JP2001183478A - Microcomputer system and electronic watt-hour meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a self-judgement on the abnormality of clocking function of a clock earlier, in accordance with the operation of a clocking quartz oscillator. SOLUTION: This microcomputer system which operates with a microcomputer-operated clocked and clocks using a clock 3 clocking according to the operation of a clocking quartz oscillator 1 separately from the microcomputer operated clock judges that the clocking is abnormal, when the frequency or cycle of pulses output by the clocking quartz oscillator or their divided pulses in not within a prescribed range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microcomputer system having a clock function and an electronic watt-hour meter, and more particularly to a microcomputer system and a watt-hour meter having a clock for clocking separately from a clock for operating the microcomputer system. It is.

[0002]

2. Description of the Related Art In a conventional microcomputer system using a quartz oscillator for timekeeping separately from the operation of itself,
The timekeeping hardware performs the timekeeping process independently of the microcomputer program, or obtains timing such as seconds from the timekeeping hardware, and the microcomputer program performs the timekeeping process. For example, a conventional electronic watt-hour meter has two clocks: a clock for microcomputer operation and a clock for timekeeping.
Have different clocks. A clock oscillated using a high frequency (usually several MHz) crystal oscillator is used as a clock for microcomputer operation, and a clock for clocking time is 50 Hz or 60 Hz when the power is on.
Of the commercial frequency, and a low frequency (32.
The clock oscillated using a clock oscillator for timekeeping of 768 kHz is frequently used and used as a clock for timekeeping. Further, when the power failure state continues for a long time, the oscillation of the clock for timekeeping is stopped to achieve low power consumption in order to reduce the consumption of the mounted battery.

In addition, when shifting from a long-lasting power failure state to a power-on state, the time until oscillation stabilization is measured in order to confirm oscillation of the timekeeping crystal oscillator, and normal oscillation is confirmed. I have. This example will be described with reference to the drawings. FIG.
Is an example of an oscillation circuit using an inverter, 21 is a crystal oscillator for timekeeping, 22 and 23 are inverters, 24 is a resistor, and 25 and 26 are capacitors. FIG. 8 shows the operation waveform at that time, and Vp1 is the connection point P between the inverters 22 and 23.
1, and Vp2 indicates the waveform at the output terminal P2 of the inverter 23. In this operation, the period of the waveform Vp2, which is the pulse output of the timekeeping crystal unit 21, is measured in the vicinity of the lapse of the time T from the power-on, and it is confirmed whether the predetermined period t is continuously output. By doing
Confirmed normal oscillation.

[0004]

In the prior art, there are the following problems to be solved. -In the conventional technology, normal oscillation is confirmed when a power outage occurs for a long time, but in the current power situation in Japan, long-term power outage does not occur frequently, so normal oscillation is checked only occasionally. Not. Also, according to this method, if dust or foreign matter is attached to the oscillation circuit portion, the oscillation amplitude becomes unstable due to the influence of the foreign material or the like being moistened, the clock is chipped, and the time measured is counted. There is a problem going crazy. In particular, when the system is used for a long period of time, when dust or foreign matter adheres to the soldered part of the timekeeping crystal oscillator, or when the oscillation frequency is incorrect due to physical destruction of the timekeeping crystal oscillator In addition, there is a problem that the wrong time is measured without noticing that the user is out of order, and the error is accumulated.・ Electronic watt-hour meters, which are used especially for money transactions, sometimes use charges differently depending on the time of day when electricity is used, and the time error is a very serious problem.

SUMMARY OF THE INVENTION An object of the present invention is to provide a microcomputer system having a timekeeping function, and a timekeeping function based on the operation of the quartz oscillator for timekeeping in an electronic watt-hour meter equipped with the microcomputer system. It is an object of the present invention to provide a microcomputer system and an electronic watt-hour meter capable of early self-determination of abnormality of the electric power.

[0006]

According to a first aspect of the present invention, there is provided a quartz oscillator for clocking a time independently of a clock for operating a microcomputer. In a microcomputer system that performs timekeeping with a timekeeping clock generated based on the operation of the above, the frequency or cycle of a pulse output from the timekeeping crystal oscillator or a frequency-divided pulse thereof is not within a predetermined range. Sometimes, it is determined that the time measurement is abnormal.

