JP5299261B2 - Electronic control unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of quickly returning to receiving processing even if a receiving controller detects a receiving error by preventing the transmission/reception of an ACK slot from being performed between controllers in an own device. <P>SOLUTION: A received signal supplied from a receiver 62 of a transceiver 60 and a control signal outputted from a transmitting terminal Tx of a CAN controller 34 are inputted to a receiving terminal Rx of the CAN controller 34 at the sub-control microcomputer 30 side by being synthesized by an AND gate 70 so that a low level of the respective signals becomes a preferential level. On the other hand, the received signal supplied from the receiver 62 of the transceiver 60 is directly inputted to the receiving terminal Rx of the CAN controller 24 at the main control microcomputer 20 side. Thus, when the ACK slot and an error plug (signal of low level) are outputted from the transmitting terminal Tx of the CAN controller 34, these signals are preferentially inputted to the receiving terminal RX of the CAN controller 34. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an electronic control device that performs communication using a CAN protocol.

  Conventionally, automobiles have been equipped with a large number of electronic control devices (so-called ECUs) for controlling in-vehicle devices, and these electronic control devices share control data and perform integrated control of vehicles. Further, they are connected to each other via a communication bus so as to be able to perform data communication. For the data communication, a CAN ("Controller Area Network" proposed by Robert Bosch, Germany) protocol is typically used.

  In addition, the number of electronic control devices mounted on the vehicle is increasing for higher functionality and safety improvement of in-vehicle devices, and the number of electronic control devices connected to the communication bus is also increasing. When the number of electronic control devices connected to the communication bus increases, the communication wiring route becomes longer, so that the route design for ensuring the communication quality becomes complicated, and it becomes difficult to ensure the communication quality.

  For this reason, in recent years, in order to reduce the number of electronic control devices mounted on a vehicle, it has been considered to consolidate functions that have been realized by a plurality of electronic control devices in one electronic control device.

  By the way, when various functions are integrated into one electronic control device, if a microcomputer that can realize all of the functions is newly designed, the cost of design (specifically, software development) is simply increased. In addition, since the processing load of the microcomputer is greatly increased, it is necessary to configure the microcomputer so that it can process at a higher speed than the conventional one. Furthermore, since the power consumption of the microcomputer increases as the processing load increases, new measures such as heat dissipation measures are also required.

  For this reason, when integrating functions that have been realized by multiple electronic control units in the past into a single electronic control unit, a multi-function microcomputer is not newly designed, but is incorporated into each conventional electronic control unit. It is preferable to incorporate a plurality of microcomputers into one electronic control device.

  On the other hand, when a plurality of existing microcomputers are incorporated into one electronic control device in this way, each microcomputer has a communication function, so that this electronic control device can be connected to a communication bus through a single communication line. There is a need to.

  For this purpose, a signal conversion circuit (transceiver) that transmits and receives control data (control signals) to and from other electronic control devices (external devices) via a communication bus can be shared among a plurality of microcomputers. For this purpose, the transmission signal taken from the communication bus by the transceiver may be distributed to each microcomputer (for example, see Patent Document 1).

JP 2007-245891 A

  However, in the electronic control device described in Patent Document 1, each of a plurality of microcomputers (specifically, controllers) is wired so that control data can be transmitted and received via a communication bus. When another microcomputer B can normally receive the transmitted data via the communication bus, the confirmation response is transmitted from the microcomputer B to the microcomputer A via the communication bus (see FIG. 7). .

  Specifically, the CAN protocol stipulates that the receiving node transmits the dominant level (dominant) of the communication bus to the transmitting node at the timing of an ACK (Acknowledgement) slot as the above-described acknowledgment. In addition, since this ACK slot is limited to the use of 1 bit length, it cannot be used to determine whether or not all receiving nodes on the communication bus have received normally, and reception that has been successfully received is only possible. It can only be used to determine whether a node exists.

