JPH0519912A - Controller - Google Patents

Abstract

PURPOSE:To secure the safety of the equipment even in an unexpected condition such as power failure or the like and to recover a control state to a state before the power failure in the case of recovering a power source at the control equipment which operation is controlled by a microcomputer. CONSTITUTION:The output of a power failure detection part 9 to detect the generation of power failure is inputted to a microcomputer 10 which controls the equipment. According to the output of the power failure detection part 9, the microcomputer 10 writes the control state of the equipment in a state storage part 11. When the power failure is recovered, the microcomputer 10 is initialized by a reset part 2 and afterwards, control data are read from the state storage part 11. According to the output of a power failure time measuring part 12 to measure the time of power failure from the generation of power failure to the recovery of power failure, the control data read from the state storage part 11 are selected, and the microcomputer is recovered to the state of the selected control data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device whose operation is controlled by a microcomputer such as a water heater.

[0002]

2. Description of the Related Art Conventionally, a control device of this type has a structure as shown in FIG. The configuration will be described below. As shown in the figure, the microcomputer 1 controls the entire device, and the reset unit 2 resets the microcomputer 1 at a predetermined voltage or less. The power supply unit 3 comprises a commercial power supply 4, a transformer 5 and a bridge diode 6, and applies a constant voltage to the microcomputer 1 via a smoothing capacitor 7 and a constant voltage power supply 8. The power failure detection unit 9 detects a power failure by stopping the pulse synchronized with the power supply frequency. The operation of the above configuration will be described. When the commercial power supply 4 is stopped while the microcomputer 1 is controlling the device, the microcomputer 1 receives a signal from the power failure detection unit 9 to detect the power failure of the power supply and turn off the load. When the resetting unit 2 resets the device and the commercial power supply 4 is restored after performing safety measures such as turning off the power and reducing the power consumption, the system is restarted from the initial state.

[0003]

In such a conventional control device, the safety of the device can be ensured even in the event of a power failure, but the microcomputer 1 is initialized when the commercial power supply 4 is restored. In addition, there are problems that it takes a very long time to return to the state before the power outage, or that the stopped state is kept and the state before the power outage is not returned.

The present invention solves the above problems, and provides a control device capable of ensuring the safety of the device even in the event of a power failure and returning the control state to the state before the power failure when the power is restored. It is an object.

[0005]

In order to achieve the above object, the present invention provides a microcomputer for controlling equipment, a reset unit for initializing the microcomputer, and a microcomputer for detecting the occurrence of a power failure. An output power failure detection unit, a status storage unit in which the device control status is written from the microcomputer according to the signal of the power failure detection unit, a power failure time from the occurrence of a power failure to a power failure recovery, and the microcomputer responds to the power failure time. A power failure time measuring unit for outputting, the microcomputer reads control data from the state storage unit after being initialized by the reset unit at the time of power failure recovery, and outputs the power failure time measuring unit. Select the control data read from the status storage section and restore the selected control data status. That in the as are the means for solving the problems.

[0006]

According to the present invention, the control means can be operated in the same state as that before the power failure even after the power failure is recovered because the control state at the time of the power failure detection is read at the time of the power failure recovery. It is also possible to distinguish the power failure for a predetermined time or longer in the section and select the control data read from the state storage section so as not to return to the control state before the power failure.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The same components as those of the above-mentioned conventional example are designated by the same reference numerals and the description thereof will be omitted.

As shown in the figure, the microcomputer 1
0 is for controlling the device, and the current device control data is sent to the state storage unit 11 by the power failure detection signal from the power failure detection unit 9.
After being written in, the reset unit 2 initializes and stops. The state storage unit 11 is composed of a non-volatile memory. Upon recovery from a power failure, the microcomputer 10 is initialized and activated by the reset unit 2. The startup microcomputer 10 reads the control data written in the state storage unit 11 and inputs the signal of the power failure time measuring unit 12 that outputs according to the power failure time, and responds to the signal of the power failure time measuring unit 12 according to the signal. The control data read from the state storage unit 11 is selected, and the control state of the device is restored to the state of the selected control data. The power failure detection unit 9 is the power supply unit 3
The resistors 13 and 14 connected to the output of, the resistor 15 connected to the output of the constant voltage power source 8 and the transistor 16,
The connection point between the resistor 15 and the transistor 16 is connected to the input of the microcomputer 10. Blackout time measuring unit 12
Is a resistor 17 and a diode 1 between the constant voltage power source 8 and GND.
8 and the capacitor 19 are connected in series, and the diode 1
8 and the capacitor 19 are connected to the base of the transistor 21 via the resistor 20, the resistor 22 is connected in series to the transistor 21, and the constant voltage power source 8 is connected to the resistor 22.
The connection point between the
Connected to 0 input.

The operation of the above configuration will be described. When a power failure occurs, the commercial power supply 4 is stopped and the transistor 1 is stopped.
6 is stopped, the power failure detection unit 9 to the microcomputer 1
A power failure is detected when the signal to 0 stops. The microcomputer 10 writes the current control data to the non-volatile memory, which is the state storage unit 11, while the capacitor 7 accumulates the electric charge capable of sufficiently operating the circuit. After that, when the power supply voltage becomes equal to or lower than the reset voltage of the reset unit 2 due to the discharging of the capacitor 7, the initialization of the microcomputer 10 is stopped. When the power is restored,
The microcomputer 10 is initialized and activated when the reset unit 2 reaches a predetermined voltage or higher, and reads the control data written in the nonvolatile memory. At this time, data to be re-executed is selected from the read control data according to the output of the power failure time measuring unit 12.

