JP6185371B2 - Sub-microcomputer program rewriting method - Google Patents

Description

  The present invention relates to a program rewriting method for a sub-microcomputer.

  Japanese Patent Laying-Open No. 2009-205569 (Patent Document 1) discloses a technique for transferring a control program to a sub-microcomputer when the main microcomputer detects rewriting of the control program of the sub-microcomputer.

JP 2009-205569 A

  However, when the main microcomputer and the sub microcomputer transmit and receive control signals using a predetermined protocol for a predetermined serial communication, if the rewrite data of the sub microcomputer program is transmitted using the same predetermined protocol, the influence of the communication parameters of the predetermined protocol In response, the sub-microcomputer program may not be rewritten.

  Therefore, an object of the present invention is to rewrite the program of the sub microcomputer without being affected by the communication parameters of the predetermined protocol when the main microcomputer and the sub microcomputer transmit and receive control signals by the predetermined protocol of serial communication. A sub-microcomputer program rewriting method is provided.

  In order to solve the above problems, the present invention is a method of rewriting a program of a sub microcomputer in a system in which a main microcomputer and a sub microcomputer are connected by a serial communication line, and the main microcomputer and the sub microcomputer can change communication parameters. A step of transmitting / receiving a control signal according to a first possible protocol, a step of transmitting a low level signal to the sub-microcomputer for a predetermined time or more when a sub-microcomputer program rewrite request is generated, and a sub-microcomputer Receiving a low level signal for a certain period of time to identify a program rewrite request, and the main microcomputer transmitting program rewrite data according to a second protocol other than the first protocol; Sub-microcomputer is the second prototype According Le, and a step of receiving data for program rewrite.

  According to the present invention, when the main microcomputer and the sub-microcomputer serially communicate control signals with a predetermined protocol, the sub-microcomputer program can be rewritten without being affected by the communication parameters of the predetermined protocol.

It is a figure for demonstrating the structure of ECU of the hybrid vehicle of this Embodiment. It is a figure showing the example of communication of a control message. It is a figure showing the example of the transfer of the data for reprograms using a control message. It is a figure for demonstrating the transfer method of the data for reprogramming of this Embodiment. It is a flowchart showing the reprogramming request | requirement by the main microcomputer, and the transmission procedure of the data for reprogramming. It is a flowchart showing the reception procedure of the reprogram request and the data for reprogram by a submicrocomputer. It is a flowchart showing the procedure of the determination process of the reprogram request in step S203 of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram for explaining a configuration of an ECU (Electric Control Unit) of the hybrid vehicle according to the present embodiment.

  The ECU 1 controls each device in the hybrid vehicle. The ECU 1 includes a main microcomputer 2 and a sub microcomputer 3.

The main microcomputer 2 and the sub microcomputer 3 are connected by a serial communication line 6.
As shown in FIG. 2, the main microcomputer 2 and the sub-microcomputer 3 transmit and receive a control message including a control signal of the hybrid vehicle through a serial communication line 6 by a UART (Universal Asynchronous Receiver Transmitter) protocol which is a kind of serial communication. .

  Data for reprogramming the main microcomputer 2 from the rewriting tool 4 via a CAN (Controller Area Network) bus 7 in order to rewrite the program in the main microcomputer 2 and the program in the sub-microcomputer 3 (hereinafter also referred to as reprogramming). Data for reprogramming of the sub-microcomputer 3 is transferred.

  The main microcomputer 2 rewrites the program in the main microcomputer 2 based on the received reprogramming data for the main microcomputer 2. Further, the main microcomputer 2 transfers data for reprogramming the sub microcomputer 3 to the sub microcomputer 3 through the serial communication line 6.

Next, transfer of reprogramming data to the sub-microcomputer 3 will be described.
FIG. 3 is a diagram illustrating an example of reprogramming data transfer using a control message for controlling a hybrid vehicle.