  For this reason, if transmission / reception of an ACK slot is performed within the same electronic control unit as described above, the transmission node will miss the opportunity to receive an acknowledgment from an external device on the communication bus, and There is a problem that it cannot be used as a material for determining whether or not there is an external device that can normally receive transmission data.

  Therefore, the microcomputer A is used as the only main control microcomputer that transmits control data to the external device via the communication bus, and the microcomputer B is used as the receiving microcomputer. It may be possible to prohibit transmission / reception of an ACK slot in the same electronic control device by opening the trusted terminal (see FIG. 8).

  However, in the electronic control device configured as described above (hereinafter referred to as ACK-compatible ECU), when the transmission terminal of the controller on the reception microcomputer side is opened, this controller detects a reception error. There is a problem that error processing for transmitting an error flag composed of a dominant of 6 bits is repeated.

  In other words, the controller on the receiving microcomputer side does not reflect the error flag due to its own error processing on the communication bus, so the control data detected from the communication bus via the receiving terminal has a recessive (inferior level on the communication bus). If it is included, the control data and the error flag cannot be matched, thereby detecting a transmission error and starting error processing again (see FIG. 9).

  As a result, in the conventional ACK-compatible ECU, the controller on the receiving microcomputer side cannot return to the receiving process of transferring the control signal on the communication bus to the CPU in the microcomputer by repeating the error process, and from the external device There is a problem that the period during which the control data cannot be received may increase.

  In order to solve the above problems, the present invention prevents the transmission / reception of ACK slots from being performed between the controllers in its own device, and quickly returns to the reception process even if the reception controller detects a reception error. It aims at providing the technology which can be done.

  The electronic control device according to claim 1, which is the first invention made to achieve the above object, includes a plurality of microcomputers having a controller provided with a transmission terminal and a reception terminal for performing communication according to the CAN protocol. A main control microcomputer that transmits control data to another electronic control device via an external communication bus, and one or more of the microcomputers other than the main control microcomputer. This microcomputer is configured to be used as a receiving microcomputer.

  In addition, the electronic control device of the present invention provides a driver for transmitting a control signal output from the transmission terminal of the controller of the main control microcomputer to the communication bus, and a transmission signal flowing through the communication bus to each controller included in the plurality of microcomputers. A transceiver having a receiving receiver.

  Here, in the electronic control device of the present invention, the signal synthesis means sets the transmission signal supplied from the receiver and the transmission signal output from the transmission terminal of the controller on the receiving microcomputer side to the dominant level of the communication bus. The corresponding signal levels are combined so as to become the priority level, and the combined signal (synthesized signal) is supplied to the receiving terminal of the controller of the receiving microcomputer.

  In the electronic control device configured as described above, after the transmission signal output from the transmission terminal of the controller of the receiving microcomputer is synthesized through the signal synthesizing means, the signal is sent to the receiving terminal of the controller of the receiving microcomputer. Therefore, even if the controller of the receiving microcomputer outputs an ACK slot as a transmission signal, it is input to the controller itself, and the ACK slot is not input to other microcomputers in the electronic control unit.

  In addition, since each controller which a some microcomputer has has the existing structure which communicates according to CAN protocol, except for the period which transmits control data to another electronic control unit (external device), non-dominance of a communication bus A signal level corresponding to the level (inferior level) is output as a transmission signal from the transmission terminal of the own controller.

  As a result, when the transmission signal supplied from the receiver indicates an inferior level (recessive), the receiving microcomputer controller receives a signal corresponding to the non-priority level as a composite signal and sets the dominant level (dominant). In the case shown, since the dominant corresponding to the priority level is received as the synthesized signal, the control data can be correctly received from the external device via the communication bus.

  In addition, the controller of the reception microcomputer, for example, when detecting a reception error due to temporary noise, also outputs an error flag consisting of a 6-bit dominant from the transmission terminal of its own controller, Since a 6-bit dominant corresponding to the priority level is input as the composite signal, it is not necessary to detect a transmission error when transmitting the error flag, and the error processing can be reliably terminated.

