JP2003241994A - Inspection and setting method for input circuit of electronic control unit, and electronic control unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform the inspection of a system time constant in the input signal of an electronic control unit without requiring the connecting of an external element, and precisely set the system time constant. <P>SOLUTION: An I/O port 2-1 is switched to an output port to form a low state, where the terminal voltage of a capacitor 34 is made to zero to lay a filter circuit 3 in a prescribed initialized state. Thereafter, the I/O port 2-1 is switched to an input port, whereby the capacitor 34 is gradually raised. The time until the I/O port 2-1 recognizes a high-level input is counted, and the time constant TH of a filter circuit 3 is calculated from the count result to inspect the adaptability of the time constant of the filter circuit 3. When the time constant TH is smaller than a system time constant Ts, the difference ΔT is compensated within a microcomputer 2 by software processing. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting and setting an input circuit of an electronic control unit and an electronic control unit.

[0002]

2. Description of the Related Art An electronic control unit constructed by using a microcomputer for controlling various devices is used in various fields. For example, a control unit for controlling the operation of a vehicle engine also includes one or more microcomputers, and signals from switches, sensors, etc. are input to these microcomputers. The signal input to the electronic control unit is usually a low level signal, and it is conceivable that a noise signal from the outside will be superimposed and the quality of the input signal will be degraded due to wiring of the input side. In particular, when it is installed close to a strong noise signal source such as an engine ignition system or a motor, such as an electronic control unit for a vehicle, it is necessary to take sufficient measures against it.

Therefore, in the conventional electronic control unit of this type, a time constant circuit such as an RC filter is provided between the input terminal of the microcomputer and the input terminal of the electronic control unit to prevent noise signals. The components are prevented from being input to the microcomputer, and even if a high level signal is applied to the input terminal of the electronic control unit for some reason, this is directly applied to the input terminal of the microcomputer and the microcomputer is damaged. It is configured so that it can be prevented.

Therefore, in order for the electronic control unit to satisfactorily perform the required control, the time constant of the time constant circuit provided on the input side of the electronic control unit must be set to an optimum value according to its purpose. There is.

However, the time constant of the input circuit portion of the electronic control unit may be a value outside the standard due to variations in the values of elements and the like at the time of manufacture. It is expected that the value will deviate from the required optimum value due to factors such as physical factors and changes over time. For this reason, conventionally, at the time of shipment, etc., it is inspected whether the time constant at the input terminal is an appropriate value with the external load connected between the input terminal and the output terminal of the electronic control unit. .

This conventional inspection method will be described with reference to FIG.

In FIG. 6, reference numeral 100 denotes an electronic control unit, which is a microcomputer 1 having a large number of I / O ports.
It is equipped with 01. I / of the microcomputer 101
The O port is configured to be freely switchable to an input port or an output port by software. In the example shown in FIG. 6, two I / O ports out of many I / O ports are used.
Only ports 101A and 101B are shown. When the electronic control unit 100 enters the control operation mode, I
I / O port 101A is used as an input port and I / O
The O port 101B is used as an output port.

Input terminal 100 of electronic control unit 100
A filter circuit 102, which is a time constant circuit, is arranged between A and the I / O port 101A. The filter circuit 102 includes resistors 102A to 102C and a capacitor 10
2D and 2D are connected as shown in the figure to form a known RC filter circuit. Here, the input terminal 100
A resistor 102A is connected between A and the power supply voltage VB,
As a result, the input terminal 100A is pulled up to the power supply voltage level.

When the time constant of the filter circuit 102 is to be diagnosed by the microcomputer 101, an element such as a non-inductive resistor is connected as an external load 103 between the input terminals 100A and 100B, and the following operation is performed. Let them be done sequentially. 1) I / O port 101A is an input pin, I / O port 1
The microcomputer 101 is initialized by using 01B as an output pin. 2) The I / O port 101B set as the output is put in the low state. 3) The I / O port 101B is changed from the low state to the high state, and at the same time, the internal timer of the microcomputer 101 is turned on to start counting. 4) When the I / O port 101A recognizes the high state, the count of the internal timer is stopped. 5) The time constant of the input terminal 100A is measured by reading the time measured by the timer. 6) The preset value of the time constant is compared with the measurement value measured by the counter, and if the measurement value exceeds a predetermined allowable value, an error is displayed.

