLC2 indicating the data length in the data pattern 12 (this embodiment) In the embodiment, 4) is stored in the DLC register R2, and the process proceeds to S250.

  When the process proceeds to S250, the CAN controller 11 is caused to execute the process of framing and transmitting the message stored in the message buffer MB in the process of S230 or S240, and the transmission message storage process is temporarily terminated.

Next, the procedure of received message storage processing in the second embodiment will be described with reference to FIG. FIG. 8 is a flowchart showing the received message storage process of the second embodiment.
When this received message storage process is executed, the CPU 31 of the control unit 13 first determines in S310 whether or not a message is stored in the message buffer MB. If no message is stored in the message buffer MB (S310: NO), the received message storage process is temporarily terminated. On the other hand, if a message is stored in the message buffer MB (S310: YES), the data length of the message buffer MB determined in S310 that the message is stored in S320 matches the data length value DLC1. Judge whether or not.

  If the data length matches the data length value DLC1 (S320: YES), the process proceeds to S340. On the other hand, if the data length does not match the data length value DLC1 (S320: NO), the data length of the message buffer MB determined in S310 that the message is stored in S330 is the data length value DLC2 It is judged whether or not.

  If the data length matches the data length value DLC2 (S330: YES), the process proceeds to S340. On the other hand, if the data length does not match the data length value DLC2 (S330: NO), the received message storage process is temporarily terminated.

  In S340, the message stored in the message register R3 of the message buffer MB determined to have been stored in S110 is copied to the control RAM, and the received message storage process is temporarily terminated.

  In the ECU 10 configured as described above, when the frame transmission timing set in advance for each CANID approaches the data pattern 11 (S210: YES, S220: YES), the data of the data pattern 11 and the data length value DLC1 Is stored in the message buffer MB in which the CANID corresponding to this timing is stored (S230), and when the timing of transmitting a frame with the data pattern 12 is approached (S210: YES, S220: NO), The data and the data length value DLC2 are stored in the message buffer MB in which the CANID corresponding to this timing is stored (S240).

  Therefore, first, the data of the data pattern 11 and the data length value DLC1 are stored in the message buffer MB, so that the CANID stored in the message buffer MB, the data of the data pattern 11, and the data length value DLC1 are included. Frame is transmitted. Further, by storing the data of the data pattern 12 and the data length value DLC2 in the message buffer MB, a frame including the CANID stored in the message buffer MB, the data of the data pattern 12, and the data length value DLC2 is generated. Sent. That is, two types of frames including the same CANID and including different data types are transmitted at different timings. Each of the two types of frames includes information indicating the data type (that is, data length values DLC1, 2) (hereinafter, the frame including the data of the data pattern 11 and the data length value DLC1 is the third frame). A frame including a frame, data of data pattern 12 and data length value DLC2 is also referred to as a fourth frame).

  Therefore, the ECU 10 that has received the third frame stores the message extracted from the frame (that is, the data of the data pattern 11 and the data length value) in the message buffer MB that stores the CANID that matches the CANID extracted from the received frame. DLC1) is stored, and the ECU 10 that has received the fourth frame stores the message extracted from the frame (that is, the data of the data pattern 12) in the message buffer MB in which the CANID that matches the CANID extracted from the received frame is stored. And the data length value DLC2) are stored.

  Therefore, two types of data having different data types can be stored in a time division manner in the message buffer MB in which the same CANID is stored, and the data stored in the message buffer MB in which the same CANID is stored. Can be recognized by the data length values DLC1 and DLC2.

  As a result, the data amount of the data pattern 11 and the data of the data pattern 12 does not exceed the amount of data that can be stored in one message buffer MB, and the data of the data pattern 11 and the data of the data pattern 12 When the total amount of data exceeds the amount of data that can be stored in one message buffer MB, the message buffer MB for storing the data of the data pattern 11 and the data for storing the data of the data pattern 12 There is no need to provide the message buffer MB separately, and it is possible to cope with an increase in the amount of communication data using the message buffer MB provided in advance.

  The data length has been widely used as information included in the frame in the past. In the vehicle communication system 1 configured to transmit and receive a frame including the data length value, new information is added to the frame. It is possible to distinguish the data of the data pattern 11 from the data of the data pattern 12 without adding.

In the embodiment described above, the process of S230 is the first storage means in the present invention, and the process of S240 is the second storage means in the present invention.
Further, the timing determined as YES in S210 and S220 is the first timing in the present invention, the data of the data pattern 11 is the data of the first data type in the present invention, the data length value DLC1 is the first data type information in the present invention, The timing when YES is determined in S210 and NO is determined in S220 is the second timing in the present invention, the data of the data pattern 12 is the data of the second data type in the present invention, and the data length value DLC2 is the second data type in the present invention. Information.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, As long as it belongs to the technical scope of this invention, a various form can be taken.
For example, in the above embodiment, two types of data patterns are shown, but three or more types may be used.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle communication system, 10 ... ECU, 11 ... CAN controller, 12 ... CAN transceiver, 13 ... Control part, 21 ... Data storage part, 22 ... Protocol core part, 23 ... Access control part, 31 ... CPU, 32 ... ROM, 33 ... RAM, BS ... communication bus, MB ... message buffer, R1 ... CANID register, R2 ... DLC register, R3 ... message register

Claims (3)

A plurality of message buffers storing at least a message and a message identification code indicating a message type which is the type of the message;
The data stored in the message buffer is extracted to form a frame and transmitted on the communication bus. When the frame is received via the communication bus, the message identification code extracted from the received frame A vehicular communication apparatus comprising: transmission / reception means for storing the message extracted from the frame in the message buffer in which the message identification code that matches
When the first timing preset for each message identification code is reached, the data of the first data type preset for the message of the message identification code corresponding to the first timing and the first data type are indicated. First storage means for storing first data type information in the message buffer in which the message identification code corresponding to the first timing is stored;
When the second timing preset for each message identification code differs from the first timing, the message of the message identification code corresponding to the first timing is set differently from the first data type. A second storage for storing the second data type data and the second data type information indicating the second data type in the message buffer in which the message identification code corresponding to the second timing is stored A vehicle communication device. The first data type information is a first checksum value calculated based on a preset first checksum calculation formula for the data of the first data type,
The second data type information is a second checksum value calculated based on a second checksum calculation formula set in advance differently from the first checksum calculation formula for the data of the second data type. The vehicle communication device according to claim 1, wherein: The first data type information is a data length for data of the first data type,
The second data type information is a data length for data of the second data type,
The vehicular communication device according to claim 1, wherein the first data type data and the second data type data have different data lengths.

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