JP3973315B2 - Microcomputer for vehicle control - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a microcomputer (hereinafter simply referred to as “microcomputer”) mounted on a vehicle for electronically controlling an automobile engine or the like, and more particularly to a vehicle control microcomputer capable of checking program execution in the mounted state. Is.
[0002]
[Prior art]
With the improvement of functions of vehicles such as automobiles, electronic control using a microcomputer is widely adopted as the control system. Such a microcomputer for vehicle control includes a central processing unit (hereinafter referred to as “CPU”) that performs overall control processing, a read-only memory (hereinafter referred to as “ROM”) in which programs and data necessary for control are stored, A readable / writable memory (hereinafter referred to as “RAM”) for temporarily storing data during control, an input interface circuit for inputting various state signals of the vehicle, and for outputting control signals to various parts of the vehicle Output interface circuit, an analog / digital (hereinafter referred to as “A / D”) conversion circuit for converting an analog state signal into digital data, and the like.
In addition, since the vehicle control microcomputer directly controls the traveling of the vehicle, an extremely reliable operation is required for its safety. Furthermore, since the vehicle control microcomputer is used in the vicinity of a device that generates high-level electromagnetic noise, such as an engine ignition device, for example, it is strictly controlled to prevent malfunction due to such noise. It is electromagnetically shielded and mounted on the vehicle.
Therefore, once the vehicle control microcomputer is mounted on the vehicle, after that, inspection such as opening the housing and checking the internal test terminal is impossible, and operation check in the mounted state is extremely difficult. .
[0003]
Conventionally, the following three methods are generally performed as a method for checking the operation of the microcomputer for controlling a vehicle after being mounted on such a vehicle.
(I) A dedicated input / output terminal for serial communication of test data with the outside is provided in the vehicle control microcomputer. Then, a test device such as a RAM monitor is connected to the input / output terminal, and test data for testing the function of the RAM inside the microcomputer is transmitted from the test device, and a response from the microcomputer is received to operate. Check if is normal or abnormal.
(Ii) A dedicated debug terminal for connecting a debugging device to the vehicle control microcomputer is provided. Then, a debugging device is connected via a multi-core debugging cable, and the operation of the CPU is controlled and monitored by this debugging device to check whether the operation is normal or abnormal.
(Iii) Remove the resin coating layer provided on the vehicle control microcomputer for the purpose of preventing current short-circuit due to water droplets and dust, and monitor the voltage waveform at the input / output terminals with the probe terminal of the oscilloscope. To check.
[0004]
[Problems to be solved by the invention]
However, the conventional vehicle control microcomputer has the following problems.
That is, since it is necessary to provide a dedicated input / output terminal and a debug terminal for the operation test, the circuit scale becomes large, and if these external connection terminals and circuits are abnormal, the operation check cannot be performed.
In addition, it is necessary to incorporate in advance a test function for dealing with the check items of the test apparatus and the debug apparatus, and it has been impossible to check operations other than the predetermined items.
In addition, it is cumbersome to peel off the resin-based coating layer provided on the vehicle control microcomputer for the purpose of preventing current short-circuit due to water droplets and dust, and it is necessary to form the resin-based coating layer again after the check is completed. .
The present invention solves the problems of the prior art, does not require the incorporation of a dedicated external connection terminal for operation check or a specific test function, and performs the peeling of the resin coating layer. In addition, the present invention provides a vehicle control microcomputer that can check the operation after mounting.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a first invention of the present invention shows an input means to which an input signal necessary for electronic control of a vehicle engine is given in a vehicle control microcomputer, and a procedure of the electronic control. Storage means for storing a program and control means for generating a control signal necessary for controlling the vehicle engine based on the program and an input signal given to the input means. Furthermore, the vehicle control microcomputer generates an operation monitoring pulse having a pulse width that does not affect the control of the vehicle engine when the control means performs a predetermined operation according to the program. A pulse generating means for generating the composite control signal by superimposing the operation monitoring pulse generated by the pulse generating means on the control signal generated by the control means, and the composite control signal for engine control. Output means for converting the signal into a predetermined level signal and outputting it.
In a second aspect of the invention, the pulse generation means in the vehicle control microcomputer of the first aspect is configured to generate a different number of operation monitoring pulses corresponding to a plurality of predetermined predetermined operations. Yes.
