JP6384332B2 - Electronic control unit - Google Patents

Description

  The present invention relates to an electronic control device capable of communicating with an external device via a communication bus.

  Conventionally, there is an electronic control device described in Patent Document 1 as an example of an electronic control device that can communicate with an external device via a communication bus. This electronic control device is connected to an external communication bus with a plurality of microcomputers having a function of performing communication via a communication bus, captures transmission signals flowing through the communication bus, and transmits transmission signals generated by each microcomputer. And a communication transceiver for outputting to the communication bus.

JP 2010-278959 A

  By the way, there is a possibility that the electronic control device may not be able to transmit a transmission signal to the communication bus due to an abnormality occurring in the communication bus. Then, the electronic control device sends an error signal to the communication bus depending on whether its microcomputer transmits a transmission signal to the communication bus and receives a response signal indicating completion of reception from another electronic control device connected to the communication bus. It is conceivable to detect whether or not this occurs.

  However, in the electronic control device, a line when each microcomputer transmits a transmission signal to the communication bus and a line when each microcomputer receives a transmission signal from the communication bus are connected. That is, each microcomputer is connected to be communicable within the electronic control unit. For this reason, even if an abnormality occurs in the communication bus, the electronic control unit sends a response signal from one microcomputer, and another microcomputer returns a response signal, so that transmission is performed normally. It will be judged. Therefore, there is a problem that the electronic control unit cannot detect an abnormality in the communication bus.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an electronic control device that can detect a communication bus abnormality while including a plurality of microcomputers.

In order to achieve the above object, the present invention provides:
One of a plurality of nodes connected to the communication bus, and includes a plurality of microcomputers (10, 20) for receiving transmission signals flowing in the communication bus and transmitting transmission signals to the communication bus. An electronic control device configured to transmit a transmission signal to be transmitted to each microcomputer without going through a communication bus, and each microcomputer receives a transmission signal,
Each of the microcomputers transmits a transmission signal to the communication bus, and whether or not an abnormality has occurred in the communication bus depending on whether or not a response signal indicating completion of reception has been received from another node connected to the communication bus. Is to detect,
Estimating means for estimating that an abnormality has occurred in the communication bus when a non-reception time during which a transmission signal transmitted in a preset transmission cycle cannot be received from at least one of the other nodes exceeds the transmission cycle (S11) When,
When it is estimated by the estimating means that an abnormality has occurred in the communication bus, only the main microcomputer (10), which is one of the plurality of microcomputers, is set in the transmit / receive enabled state, and the other microcomputers (20) excluding the main microcomputer are set in the transmit disabled state. Transmission disable means (S14) to perform,
It is characterized by having.

  Thus, the present invention receives a transmission signal transmitted from at least one of the other nodes at a preset transmission cycle. And this invention presumes that abnormality has arisen in the communication bus, when the non-reception time which cannot receive the transmission signal transmitted with a transmission period exceeds a transmission period. Therefore, the present invention can estimate that an abnormality has occurred in the communication bus when an abnormality that cannot communicate with other nodes actually occurs.

  By the way, this invention is comprised so that the transmission signal transmitted to a communication bus may be transmitted to each microcomputer, without passing through a communication bus, and each microcomputer may receive a transmission signal. However, according to the present invention, when it is estimated that an abnormality has occurred in the communication bus, only the main microcomputer is set in a transmission / reception enabled state, and other microcomputers are set in a transmission disabled state. Therefore, when it is estimated that the other microcomputer has an abnormality in the communication bus, even if the other microcomputer receives the transmission signal transmitted by the main microcomputer, it cannot transmit the transmission signal. Further, when it is estimated that an abnormality has occurred in the communication bus, the main microcomputer can transmit a transmission signal and only receive a transmission signal flowing in the communication bus. Therefore, the main microcomputer transmits a transmission signal to the communication bus and receives a response signal indicating completion of reception from another node connected to the communication bus even when a communication bus abnormality actually occurs. Whether or not an abnormality has occurred in the communication bus can be detected.

  The reference numerals in parentheses described in the claims and in this section indicate the correspondence with the specific means described in the embodiments described later as one aspect, and the technical scope of the invention is as follows. It is not limited.