  As shown in FIG. 3, the control message includes header information, a reprogram request, reprogram data (DATA1, DATA2, DATA3,...), And CHECKSUM for error detection.

  As shown in FIG. 3, when a reprogram request and reprogram data are transmitted using a control message, the following problems occur.

  The main microcomputer 2 transmits a control message including a reprogram request and reprogram data to the sub microcomputer 3, and the sub microcomputer 3 rewrites the program in the sub microcomputer 3 by receiving the control message ( Reprogram). After the reprogram is completed, the sub-microcomputer 3 transmits a control message indicating the completion of the reprogram to the main microcomputer 2. After receiving this control message, the main microcomputer 2 rewrites the program in the main microcomputer 2 (reprogram).

  When the power is turned off after the reprogramming of the sub-microcomputer 3 and before the main microcomputer 2 reprograms, the generation of the program of the sub-microcomputer 3 and the program of the main microcomputer 2 are different. When the reprogramming data includes a UART protocol communication parameter change (for example, communication speed A → B), the communication speed is A on the main microcomputer 2 side, but the communication speed on the sub-microcomputer 3 side. Becomes B, and communication between the main microcomputer 2 and the sub-microcomputer 3 becomes impossible. Due to the difference in communication speed between them, not only reprogramming will be impossible, but also control signal communication will not be possible. In order to avoid such a situation, when a reprogram request and reprogram data are transmitted by a control message, it is necessary to disable the change of communication parameters.

  The cause of such a problem is that a reprogram request and data for reprogramming are transmitted using a control message for transmitting a control signal between the sub microcomputer 3 and the main microcomputer 2. In order to solve such a problem, it may be possible to newly add a dedicated communication line for reprogramming, but there is a problem that the cost increases.

  FIG. 4 is a diagram for explaining a reprogram request and a data transfer method for reprogram according to the present embodiment.

  When the main microcomputer 2 exchanges control messages with the sub-microcomputer 3 according to the UART protocol, a reprogram request on the sub-microcomputer 3 side occurs for a certain time (for example, 3 seconds). A low level signal is transmitted. Since the low level signal for a certain period is not affected by the communication parameters of the UART protocol, the sudden interruption of the power supply between the main microcomputer 2 on the transmission side and the sub microcomputer 3 on the reception side as described above. Even if the communication parameters of the UART protocol are different, the reprogram request can be transmitted to the sub-microcomputer 3.

  The sub-microcomputer 3 receiving a signal according to the UART protocol detects the occurrence of an error when receiving a low-level signal for a predetermined time (1 second or less). That is, the possibility of a reprogram request can be detected when a signal is received according to the UART protocol. Here, when the transmitting side transmits a high level signal for a certain period of time, the receiving side that receives the signal in accordance with the UART protocol determines that there is no message from the transmitting side and enters a standby state, so an error is detected. Therefore, a high level signal cannot be used in place of a low level signal. The sub-microcomputer 3 can detect a reprogram request when it receives a low level signal for a certain time (for example, 2 seconds) after detecting the occurrence of an error.

  Thereafter, the main microcomputer 2 transmits data for reprogramming. By including communication parameters of the UART protocol in the reprogram data, the communication parameters for communication of control messages according to the UART protocol can be changed.

  In order not to be affected by the communication parameters of the UART protocol, the reprogram data is transmitted by a predetermined communication parameter (usually not changed) in accordance with a reprogram-dedicated communication protocol.

  FIG. 5 is a flowchart showing a reprogram request and reprogram data transmission procedure by the main microcomputer 2.

  First, the main microcomputer 2 receives a rewrite (reprogram) request for the program of the sub-microcomputer 3 from the rewrite tool 4 (step S101).

  Next, the main microcomputer 2 transmits a low level signal for a predetermined time (for example, 3 seconds) (step S102).

  Next, the main microcomputer 2 transmits reprogramming data with predetermined communication parameters in accordance with a reprogramming dedicated communication protocol (step S103).

