JPH01111202A - Arithmetic unit for cycle of pulse signal - Google Patents

Abstract

PURPOSE:To calculate an accurate cycle of an input pulse by dividing the time required for the edge of the input pulse set at the previous request of an interruption through the edge of the input pulse set after lapse of a prescribed time by the number of pulse signals supplied during said period of time. CONSTITUTION:When an interruption control circuit 66 has a request for interruption, an input pulse counter IPC 78 counts the edge detecting signals received from an edge detecting circuit 62. At the same time, the circuit 66 inhibits the input of the edge detecting signals to a free-run counter FRC 60 which counts the time and the circuit 66 itself before a prescribed period of time passes. Then the FRC 60 reads and stores the present time point after the output of the edge detecting signal. When the circuit 66 gives a request to a logical arithmetic circuit, this arithmetic circuit divides the deviation of the past time points equivalent at least to two times counted by the FRC 60 by the pulse count result of the IPC 78. Thus the cycle of the input pulse is calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pulse signal period calculating device that calculates the period of a pulse signal by program processing of a microcomputer.

[Prior Art] Conventionally, as one of the period calculation devices for calculating the period of a pulse signal by a microcomputer, as shown in FIG. a free run counter (hereinafter referred to as FRC) 90,
An edge detection circuit 92 detects the rising or falling edge of a human pulse; and an input capture register (hereinafter referred to as ICR) that reads the current time T1 from the FRC 90 when the edge detection circuit 92 detects an edge of the input pulse. ) 94, and an interrupt control circuit 96 which issues an interrupt request for periodic calculation when an edge of a human pulse is detected by the edge detection circuit 92, and is connected via an internal bus 9. For logical operation circuits (hereinafter referred to as ALUs) that do not
Some devices are configured to execute period calculation processing for calculating a pulse period that calculates a human pulse from the deviation between the current time stored in the ICR 94 and the time previously measured by the ICR 94 (for example, the ICR 94 manufactured by MOTOROLA) IC, M
C68HCO5C4). .

[Problems to be solved by the invention] In this type of device, as shown in FIG. 7(a), the FRC9
The clock data of 0 is latched in the ICR94 and an interrupt request for pulse period calculation is made to the ALU. Therefore, if the period of the input pulse is long, the period calculation is executed at the same time as the interrupt request, and the pulse signal is The period can be calculated without any problem, but if the period of the human pulse becomes short and interrupt requests are made frequently, the period of the interrupt request becomes shorter than the time △T required for period calculation, and the interrupt There was a problem in that the period calculation could not be performed for each request, making it impossible to accurately calculate the pulse period. In other words, when the pulse period becomes short, the period of two pulse signals from time tll to t12 is calculated as the pulse period in the period calculation process shown in FIG. 7(a).

Furthermore, even if the period of the human pulse is longer than the time △T required for periodic calculation and the periodic calculation can be executed for each interrupt request, if the period of the input pulse becomes short, the area B shown in FIG. , the time to perform calculations other than periodic calculations △
t becomes short, making it impossible to properly execute the main program such as control processing executed by the ALU based on the periodic calculation results.

On the other hand, in order to solve the above-mentioned problem and to be able to perform period calculations even if the period of the input pulse becomes short, it has been considered to divide the frequency of the manually-powered pulse and input it manually to the edge detection circuit. However, when configured in this way, a problem arises in that when the period of the human pulse is long, the calculation other than the period becomes large and the responsiveness of the period calculation decreases.

SUMMARY OF THE INVENTION Therefore, the present invention provides a device that calculates the period of a pulse signal using a microcomputer as described above, so that the pulse period can always be calculated stably and accurately even if the period of the human pulse changes greatly. It was done for that purpose.