It is a block diagram showing a schematic structure of an electronic control unit in an embodiment. It is a flowchart which shows the processing operation of the 1st microcomputer in embodiment. It is a flowchart which shows the processing operation of the 2nd microcomputer in embodiment. It is a flowchart which shows the bus-off estimation process of the 1st microcomputer in embodiment. It is a flowchart which shows the bus | bowl off abnormality determination process of the 1st microcomputer in embodiment. It is a flowchart which shows the control processing of the 1st microcomputer in embodiment. It is a block diagram which shows schematic structure of the communication network containing the electronic controller in a modification.

  Hereinafter, a plurality of embodiments for carrying out the invention will be described with reference to the drawings. In each embodiment, portions corresponding to the matters described in the preceding embodiment may be denoted by the same reference numerals and redundant description may be omitted. In each embodiment, when only a part of the configuration is described, the other configurations described above can be applied to other portions of the configuration.

  In this embodiment, an example in which the present invention is applied to the electronic control device 100 is employed. As the electronic control device 100, for example, an in-vehicle control device mounted on a vehicle can be adopted. As shown in FIG. 1, the electronic control device 100 includes a first microcomputer 10, a second microcomputer 20, an AND circuit 30, a communication interface 40, and the like. The electronic control device 100 is connected to the communication bus 200. In the following description, when there is no need to distinguish between the first microcomputer 10 and the second microcomputer 20, they may be simply referred to as the microcomputers 10 and 20, respectively.

  The communication bus 200 is a two-wire communication line including a high potential side line 210 and a low potential side line 220. Note that the high potential and the low potential in the high potential side line 210 and the low potential side line 220 indicate relative potentials between the lines. Communication via the communication bus 200 is a communication method in which communication is established by a differential voltage (potential difference) generated between the high potential side line 210 and the low potential side line 220. The electronic control device 100 is configured to be able to communicate with other devices connected to the communication bus 200 by this communication method. That is, the electronic control device 100 is one of a plurality of nodes connected to the communication bus 200. Each node transmits a transmission signal including identification information (hereinafter referred to as ID) unique to itself.

  An example of such a communication method is CAN communication. CAN is an abbreviation for Controller Area Network. CAN is a registered trademark. Therefore, for example, a CAN bus can be adopted as the communication bus 200. In the present embodiment, CAN communication is employed as an example of communication performed via the communication bus 200.

  The first microcomputer 10 corresponds to the main microcomputer in the claims. On the other hand, the second microcomputer 20 corresponds to another microcomputer in the claims. Each of the microcomputers 10 and 20 is a so-called microcomputer having a CPU, a ROM, a RAM, a register, and the like. Each of the microcomputers 10 and 20 receives a transmission signal flowing through the communication bus 200 and transmits a transmission signal to the communication bus 200. Accordingly, each of the microcomputers 10 and 20 includes a communication controller for performing communication via the communication bus 200. The communication controller corresponds to the communication unit in the claims. For example, each of the microcomputers 10 and 20 executes various controls using information included in the received transmission signal as a control value. Note that information included in a transmission signal can also be referred to as a received value.

  CPU is an abbreviation for Central Processing Unit. ROM is an abbreviation for Read Only Memory. RAM is an abbreviation for Random Access Memory.

  Further, the first microcomputer 10 includes a first input / output port 11, a first transmission port Tx1, and a first reception port Rx1. On the other hand, the second microcomputer 20 includes a second input / output port 21, a second transmission port Tx2, and a second reception port Rx2.

  The first input / output port 11 and the second input / output port 21 are well-known I / O ports and correspond to ports in the claims. The first input / output port 11 and the second input / output port 21 are electrically connected to each other. Therefore, the first microcomputer 10 and the second microcomputer 20 are electrically connected via the first input / output port 11 and the second input / output port 21. For example, the first microcomputer 10 can instruct the second microcomputer 20 via the second input / output port 21 by turning the first input / output port 11 on and off.

  The first transmission port Tx1 and the second transmission port Tx2 are ports for outputting a transmission signal transmitted through the communication bus 200. The first transmission port Tx1 is connected to one input terminal of the AND circuit 30. On the other hand, the second transmission port Tx <b> 2 is connected to the other input terminal of the AND circuit 30. Therefore, the transmission signal of the first microcomputer 10 and the transmission signal of the second microcomputer 20 are synthesized by the AND circuit 30.