[0010]

As described above, according to the conventional method, the time constant of the input terminal cannot be diagnosed unless the load is connected to the outside of the electronic control unit. However, the cost is high because of the increase in the number and the time and effort required for the diagnosis.

Further, in order to make the time constant of the time constant circuit provided in the input circuit fall within a predetermined range, it is necessary to use high-precision and expensive elements as each element constituting the time constant circuit. This will increase the cost of the control unit. Therefore, in order to reduce the cost, it is necessary to use an inexpensive element with low accuracy, and the input time constant characteristics of the finished product greatly vary, which is an unfavorable result.

It is an object of the present invention to provide an inspection and setting method for an input circuit of an electronic control unit and an electronic control unit which can solve the above-mentioned problems in the prior art.

[0013]

According to the invention of claim 1, I / O of a microcomputer capable of input / output switching.
A method for inspecting an input circuit of an electronic control unit configured to apply an external input signal to a port via a time constant circuit, the I / O port being switched to an output port. Is set to a level for setting the time constant circuit to a predetermined initialization state, and then the I / O port is switched to an input port, and when the level of the input voltage of the I / O port changes, There is proposed a method for testing an input circuit of an electronic control unit, which is characterized in that a constant is tested.

According to a second aspect of the present invention, an electronic control having an input circuit configured to apply an external input signal to an I / O port of a microcomputer capable of input / output switching through a time constant circuit. In the unit, I /
First switching means for switching the O port to the output; and in response to the switching of the I / O port to the output by the first switching means, setting the I / O port to the time constant circuit to a predetermined initial stage. And a second means for switching the I / O port to an input after the time constant circuit has been brought to the predetermined initialization state.
Switching means, timing detecting means for detecting the timing when the voltage level of the I / O port reaches a predetermined level after the I / O port is switched to the input by the second switching means, and the output Calculating means for calculating the time constant of the input circuit based on the time from the output timing of the step voltage from the means to the timing detected by the timing detecting means, and the calculating means for calculating the time constant of the input circuit An electronic control unit is proposed, which comprises means for evaluating an input circuit and displaying the evaluation result.

According to the third aspect of the invention, the input circuit of the electronic control unit is configured so that an input signal from the outside is applied to the I / O port of the microcomputer capable of input / output switching through the time constant circuit. In the time constant setting method, the I / O port is switched to an output port, and then the I / O port is set to a level for setting the time constant circuit to a predetermined initialization state. The time constant of the input circuit is measured from the state of the level change of the input voltage of the I / O port after switching to the input port, and when the measured time constant is smaller than the required time constant, the shortfall is made to the microcomputer. There is proposed a method of setting an input circuit of an electronic control unit, which is characterized in that it is provided in-house.

According to a fourth aspect of the present invention, an electronic control having an input circuit configured to apply an external input signal to an I / O port of a microcomputer capable of input / output switching via a time constant circuit. In the unit, I /
First switching means for switching the O port to the output; and in response to the switching of the I / O port to the output by the first switching means, setting the I / O port to the time constant circuit to a predetermined initial stage. And a second means for switching the I / O port to an input after the time constant circuit has been brought to the predetermined initialization state.
Switching means, timing detecting means for detecting the timing when the voltage level of the I / O port reaches a predetermined level after the I / O port is switched to the input by the second switching means, and the output Calculating means for calculating the time constant of the input circuit based on the time from the output timing of the step voltage from the means to the timing detected by the timing detecting means, and the time constant calculated in response to the calculating means And a means for causing a deficiency in the microcomputer when is smaller than the required time constant.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An example of an embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing an example of an embodiment of an electronic control unit according to the present invention. The electronic control unit 1 is for electronically controlling the operation of a vehicle engine (not shown), and includes a microcomputer 2 for performing various data processing for operation control. The microcomputer 2 is provided with a plurality of I / O ports 2-1 to 2-N, and these I / O ports 2-1 to 2-N are input ports by software processing in the microcomputer 2. Alternatively, it has a known configuration in which any of the output ports can be arbitrarily switched.