[Means for Solving the Problems] That is, the present invention, which has been made to achieve the above object, comprises: a clock circuit that measures time; an edge detection circuit that detects the rising or falling edge of a human pulse; and the edge detection circuit. a time measurement circuit that receives an edge detection signal from the clock circuit and reads and stores the current time from the clock circuit; an interrupt control circuit that also receives an edge detection signal from the edge detection circuit and requests an interrupt; a logic operation circuit that suspends normal operation in response to an interrupt request from a control circuit and calculates the period of the human pulse from the deviation of at least two past measurement results of the time measurement circuit according to a preset program; , In the pulse signal period calculating device, the edge detection signal outputted from the edge detection circuit is counted until a predetermined time has elapsed after the interrupt control circuit issues an interrupt request, and the edge detection signal is An input pulse count circuit is provided that prohibits input of the detection signal to the time measurement circuit and the interrupt control circuit, and the logic operation circuit calculates at least two past measurement results of the time measurement circuit in the interrupt processing. The gist of the present invention is a pulse signal period calculating device for special effects, which is configured to calculate the pulse period by dividing the deviation by the count result of the input pulse counting circuit.

[Function] In the pulse signal period calculation device of the present invention configured as described above, when the interrupt control circuit issues an interrupt request based on the edge detection signal from the edge detection circuit, the manual pulse count circuit then Manual input of edge detection signals to the time measurement circuit and interrupt control circuit is prohibited until a predetermined period of time has elapsed, and during that period, the edge detection signals output from the edge detection circuit are counted. Then, when the edge detection signal is output from the edge detection circuit, the time measurement circuit reads and stores the current time (that is, the output time of the edge detection signal) from the time measurement circuit, and the interrupt control circuit interrupts the logic operation circuit. Make a request for inclusion. Then, the logic operation circuit temporarily stops normal operation in response to this interrupt request, performs periodic calculation processing of the human pulse, and inputs the deviation of at least two past times measured by the time measurement circuit into the input pulse count circuit. Divide by the pulse count result to calculate the period of the input pulse.

Therefore, the elapsed time after the interrupt request, which is measured by the human pulse counting circuit, is the time △T required for executing periodic operation processing in the logical operation circuit, and the time required for executing other processing (main program, etc.). If it is set to a value that is the sum of the minimum required time and the minimum required time, as shown in FIG. Processes other than periodic calculations based on interrupt requests can also be sufficiently executed.

The period of the human pulse is calculated by dividing the time from the edge of the human pulse when the previous interrupt request was made to the edge of the human pulse after a predetermined period of time by the number of pulse signals manually input during that time. Therefore, the period of the input pulse can be accurately calculated without erroneously calculating the human power time of a plurality of pulse signals as the period of one pulse signal as in the conventional case.

Furthermore, if the period of the input pulse is large, multiple pulse signals will not be manually input until the predetermined time elapses, and the number of pulses counted by the manual pulse counter will be one, which is the same as before. Since the pulse period can be calculated quickly and the period of the pulse signal is calculated as the average value of a plurality of pulse signals only when the pulse period is short, the accuracy of period calculation does not deteriorate.

[Embodiment] Next, a pulse signal period calculation device incorporated in a control device for an internal combustion engine will be described as a preferred embodiment of the present invention.

First, FIG. 2 is a schematic configuration diagram showing the configuration of an internal combustion engine control device.

As shown in the figure, an internal combustion engine 1 includes an intake system 10 that sucks air from the atmosphere, mixes fuel and air injected from a fuel injection valve 8, and guides the mixture to an intake boat 9, and an electric spark formed at a spark plug 12. The combustion chamber 15 extracts the energy of the combustion of the air-fuel mixture ignited by the piston 14 as rotational motion, and the exhaust system 15 exhausts the gas after combustion through the exhaust boat 17. .