  The AND circuit 30 has an output terminal connected to the communication interface 40. The AND circuit 30 outputs a low level when any of the transmission signals from the microcomputers 10 and 20 is at a low level, and outputs a high level when both of the transmission signals from the microcomputers 10 and 20 are at a high level. Output level.

  The first reception port Rx1 and the second reception port Rx2 are ports to which transmission signals flowing through the communication bus 200 are input. The first reception port Rx1 and the second reception port Rx2 are connected to the communication interface 40. Therefore, each microcomputer 10, 20 receives a transmission signal via the communication interface 40.

  The communication interface 40 establishes communication on the communication bus 200 by causing a potential difference between the high potential side line 210 and the low potential side line 220 in accordance with the output level (logic level) of the AND circuit 30. That is, the communication interface 40 sets the communication bus 200 to a dominant or recessive potential according to the output level of the AND circuit 30. Further, the communication interface 40 converts the potential difference between the high potential side line 210 and the low potential side line 220 into a logic level in each of the microcomputers 10 and 20, and outputs the logical level to the first reception port Rx1 and the second reception port Rx2. Note that the communication interface 40 can also be referred to as a CAN-IC.

  A transmission line connecting the communication interface 40 and the AND circuit 30 is connected to the communication bus 200 via the communication interface 40. The reception line connecting the communication interface 40 to the first reception port Rx1 and the second reception port Rx2 is connected to the communication bus 200 via the communication interface 40. Further, the transmission line and the reception line are connected within the communication interface 40.

  For this reason, the electronic control unit 100 is configured such that a transmission signal to be transmitted to the communication bus 200 is transmitted to each of the microcomputers 10 and 20 without passing through the communication bus 200, and each of the microcomputers 10 and 20 receives the transmission signal. Yes. For example, a transmission signal transmitted by the first microcomputer 10 is output to the communication bus 200 and transmitted to the second microcomputer 20 without passing through the communication bus 200. Note that the first microcomputer 10 and the second microcomputer 20 can also communicate via the communication bus 200.

  In the present embodiment, the electronic control device 100 including the two microcomputers 10 and 20 is employed. However, the present invention is not limited to this. The electronic control device 100 may include three or more microcomputers.

  Here, the processing operation of the electronic control apparatus 100 will be described. First, the abnormality detection process in each of the microcomputers 10 and 20 will be described. Each of the microcomputers 10 and 20 transmits a transmission signal to the communication bus 200, and an abnormality occurs in the communication bus 200 depending on whether or not a response signal indicating reception completion is received from another node connected to the communication bus 200. Detect whether or not. In other words, each of the microcomputers 10 and 20 detects the bus off depending on whether or not a response signal is received. For example, each of the microcomputers 10 and 20 determines that an abnormality has occurred in the communication bus when the number of times the response signal cannot be received reaches a predetermined number. More specifically, when the microcomputers 10 and 20 cannot receive the response signal, the value of the transmission error count register is incremented. Then, when each of the microcomputers 10 and 20 detects an abnormality in the transmission unit, the count value of the transmission error counter is incremented. When each of the microcomputers 10 and 20 has a count value> 255, the bus-off flag register is temporarily in a bus-off state. This bus off flag register corresponds to the register in the claims. The bus off state corresponds to an abnormal state in the claims.

  Bus off indicates a state in which communication on the communication bus 200 cannot be participated. That is, when it is determined that an abnormality has occurred in the communication bus 200 as described above, each of the microcomputers 10 and 20 enters a state where it cannot participate in communication on the communication bus 200. Therefore, the bus-off occurs when the high potential side line 210 is fixed at a low potential, the low potential side line 220 is fixed at a high potential, or the high potential side line 210 and the low potential side line 220 are short-circuited. .

  Next, the processing operation of the first microcomputer 10 will be described with reference to FIG. The first microcomputer 10 executes the process shown in the flowchart of FIG. 2 every predetermined time.

  In step S10, it is determined whether or not the bus-off estimation flag is on. The first microcomputer 10 proceeds to step S15 when it is determined that the bus-off estimation flag is on, and proceeds to step S11 when it is determined that the bus-off estimation flag is off. The bus off estimation flag will be described later.

  In step S11, a bus-off estimation process is performed (estimating means). The bus-off estimation process is a process for estimating whether or not the first microcomputer 10 is turned off, in other words, a process for estimating whether or not an abnormality has occurred in the communication bus 200.

