JPH0731253B2 - Digital controller - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital controller using a microcomputer, and more particularly to a function of measuring elapsed time (so-called programmable timer).

[0002]

2. Description of the Related Art In a digital control device using a microcomputer, for example, a control device for an internal combustion engine, control contents (fuel injection amount, etc.) are frequently switched according to the elapsed time from a certain time. Therefore, a means for measuring the elapsed time is required, but in the past, for example, a timer (time measuring means) as shown in FIG. 3 has been used.
In FIG. 3, 1 is a central processing unit (hereinafter referred to as CPU) of a microcomputer, 2 is a latch capable of addressing an appropriate bit, 3 is a counter capable of addressing the same bit, and 4 is a data bus. Usually latch 2
The counter 3 is reset by performing a write operation to the counter 3 and preset to a predetermined value. From that point, the counter 3 sequentially subtracts the number of clock pulses from the preset content every time the clock pulse S ₁ is input, When 0, that is, when the number of clock pulses reaches a preset predetermined value, a signal is generated.
This signal is used to set an appropriate interrupt flag and interrupt the CPU 1.

[0003]

However, in the conventional timer as described above, the number of latches and counters corresponding to the number of timer operations and operation modes is required, so that the apparatus is complicated and expensive, and the measurement is also difficult. Since the time is input to the CPU by the interrupt operation, when many timer operations are used, there is a problem that the number of interrupts increases and the interrupt processing time increases, which affects other arithmetic processing.

The present invention has been made in order to solve the problems of the prior art as described above, and provides a digital control device which simplifies the device and solves the problems such as the increase in the number of interrupts accompanying the timer operation. The purpose is to

[0005]

In order to achieve the above object, the present invention is constructed as described in the claims. That is, in the present invention, the central performance
The arithmetic unit, the storage unit, and the central processing unit are installed separately.
Interrupt signal generating means, and
The signal generating means causes the central processing unit to generate an interrupt.
Signal, that is, an interrupt signal, is generated at a predetermined timing
In the central processing unit, the interrupt signal is
The controlled device is controlled by an interrupt that occurs each time it is given.
A program for determining the control amount is started, and the contents of a predetermined memory area of the storage device are cleared at a predetermined time point based on the interrupt signal to control the controlled device .
The content of the memory area is stepped up each time an interrupt for activating the program for determining the amount is generated, and the number of executions of the program started by the interrupt from the point of clearing is measured by the content of the memory area. , Is configured.

[0006]

As described above, the content of the predetermined memory area in the storage device is cleared at a predetermined time point based on the interrupt signal that activates the program that determines the control amount of the controlled device , and every time there is an interrupt request. When the steps are sequentially performed, the number of interrupt requests given at every constant time from the time of the clear is counted and stored in the memory area. Therefore, the elapsed time can be known by reading the contents of the above memory area in one arithmetic routine. Further, by comparing the above contents with a predetermined value, it is possible to detect whether or not the elapsed time has reached a predetermined set value. In addition, the above interrupt is independent of the central processing unit.
Depending on the interrupt signal from the provided interrupt signal generation means
Program that is not activated by the interrupt signal
Is a program that determines the controlled variable of the controlled device.
Causes the number of interrupts to increase and interrupt processing time to increase.
To avoid problems such as affecting other arithmetic processing
You can

[0007]

FIG. 1 is a block diagram of an embodiment of the present invention. In FIG. 1, 5 is a memory, and M _{1 to} M _n are memory areas used for timer operations. Reference numeral 6 is a clock pulse generator. Clock pulse generator 6
Is a clock pulse S every predetermined time (eg, every 10 ms)
₂ is output, and an interrupt request is generated to the CPU 1 by this clock pulse S ₂ . It should be noted that this interrupt request is an interrupt for starting a calculation and is generated in a normal calculation process. The CPU 1 executes an arithmetic routine in response to the above interrupt request, and causes the time counting operation to be performed within this arithmetic routine. First, the contents of predetermined memory area M ₁ ~M _n in the memory 5, and cleared by a predetermined time on the basis of a signal for generating the interrupt, is sequentially incremented each time an interrupt request. Therefore, in the memory areas M _{1 to} M _n , the number of interrupt requests given at every constant time after the time of clearing is counted and stored. Next, in one calculation routine to read out specific contents of the memory area in the memory area M ₁ ~M _n, it is possible to know the elapsed time. Further, by comparing the above contents with a predetermined value, it is possible to detect whether or not the elapsed time has reached a predetermined set value. According to the above configuration, since all the timekeeping operations are performed inside the microcomputer, the memory areas M _{1 to} M _{n are}
It is only necessary to prepare as many as necessary timer functions, and the configuration can be greatly simplified.