  FIG. 6 is a flowchart showing a procedure for receiving a reprogram request and data for reprogram by the sub-microcomputer 3.

First, the sub-microcomputer 3 receives a reception interrupt (step S201).
When the main microcomputer 2 fixes the transmission signal at a low level and the sub-microcomputer 3 determines that there is a reception error (YES in step S202), a reprogram request determination process is performed (step S203).

  FIG. 7 is a flowchart showing the procedure of the reprogram request determination process in step S203 of FIG.

  In step S301, when the level of the received signal is low, the process proceeds to step S302. When the level of the received signal is high, the process proceeds to step S303.

  In step S302, the sub-microcomputer 3 increments the low time measurement counter.

  In step S303, the sub-microcomputer 3 clears the low time measurement counter and ends the process.

  In step S304 after step S303, if the count value of the low time measurement counter exceeds a predetermined value (for example, 2 seconds), the process proceeds to step S305. If the count value is equal to or less than the predetermined value, the process is performed. Returns to step S301.

In step S305, the sub-microcomputer 3 determines that there is a reprogram request.
In step S306, the sub-microcomputer 3 receives data for reprogramming with predetermined communication parameters according to a reprogramming dedicated communication protocol.

  As described above, according to the present embodiment, when the main microcomputer 2 and the sub-microcomputer 3 serially communicate control signals using the UART protocol, the main microcomputer 2 sends a subprogram request by a low-level signal for a certain period of time. The microcomputer 3 is notified, and the main microcomputer 2 transfers reprogram data to the sub-microcomputer 3 in accordance with a dedicated protocol different from the UART protocol. As a result, data for reprogramming is transmitted without being affected by the communication parameters of the UART protocol. Therefore, the power supplied to the ECU is suddenly cut off, so that the main microcomputer 2 and the sub-microcomputer 3 are disconnected. Even if the communication parameters of the UART protocol become inconsistent, the program of the sub-microcomputer 3 can be rewritten.

  When the communication parameters of the UART protocol do not match between the main microcomputer 2 and the sub-microcomputer 3, the main microcomputer 2 changes the communication parameters of the UART protocol to the sub-microcomputer 3 so that they match. Send data. As a result, transmission and reception of control signals between the main microcomputer 2 and the sub-microcomputer 3 using the UART protocol are also restored normally.

  In this embodiment, the communication speed is described as the communication parameter. However, the communication speed is not limited to this, and includes, for example, the number of parity bits and the number of stop bits.

  In the above-described embodiment, the case where UART communication that is clock asynchronous communication is used as a kind of serial communication has been described. However, the present invention is not limited to this. For example, serial communication such as SCI (Communication Interface), I2C (Inter-Integrated Circuit), CAN, LIN (Local Interconnect Network), or clock synchronous serial communication may be used. In the case of clock synchronous serial communication, the main microcomputer 2 may transmit a reprogram request to the sub-microcomputer 3 by setting the clock signal to a high level or a low level for a certain period of time.

The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 ECU, 2 main microcomputer, 3 sub icon, 4 rewriting tool, 5 CAN bus, 6 serial communication line.

Claims (1)

A method of rewriting a program of the sub microcomputer in a system in which a main microcomputer and a sub microcomputer are connected by a serial communication line,
The main microcomputer and the sub-microcomputer send and receive control signals according to a first protocol capable of changing communication parameters;
When a rewrite request for the program of the sub-microcomputer occurs, the main microcomputer transmits a low level signal to the sub-microcomputer for a predetermined time or more;
The sub-microcomputer identifying a rewrite request of the program by receiving a low level signal for a predetermined time; and
The main microcomputer transmits the program rewriting data according to a predetermined communication parameter according to a second protocol dedicated to reprogramming other than the first protocol;
The sub-microcomputer, in accordance with the second protocol, the given communication parameters, e Bei and receiving data for the program rewriting, data for the program rewriting, the communication parameters of the first protocol Including sub-microcomputer program rewriting method.

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