  This bus-off estimation process will be described with reference to FIG. The first microcomputer 10 is set so that the transmission signal is transmitted from a predetermined transmission cycle, that is, a predetermined transmission cycle, from at least one of the other nodes. The first microcomputer 10 measures the reception cycle and grasps the preset transmission cycle. Here, the first microcomputer 10 is set so that the transmission signal is transmitted from the first ID node at a preset transmission cycle, and the transmission signal is transmitted from the second ID node at a preset transmission cycle. Has been.

  In step S40, it is determined whether or not the non-reception time of the first ID is twice or more the transmission cycle. The first microcomputer 10 proceeds to step S41 when it is determined that it is twice or more, and proceeds to step S43 when it is determined that it is not twice or more.

  In step S41, it is determined whether or not the non-reception time of the second ID is twice or more the transmission cycle. If the first microcomputer 10 determines that the number is twice or more, the process proceeds to step S42. However, if the first microcomputer 10 determines that it is not twice or more, it proceeds to step S43.

  In step S42, it is determined that the bus-off estimation is abnormal. For example, the first microcomputer 10 stores in the RAM or the like that there is a bus-off estimation abnormality. On the other hand, in step S43, it is determined that the bus-off estimation is normal. For example, the first microcomputer 10 stores in the RAM or the like that the bus-off estimation is normal. Then, after the processing in step S42 or step S43, the first microcomputer 10 ends the processing in FIG. 4 and returns to step S12 in FIG.

  Note that the double here is an example. The first microcomputer 10 may execute only one of step S40 and step S41. That is, the first microcomputer 10 causes an abnormality in the communication bus 200 when the unreceived time during which a transmission signal transmitted from at least one of the other nodes cannot be received in a preset transmission cycle exceeds the transmission cycle. Anything that can be estimated to be present. At this point, it is not determined that an abnormality has occurred in the communication bus 200, but only an estimation. This is because the cause of the non-reception time exceeding the transmission cycle is not the abnormality of the communication bus 200 but the failure of the node side that transmits the transmission signal.

  In step S12, it is determined whether or not there is a bus-off estimation abnormality. If the first microcomputer 10 determines that the bus-off estimation abnormality has occurred, the process proceeds to step S13. If the first microcomputer 10 determines that the bus-off estimation abnormality has not occurred, the first microcomputer 10 ends the processing of FIG. That is, the first microcomputer 10 proceeds to step S13 when it is determined that the bus-off estimation abnormality is detected in the process in step S11. Moreover, the 1st microcomputer 10 will complete | finish the process of FIG. 2, when it determines with bus-off estimation normal by the process in step S11. The first microcomputer 10 sets the bus off estimation flag to ON in step S13.

  In step S14, a bus disconnection request process to the second microcomputer 20 is performed (transmission disabled means). The first microcomputer 10 requests the second microcomputer 20 to be in a transmission disabled state. The transmission disabled state is a state where a transmission signal cannot be output, in other words, a state where output of a transmission signal is prohibited. The transmission disabled state can also be referred to as a state in which only transmission signals can be received or a reset state. Furthermore, it can be said that the first microcomputer 10 requests the second microcomputer 20 so that the output from the second transmission port Tx2 is not possible. That is, the first microcomputer 10 requests the second microcomputer 20 to leave the communication bus 200. As described above, the electronic control unit 100 sets only the first microcomputer 10 in a transmittable / receivable state and sets the second microcomputer 20 in a transmit disabled state. The transmission / reception enabled state is a state in which a transmission signal can be transmitted and a transmission signal can be received. Therefore, the first microcomputer 10 can output from the first transmission port Tx1 and input to the first reception port Rx1 when transmission / reception is possible.

  When the first microcomputer 10 requests the second microcomputer 20 to leave the bus, the first microcomputer 10 can perform the request via the first input / output port 11. That is, the first microcomputer 10 requests the second microcomputer 20 to leave the bus by turning the first input / output port 11 off and on. Therefore, the electronic control device 100 can be mounted with simple logic. In other words, the electronic control unit 100 can request the bus removal from the first microcomputer 10 to the second microcomputer 20 with simple logic.