[0006]
According to the present invention, since the vehicle control microcomputer is configured as described above, the following operation is performed.
The control means sequentially reads out the program stored in the storage means and generates a control signal for engine control based on the input signal given to the input means. Further, when a predetermined operation predetermined by the control means is performed, an operation monitoring pulse having a short pulse width that does not affect the engine control is generated by the pulse generation means. The operation monitoring pulse is superimposed on the control signal for engine control by the pulse superimposing means to generate a combined control signal. The synthesis control signal is converted into a signal of a predetermined level by the output means, and is output as an engine control signal. Therefore, the operation state of the vehicle control microcomputer can be checked by measuring the operation monitoring pulse superimposed on the engine control signal output from the output means.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a configuration diagram of a microcomputer for vehicle control showing an embodiment of the present invention.
This vehicle control microcomputer has input means (for example, input unit 1 and selection unit 2) to which an input signal necessary for electronic control of the vehicle engine is given. The input unit 1 inputs analog signals such as a rotation pulse RP from a rotation speed sensor that detects the rotation speed of a crankshaft of an engine to be controlled and a crank angle pulse CA from a crank angle sensor. The input unit 1 has a function of superimposing an analog signal and removing a noise component entering from the outside, and converting it into a pulse signal having a voltage suitable for the control means (for example, CPU) 3. The output side of the input unit 1 is connected to the input ports I1 and I2 of the CPU 3.
The selection unit 2 includes a negative pressure signal PB from a negative pressure sensor that detects the negative pressure of the intake pipe, an air temperature signal TA from the intake air temperature sensor that detects the temperature of the intake air, and a water temperature sensor that detects the temperature of the cooling water. Analog signals such as the water temperature signal TW are given in parallel, and these analog signals are selected and output one by one in order. An A / D conversion unit 4 that converts an analog signal into digital data is connected to the output side of the selection unit 2, and an output side of the A / D conversion unit 4 is connected to an input port I 3 of the CPU 3.
[0008]
A memory such as storage means (for example, ROM) 6, RAM 7, and electrically erasable and writable nonvolatile memory (hereinafter referred to as “EEPROM”) 8 is connected to the CPU 3 via a system bus 5. Yes. The ROM 6 stores programs and data for overall control processing including a procedure for electronic control of the vehicle engine by the CPU 3. The RAM 7 is for temporarily storing data during control. The EEPROM 8 is a memory for holding various data obtained during the control or the like without erasing them even after the engine is stopped in order to use it for the next control.
The CPU 3 generates various control signals for controlling the vehicle engine on the basis of the program stored in the ROM 6 and the input signals given to the input unit 1 and the selection unit 2. Output ports O1, O2, and O3 for outputting the control signals. A fuel pump control signal FP for operating the fuel pump is output to the output port O1, an ignition timing control signal ING that determines the ignition timing of the ignition device is output to the output port O2, and fuel is supplied to the engine via the output port O3. The injection control signals IJC for controlling the injectors for performing are respectively output. For example, the injection control signal IJC controls the injector via an actuator such as a solenoid, and is a signal having a duration of about 1 ms for the mechanical operation of this actuator.
[0009]
The CPU 3 has an output port O4 for outputting the number of pulse signals PLS corresponding to the type of operation when a predetermined operation is performed in accordance with a program stored in the ROM 6. . In the ROM 6, in addition to a program indicating the procedure for electronic control of the vehicle engine, for example, when the microcomputer starts operating, the function check of the ROM 6, RAM 7 and A / D converter 4 is performed prior to normal engine control. An initial check program is built in to do. When the initial check program determines that the functions of the ROM 6, RAM 7, and A / D converter 4 are normal, it outputs one, two, and three pulse signals PLS from the output port O4, respectively. It is supposed to be. Further, the ROM 6 has a predetermined number of pulse signals PLS in accordance with the contents of the process when the predetermined process is performed even after the initial check is completed and the routine shifts to the normal engine control. Is installed from the output port O4.
