JP2020013177A - Electronic control apparatus - Google Patents

Abstract

To improve degree of freedom of a circuit design in an electronic control apparatus in which a microcomputer having a plurality of functions is mounted on a terminal.SOLUTION: The present invention includes external circuits 201-20N corresponding to a function of a terminal of a microcomputer 1, and switching means 10 that switches the function of the terminal of the microcomputer 1 and the external circuits 201-20N according to an operating mode of a software written into the microcomputer 1.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an electronic control unit for a vehicle.

  As a background art in this technical field, there is Patent Document 1 (Japanese Patent Application Laid-Open No. 2017-091047). Patent Literature 1 discloses that one function and an external circuit corresponding thereto are assigned to one microcomputer (hereinafter, microcomputer) terminal in an ECU (Electrical Control Unit).

JP-A-2017-091047

  A single terminal provided in the microcomputer realizes a plurality of functions, and these functions can be generally assigned by writing the configuration of a register corresponding to the microcomputer terminal by software.

  In Patent Document 1, one function for one assigned microcomputer terminal and an external circuit corresponding thereto are not changed. For this reason, there has been a problem that, at the time of pattern design, this assignment must be determined one by one for all microcomputer terminals.

  Further, in this step, the use of the microcomputer terminal may be limited due to the restriction of the pattern design as described above. In such a case, since the function of the microcomputer terminal cannot be freely determined, it can be said that the degree of design freedom is low.

  As an example of the present invention, a microcomputer, an external circuit corresponding to a function of a terminal of the microcomputer, and switching of switching a function of a terminal of the microcomputer and the external circuit depending on an operation mode of software written in the microcomputer Means.

  According to the present invention, the degree of freedom in circuit design can be improved in an electronic control device equipped with a microcomputer having a plurality of functions.

FIG. 2 is a diagram illustrating a configuration of a general microcomputer. FIG. 4 is a diagram illustrating a function selection of a microcomputer terminal. This is an example in which the function of the microcomputer terminal and the external circuit are switched according to the operation mode of the microcomputer. This is an example in which a function of a microcomputer terminal and an external circuit are switched by an external input signal. This is an example in which a function of a microcomputer terminal and an external circuit are switched by a plurality of external input signals. This is an example in which the function of the microcomputer terminal and the external circuit are switched according to the operation mode of the microcomputer and the external input signal.

  The ECU is controlled by a microcomputer. The microcomputer is provided with microcomputer terminals to which various functions are assigned and external circuits corresponding to the microcomputer terminals, and controls the target device by a control program stored in a code flash which is a nonvolatile memory. In an automobile, for example, fuel injection and ignition of an engine are controlled.

  In recent years, the functions that must be realized by the ECU have increased due to the sophistication and complexity of control of automobiles. On the other hand, since there is a demand for the size of the ECU, it is necessary to increase the circuit density. For this reason, the difficulty in circuit pattern design is increasing, which causes a reduction in the degree of freedom in terminal selection of the microcomputer.

  Factors that make pattern design difficult include, for example, that the ground pattern must be as thick as possible, so that terminals in a certain section of the microcomputer cannot be used, and that sensitive signals and high-frequency lines should be separated as much as possible. Therefore, the microcomputer terminals that can be actually used and the functions thereof are limited.

  Due to the balance with the circuit outside the microcomputer, the function assignment of the microcomputer terminal once determined usually does not change thereafter. However, some of these functions can be used only under certain conditions (for example, a communication function used only at the time of shipping inspection), so use of such a microcomputer terminal is considered.

  In other words, the microcomputer terminal realizes a plurality of functions by switching a register for selecting a function or an external circuit or both of them during execution of software for an arbitrary microcomputer terminal. Switching of the function is performed according to the operation mode of the software or a signal input from the outside.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, an electronic control device that dynamically changes the configuration will be mainly described, but the present invention is not particularly limited to this.