  In addition, when the electronic control unit 100 includes a microcomputer capable of communicating via the communication bus 200 in addition to the first microcomputer 10 and the second microcomputer 20, the first microcomputer 10 is also disconnected from the microcomputer. Make a request. That is, the electronic control unit 100 sets only the first microcomputer 10 in a transmittable / receiveable state, and sets other microcomputers other than the first microcomputer 10 in a transmission disabled state.

  Further, the present invention can be adopted even in an electronic control device including a dedicated device that performs a bus-off estimation process and a bus leave request process. However, the electronic control device 100 is preferable because the first microcomputer 10 does not have to include a dedicated device because the bus microcomputer performs the bus-off estimation process and the bus disconnection request.

  In step S15, a bus off abnormality determination process is performed. The bus off abnormality determination process will be described with reference to FIG.

  In step S50, it is determined whether a diagnosis condition is satisfied. If the first microcomputer 10 determines that the diagnosis condition is satisfied, the process proceeds to step S51. If the first microcomputer 10 determines that the diagnosis condition is not satisfied, the process of FIG. The diagnosis condition is a condition for detecting the bus off. The first microcomputer 10 determines whether or not the bus-off is being detected depending on whether or not the diagnosis condition is satisfied. As an example of the diagnosis condition, the ignition switch is turned on, the battery voltage is a predetermined value or more, and the like.

  In step S51, it is determined whether or not the bus is off. The first microcomputer 10 determines whether or not the bus off flag register is in the bus off state. If it is determined that the bus is off, the process proceeds to step S52. If it is determined that the bus is not off, the process proceeds to step S54. That is, when the bus off flag register is in the bus off state, the first microcomputer 10 determines that the number of times the response signal cannot be received has reached a predetermined number and determines that an abnormality has occurred in the communication bus 200. Therefore, the first microcomputer 10 can easily detect the bus off abnormality by checking the bus off flag register.

  In step S52, it is determined that the bus is off abnormally. For example, the first microcomputer 10 stores in the RAM or the like that the bus is off abnormally.

  In step S53, the communication controller is reset. The cause of the bus off flag register being in the bus off state may be an abnormality in the communication controller of the first microcomputer 10. Therefore, the first microcomputer 10 may be able to eliminate the abnormality by resetting its own communication controller even if the abnormality of the communication controller occurs. Then, after the processing in step S53, the first microcomputer 10 ends the processing in FIG. 5 and returns to step S16 in FIG. The second microcomputer 20 may reset its own communication controller when the bus off flag register is set to the bus off state.

  In step S54, it is determined whether or not the non-bus off state continues for a predetermined time or more. If the bus off flag register has not been in the bus off state for a predetermined time or longer, the first microcomputer 10 regards the non-bus off state as continuing for the predetermined time or longer and proceeds to step S55. That is, when the first microcomputer 10 estimates that an abnormality has occurred in the communication bus 200 and the bus off flag register does not enter the bus off state for a predetermined time or more, an abnormality has occurred in the communication bus 200. Judge that there is no.

  In addition, when the bus off flag register enters the bus off state without the lapse of the predetermined time, the first microcomputer 10 regards the non-bus off state as not continuing for the predetermined time or more and ends the process of FIG. When the first microcomputer 10 makes a NO determination in step S54 and ends the process of FIG. 5, the process returns to step S16 of FIG.

  In step S55, it is determined that the bus is off normally. For example, the first microcomputer 10 stores in the RAM or the like that the bus is off normally. Then, after the processing in step S55, the first microcomputer 10 ends the processing in FIG. 5 and returns to step S16 in FIG.

  In step S16, it is determined whether or not the bus is abnormal. The first microcomputer 10 proceeds to step S17 if it is determined that there is a bus off abnormality, and proceeds to step S18 if it is determined that there is no bus off abnormality. That is, the first microcomputer 10 proceeds to step S17 when it is determined in step S15 that the bus is off abnormally. The first microcomputer 10 sets the bus off abnormality flag to ON in step S17.

  In step S18, it is determined whether the bus is off normally. If it is determined that the bus off is normal, the first microcomputer 10 proceeds to step S19. If it is determined that the bus off is not normal, the process of FIG. That is, if the first microcomputer 10 determines that the bus is off normally in the process at step S15, the process proceeds to step S19. Further, the first microcomputer 10 ends the process of FIG. 2 when it is not determined that the bus off is abnormal or the bus off is normal in the process at step S15.