  Therefore, according to the electronic control device of the present invention, one of the plurality of microcomputers is a main control microcomputer that transmits control data to an external device via a communication bus, and the other microcomputer is a reception microcomputer. Assuming the configuration to be used, transmission / reception of the ACK slot is prevented from being performed between the controllers in its own apparatus, and even if the controller of the reception microcomputer detects a reception error, it can return to the reception process immediately.

  In the electronic control device of the present invention, the signal synthesizing means may be mounted in the receiving microcomputer as described in claim 2, or in the transceiver as described in claim 3. May be implemented. Specifically, the circuit corresponding to the signal synthesis means may be configured as one integrated circuit together with the controller, or may be configured as one integrated circuit together with the driver and the receiver.

In these cases, it is possible to reduce the size and cost of the electronic control device by reducing the wiring and terminals between the microcomputer and the transceiver.
By the way, although the electronic control device of the first invention is configured to include a plurality of microcomputers, the same object as that of the first invention is achieved even when the electronic control device is configured by one microcomputer having a plurality of controllers. be able to.

  In other words, the electronic control device of the second invention includes a microcomputer having a plurality of controllers provided with a transmission terminal and a reception terminal for performing communication according to the CAN protocol. ) Is used as a main controller that transmits control data to another electronic control device via an external communication bus, and one or more controllers other than the main controller are used as receiving controllers.

  According to a second aspect of the present invention, there is provided an electronic control device comprising: a driver that transmits a control signal output from a transmission terminal of the main controller to a communication bus; and a receiver that supplies a transmission signal flowing through the communication bus to a plurality of controllers. It has one transceiver.

  Here, in the electronic control device according to the second aspect of the invention, the signal synthesizing unit corresponds the transmission signal supplied from the receiver and the transmission signal output from the transmission terminal of the reception controller to the dominant level of the communication bus. The signals are combined so that the signal level becomes the priority level, and the combined signal (synthesized signal) is supplied to the receiving terminal of the receiving controller.

  Therefore, according to the electronic control device of the second invention, one of the plurality of controllers is a main controller that transmits control data to an external device via a communication bus, and the other microcomputer is a reception controller. Assuming the configuration to be used, transmission / reception of the ACK slot is prevented from being performed between the controllers in the own apparatus, and even when the reception controller detects a reception error, it can return to the reception process immediately.

It is a block diagram showing the whole structure of the electronic controller to which this invention was applied. It is explanatory drawing for demonstrating operation | movement of the CAN controller by the side of a sub control microcomputer. It is the 1st schematic diagram showing the modification of the electronic control unit to which the present invention was applied. It is a 2nd schematic diagram which shows the modification of the electronic controller to which this invention was applied. It is the 3rd schematic diagram which shows the modification of the electronic controller to which this invention was applied. It is the 4th schematic diagram showing the modification of the electronic control unit to which the present invention was applied. It is the 1st schematic showing the whole electronic control unit composition. It is the 2nd schematic diagram showing the whole electronic control unit composition. It is explanatory drawing for demonstrating operation | movement of the CAN controller by the side of the conventional microcomputer for reception.

Embodiments of the present invention will be described below with reference to the drawings.
<Overall configuration>
FIG. 1 is a block diagram showing an overall configuration of an electronic control device (hereinafter simply referred to as an ECU) to which the present invention is applied.

  As shown in FIG. 1, the ECU 1 is mounted on an automobile and used to control a predetermined control target device such as an engine, and is a communication bus together with ECUs 2, 3,... That control other on-vehicle devices. 10 is configured to exchange data necessary for the control target device by performing data communication with the other ECUs 2, 3,... Via the communication bus 10 by the CAN protocol. The communication bus 10 is constituted by a two-wire communication line including a CAN-H line and a CAN-L line used in the CAN protocol.