The intake system 10 includes, from upstream, an air cleaner 20, a rectifier grating 21 that adjusts the flow of intake air, an optical Karman vortex airflow meter 22 that outputs a pulse signal at a cycle according to the intake air amount Q, and an air intake system 10 that controls the intake air amount Q. Throttle valve 23 to control, surge tank 25 to smooth the pulsation of intake air
is provided. The intake air amount Q is normally controlled by the opening degree of the throttle valve 23 which is linked to an accelerator pedal (not shown), but when the throttle valve 23 is fully closed (during idling), the throttle valve 23
It is controlled by an idle speed control valve (hereinafter referred to as 15CV) provided in the bypass passage 26 that bypasses the. The intake system 10 includes a built-in idle switch that is turned on when the throttle valve 23 is fully closed, and a throttle sensor 30 that also detects the opening degree of the throttle valve 23 and a throttle sensor 30 that detects the temperature T of the intake air.
An intake temperature sensor 31 for detecting HA is also provided.

Air taken in through the intake system 10 and the fuel injection valve 8
The mixture with the fuel injected is drawn into the combustion chamber 15, compressed by the piston 14, and then ignited.
The air-fuel mixture is ignited by an electric spark formed at the spark plug 12.

The spark plugs 12 provided in each cylinder of the internal combustion engine 1 are connected to a distributor 35 that distributes high voltage generated in an igniter 33 in synchronization with the rotation of the output shaft 2 by a high voltage cord (not shown). Furthermore, inside the distributor 35, there is a cylinder discrimination sensor 36 which generates one pulse every 201 rotations of the output shaft, and a cylinder discrimination sensor 36 which generates one pulse every 30 degree rotation of the output shaft 2.
A rotation speed sensor 37 that generates pulses is provided.

The piston 14 is ignited by the spark and combusts explosively.
The air-fuel mixture that has been pushed down is then exhausted as exhaust gas, but the exhaust system uses an oxygen moisture sensor 38 that detects the air-fuel ratio of the air-fuel mixture based on the composition of the exhaust gas and a three-way catalyst that purifies the exhaust gas. The device 39 is further provided with an exhaust temperature sensor 40 for detecting exhaust temperature.

The cylinder block 41 of the internal combustion engine 1 is cooled by circulating cooling water, and the temperature THW of this cooling water is detected by a cooling water temperature sensor 43.

The output signals of the above-mentioned sensors that detect the operating state of the internal combustion engine 1 are manually input to the control circuit 5, and depending on the operating state of the internal combustion engine 1, the fuel injection valve 8, l5CV2B, and igniter 3 are controlled.
3rd grade control is performed.

The control circuit 5 includes a one-chip CPU 45 that includes a pulse period calculation device as an embodiment, and has built-in ROM, RAM, human output port, etc., and an analog-to-digital converter that manually converts voltage signals from each sensor into analog and digital. (hereinafter referred to as an A/D converter) 47. The above-mentioned throttle sensor 30, intake temperature sensor 31,
The exhaust on sensor 40 and the cooling water temperature sensor 43 are
are connected to the D converter 47, and their output signals are
After being converted into a digital signal, it is manually input to the Echitsubu CPU 45. The 1-chip CPU 45 includes a well-known ALU 52, ROM 53, and R
AM 54 , a human power port 55 , an output port 56 , and a pulse human power control circuit 57 for manually controlling pulse signals from the Karman vortex airflow meter 22 . A/D converter 47
The signals from each sensor and the signals from the rotation speed sensor 37, oxygen sensor 38, etc. converted into digital signals by
It is powered by humans via a human powered boat 55. -Force output port 5
6 is connected to the fuel injection valve 8 provided in the intake boat 9 of each cylinder, the l5CV2B provided in the bypass passage 26, or the igniter 33 that generates high voltage, etc.
The 1-chip CPU outputs control signals to these actuators from this output port 56.

Next, the pulse manual control circuit 57 creates periodic calculation data necessary for calculating the period of the pulse signal output from the Karman vortex airflow meter 22 (i.e., the intake air amount Q) through periodic calculation processing described later in the ALU 52. At the same time,
This is to start the calculation process.