  The first microcomputer 10 sets the bus off abnormality flag to OFF in step S19, and sets the bus off estimation flag to OFF in step S20.

  In step S21, a bus return request process to the second microcomputer 20 is performed (return request means). The first microcomputer 10 requests the second microcomputer 20 to be ready for transmission / reception. That is, the first microcomputer 10 requests the second microcomputer 20 that has requested to leave the communication bus 200 in step S14 to return to the communication bus 200. As described above, when the first microcomputer 10 detects that no abnormality has occurred in the communication bus 200 when the second microcomputer 20 is in a transmission disabled state, the first microcomputer 10 is in a state in which transmission and reception with respect to the second microcomputer 20 are possible. To request. Therefore, even when the second microcomputer 20 is in a transmission disabled state, the electronic control device 100 can return the second microcomputer 20 to a state in which transmission and reception are possible when there is no abnormality in the communication bus 200.

  When the first microcomputer 10 requests the second microcomputer 20 to return to the bus, the first microcomputer 10 can perform the request via the first input / output port 11. That is, the first microcomputer 10 requests the second microcomputer 20 to return to the bus by turning on and off the first input / output port 11. Therefore, the electronic control device 100 can be mounted with simple logic. In other words, the electronic control unit 100 can request the bus recovery from the first microcomputer 10 to the second microcomputer 20 with simple logic.

  In addition, when the electronic control unit 100 includes a microcomputer capable of communicating via the communication bus 200 in addition to the first microcomputer 10 and the second microcomputer 20, the first microcomputer 10 returns the bus to the microcomputer. Make a request.

  Next, the processing operation of the second microcomputer 20 will be described with reference to FIG. The second microcomputer 20 executes the process shown in the flowchart of FIG. 3 every predetermined time.

  In step S30, it is determined whether there is a bus leave request. The second microcomputer 20 determines whether there is a bus withdrawal request from the first microcomputer 10 based on the state of the second input / output port 21. That is, the second microcomputer 20 determines whether there is a bus disconnection request from the first microcomputer 10 by turning on and off the second input / output port 21. The second microcomputer 20 proceeds to step S31 when determining that there is a bus leaving request, and proceeds to step S32 when determining that there is no bus leaving request.

  In step S31, a bus leaving process is performed. The 2nd microcomputer 20 sets so that it may become a transmission impossible state by itself. Note that the method of bus departure processing is not particularly limited.

  In step S32, it is determined whether there is a bus return request. The second microcomputer 20 determines whether there is a bus return request from the first microcomputer 10 based on the state of the second input / output port 21. That is, the second microcomputer 20 determines whether there is a bus return request from the first microcomputer 10 by turning on and off the second input / output port 21. If it is determined that there is a bus return request, the second microcomputer 20 proceeds to step S33, and if it is determined that there is no bus return request, the process of FIG.

  In step S33, a bus return process is performed. The second microcomputer 20 is set so that it can transmit and receive itself. Note that the bus recovery processing method is not particularly limited.

  The first microcomputer 10 performs various controls using a transmission signal received via the communication bus 200. For example, the first microcomputer 10 controls in-vehicle devices such as an engine and a motor mounted on the vehicle. That is, the first microcomputer 10 executes the control process shown in FIG. This control process is performed independently of the bus off detection.

  In step S60, it is determined whether or not normal reception is possible. The first microcomputer 10 determines whether or not the transmission signal transmitted via the communication bus 200 has been normally received. The first microcomputer 10 proceeds to step S61 and step S62 when it is determined that the signal has been normally received, and proceeds to step S63 and step S64 when it is determined that the signal has not been normally received.

  In step S61, the first control value is updated with the received value. Similarly, in step S62, the second control value is updated with the received value. When executing various controls using the first control value and the second control value, the first microcomputer 10 updates the received value included in the transmission signal that has received the first control value and the second control value. Then, the first microcomputer 10 executes various controls using the updated first control value and second control value. That is, when the first microcomputer 10 receives a reception value for updating the first control value or the second control value, the first microcomputer 10 updates the first control value or the second control value with the reception value.