  Further, the ECU 1 of the present embodiment includes a microcomputer (main control microcomputer) 20 as a main control circuit and a sub control circuit that operates in accordance with instructions from the main control microcomputer 20 as control circuits for controlling the control target equipment. A microcomputer (sub-control microcomputer) 30 is provided, and the control microcomputers 20 and 30 are connected to the internal bus 11.

  Note that the ECU 1 has input circuits 21 and 31 for inputting detection signals from various sensors and switches for detecting the operation state of the control target device to the control microcomputers 20 and 30, and the control microcomputers. Output circuits 22 and 32 are provided for outputting the command signals output from 20 and 30 to various electric loads (actuators and the like) provided in each part of the control target device.

  Each of the control microcomputers 20 and 30 determines the control amounts of various electric loads necessary to control the control target device to the target state based on the detection signals from the sensors and switches input via the input circuits 21 and 31. By calculating and outputting a command signal corresponding to the controlled variable to the output circuits 22 and 32, the control target device is controlled.

  Each of the control microcomputers 20 and 30 includes a CPU 23 and 33 for performing various control calculations, and a communication control circuit (CAN controller) 24 for performing data communication with an external device via the communication bus 10 according to the CAN protocol. , 34.

  Although not shown in the drawings, the control microcomputers 20 and 30 receive various detection signals from a control program executed by the CPUs 23 and 33 and a memory storing data necessary for the execution of the programs and input circuits 21 and 31. An input interface (I / O) for capturing, an output interface (I / O) for outputting various command signals to the output circuits 22 and 32, and the like are also provided.

  The main control microcomputer 20 transmits / receives control data to / from other ECUs 2, 3,... Via the CAN controller 24, and transmits / receives control data from the sub-control microcomputer 30 via the internal bus 11. By performing the above, various control data are acquired and used for control amount calculation and the like.

  The sub-control microcomputer 30 receives control data from the other ECUs 2, 3,... (And the main control microcomputer 20) via the CAN controller 34, and communicates with the main control microcomputer 20 via the internal bus 11. Various control data are acquired by transmitting / receiving control data between them, and are used for control amount calculation or the like.

  That is, the main control microcomputer 20 is a transmission / reception microcomputer capable of transmitting / receiving control data to / from an external device via the communication bus 10, and the sub-control microcomputer 30 is connected to the external device (and the main control microcomputer via the communication bus 10). 20) is used as a receiving microcomputer capable of receiving control data.

  Each of the CAN controllers 24 and 34 has a transmission terminal Tx and a reception terminal Rx, and has a known configuration that performs various processes according to the CAN protocol. For example, each of the CAN controllers 24 and 34 transmits a signal based on the control data generated by the CPUs 23 and 33 via the transmission terminal Tx, or transmits a transmission signal flowing through the communication bus 10 as a reception terminal. The receiving process is performed via Rx and supplied to the CPUs 23 and 33.

  Each CAN controller 24, 34, when detecting a reception error such as a bit stuff rule violation or a CRC error based on a signal input via the reception terminal Rx, displays an error flag having a 6-bit length, When error processing is performed via the transmission terminal Tx or when a reception error is not detected (data can be received normally), an ACK slot consisting of 1-bit length is transmitted via the transmission terminal Tx. The confirmation process to output is performed.

  The error flag and the ACK slot are output at a signal level corresponding to the dominant level (dominant) on the communication bus 10. When each of the CAN controllers 24 and 34 detects a signal level corresponding to the inferior level (recessive) on the communication bus 10 from the signal input via the reception terminal Rx at the time of these outputs, the input signal and the output A transmission error due to a mismatch with the signal is detected, and error processing is performed again.

  Further, the ECU 1 includes a protection circuit 40 that is connected to the communication bus 10 and prevents external surges from entering, a choke coil 50 that adjusts the waveform of a signal input from the communication bus 10 via the protection circuit 40, A signal conversion circuit (CAN transceiver) 60 disposed on a communication path between the control microcomputers 20 and 30 and the choke coil 50 and an AND gate 70 (corresponding to the signal synthesis means of the present invention) described later are provided. It has been.