As shown in FIG. 3, the Karman vortex airflow meter 22 of this embodiment includes a vortex generator 22a in the intake passage 10a, and generates a vortex at a frequency proportional to the flow velocity of intake air downstream of the vortex generator 22a. The pressure of the vortex is introduced to the surface of the metal foil (mirror) 22c through the pressure-conducting hole 22b, and the mirror 22 due to the vortex is
The air flow meter 22 is configured to optically detect the vibration of the air flow sensor c by a pair of light emitting/receiving elements 22d, and the air flow meter 22 outputs a pulse signal with a frequency varying in the range of 0 to several kHz depending on the intake air amount Q. be done. Therefore, the intake air amount Q is determined by the pulse signal output from the air flow meter 22.
To accurately measure the pulse period, it is necessary to measure the pulse period with a resolution of about 1 μsec.
7 is configured to create periodic calculation data using an FRC that measures time using an internal clock of the ALU 52.

The circuit configuration of this pulse manual control circuit 570 will be explained below using FIG. 1.

As shown in the figure, the pulse input control circuit 57 of this embodiment includes:
Similar to the pulse manual control circuit of the conventional device shown in Fig. 6,
It is equipped with an FRC 60 that measures time, an edge detection circuit 62 that detects the rising edge of a human pulse, an ICR 64 that reads and stores the current time from the FRC 60, and an interrupt control circuit 66 that issues an interrupt request for periodic calculation to the ALU 52. , the rise time of the human pulse is measured by the ICR 64, and an interrupt request is made to the ALU 52 from the interrupt control circuit 66 to determine the time from the rise to the rise of the human pulse to the ALU 52.

That is, it is designed to execute a period calculation process for calculating the period of the human pulse.

By the way, when the internal combustion engine 1 is operated at high load and high rotation speed, the intake air amount Q increases and the cycle of the pulse signal output from the air flow meter 22 becomes short to 1 m5 ec or less. Therefore, if an interrupt request is made every time the input pulse rises as in the past, the execution time of the main program in the ALU 52 (i.e., the program for fuel injection control and ignition timing control) will be shortened, and furthermore, The main program cannot be executed and the cycle cannot be calculated accurately.

Therefore, the pulse manual control circuit 57 sets a time period after an interrupt request is executed until the next interrupt request can be executed so that interrupt requests to the ALU 52 are not made frequently when the internal combustion engine 1 is under high load and at high rotation speed. The timing setting register (hereinafter referred to as TS)
It is written as R. ) 6 days, the timing counter (hereinafter referred to as TC) 70 measures the elapsed time after execution of the interrupt request, and the comparator 72 sets TC 70.
It is determined whether or not the measurement result is longer than the time set in TSR6B, and the -number output circuit 74 outputs the comparator 72
After detecting that the value of TSR6B and the value of TC70 match based on the output signal from configured to send.

Note that the timing counter control circuit 76 is a negative number output circuit 7.
The edge detection signal from the edge detection circuit 62 is not only transferred to the ICR 64 and the interrupt control circuit 66 by the coincidence detection signal from the edge detection circuit 66, but also the timing counter TC70 is transferred at the same time as the error = 15- ji detection signal is transferred.
and outputs a clock signal for counting to the timing counter TC.

In addition, with this configuration, the next interrupt request after an interrupt request is made at the time when the human power pulse rises after a predetermined time has elapsed since the previous interrupt request, and the value of ICR64 is also set to the time at that point. Therefore, if the internal combustion engine 1 is operated under high load and high rotation speed, and the period of the manual pulse becomes short, and a plurality of pulse signals are supplied manually until a predetermined time elapses from the previous interrupt request, It is not possible to calculate the period of the manual pulse on the ALU 52 side only from the value of the ICR 64.

Therefore, this pulse manual control circuit 57 includes a manual pulse counter (hereinafter referred to as IPC) 78 that counts the edge detection signal from the edge detection circuit 62, and an IPC
Manual pulse counting that memorizes the count results of 7B◆
Register (hereinafter referred to as ■ PCR) 80 and -
Every time the count output circuit 74 determines that the value of TSR6B and the value of TC70 match, the count value of IPC78 is input to IP.
A manual pulse counter control circuit 82 is provided to memorize the pulse signal in the CR80 and clear the IPC7B.
Stored in R80.