In this embodiment, the I / O port 2-1 is used as an input port for data processing in the engine operation control mode.
An input signal externally applied to the input terminal 1-1 of the electronic control unit 1 is input to the I / O port 2-1 via the filter circuit 3 which is a time constant circuit and processed.

The filter circuit 3 is configured as an RC type filter circuit in which resistors 31 to 33 and a capacitor 34 are connected as shown in the drawing, and the input terminal 1-1 is connected to the power source voltage + V by the resistor 31. Has been pulled up. The filter circuit 3 removes a high frequency noise signal component included in the input signal applied to the input terminal 1-1, and when the level of the input signal becomes an abnormally high level for some reason. But I of microcomputer 2
It is provided to protect the microcomputer 2 by suppressing the level of the input signal so that a voltage signal higher than the allowable level is not applied to the / O port 2-1.

Therefore, it is necessary that the time constant of the filter circuit 3 is within a predetermined allowable range including the system time constant Ts which is predetermined in the input circuit of the electronic control unit 1. Here, the lower allowable value is Td (= Ts-
a), the upper allowable value is defined as Tu (= Ts + b).

Although the electronic control unit 1 is provided with a plurality of input terminals and output terminals in addition to the input terminal 1-1, FIG. 1 illustrates all of these terminals for illustration. Omit it.

The electronic control unit 1 checks whether or not the time constant of the filter circuit 3 constructed by assembling individual parts is within the above-mentioned range by the input terminal 1-1.
If the time constant of the inspection unit 21 and the filter circuit 3 as a result of the inspection by the inspection unit 21 is smaller than a predetermined specified value, the shortage of the shortage Is compensated by software processing in the microcomputer 2 so that the time constant of the input circuit of the electronic control unit 1 can be exactly matched with the system time constant Ts which is a specified value. It has and.

First, the inspection unit 21 will be described with reference to FIG. FIG. 2 is a flowchart showing an inspection program stored and executed in the microcomputer 2 to perform the above-described inspection function. By executing this inspection program, the I / O port 2-1 is switched to the output port, the I / O port 2-1 is set to the low state, the terminal voltage of the capacitor 34 is set to zero, and the filter circuit 3 is set to a predetermined level. I / O port 2 after initialization
-1 is switched to the input port, which causes capacitor 3
I / O port 2-1
The time constant until the I / O port 2-1 recognizes a high level input is counted, the time constant TH of the filter circuit 3 is calculated from the count result, and the time constant TH of the time constant TH thus obtained is calculated. The quality of the time constant of the filter circuit 3 is checked depending on whether the value is within a required range.

First, in step S1, the system time constant Ts
To set. Here, the required time constant of the filter circuit 3 is set in "seconds". This setting may be input each time from input means such as a ten-key input device (not shown),
Write data in this inspection program in advance,
This may be read out.

Next, in step S2, the I / O port 2-1 is set to the output, and in step S3, the I / O is set so that the charge stored in the capacitor 34 becomes zero and the terminal voltage of the capacitor 34 once becomes zero. Set the port 2-1 to the low state. After the terminal voltage of the capacitor 34 is once set to zero in this way, step S4 is entered, the I / O port 2-1 is switched to an input, and a timer (not shown) internally configured as software is reset. To do. This allows the timer to start counting, and the terminal voltage of the capacitor 34 gradually begins to rise. Power supply voltage +
This is because V flows to the capacitor 34 via the resistors 31 and 32 and the capacitor 34 starts to be charged.

In the next step S5, it is determined whether or not the I / O port 2-1 has recognized the high level state of the input signal. When the terminal voltage (charging voltage) of the capacitor 34 is still low and the I / O port 2-1 has not yet recognized the high level state of the input signal, the determination result in step S1 is NO, and the process proceeds to step S6. Step S6
In, the timer counts up by a predetermined value and the process returns to step S5. Steps S5 and S6 are repeatedly executed as described above until the charging voltage of the capacitor 34 rises and the I / O port 2-1 can recognize the high level state of the input signal. Then, when the I / O port 2-1 recognizes the high level state of the input signal, the determination result of step S5 becomes YES, and the process proceeds to step S7.