  The transceiver 60 outputs a transmission signal output from the transmission terminal Tx of the CAN controller 24 on the main control microcomputer 20 side to the communication bus 10 via the choke coil 50 and the protection circuit 40, and the communication bus 10 It has a receiver 62 that captures a flowing transmission signal through the choke coil 50 and the protection circuit 40.

  The driver 61 changes the voltage difference between the CAN-H line and the CAN-L line of the communication bus 10 to change the logical value 0 corresponding to the dominant level (dominant) on the communication bus 10 and the communication bus 10. Control data including a logical value 1 corresponding to the upper inferior level (recessive) is transmitted to an external device.

  The receiver 62 detects a voltage difference between the CAN-H line and the CAN-L line of the communication bus 10, thereby communicating with a low level signal (logic value 0) corresponding to a dominant on the communication bus 10. A high level signal (logical value 1) corresponding to recessive on the bus 10 is generated, and the generated signal is received as a reception signal to the reception terminal Rx and the AND gate 70 of the CAN controller on the main control microcomputer 20 side. It is configured to output.

  Here, the AND gate 70 uses the reception signal supplied from the receiver 62 and the transmission signal output from the transmission terminal Tx of the CAN controller 34 on the sub-control microcomputer 30 side, with the low level of each signal as the priority level. And the synthesized signal (synthesized signal) is output to the receiving terminal Rx of the CAN controller 34.

  That is, the AND gate 70 receives the reception terminal Rx of the CAN controller 34 using the high level signal (logic value 1) as a combined signal only when the reception signal and the transmission signal are both high level signals (logic value 1). If either the reception signal or the transmission signal is a low level signal (logic value 0), the low level signal (logic value 0) is output to the reception terminal Rx of the CAN controller 34 as a composite signal. .

<Operation of CAN controller on sub-control microcomputer side>
In the ECU 1 configured as described above, a high level signal (logical value 1) is output from the transmission terminal Tx of the CAN controller 34 except for a period in which an ACK slot and an error flag (low level signal) are output. Is output. In this state, if the reception signal supplied from the receiver 62 is a high level signal (logic value 1), after being synthesized by the AND gate 70, the high level signal (logic value 1) is converted into a CAN controller. 34, if the signal is a low level signal (logical value 0), after being synthesized by the AND gate 70, the low level signal (logical value 0) is received by the receiving terminal Rx of the CAN controller 34. Is input.

  In other words, unless a low level signal (logical value 0) is output from the transmission terminal Tx of the CAN controller 34 to the reception terminal Rx of the CAN controller 34, the signal of the communication bus 10 via the receiver 62 and the AND gate 70. A signal reflecting the level is input. On the other hand, a signal reflecting the signal level of the communication bus 10 is directly input from the receiver 62 to the reception terminal Rx of the CAN controller 24 on the main control microcomputer 20 side without passing through the AND gate 70.

  In addition, the CAN controller 34 on the sub-control microcomputer 30 side checks whether there is a reception error such as a bit stuff rule violation or a CRC error according to the CAN protocol for the reception signal input to the reception terminal Rx of the CAN controller 34. Perform monitoring processing. If a reception error is not detected in the monitoring process, a reception process for supplying control data based on the received signal to the CPUs 23 and 33 is performed, and an ACK slot is output from the transmission terminal Tx of the CAN controller 34.

  That is, when the CAN controller 34 on the sub-control microcomputer 30 side can normally receive control data from the ECU 2, 3,... Or the main control microcomputer 20 via the communication bus 10, a low-level signal as an ACK slot is After being output from the transmission terminal Tx of the CAN controller 34 and synthesized by the AND gate 70, a low level signal is input to the reception terminal Rx of the CAN controller 34.

  On the other hand, as shown in FIG. 2, when the CAN controller 34 on the sub-control microcomputer 30 side detects a reception error in the monitoring process, a 6-bit low level signal is sent as an error flag to the transmission terminal of the CAN controller 34. After being output from Tx and synthesized by the AND gate 70, a 6-bit low level signal is input to the receiving terminal Rx of the CAN controller 34.