[0010]
Pulse generation means (for example, a pulse generation unit) 9 is connected to the output port O4 of the CPU 3. The pulse generator 9 is composed of, for example, a monostable multivibrator or the like, and is shorter than the pulse width (that is, 1 ms) of the injection control signal IJC in synchronism with the rise of the pulse signal PLS, and does not affect the operation of the actuator. The operation monitoring pulse SVP having such a pulse width (for example, 1 μs) is output. The output port O3 of the CPU 3 and the output side of the pulse generator 9 are connected to the input side of pulse superimposing means (for example, an exclusive OR gate, hereinafter referred to as “EXOR”) 10. The EXOR 10 takes the exclusive OR of the injection control signal IJC output from the output port O3 of the CPU 3 and the operation monitoring pulse SVP output from the pulse generator 9, thereby superimposing these signals and performing synthesis control. The signal CON is generated.
The output ports O 1 and O 2 of the CPU 3 and the output side of the EXOR 10 are connected to the input side of the output means (for example, output unit) 11. The output unit 11 converts a logic level signal output from the CPU 3 or EXOR 10 into a voltage or current at a level necessary for driving the fuel pump, the ignition device, the injector, and the like, and outputs the converted voltage or current.
[0011]
Although not shown, this vehicle control microcomputer is designed to prevent noise from entering the input / output signal lines and power supply lines so that external electromagnetic noise does not enter and cause malfunctions or circuit damage. A noise filter for preventing the noise is inserted and housed in a casing with strict electromagnetic shielding. The vehicle control microcomputer is mounted on a vehicle such as an automobile after performing a function test as a single unit and confirmed to be normal. A power line (not shown) is connected to a power source such as a battery and the input unit 1 The selection unit 2 and the output unit 11 are connected to various sensors such as a rotational speed sensor and various actuators such as a solenoid and a relay for driving a fuel pump and the like.
[0012]
FIG. 2 is a sequence diagram showing an example of the operation of the vehicle control microcomputer of FIG. The operation of FIG. 1 will be described below with reference to FIG.
When power is supplied to the vehicle control microcomputer at time t0 in FIG. 2, an initial check program stored in, for example, address 0 of the ROM 6 is read and the ROM check is performed by the CPU 3. At this time, since normal vehicle control is not performed, the output signals of the output ports O1 to O3 of the CPU 3 are all at the level “L”. In the ROM check, for example, data in all the storage areas of the ROM 6 are sequentially read out and added for each corresponding bit, and the addition result corresponding to the bit is compared with a value stored in the ROM 6 in advance. This is to check whether the data has been destroyed.
[0013]
If there is no abnormality in the result of the ROM check, one pulse signal PLS is output from the output port O4 of the CPU 3 at time t1. The pulse signal PLS is supplied to the pulse generator 9, and the pulse generator 9 generates an operation monitoring pulse SVP having a pulse width of 1 μs and applies it to one input side of the EXOR 10. Since the injection control signal IJC of “L” is given from the output port O3 of the CPU 3 to the other input side of the EXOR 10, the synthesis control signal of the level “H” with the pulse width of 1 μs is supplied to the output side of the XOR 10. CON is output. The composite control signal CON is converted into a voltage for driving the injector by the output unit 11 and output as a fuel injection pulse IJP. However, since the fuel injection pulse IJP output at time t1 is a short pulse having a pulse width of 1 μs, an actuator such as a solenoid does not operate even if this short pulse is given.
[0014]
After the ROM check is completed and the CPU 3 outputs the check result pulse signal PLS, the RAM check is started at time t2. In the RAM check, for example, all “0” and all “1” test data are sequentially written to and read from all the storage areas of the RAM 7 to check whether or not the data can be correctly read and written.
If there is no abnormality in the result of the RAM check, two pulse signals PLS are output at a predetermined interval from the output port O4 of the CPU 3 at time t3. The pulse signal PLS is supplied to the pulse generator 9, and two operation monitoring pulses SVP are generated by the pulse generator 9 and supplied to the EXOR 10. As a result, two operation monitoring pulses SVP having a pulse width of 1 μs are output to the output side of the XOR 10 at a predetermined interval. The operation monitoring pulse SVP is output as the fuel injection pulse IJP via the output unit 11, but the actuator does not operate because the pulse width is short.
[0015]
After the RAM check is completed and the check result is output from the CPU 3, the A / D check is started at time t4. The A / D check is to check the function of the A / D conversion unit 4. For example, can the negative pressure signal PB of the intake pipe before the engine start be converted into digital data to obtain data within a predetermined range? It is to check whether or not.