In step S7, the counting operation of the timer is stopped, and in step S8, the time constant of the filter circuit 3 is calculated based on the count value of the timer. That is, the time constant TH of the filter circuit 3 is calculated from the count value of the counter, which is the time required from the output of the I / O port 2-1 being switched to the input until the determination result of step S5 becomes YES, Go to step S9.

In step S9, the value of the time constant TH calculated in step S8 is the given lower limit value Td and upper limit value T.
It is determined whether or not it is between u and Td <TH <
If it is Tu, the determination result of step S9 is YES,
The execution of the inspection program is terminated as it is.

On the other hand, the time constant T calculated in step S8
If the value of H is not between the given lower limit value Td and upper limit value Tu, the determination result in step S9 is NO, the process proceeds to step S10, and the time constant of the filter circuit 3 is a nonstandard value. A message to that effect is displayed on the display unit 4 (see FIG. 1), and the execution of the inspection program ends.

According to the inspection unit 21, the time constant of the input circuit of the input terminal 1-1 of the electronic control unit 1 is within an appropriate range without connecting any external element to the input terminal 1-1. If the time constant of the input circuit is not within the given appropriate range as a result, it is possible to display a message to that effect and prompt the operator to take appropriate action. it can.

Further, by diagnosing the time constant when the electronic control unit 1 is started up, it is possible to detect the failure of the input / output circuit and the deterioration of the elements and to confirm the noise resistance, so that the reliability and safety of the electronic control unit 1 are improved. It is possible to improve the sex. Furthermore, since the time constant can be diagnosed without connecting an external load, the number of man-hours for the diagnosis can be reduced and the cost for the diagnosis can be reduced as compared with the conventional case.

Next, the time constant setting for setting the time constant of the input circuit at the input terminal 1-1 of the electronic control unit 1 to a given value using the calculation result of the time constant TH in the inspection section 21. The section 22 will be described with reference to FIGS. 3 and 4.

In FIG. 3, the microcomputer 2 is used so that the time constant of the input circuit of the input terminal 1-1 becomes the system time constant Ts by using the calculation result of the time constant TH in the inspection unit 21.
FIG. 4 is a flowchart showing a time constant setting program stored and executed in FIG. 4, and FIG. 4 is a partial detailed flowchart of the flowchart shown in FIG.

When the execution of the time constant setting program is started, first, in step S21, the time constant TH calculated in step S8 of the inspection program is read, and in step S22, the difference ΔT from the system time constant Ts is calculated. It In step S23, it is determined whether the difference ΔT is larger than zero.

Time constant TH indicating the time constant of the filter circuit 3
If the value of is larger than the system time constant Ts, that is, the specified value of the time constant when the input circuit is viewed from the input terminal 1-1, ΔT becomes a negative value, and compensation by setting the time constant by software processing is not performed. Since it is impossible, the determination result of step S23 is NO in this case, and the execution of this program is terminated here. Further, when ΔT = 0, that is, TH = Ts, compensation by setting the time constant by software processing is not necessary, and in this case also, step S
The determination result of 23 is NO, and the execution of the program is terminated as it is.

When Ts> TH, the value of the difference ΔT is positive, so the result of the determination in step S23 is YES, the process proceeds to step S24, where the microcomputer 2
A time constant corresponding to ΔT is set by software.

FIG. 4 shows a detailed flowchart of step S24. The process in step S24 will be described. First, when the input signal is asserted so as to change the level of the input terminal 1-1 from the low state to the high state in step S31, the I / O port 2-1 receives the high level input. It is determined whether or not it is recognized. When the high level input is not recognized, the determination result of step S32 is NO, and step S31 is executed again.

As time passes, I / O port 2
If it is determined that -1 has recognized the high level input, the determination result of step S31 is YES, and step S32
Then, the counting by the timer configured in the microcomputer 2 is started here.

In step S33, it is determined whether or not the count value of the timer has reached ΔT. If the count value has not yet reached ΔT, the determination result in step S33 is NO, and the process proceeds to step S34. In step S34, the timer is counted up by a predetermined value and the process returns to step S33. In this way, when the count value of the timer reaches ΔT, the determination result of step S33 becomes YES, and the process proceeds to step S35.