  That is, even if the CAN controller 34 on the side of the sub-control microcomputer 30 outputs an error flag (low level signal), the low level signal is given priority to the receiving terminal Rx of the CAN controller 34 via the AND gate 70. Since these signals are input, these input signals and output signals match. For this reason, when the output of the error frame obtained by adding an 8-bit high level signal as an error delimiter to the error flag is completed, the monitoring process can be resumed to return to the reception process.

<Effect of this embodiment>
As described above, the ECU 1 of the present embodiment is provided with two microcomputers, the main control microcomputer 20 and the sub-control microcomputer 30, and further external devices (ECUs 2, 3, ECUs) connected to the communication bus 10. ..)), A transceiver 60 is provided so that the main control microcomputer 20 can transmit and receive data and the sub-control microcomputer 30 can receive data.

  A reception signal supplied from the receiver 62 of the transceiver 60 and a transmission terminal Tx of the CAN controller 34 on the sub-control microcomputer 30 side are output to the reception terminal Rx of the CAN controller 34 on the sub-control microcomputer 30 side. The control signal is combined and input by the AND gate 70 so that the low level of each signal becomes the priority level. On the other hand, the reception signal supplied from the receiver 62 of the transceiver 60 is directly input to the reception terminal Rx of the CAN controller 24 on the main control microcomputer 20 side.

  Therefore, in the ECU 1 of this embodiment, even if the CAN controller 34 on the sub control microcomputer 30 side outputs the ACK slot, this output signal is input to the CAN controller 34 itself and input to the main control microcomputer 20. There is no. Even if the CAN controller 34 outputs an error flag (low level signal), the output signal and the input signal (composite signal) to the CAN controller 34 match, so a transmission error is output when the error flag is output. It is possible to reliably end error processing without detection.

  Therefore, according to the ECU 1 of the present embodiment, on the premise of a configuration using two microcomputers, that is, the main control microcomputer 20 that transmits / receives data to / from an external device via the communication bus 10 and the reception sub-control microcomputer 30. Thus, transmission / reception of the ACK slot is prevented from being performed between the microcomputers in the own apparatus, and even if the CAN controller 34 on the sub-control microcomputer 30 side detects a reception error, it can return to the reception process immediately.

  Further, in the ECU 1 of the present embodiment, the main control microcomputer 20 and the sub control microcomputer 30 control one control target device in cooperation with each other, and therefore, compared with a case where each control microcomputer 20, 30 controls different control target devices. Thus, the processing load on the CPUs 23 and 33 can be reduced.

  Further, in the ECU 1 of the present embodiment, the existing configuration for performing CAN communication such as the CAN controllers 24 and 34 and the transceiver 60 is used except that the AND gate 70 is added. be able to.

[Other Embodiments]
As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, In the range which does not deviate from the summary of this invention, it is possible to implement in various aspects.

  For example, the ECU 1 of the above embodiment is provided with two microcomputers, ie, the main control microcomputer 20 and the sub control microcomputer 30, but the sub control microcomputer 30 is not limited to one, and a plurality of microcomputers are provided. Also good. For example, as shown in FIG. 3, when the ECU 1 includes two sub-control microcomputers 30, an AND gate 70 may be arranged for each sub-control microcomputer 30 as in the above embodiment.

  In the ECU 1 of the above embodiment, the AND gate 70 is provided separately from the sub-control microcomputer 30 and the transceiver 60. However, the present invention is not limited to this and may be mounted inside the sub-control microcomputer 30. However, it may be mounted inside the transceiver 60 (see FIG. 5). Specifically, the AND gate 70 may be configured as one integrated circuit together with the CAN controller 34 and the CPU 33 of the sub-control microcomputer 30, or may be configured as one integrated circuit together with the driver 61 and the receiver 62 of the transceiver 60. Also good.