According to a second aspect of the present invention, there is provided an electronic watt-hour meter equipped with the microcomputer system according to the first aspect of the present invention, wherein the time measuring device is used at the time of a power failure. It is characterized in that the abnormality determination of the clock is always performed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention uses a microcomputer program to oscillate the oscillation frequency of a quartz oscillator for timekeeping, or
The cycle of dividing the oscillation output pulse is monitored, and if there is an abnormality, the time user is made to notify the time user by some means that the stored time is abnormal. Details will be described below with reference to FIGS.

FIGS. 1 and 2 show the configuration of an embodiment of the present invention. A clock oscillator 1 for timekeeping is connected to a real-time clock generator 2, which counts the oscillation pulses of the crystal oscillator 1 and counts the time.
Done within. The CPU 6 reads the time data 5 from the real-time clock generation circuit 2 as necessary, and inputs the one-second pulse signal 3 output from the real-time clock generation circuit 2 for monitoring. As an operation clock of the CPU 6, a clock obtained by dividing a pulse of the microcomputer operation crystal oscillator 7 is used, and a one-second pulse signal 3 (time clock) input from the real-time clock generation circuit 2 according to the cycle of the microcomputer operation clock is used. Clock accuracy) is determined. That is, the one-second pulse signal 3 input from the real-time clock generation circuit 2 is 1
The pulse period is doubled by the 分 frequency divider 9, and 1 second H
C for the state signal 11 which becomes a signal of “low” for 1 second.
It is input to the interrupt signal terminal 13 of PU6. The AND gate 10 outputs the signal of 1 second High and 1 second Low and the CPU
By performing an AND operation with the microcomputer operation clock 8 from 6, the microcomputer operation clock 8 is output for one second and a signal for stopping the microcomputer operation clock 8 for one second is generated. This is input to the counter 12 inside the CPU 6. On the other hand, as the program processing of the CPU 6, the interrupt processing is in the stopped state of the counter 12 (the state signal 11 is Low).
At the moment when the level is reached), and when this interrupt occurs, the counter 12 checks the count value for one second to determine whether or not it is within the specified range. To detect. Thereafter, the counter 12 is set to the initial state in preparation for the next counting operation. The time display 14 normally displays the current time, and displays an abnormality when an abnormality is detected.

FIG. 3 is a signal waveform diagram for supplementarily explaining the operation of the circuit shown in FIG. Since the interrupt timing occurs at times T1 and T2, that is, every two seconds, CP
U6 is a one-second pulse signal 3 that is always generated based on the operation of the quartz crystal 1 for time keeping while performing time keeping processing.
(Timekeeping clock) is determined to be abnormal.

When the microcomputer system shown in FIGS. 1 and 2 is mounted on an electronic watt-hour meter, a CPU 6, a crystal oscillator 7 for microcomputer operation, a time display 14, a crystal for timekeeping are usually provided by a commercial power supply. The vibrator 1, the real-time clock generation circuit 2 and the control circuit 4 operate, but the one-second pulse signal 3 generated by the time-keeping crystal resonator 1, the real-time clock generation circuit 2 and the control circuit 4 is used as a time-keeping clock. Is not used. When the commercial power is supplied, the frequency obtained by dividing the commercial frequency is used by the CPU 6 as a clock for timekeeping since the frequency is high precision, and timekeeping is performed. When the commercial power supply fails, the power supply is switched to a power supply for power failure such as a battery (not shown), and the 1-second pulse signal 3 generated by the quartz crystal for timekeeping 1, the real-time clock generation circuit 2 and the control circuit 4 is used for timekeeping. It is used by the CPU 6 as a clock for use.

If the power failure continues for a long period of time (for example, 10 days), the real-time clock generation circuit 2 stops operating in order to reduce the consumption of the battery serving as the power failure power source.

FIG. 4 is a flowchart showing the interrupt processing of the CPU 6. In step S1, an abnormality flag (RT
(Variable such as C-ERR) is set to detect whether or not the real-time clock generation circuit 2 is abnormal. If it has been set, this interrupt processing ends. If not set, the contents of the counter 12 in FIG. 2 are read in step S2, and the contents of the counter 12 are cleared to the initial state in step S3. Thereafter, in step S4, it is determined whether the contents of the counter 12 read in step S2 are normal. If it is determined in step S4 that an abnormality has occurred, an abnormality flag (RTC-ERR) indicating an abnormality in the real-time clock generation circuit 2 is determined in step S5.
) Is set, and the abnormality processing in step S6 is executed.
Here, the abnormality processing in step S6 indicates special processing such as sounding a buzzer when an abnormality is detected. Therefore, it is unnecessary when there is no special processing.