  FIG. 1 shows a part of the configuration of a general ECU. With respect to the microcomputer 1 mounted on the ECU board 0, an external circuit 201 is connected to one microcomputer terminal function 21, and the output is guided to an external terminal 301 connected to a harness. On the other hand, there is also a circuit that is not connected to an external terminal, such as the external circuit 202. For example, a configuration such as an SPI (Synchronous Peripheral Interface) communication function and an ASIC (Application Specific Integrated Circuit) operated by the function is associated with the function. No.

  FIG. 2 shows how the function of the microcomputer terminal is determined. For example, if a certain microcomputer terminal has 16 functions, a microcomputer terminal function selection register consisting of 4 bits is shown. The second microcomputer terminal function 22 is selected by writing a value to 401. Normally, writing to this microcomputer terminal function selection register is performed during the activation process of software.

  Here, in some cases, there may be conflicts in the selection of functions, such as when there is a function that you want to use for the relevant pin, but there is a function that can only be used for the relevant pin. You can't. Specifically, from the viewpoint of comprehensive pattern design including components other than the microcomputer, such as the layout of the ASIC and the external terminals, the functions of the microcomputer terminals may be limited one after another.

  In the present embodiment, in this situation, a plurality of functions are assigned to the microcomputer terminal, and if necessary, an external circuit corresponding to each function is provided, and switching is used to provide a degree of freedom to the pattern design, and the same. It is intended to use the ECU for multiple applications.

(Embodiment 1)
FIG. 3 shows an example in which the functions of the plurality of microcomputer terminals and the external circuits corresponding to the respective functions are switched according to the operation mode of the microcomputer or the software during execution of the software.

  On the ECU board 0, a microcomputer 1 having a plurality of functions at each terminal, external circuits 201 to 203 connected to the respective microcomputer terminals, and switches 101 to 103, 111 to 113 for switching the connection of the external circuits are mounted. An external terminal 301 is provided for connecting parts (battery, various sensors, injectors, actuators, network devices, etc.) external to the ECU via a harness.

  In this example, the switching flag (switching means) 10 is changed according to the operation mode of the microcomputer and the software, thereby switching the switch signal 11 output from the microcomputer terminal. As a result, the functions 21 and 31 of the microcomputer terminal are switched, and at the same time, the switches 101 and 111 of the external circuit are switched to select an external circuit corresponding to the function of each microcomputer terminal. Here, the function of the microcomputer terminal is switched from the CFG function used for setting the microcomputer hardware (power supply method selection, boot mode selection, etc.) to the general purpose input (General Purpose Input, GPI) function, and the external circuit is adjusted accordingly. Switching from the pull-up circuit to the filter circuit. The microcomputer terminal and the external terminal 301 are connected to the filter circuit, and are connected to parts outside the ECU via a harness.

  This operation is the same for the functions 22 and 32 of the microcomputer terminal and the switch 102 of the external circuit, except that the CFG function is switched to the SPI communication function for communicating with the ASIC. Since this is switching between functions completed within the ECU board, there is no switch on the external terminal 301 side, and only switching between the pull-down circuit directly connected to the microcomputer terminal and the ASIC is performed.

  Similarly, the functions of the microcomputer terminals 23 and 33 and the switches 103 and 113 of the external circuit are switched from the pull-up circuit to the driver circuit in accordance with the switching from the CFG function to the PWM (Pulse Width Modulation) output function. I have.

  Although three microcomputer terminals are considered in the range shown here, the same concept is applied to the combination of the microcomputer terminal functions 2N / 3N, the external circuit 20N, and the external circuit changeover switches 10N / 11N, thereby increasing the number. The functions of the microcomputer terminals can be switched and used.

(Embodiment 2)
In the first embodiment, the signal that triggers the switching of the function and the external circuit is a flag corresponding to the operation mode of the microcomputer and the software. However, the signal may be a signal input from outside the ECU.

  FIG. 4 shows an example. Here, when a switch signal SS0 input from the outside is input from an external terminal of the ECU board to the microcomputer terminal, the switching flag 10 changes, and the functions 21 to 2N and 31 to 3N of each microcomputer terminal are switched. At the same time, switches 101 to 10N and 111 to 11N for switching external circuits connected to the microcomputer terminals are also switched by the external switch signal SS0.