  However, when the bus is abnormal, the transmission signal cannot be received normally. In such a case, the first microcomputer 10 executes Step S63 and Step S64. That is, the first microcomputer 10 holds the first control value at the previous value, or updates the second control value with an invalid value.

  As described above, the electronic control apparatus 100 receives a transmission signal transmitted from at least one of the other nodes at a preset transmission cycle. The electronic control device 100 estimates that an abnormality has occurred in the communication bus 200 when the non-reception time during which the transmission signal transmitted in the transmission cycle cannot be received exceeds the transmission cycle. Therefore, the electronic control unit 100 can estimate that an abnormality has occurred in the communication bus 200 when an abnormality that cannot communicate with other nodes actually occurs.

  By the way, the electronic control unit 100 is configured such that a transmission signal to be transmitted to the communication bus 200 is transmitted to each of the microcomputers 10 and 20 without passing through the communication bus 200, and each of the microcomputers 10 and 20 receives the transmission signal. . However, when it is estimated that an abnormality has occurred in the communication bus 200, the electronic control unit 100 sets only the first microcomputer 10 in a transmittable / receiveable state and sets the second microcomputer 20 in a transmission disabled state. Therefore, when it is estimated that an abnormality has occurred in the communication bus 200, the second microcomputer 20 cannot transmit a transmission signal even if it receives the transmission signal transmitted by the first microcomputer 10. Further, when it is estimated that an abnormality has occurred in the communication bus 200, the first microcomputer 10 can transmit a transmission signal and receive only the transmission signal flowing in the communication bus 200. Accordingly, the first microcomputer 10 can transmit a transmission signal to the communication bus 200 even when the abnormality of the communication bus 200 has actually occurred. The first microcomputer 10 can detect whether or not an abnormality has occurred in the communication bus 200 based on whether or not a response signal indicating completion of reception has been received from another node connected to the communication bus 200. As described above, the electronic control device 100 can detect an abnormality in the communication bus 200 while including the plurality of microcomputers 10 and 20.

Further, the first microcomputer 10 cannot receive the response signal when the abnormality of the communication bus 200 has actually occurred, so the count value of the transmission error counter is continuously incremented,
The bus off flag register can be in a bus off state. Therefore, the electronic control apparatus 100 can be in a state where it cannot participate in communication on the communication bus 200.

  Further, the electronic control unit 100 estimates whether or not an abnormality has occurred in the communication bus 200 by monitoring transmission signals that are periodically transmitted. That is, the electronic control unit 100 can estimate whether or not an abnormality has occurred in the communication bus 200 using only the existing transmission signal flowing in the communication bus 200.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  The request from the first microcomputer 10 to the second microcomputer 20 is not limited to turning the first input / output port 11 on and off.

  For example, the electronic control device 100 is configured such that the first microcomputer 10 and the second microcomputer 20 are capable of serial communication. In other words, the first microcomputer 10 performs serial communication with the second microcomputer 20 for the purpose different from the bus disconnection request and the bus return request. In this case, the first microcomputer 10 may make a request to the second microcomputer 20 by serial communication. For example, the first microcomputer 10 causes the second microcomputer 20 to include information indicating a request for bus disconnection or a request for bus recovery in serial communication data having a purpose different from a request for bus disconnection or a request for bus recovery. A request to leave the bus or a request to return to the bus can be made. By doing in this way, the electronic control unit 100 can make a request for bus disconnection or a bus return request from the first microcomputer 10 to the second microcomputer 20 without preparing an extra port. In other words, the electronic control device 100 issues a bus disconnection request or a bus recovery request from the first microcomputer 10 to the second microcomputer 20 without using the first input / output port 11 or the second input / output port 21. be able to. In addition, as serial communication, SPI communication etc. are employable, for example.

  Further, it is assumed that the electronic control device 100 is connected to the second communication bus 300 in addition to the communication bus 200, as shown in FIG. That is, the electronic control device 100 communicates with the external control devices 130 and 140 that are nodes connected to the second communication bus 300 in addition to the external control devices 110 and 120 that are nodes connected to the communication bus 200. It is configured to be possible. The second communication bus 300 is a CAN bus like the communication bus 200 and includes a high potential side line 310 and a low potential side line 320.