In step S35, the corresponding bit B11 of the first register RG1 for temporarily storing the input from the I / O port 2-1 and the other I / O port which is the input port is stored. Corresponding bit B21 of the second register RG2 provided corresponding to this
Is stored (see FIG. 1). In this case, the bit B1 of the first register RG1 set to "1" in response to the recognition of the high level input in step S31.
The content of 1 corresponds to the corresponding bit B of the second register RG2 at the timing when the determination result of step S33 is YES.
21 and the contents are changed from "0" to "1".

That is, the content of the bit B21 of the second register RG2 is changed from "0" to "1" after a lapse of .DELTA.T from the recognition of the high level input in the I / O port 2-1. That is, a time delay of ΔT occurs in the microcomputer 2.

In step S36, a process of using the value of bit B21 of the second register RG2 for controlling the system is executed.

In this way, the time constant TH of the filter circuit 3 is
However, if it is smaller than the system time constant Ts, the shortage can be compensated for in the microcomputer 2 and the time constant in the input circuit of the input terminal 1-1 of the electronic control unit 1 can be substantially Ts. .

Therefore, even if the time constant TH of the filter circuit 3 is different from the system time constant Ts due to the accuracy of each element constituting the filter circuit 3, this can be corrected by software processing. Therefore, even if the system time constant Ts deviates from a predetermined value due to variations in assembly at the factory or changes over time, it is possible to correct this, and always set the system time constant required by the system correctly. Can be set. This correction is economical because it does not require any special device to be installed externally, and the system time constant can be freely changed at any time after manufacturing, so it is possible to flexibly respond to changes in specifications. be able to. As can be seen from the above description, if the time constant TH of the filter circuit 3 is set to be smaller than the system time constant Ts without fail, the time constant of the filter circuit 3 is measured when the electronic control unit is started, and the value is set as By combining the time constants created by the processing, it is possible to set and maintain the time constant intended for the electronic control unit.

According to the configuration of the electronic control unit 1, it is possible to maintain the performance and improve the reliability of the electronic control unit. When controlling a rotating object such as an engine, it is important to accurately recognize its rotation speed and position, but since the time constant can be set accurately, the timing of the rotation input pulse is important. It is possible to accurately recognize the timing at the input.

In the above embodiment, the filter circuit 3 has the circuit configuration in which the input terminal 1-1 is pulled up to the side of the power supply voltage + V. However, as shown in FIG.
Even when a filter circuit 3'having a circuit configuration using a resistor 35 for pulling down that connects the input terminal 1-1 to the ground instead of 1 is used as a time constant circuit,
Similarly, the present invention can be applied to obtain similar effects.

When the filter circuit 3'shown in FIG. 5 is used, first, the I / O port 2-1 is switched to the output to bring it to a high level state, thereby charging the capacitor 34 and setting the filter circuit 3'to a predetermined level. Is initialized, and then the I / O port 2-1 is switched to the input to discharge the charge stored in the capacitor 34 through the resistors 32, 33 and 35, which causes a decrease in the terminal voltage of the capacitor 34. I / O port 2 in the microcomputer 2
The time until -1 is recognized as a low level input may be counted.

[0049]

According to the present invention, as described above, the time constant of the input circuit of the I / O port of the electronic control unit is kept in an appropriate range without connecting any external element to the I / O port. Since it can be easily inspected whether or not it is present, the number of man-hours for diagnosis can be reduced and the cost for diagnosis can be made lower than in the past.

Further, by diagnosing the time constant when starting the electronic control unit, it is possible to detect the failure of the input / output circuit and the deterioration of the element and to confirm the noise resistance, so that the reliability and safety of the electronic control unit can be improved. Can be improved.

Further, even if the time constant of the time constant circuit is different from the required system time constant due to the accuracy of each element constituting the time constant circuit, by correcting this by a software process, the factory constant Even if the required time constant deviates from the specified value due to variations in assembly or changes over time, it is possible to accurately correct this, and the required time constant required for the system can always be set correctly. it can. This correction is economical because it does not require any special equipment to be installed externally, and the required time constant can be freely changed at any time after manufacturing. can do. In this way, measure the time constant of the time constant circuit of the electronic control unit,
By combining the value with the time constant created by software processing, the time constant aimed at the electronic control unit can be set and maintained at low cost.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of an embodiment of an electronic control unit according to the present invention.