The capacitor 19 of the power failure time measuring unit 12 is
It is charged up to the power supply voltage with the time constant of the resistor 17 and the capacitor 19, and is discharged through the transistor 21 with the time constant of the resistor 20 and the capacitor 19. Therefore, the capacitor 19
Is charged, the transistor 21 can continue to be turned on by the discharge current of the capacitor 19 even if the power supply voltage becomes 0 V due to a power failure, and the voltage across the capacitor 19 is discharged to VBE or less of the transistor 21 or less. The output to the microcomputer 10 is kept low at the momentary voltage stop in which the power supply is restored during the period. By adjusting the resistance values of the resistors 17 and 20, it is possible to measure a power failure period that is longer than or equal to a predetermined time, and the microcomputer 10 is initialized by the reset unit 2 and reads the control data from the nonvolatile memory. At this point, when there is a power failure for a predetermined time or longer in the state of the signal from the power failure time measuring unit 12, it is possible to select not to use a part of the read control data.

FIGS. 3A to 3D are timing charts at the time of power failure and recovery in the circuit configuration of FIG.
In order to make the explanation easy to understand, the device is a water heater, and the data written in the state storage unit (non-volatile memory) 11 is two types of data: total usage time data and combustion state data of the device, and the power failure time is within a predetermined time Shall restore the total usage time data and restore the combustion state to the state before the power failure after the power failure recovery, and only restore the total usage time data when the power failure time is longer than a predetermined time.

When the power is turned on at the timing t1 in FIG. 3, the voltage VDD of the constant voltage power source 8 rises, and when the voltage VDD exceeds VRTH, the output VRST of the reset section 2 becomes high at the time t2 and the microcomputer 10 is initialized. Activate. At time t1, the voltage VC of the capacitor 19 is
Has been completely discharged, charging starts with the time constant of the resistor 17 and the capacitor 19. The input voltage VIN from the power failure time measuring unit 12 to the microcomputer 10 becomes equal to the power supply voltage until the voltage VC of the capacitor 19 becomes equal to or higher than VQTH, that is, VBE of the transistor 21. Therefore, in the case of a power failure for a long time which exceeds the time when the capacitor 19 is completely discharged, VIN becomes high at time T1 after being reset at time t2. Therefore, the microcomputer 10 operates to cancel the combustion control data out of the total usage time data and the combustion state data read at the time of initialization start.

When a power failure occurs at the timing t3,
The microcomputer 10 writes the current total usage time data and the combustion state data to the non-volatile memory by the time t4 due to the signal stoppage of the power failure detection unit 19, and VDD becomes VR.
The initialization is stopped at the timing t4 when it becomes TH or less. From this time, the capacitor 19 starts discharging with the time constant of the resistor 20. Even if the voltage VC of the capacitor 19 drops due to this discharge, the input voltage VIN to the microcomputer 10 remains low until it becomes VQTH or less. When the power supply voltage is restored in this state (timing t4), the input voltage VIN is low at the time t6 of initialization startup,
Both the total usage time data and the combustion state data that have been read will be restored.

[0014]

As is apparent from the above embodiments, according to the present invention, the microcomputer reads the control data from the state storage unit after being initialized by the reset unit at the time of power failure recovery, and the power failure time measuring unit. The control data read from the status storage section is selected by the output of the above, and the state of the selected control data is restored.Therefore, a safe stop of the equipment due to a power failure is ensured, and the power failure occurs within the time that can be set arbitrarily. As long as it is possible to return to the state at the time of a power failure, it is possible to provide a user-friendly control device.

Further, when the microcomputer is stopped, the output from the power failure time measuring unit is lower than the power supply voltage of the microcomputer, so that there is no danger of latch-up of the microcomputer.

[Brief description of drawings]

FIG. 1 is a block diagram of a control device according to an embodiment of the present invention.

FIG. 2 is a control circuit diagram of the control device.

3 (a) to (d) are timing charts of voltages of respective parts of the control device.

FIG. 4 is a control circuit diagram of a conventional control device.

[Explanation of symbols] 2 reset section 9 Power failure detection section 10 Microcomputer 11 State storage 12 Power failure time measurement section

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shinji Miyauchi             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd.

Claims (4)

[Claims] 1. A microcomputer that controls equipment, a reset unit that initializes the microcomputer, a power failure detection unit that detects the occurrence of a power failure and outputs the power failure to the microcomputer, and a signal from the power failure detection unit that causes the power failure to occur. The microcomputer includes a state storage unit in which the device control state is written from the microcomputer, and a power failure time measuring unit that measures a power failure time from the occurrence of a power failure to a power failure recovery and outputs to the microcomputer according to the power failure time, When power is restored, the control data is read from the state storage unit after being initialized by the reset unit, and the control data read from the state storage unit by the output of the power failure time measuring unit is selected and selected. A control device that restores the state of control data. 2. The control device according to claim 1, wherein the state storage unit is composed of an electrically rewritable nonvolatile memory. 3. The power failure time measuring unit is provided between the power supply and the GND.
The resistor, the diode, and the capacitor are connected in series, and the diode and the capacitor are connected to the base of the transistor whose emitter is grounded through the second resistor,
2. The control device according to claim 1, wherein a power supply is connected to a collector of the transistor via a third resistor, and a connection point between the third resistor and the collector of the transistor is an output to a microcomputer. 4. The control device according to claim 1, wherein the output from the power failure time measuring unit to the microcomputer is lower than the power supply voltage of the microcomputer even during the power failure and after the power failure is restored.