FIG. 5 is a flow chart showing the time display process, but it may not be necessary depending on the constituent systems. In step S11, an error flag (RTC-ERR
Check if) is set. If it is not set, the time is read from the real-time clock generation circuit 2 in step S12 (or in the case of an electronic watt-hour meter, the time is measured in the CPU 6 using a clock for time measurement obtained by dividing the frequency of the commercial power supply). To use the time of the time counting process) to generate time display data. If it is set, abnormal display data is generated in step S13 in order to notify an abnormal situation.
At 4, the time is displayed by the time display 14. As an example of a display at the time of abnormality, a display different from the time is performed as shown in FIG. Thus, when an abnormality is detected in the real-time clock generation circuit 2, a character or graphic indicating the abnormality is displayed, and when no abnormality is detected, the current time is displayed.

FIG. 6 is a flowchart showing an example of the case where the time is transmitted by communication. Normally, when sending time by communication, a method of transmitting some data and attaching the time in order to clarify the time at which the data was sent is often used. FIG. 6 shows a flow in the case of sending some data and then sending the time. In FIG. 6, some data is transmitted in step S21. afterwards,
In step S22, it is checked whether an abnormal flag (RTC-ERR) is set. If it is set, it is considered that an abnormality has occurred at the time of clock measurement, and abnormal-time transmission data is generated in step S24. If the abnormality flag (RTC-ERR) has not been set in step S22, the current time is read from the real-time clock generation circuit 2 in step S23 (or, in the case of an electronic watt-hour meter, the commercial power Using the time that has been time-measured in the CPU 6 or the like using a time-measuring clock obtained by dividing the frequency), time transmission data is generated. Thereafter, the time is transmitted in step S25. Thus, when an abnormality is detected in the real-time clock generation circuit 2, time data at the time of abnormality is transmitted, and when no abnormality is detected, the current time is transmitted.

In the above description, whether the period of the one-second pulse signal 3 as the clock for timekeeping is within the specified range is determined as normal or abnormal. Normal or abnormal may be determined based on whether or not the frequency or cycle of the output pulse or its divided pulse falls within a prescribed range.

[0017]

As described above, according to the present invention,
In a microcomputer system having a timekeeping function and an electronic watt-hour meter equipped with the microcomputer system, it is possible to early self-determine an abnormality of the timekeeping function based on the operation of the quartz oscillator for timekeeping.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a more detailed configuration of an embodiment of the present invention.

FIG. 3 is a diagram showing signal waveforms at various parts in FIG. 2;

FIG. 4 is a flowchart showing an interrupt process of the CPU of FIG. 1;

FIG. 5 is a flowchart showing a display process of a CPU in FIG. 1;

FIG. 6 is a flowchart illustrating an example of communication processing of a CPU in FIG. 1;

FIG. 7 is a diagram illustrating an example of a conventional oscillation circuit using an inverter.

8 is a diagram showing operation waveforms in the oscillation circuit of FIG.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 timekeeping crystal oscillator 2 real-time clock generation circuit (timekeeping clock) 3 1-second pulse signal 4 control circuit 5 time data 6 CPU 7 microcomputer operation crystal oscillator 8 microcomputer operation clock 9 1/2 frequency divider circuit DESCRIPTION OF SYMBOLS 10 AND gate 11 Status signal 12 Counter 13 Interrupt signal terminal 14 Time indicator

Claims (2)

[Claims] 1. A microcomputer system which operates with a microcomputer operation clock and performs time measurement with a time measurement clock generated based on the operation of a time measurement crystal oscillator separately from the microcomputer operation clock. When the frequency or cycle of a pulse output from the quartz crystal for timekeeping or a frequency-divided pulse thereof is not within a predetermined range, the timekeeping is determined to be abnormal. Microcomputer system. 2. An electronic watt-hour meter equipped with the microcomputer system according to claim 1, wherein an abnormality determination of said time clock used at the time of a power failure is always performed. Watt hour meter.