If there is no abnormality in the result of the A / D check, three pulse signals PLS are output at a predetermined interval from the output port O4 of the CPU 3 at time t5. The pulse signal PLS is supplied to the pulse generator 9, and three operation monitoring pulses SVP are generated by the pulse generator 9 and supplied to the EXOR 10. As a result, three operation monitoring pulses SVP having a pulse width of 1 μs are output to the output side of the XOR 10 at a predetermined interval. The operation monitoring pulse SVP is output as the fuel injection pulse IJP via the output unit 11, but the actuator does not operate because the pulse width is short.
[0016]
When all initial checks are completed at time t6, the microcomputer shifts to normal engine control. When the engine is started at time t7, for example, the injection control signal IJC is output from the output port O3 of the CPU 3 in synchronization with the crank angle pulse CA of the engine, and the output signal of the output port O3 becomes “H”. Become. The injection control signal IJC is a signal for driving the injector via an actuator such as a solenoid, and has a pulse width of about 1 ms that continues until time t10. The injection control signal IJC is given to the output unit 11 via the EXOR 10, and is output from the output unit 11 as a fuel injection pulse IJP. As a result, an actuator for driving the injector is operated, and fuel is injected into the engine.
[0017]
At time t8, when the CPU 3 performs a predetermined process while the injection control signal IJC is being output, the operation monitoring program in the ROM 6 is activated, and a predetermined number according to the content of the process ( For example, four pulse signals PLS are output from the output port O4 at a predetermined interval. The pulse signal PLS is supplied to the pulse generation unit 9, and four operation monitoring pulses SVP having a pulse width of 1 μs are generated by the pulse generation unit 9 and supplied to one input side of the EXOR 10. Since the “H” injection control signal IJC is supplied from the output port O3 of the CPU 3 to the other input side of the EXOR 10, the combined control signal CON on the output side of the XOR 10 is “L” with a pulse width of 1 μs. Four short pulses are superimposed at a predetermined interval. Thus, the operation monitoring pulse SVP is superimposed on the fuel injection pulse IJP output from the output unit 11 from time t8 to time t9. However, since the superimposed operation monitoring pulse SVP has a short pulse width, it does not affect the operation of the actuator.
[0018]
When the injection control signal IJC output from the output port O3 of the CPU 3 is stopped at time t10, the operation of the actuator is thereby stopped.
When the CPU 3 performs another predetermined process at time t11, the operation monitoring program in the ROM 6 is activated, and a predetermined number (for example, five) pulses according to the content of the process. Signal PLS is output from output port O4 at a predetermined interval. The pulse signal PLS is supplied to the pulse generation unit 9, and five operation monitoring pulses SVP having a pulse width of 1 μs are generated by the pulse generation unit 9 and supplied to one input side of the EXOR 10. Since the “L” signal is given from the output port O3 of the CPU 3 to the other input side of the EXOR 10, a pulse that becomes “H” with a pulse width of 1 μs is generated as the composite control signal CON on the output side of the XOR 10. Five are output at predetermined intervals. Thus, five fuel injection pulses IJP having a pulse width of 1 μs are output from the output unit 11 at a predetermined interval from time t11 to time t12. However, since the fuel injection pulse IJP has a short pulse width, the actuator does not operate and the control of the engine is not affected.
[0019]
On the other hand, by observing the waveform of the fuel injection pulse IJP output from the output unit 11 with a test device or the like, the generation timing of the operation monitoring pulse SVP superimposed on the fuel injection pulse IJP and its continuous number are measured. be able to. By checking the output state of the operation monitoring pulse SVP, it is possible to check whether or not a predetermined process is performed at a predetermined timing.
As described above, the microcomputer for vehicle control according to the present embodiment includes the ROM 6 that stores the control program including the operation monitoring program, the pulse generator 9 that generates the operation monitoring pulse SVP having a short pulse width that does not affect the control of the engine, And an EXOR 10 that generates a composite control signal CON by superimposing an injection control signal IJC for engine control and an operation monitoring pulse SVP. This makes it possible to output the operating state of the microcomputer for vehicle control to the outside by superimposing it on the output signal for normal control without affecting the control of the engine. There is an advantage that a terminal for connection is not required. Furthermore, there is an advantage that an operation check after mounting can be easily performed without incorporating a specific test function in advance in the vehicle control microcomputer.
[0020]
In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible. Examples of this modification include the following (a) to (h).