FIG. 2 shows an example of the actual contents of calculation.

FIG. 2 is a flow chart in the case of calculating the fuel injection amount of the internal combustion engine in the case of increasing the fuel amount for a predetermined time (for example, 3 seconds) at the time of starting the engine. That is, in this case, it is necessary to measure whether or not 3 seconds have elapsed from the start of starting. In FIG. 2, first, P
_{At 1} , the basic fuel injection amount PW ₁ is calculated. Next, in P _2, a starter switch for actuating the starter motor, it is determined whether ON or OFF, and if not set to OFF namely in startup, flag for detecting the start flag (the start beginning to go to P ₃ ) Is set to 0, and immediately goes to END. On the other hand, when P ₂ is ON, it goes to P ₄ and determines whether the start flag is 1 or 0. If the start flag is 0 at P ₄ , that is, at the start of starting (immediately after the starter switch is turned on), go to P ₅ and clear the memory area M ₁ (in this case, the memory area that operates as a timer). , And after setting the start flag to 1, go to P ₆ . On the other hand, if the start flag is 1 at P ₄ , that is, if the engine is being started, the program immediately goes to P ₆ . P ₆ is a routine for determining the elapsed time, and compares the content of the memory area M ₁ with a predetermined value to determine whether it is 3 seconds or more or less. For example, the cycle of the clock pulse S ₂ is 1
When it is 0 ms, it corresponds to 3 seconds when the content of the memory area M ₁ is 300.

If P ₆ is YES, that is, if 3 seconds or more have elapsed from the start of the engine start, the fuel consumption is not increased and the engine immediately goes to END. When P ₆ is NO, that is, when it is less than 3 seconds, the predetermined fuel amount is increased at P ₇ (PW ₂ = P
W ₁ go × K) are performed, and then to END. As described above, if the content of a specific memory area in the memory is stepped at regular intervals and the content of the memory area is compared with a predetermined value, it is determined whether or not a predetermined time has passed from the time of clearing. You can do it.

[0011]

As described above, according to the present invention, since the elapsed time is measured only by the calculation in the microcomputer, there is no increase in extra interrupt request as in the conventional case, and the calculation is not performed. The processing time can be shortened. Moreover, since an additional device such as a latch or a counter is not required, there is an effect that the configuration is simple and the cost is low.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is an embodiment of a flowchart showing a calculation process of the present invention.

FIG. 3 is a block diagram of an example of a conventional device.

[Explanation of symbols]

1 ... central processing unit of a microcomputer (CPU) 2 ... addressable latch 3 ... addressable counter 4 ... data bus 5 ... memory 6 ... clock pulse generator S _1, S ₂ ... clock pulse M ₁ ~M _n ... Memory area used for timer operation

Claims (1)

[Claims] 1. A central processing unit, a storage unit, and the central operating unit.
An interrupt signal generating means which is provided separately from the calculation unit, the
The interrupt signal generating means is provided in the central processing unit.
A signal that causes an interrupt, that is, an interrupt signal, is
The above central processing unit
Is an interrupt generated each time the above interrupt signal is given.
Therefore, start the program that determines the controlled variable of the controlled device.
Together is, the memory area each time the interrupt to activate the program a predetermined content of the memory area of the storage device based on the interrupt signal is cleared at a predetermined time, determines a control amount of the control target equipment is generated The digital control device is characterized in that the number of executions of the program started by the interrupt from the time of the clear is measured based on the content of the memory area.