In these cases, the wiring and terminals between the sub-control microcomputer 30 and the transceiver 60 can be reduced, and the ECU 1 can be reduced in size and cost.
Moreover, in ECU1 of the said embodiment, although the main control microcomputer 20 and the sub control microcomputer 30 are comprised so that one control object apparatus may be controlled in cooperation, not only this but each control microcomputer 20,30. May be configured to control different control target devices. In this case, the main control microcomputer 20 and the sub control microcomputer 30 do not necessarily have to be connected via the internal bus 11.

  By the way, although ECU1 of the said embodiment is comprised including the some microcomputers 20 and 30, you may be comprised by the one microcomputer 20 which has a some controller. For example, as shown in FIG. 6, a main controller 24 that transmits control data to one of the two CAN controllers in one microcomputer 20 to the other ECUs 2 and 3 via an external communication bus, The other CAN controller is configured to be used as the reception controller 34. Each CAN controller 24, 34 is connected to one CPU 23.

  In this case, the AND gate 70 combines the reception signal supplied from the receiver 62 and the transmission signal output from the transmission terminal Tx of the reception controller 34 so that the low level of each signal becomes the priority level. The synthesized signal (synthesized signal) is output to the receiving terminal Rx of the receiving CAN controller 34.

  According to the ECU 1 configured as described above, a plurality of existing CAN controllers 24 and 34 can be used together in one microcomputer, and thereby the reception capacity of the microcomputer 20 can be increased.

  In addition, although ECU1 of the said embodiment was demonstrated as what is an electronic control apparatus mounted in a motor vehicle, not only this but what kind of thing should just be an electronic control apparatus which performs communication by a CAN protocol. Is also applicable.

  DESCRIPTION OF SYMBOLS 1 ... ECU, 10 ... Communication bus, 20 ... Main control microcomputer, 24 ... CAN controller, 30 ... Sub control microcomputer, 34 ... CAN controller, 60 ... Transceiver, 61 ... Driver, 62 ... Receiver, 70 ... AND gate, Rx ... Reception terminal, Tx: Transmission terminal.

Claims (4)

A plurality of microcomputers having a controller provided with a transmission terminal and a reception terminal for performing communication according to the CAN protocol;
Among the plurality of microcomputers, the only microcomputer that transmits control data to another electronic control device via an external communication bus is a main control microcomputer, and one or more microcomputers other than the main control microcomputer are used as receiving microcomputers.
A driver for outputting a transmission signal output from the transmission terminal of the controller of the main control microcomputer to the communication bus; and a receiver for supplying a transmission signal flowing through the communication bus to each controller included in the plurality of microcomputers. One transceiver,
In an electronic control device comprising:
The transmission signal supplied from the receiver and the transmission signal output from the transmission terminal of the controller of the receiving microcomputer are combined so that a signal level corresponding to the dominant level of the communication bus becomes a priority level. And an electronic control unit comprising signal synthesis means for supplying the synthesized signal to the reception terminal of the controller of the reception microcomputer.   The electronic control device according to claim 1, wherein the signal synthesizing unit is mounted inside the receiving microcomputer.   The electronic control device according to claim 1, wherein the signal synthesizing unit is mounted inside the transceiver. A microcomputer having a plurality of controllers provided with a transmission terminal and a reception terminal for performing communication according to the CAN protocol;
Among the plurality of controllers, the only controller that transmits control data to another electronic control unit via an external communication bus is a main controller, and one or more controllers other than the main control microcomputer are used as receiving controllers.
A transceiver having a driver for outputting a transmission signal output from the transmission terminal of the main controller to the communication bus, and a receiver for supplying a transmission signal flowing through the communication bus to the plurality of controllers;
An electronic control device comprising:
The transmission signal supplied from the receiver and the transmission signal output from the transmission terminal of the reception controller are combined so that a signal level corresponding to the dominant level of the communication bus is a priority level, An electronic control device comprising signal synthesizing means for supplying the synthesized signal to the receiving terminal of the receiving controller.

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