Next, the pulse input control circuit 5 configured as described above
7 will be explained using the timing chart shown in FIG.

As shown in the figure, first, at time t1, when an edge detection signal from the edge detection circuit 62 is inputted to the ICR 64 and the interrupt control circuit 66 via the timing counter control circuit 76, the edge detection signal is sent from the interrupt control circuit 66 to the ALU 52. An interrupt request is made, and the count value (ie, current time) Cn-1 of the FRC 60 is stored in the ICR 64. Also, at this time t1, the timing counter control circuit 76 controls the timing of TC7.
0 is cleared, and the count f of the FRC 60 (that is, the current time) Cn-1 is stored in the ICR 64, and the T
The edge detection signal from the edge detection circuit 62 is counted by the PC 7B. Thereafter, the T'C 70 counts the clock signal from the timing counter control circuit 76, thereby measuring the time after the interrupt request. This TC
70 count operation, the count result is TSR6B
During this period, even if the edge detection circuit 62 detects the rising edge of the human input pulse, the edge detection signal is not input to the ICR 64 and the interrupt control circuit 66, and the IPC7B The number of edge detection signals is counted.

Next, when the count result of TC70 and the setting 1 shift of TSR6B match and a predetermined time To has elapsed after the previous interrupt request (time t2), the counting operation of the timing counter TC is stopped and the manual pulse counter control is started. circuit 82
By the operation, the count value of the edge detection signal by IPC7B is stored in IPCR80, and IPC7B is cleared.

Then, when the edge detection circuit 62 detects the rising edge of the input pulse and outputs an edge detection signal (at time t
3) The edge detection signal is manually input to the interrupt control circuit 66 and ICR 64 via the timing counter control circuit 76, the ICR 64 stores the count value (i.e., current time) Cn of the FRC 60, and the interrupt control circuit 66 An interrupt request for periodic calculation processing is made to the ALU 52.

Next, the ALU 52 normally executes a well-known main program for fuel injection amount control and ignition timing control, and when an interrupt request is made from the pulse manual control circuit 57, the output from the Karman vortex airflow meter 22 is executed. A period calculation process for calculating the period of the pulse signal (=intake air amount Q) is executed as shown in FIG.

As shown in the figure, in this periodic calculation process, first step 1
After executing step 10 and reading the value of the ICR64 as the current time Cn, the value Cn is stored in the RAM 54 in step 120.
Store inside. In the subsequent step 130, the time Cn-1 that was read from the ICR 64 and stored in the RAM 54 when this process was executed last time is read out from the RAM 54, and the process moves to step 140. Then, in step 140, the deviation T1 between the above-mentioned time Cn and Cn-1 is determined. Further, in step 150, the value of IPCR,80 is changed to the number of manual pulses P
o, and the process proceeds to step 160, where the deviation T1 obtained above is divided by the number Po of human pulses to calculate the cycle Tn of the human pulses, and the processing of this routine ends.

That is, in this periodic calculation process, the rising time Cn of the human pulse stored in the ICR 64 and the number Po of human pulses stored in the IPCRho are read as data for lvI calculation, and the rise time of the human pulse stored in the ICR 64 last time is The period Tn of the input pulse is calculated by calculating the elapsed time T1 from time Cn-1 to the rise time Cn of the human pulse that is stored this time, and dividing the value T1 by the number of pulse signals Po input manually during that time. It is.

As described in detail above, in this embodiment, the pulse signal output from the Karman vortex airflow meter 22 is manually input to the pulse control circuit 57, and the interrupt control circuit 66 is activated by the edge detection signal from the edge detection circuit 62. After the request is made, the IP address is
C7B counts the edge detection signal from the edge detection circuit 62, and after a predetermined time To has elapsed, the edge detection circuit 62
When the edge detection signal is output from
The interrupt control circuit 66 is configured to read the current time from the RC 60 and issue an interrupt request to the ALU 52 to execute periodic arithmetic processing.