  In this case, the first microcomputer 10 may make a request to the second microcomputer 20 by communication via the second communication bus 300. That is, the first microcomputer 10 includes the information indicating the request for leaving the bus or the request for returning from the bus in the transmission signal output to the second communication bus 300, thereby requesting the second microcomputer 20 to request the bus leaving or return from the bus. Can make requests.

  Even in this case, the electronic control unit 100 does not use the first input / output port 11 and the second input / output port 21, and requests the bus from the first microcomputer 10 to the second microcomputer 20 to release the bus or return the bus. Can make requests. In the case of the serial communication, the first microcomputer 10 communicates with the second microcomputer 20 every predetermined time. On the other hand, in the case of communication via the second communication bus 300, the first microcomputer 10 can promptly request for bus disconnection or bus recovery.

  10 first microcomputer, 11 first input / output port, Tx1 first transmission port, Rx1 first reception port, 20 second microcomputer, 21 second input / output port, Tx2 second transmission port, Rx2 second reception port, 30 AND Circuit, 40 Communication interface, 100 Electronic control device, 110-140 External control device, 200 Communication bus, 210 High potential side line, 220 Low potential side line, 300 Second communication bus, 310 High potential side line, 320 Low potential side line

Claims (10)

One of a plurality of nodes connected to a communication bus, comprising a plurality of microcomputers (10, 20) for receiving a transmission signal flowing in the communication bus and transmitting a transmission signal to the communication bus, A transmission signal to be transmitted to a communication bus is transmitted to each microcomputer without going through the communication bus, and each microcomputer is configured to receive a transmission signal,
Each of the plurality of microcomputers transmits a transmission signal to the communication bus, and an abnormality is detected in the communication bus depending on whether a response signal indicating reception completion is received from another node connected to the communication bus. It detects whether or not it has occurred,
Estimating means for estimating that an abnormality has occurred in the communication bus when a non-reception time in which a transmission signal transmitted in a preset transmission cycle cannot be received from at least one of the other nodes exceeds the transmission cycle (S11),
When it is estimated by the estimating means that an abnormality has occurred in the communication bus, only the main microcomputer (10), which is one of the plurality of microcomputers, is set in a transmittable / receivable state, and the other microcomputers (20) excluding the main microcomputer are set. A transmission disabled means (S14) for setting a transmission disabled state;
An electronic control device comprising: The main microcomputer includes the estimation unit and the transmission impossibility unit,
The said transmission impossible means requests | requires that it will be in a transmission impossible state with respect to the said other microcomputer, when it is estimated that the said communication means has abnormality in the said estimation means. Electronic control device.   When the main microcomputer detects that no abnormality has occurred in the communication bus when the other microcomputer is in a transmission disabled state, the main microcomputer requests the other microcomputer to be in a state where transmission / reception is possible. The electronic control device according to claim 2, further comprising S21). The main microcomputer and the other microcomputer have ports that are electrically connected to each other,
The electronic control device according to claim 2, wherein the main microcomputer makes a request to the other microcomputer by turning on and off the port. The main microcomputer and the other microcomputer perform serial communication,
4. The electronic control device according to claim 2, wherein the main microcomputer makes a request to the other microcomputer through the serial communication. In addition to the communication bus, it is also connected to a second communication bus,
The electronic control device according to claim 2, wherein the main microcomputer makes a request to the other microcomputer by communication via the second communication bus.   7. Each of the plurality of microcomputers determines that an abnormality has occurred in the communication bus when the number of times the response signal cannot be received reaches a predetermined number. An electronic control device according to claim 1.   Each of the plurality of microcomputers includes a communication unit that receives a transmission signal and outputs a transmission signal, and resets the communication unit when it determines that an abnormality has occurred in the communication bus. The electronic control device according to claim 7. When the number of times that the response signal could not be received has reached a predetermined number of times, a register that temporarily sets an abnormal state is provided,
Each of the plurality of microcomputers, when an abnormal state is set in the register, determines that the number of times the response signal could not be received has reached a predetermined number and determines that an abnormality has occurred in the communication bus. In the state where it is estimated that an abnormality has occurred in the communication bus, if no abnormality state is set in the register for a predetermined time or more, it is determined that no abnormality has occurred in the communication bus. The electronic control device according to claim 7 or 8.   10. Each of the plurality of microcomputers is in a state where it cannot enter communication on the communication bus when it is determined that an abnormality has occurred in the communication bus. The electronic control device described.

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