  This embodiment is characterized in that, unlike the first embodiment, the microcomputer terminal function and the external circuit can be switched at an arbitrary timing.

(Embodiment 3)
In the first and second embodiments, a plurality of functions and circuits are switched by one trigger, but a plurality of triggers may be provided. FIG. 5 illustrates this. In FIG. 5, signals serving as triggers for switching the microcomputer terminal function are switch signals SS0 and SS1. As the operation of the switch signals SS0 and SS1, patterns such as switching ON / OFF independently of each other, switching sequentially, or simultaneously can be considered. The switching flags 10 and 11 are switched in accordance with ON / OFF of these switch signals, and the function of the microcomputer terminal corresponding to each switching flag is switched.

  At this time, when the external circuit can be shared (driver circuit in this case), such as when switching from the general purpose output (GPO) to the PWM output function like switching of the microcomputer terminal functions 24 and 34, a switch is not necessary. Becomes

  Although two switch signals are provided in the illustrated range, three or more switch signals may be provided to switch more microcomputer terminal functions and external circuits.

(Embodiment 4)
In the embodiments described above, either one of the flag corresponding to the operation mode of the microcomputer and the software and the switch signal input from the outside is used as the flag for switching the microcomputer terminal function, but it is also possible to use both. Can be

  FIG. 6 shows an example. In this example, switching of the microcomputer terminal functions 21 31 and 22 32 is performed using a flag corresponding to the operation mode of the microcomputer and software as a trigger, and switching of the terminal functions 23 33 and 24 34 is externally input. The switch signal SS1 is used as a trigger.

  When switching the external circuit, as in the past, when the flag corresponding to the operation mode of the microcomputer and software is used as a trigger, the switch signal SS0 is output from the microcomputer terminal, and the switch signal input from the outside is used as the trigger. This is performed using a switch signal SS1 input from the outside.

  In this example, the function that you want to switch at a fixed cycle or timing is triggered by a flag corresponding to the operation mode of the microcomputer and software, and if you want to switch the function immediately according to a certain event, an externally input switch Function selection can be flexibly performed according to the purpose, such as switching using a signal as a trigger.

  In the illustrated range, two sets of switching functions are provided for each of the two switch signals SS0 and SS1, but any number of sets may be allocated to each switch signal as in the previous embodiments. Also, three or more switch signals may be provided.

  According to each of the above embodiments, the microcomputer terminal realizes a plurality of functions by switching a register for selecting a function or an external circuit or both of them during execution of software for an arbitrary microcomputer terminal. Switching of the function is performed according to the operation mode of the software or a signal input from the outside.

0 ECU board, 1 microcomputer (microcomputer), 10-11 switch change flag (switching means), SS1 and SS2 switch signal output, 21 to 2N function of microcomputer terminal, 31 to 3N function of microcomputer terminal, 101 to 10N Switch, 111-11N switch, 201-20N External circuit corresponding to the function of microcomputer terminal, 301 External terminal connected to harness, 401 Register for selecting function of microcomputer terminal

Claims (4)

A microcomputer,
An external circuit corresponding to the function of the terminal of the microcomputer;
Switching means for switching a function of a terminal of the microcomputer and the external circuit according to an operation mode of software written in the microcomputer;
An electronic control device comprising:   2. The electronic control device according to claim 1, wherein the function of the terminal of the microcomputer and the switching of the external circuit are performed by an external signal input to the microcomputer.   3. The electronic control device according to claim 1, wherein the functions of the terminals of the plurality of microcomputers and the switching of the external circuit are performed simultaneously or sequentially.   2. The electronic control device according to claim 1, wherein the function of the terminal of the microcomputer and the switching of the external circuit are performed by an operation mode of software written in the microcomputer and an external signal input to the microcomputer. An electronic control unit characterized by the above-mentioned.

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