Therefore, even if the internal combustion engine 1 is operated at high load and high rotational speed, the intake air amount Q increases, and the period of the pulse signal output from the Karman vortex air flow meter 22 becomes short, as shown in FIG. 7(b). As shown, interrupt requests from the interrupt control circuit 66 are not made frequently, and the ALU 52 can execute the main program for periodic calculation processing and internal combustion engine control without any problem.

In addition, the period of the human pulse is determined by the period calculation process of the ALU 52, and is determined by calculating the time from the edge of the input pulse when the previous interrupt request was made to the edge of the input pulse after a predetermined period of time has elapsed, and the number of pulse signals input during that period. Since it is calculated by dividing by , it is possible to accurately calculate the human power pulse without erroneously calculating the human power time of a plurality of pulse signals as a pulse signal of a human power pulse as in the conventional case.

Furthermore, when the pulse period becomes shorter than the set time To, the pulse period is calculated as the average value of multiple manual pulses, but if the pulse period is short, the resolution is determined by the period of the measurement clock of the FRC 60 (i.e., the internal clock of the ALU 52). is determined, so even if the period calculation is performed for each pulse as in the past, the influence of the error of one clock becomes large, and even if it is averaged as in this embodiment, the period calculation accuracy will not decrease. do not have.

[Effects of the Invention] As described in detail above, the pulse signal period calculation device of the present invention allows interrupt processing for period calculations executed in logic operation circuits to be performed even if the period of a human pulse becomes short. It can be executed without problems, and the accuracy of period calculation can be improved without reducing the responsiveness of period calculation. Furthermore, since the main program executed by the logic operation circuit for periodic calculations is not affected, the logic operation circuit can execute calculation processing for various controls based on the periodic calculation results without any problem.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the configuration of the pulse manual control circuit of the embodiment, Figure 2 is a schematic diagram showing the overall configuration of the internal combustion engine control device of the embodiment, and Figure 3 is the configuration of the Karman vortex airflow meter. 4 is a time chart illustrating the operation of the pulse input circuit; FIG. 5 is a flowchart illustrating the periodic calculation process executed by the ALU;
The figure is a block diagram showing the configuration of a pulse manual control circuit in a conventional periodic calculation device, and FIG. 7 is a time chart showing a comparison of the operations of the conventional periodic calculation device and the periodic calculation device of the present invention. 22...Kalman) Chang airflow meter 45...1 chip CPU 52...ALU (logic operation circuit) 57...Pulse human control circuit 60...FRC (free run counter) 62...
・Edge detection circuit 64...ICR (input capture register) 66...Interrupt control circuit 6th...TSR (timing setting register) 70...
・TC (timing counter) 72...Comparator 74...-number output circuit 76...Timing counter control circuit 7th...IPC (human pulse counter) 80...IPCR (human pulse counter) count register)

Claims (1)

[Scope of Claims] A clock circuit that measures time; an edge detection circuit that detects the rising or falling edge of an input pulse; and receiving an edge detection signal from the edge detection circuit, reads and stores the current time from the clock circuit. an interrupt control circuit that also receives an edge detection signal from the edge detection circuit and issues an interrupt request; a logic operation circuit that calculates the period of the input pulse from the deviation of at least two past measurement results of the time measurement circuit according to a preset program; and the interrupt control circuit. Counts the edge detection signal output from the edge detection circuit until a predetermined time elapses after the interrupt request is made, and prohibits input of the edge detection signal to the time measurement circuit and interrupt control circuit. an input pulse count circuit is provided, and the logic operation circuit calculates the pulse by dividing the deviation of at least two past measurement results of the time measurement circuit by the count result of the input pulse count circuit in the interrupt processing. A pulse signal period calculation device, characterized in that it is configured to calculate a period.