(A) The configuration of the vehicle control microcomputer is not limited to the configuration of FIG. For example, the input unit 1, A / D 4, pulse generation unit 9, output unit 11, and the like may be connected to the CPU 3 via the system bus 5.
(B) Input / output signals such as the rotation pulse RP and the fuel injection pulse IJP are not limited to those illustrated. Necessary input / output signals can be used according to the control contents of the vehicle engine to be controlled.
(C) Although the operation monitoring pulse SVP is superimposed on the injection control signal IJC, the operation monitoring pulse SVP may be superimposed on other output signals.
(D) The operation monitoring program in the ROM 6 is controlled to output a predetermined number of pulse signals PLS at predetermined intervals. For example, the number of the operation monitoring pulses SVP is designated from the output port O4 to the pulse generator 9. Alternatively, the pulse generator 9 may be configured to output a predetermined number of operation monitoring pulses SVP at predetermined intervals.
[0021]
(E) Although the pulse generation unit 9 using a monostable multivibrator generates an operation monitoring pulse SVP having a predetermined pulse width, the operation monitoring pulse SVP having a predetermined pulse width is directly output from the output port O4 by program control. You may make it do.
(F) The initial check methods such as ROM check, RAM check, and A / D check are not limited to the exemplified methods, and other check methods can be used. Furthermore, an initial check of other functions may be performed.
(G) If the operation is monitored only in a state where the output signal such as the injection control signal IJC is not output as in the illustrated initial check, a logic gate such as an OR gate (OR) is used instead of the EXOR 10. Can be used.
(H) As a pulse generation means and a pulse superposition means, an output port O4 for outputting a pulse signal PLS, a pulse generation unit 9 for generating an operation monitoring pulse SVP having a predetermined pulse width, and an injection output from the output port O3 An EXOR 10 is provided for generating a composite control signal CON by superimposing an operation monitoring pulse SVP on the control signal IJC. Instead of these, an operation monitoring program in the ROM 6 may be used as the pulse generating means and the pulse superimposing means, and the composite control signal CON may be directly output from the output port O3.
[0022]
【The invention's effect】
As described above in detail, according to the first invention, the pulse generating means for generating the operation monitoring pulse having a pulse width that does not affect the engine control when the predetermined operation is performed, and this operation Pulse superimposing means for superimposing the monitoring pulse on the control signal to generate a composite control signal, and output means for converting the composite control signal to a predetermined level and outputting it for engine control. This makes it possible to output the operating state of the microcomputer externally by superimposing it on the output signal for normal control without affecting the vehicle control, and a dedicated external connection terminal for operation check In addition, there is an effect that it is possible to check the operation of the microcomputer for vehicle control after mounting without requiring the incorporation of a specific test function and without removing the resin coating layer.
According to the second aspect of the invention, the pulse generating means is configured to generate different numbers of operation monitoring pulses respectively corresponding to a plurality of predetermined operations. Thereby, it becomes possible to distinguish a plurality of operations and accurately grasp the execution timing, and there is an effect that the operation state of the microcomputer can be checked more accurately.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a microcomputer for vehicle control showing an embodiment of the present invention.
FIG. 2 is a sequence diagram showing an example of the operation of the vehicle control microcomputer of FIG.
[Explanation of symbols]
1 Input unit 2 Selection unit 3 CPU
4 A / D converter 5 System bus 6 ROM
7 RAM
8 EEPROM
9 Pulse generator 10 EXOR
11 Output section

Claims (2)

Input means for providing an input signal necessary for electronic control of the vehicle engine;
Storage means storing a program indicating the electronic control procedure;
Control means for generating a control signal necessary for controlling the vehicle engine based on the program and an input signal given to the input means;
Pulse generating means for generating an operation monitoring pulse having a pulse width that does not affect the control of the vehicle engine when a predetermined operation is performed in accordance with the program in the control means;
Pulse superimposing means for superimposing the operation monitoring pulse generated by the pulse generating means on the control signal generated by the control means to generate a combined control signal;
Output means for converting the synthesized control signal into a signal of a predetermined level for engine control and outputting the signal;
A microcomputer for controlling a vehicle, comprising: 2. The vehicle control microcomputer according to claim 1, wherein the pulse generating means generates a different number of operation monitoring pulses corresponding to a plurality of predetermined predetermined operations.

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