FIG. 2 is a flowchart showing an inspection program stored and executed in the microcomputer shown in FIG.

FIG. 3 is a flowchart showing a time constant setting program stored and executed in the microcomputer shown in FIG.

4 is a detailed flowchart of a time constant setting processing step of the flowchart shown in FIG.

5 is a circuit diagram showing another circuit example of the filter circuit shown in FIG.

FIG. 6 is a configuration diagram showing an example of a conventional electronic control unit.

[Explanation of symbols]

1 Electronic control unit 1-1 input terminal 2 microcomputer 2-1 to 2-N I / O port 3, 3'filter circuit 4 Display 21 Inspection Department 22 Time constant setting section 31-33 resistor 34 capacitor B11, B21 bit RG1 first register RG2 second register + V power supply voltage

Continued front page    (72) Inventor Eriko Matsukawa             3-13-26, Yumichocho, Higashimatsuyama City, Saitama Prefecture             Expression company Bosch Automotive System             Higashi Matsuyama Factory (72) Inventor Kanta Arai             3-13-26, Yumichocho, Higashimatsuyama City, Saitama Prefecture             Expression company Bosch Automotive System             Higashi Matsuyama Factory F term (reference) 5B048 AA14 DD10 EE01 EE02 FF03

Claims (4)

[Claims] 1. A method for testing an input circuit of an electronic control unit configured to apply an external input signal to an I / O port of an input / output switchable microcomputer through a time constant circuit. , The I / O port is switched to an output port to switch the I / O
The port is set to a level for setting the time constant circuit to a predetermined initialization state, and then the I / O port is switched to the input port to change the level of the input voltage of the I / O port from the state of the input circuit. A method for inspecting an input circuit of an electronic control unit, characterized by inspecting a time constant. 2. An electronic control unit having an input circuit configured to supply an input signal from the outside to an I / O port of a microcomputer capable of input / output switching via a time constant circuit, wherein the I / O First switching means for switching the port to the output; and in response to the switching of the I / O port to the output by the first switching means, the I / O port is initialized to a predetermined time constant circuit. Means for setting a level state for setting the state, second switching means for switching the I / O port to an input after the time constant circuit is in the predetermined initialization state, and the I / O port is Timing detection means for detecting the timing when the voltage level of the I / O port reaches a predetermined level after being switched to the input by the second switching means; Calculating means for calculating the time constant of the input circuit based on the time from the step voltage output timing to the timing detected by the timing detecting means, and the input circuit based on the calculation output from the calculating means. And a means for displaying the evaluation result of the electronic control unit. 3. A method for setting a time constant of an input circuit of an electronic control unit configured to apply an external input signal to an I / O port of a microcomputer capable of input / output switching via a time constant circuit, After switching the I / O port to an output port,
/ O port is set to a level for setting the time constant circuit to a predetermined initialization state, and then the I / O port is switched to an input port to change the input voltage from the input voltage of the I / O port. A method for setting an input circuit of an electronic control unit, characterized in that a time constant of a circuit is measured, and when the measured time constant is smaller than a required time constant, the shortage is covered in the microcomputer. 4. An electronic control unit having an input circuit configured to supply an input signal from the outside to an I / O port of a microcomputer capable of input / output switching through a time constant circuit, wherein the I / O First switching means for switching the port to the output; and in response to the switching of the I / O port to the output by the first switching means, the I / O port is initialized to a predetermined time constant circuit. Means for setting a level state for setting the state, second switching means for switching the I / O port to an input after the time constant circuit is in the predetermined initialization state, and the I / O port is Timing detection means for detecting the timing when the voltage level of the I / O port reaches a predetermined level after being switched to the input by the second switching means; The calculation means for calculating the time constant of the input circuit based on the time from the output timing of the step voltage to the timing detected by the timing detection means, and the time constant calculated in response to the calculation means are required. And a means for causing a shortage in the microcomputer when the time constant is smaller than the time constant of.