JPH05276560A - Data storage method at momentary interruption in remote controller for hot water supply equipment - Google Patents

Abstract

PURPOSE:To provide the data storage method at the time of momentary interruption in a remote controller for a hot water supply equipment in which a data storage time at momentary power interruption is extended without use of a special hardware. CONSTITUTION:A microcomputer 4 calculates a check sum of data to be stored and stores the result to a RAM 5 in advance. When a power supply voltage of the microcomputer 4 is dropped from a prescribed voltage due to momentary power failure or the like. When the power supply voltage restores to the prescribed voltage or over, the microcomputer 4 reads the data to be stored in the RAM 5, calculates the check sum, compares the check sum and that stored in the RAM 5 and initializes the data stored in the RAM 5 other than those to be stored when the both are coincident and initializes all the contents of the RAM 5 when the both are noncoincident.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an RA for storing data.
The present invention relates to a data storage method at a momentary power failure in a remote controller (hereinafter referred to as a remote controller) of a water heater including a microcomputer having M (hereinafter referred to as a microcomputer).

[0002]

2. Description of the Related Art Conventionally, in a remote controller for a water heater equipped with a microcomputer, when the power supply voltage falls below the operation limit of the microcomputer, for example, 4.5 V, during a power failure, the reset terminal is set to low level and the microcomputer is reset by hardware. Was.
Then, when the power supply voltage returns to 4.5 V or higher, all the data has been lost because all the memories have been initialized.

Therefore, in order to extend the data retention time, the capacity of a capacitor for power supply backup is increased, the microcomputer is switched to a low power consumption mode when a power failure is detected, and the microcomputer is reset in two stages. Such a device was made.

[0004]

However, the conventional method has problems that the capacitor becomes large and the reset circuit becomes complicated.

An object of the present invention is to provide a data storage method at the time of a momentary power failure in a remote controller of a water heater which can extend the data retention time at the time of a momentary power failure without using special hardware.

[0006]

SUMMARY OF THE INVENTION The present invention is a data storage method at the time of a momentary power failure in a remote controller of a water heater equipped with a microcomputer having a RAM for storing data, wherein the checksum of the data to be held is stored in the microcomputer. When the power supply voltage returns to the predetermined voltage or higher after resetting the microcomputer when the power supply voltage of the microcomputer drops below a predetermined voltage due to an instantaneous power failure, In addition, by the microcomputer, the RA
The data to be held, which is stored in M, is read and its checksum is calculated.
Comparing with the checksum stored in AM, if the two match, initialize the contents of the RAM other than the data to be held, and if the two do not match, initialize the entire contents of the RAM. Is characterized by.

[0007]

First, the microcomputer calculates the checksum of the data to be held and stores it in the RAM in advance. Then, when the power supply voltage of the microcomputer drops below a predetermined voltage due to an instantaneous power failure or the like, the microcomputer is reset.
After that, when the power supply voltage returns to above the specified voltage,
The microcomputer reads out the data to be held stored in the RAM, calculates the checksum of the data, compares the checksum with the checksum stored in the RAM, and if both match, the contents of the RAM are confirmed. Initialize data other than the data that should be held, and if both do not match, RAM
Initialize all contents of. Therefore, when there is an instantaneous power failure, RA
If the power supply voltage is restored before the storage limit of M drops to, for example, about 2 V, the data to be retained will not be lost and the data retention time at the momentary power failure can be favorably extended.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 is a schematic configuration diagram of a water heater equipped with a remote controller that employs a data storage method during an instantaneous power failure according to an embodiment of the present invention. A water heater body 1 is provided with a controller 2. A remote controller 3 is connected to the controller 2, and a microcomputer 4 is installed in the remote controller 3. A RAM 5 is installed in the microcomputer 4. Controller 2
Responds to signals from the remote controller 3 etc.
Control various equipment. The remote controller 3 supplies a signal to the controller 2 and displays the operating state of the water heater body 1 based on the operation of the user. The microcomputer 4 arithmetically processes various input signals of the remote controller 3. The RAM 5 stores data to be retained.

FIG. 2 is an explanatory diagram of the contents of the RAM 5, area A
The checksum of the data to be held in the area B, the checksum of the data to be held in the area B, the inverted data of the data to be held in the area C, and the checksum of the data to be held in the area D. Are stored respectively.

Next, the operation of the microcomputer 4 during an instantaneous power failure will be described with reference to the flowchart of FIG. In advance, the microcomputer 4 calculates a checksum of the data to be held stored in the area A of the RAM 5 and stores it in the area B, creates inverted data of the data to be held and stores it in the area C, A checksum of data that is the data to be held is inverted and stored in the area D. When the power backup capacitor is discharged during the momentary power failure and the power supply voltage of the microcomputer 4 drops below the operation limit of the microcomputer 4, for example, 4.5 V, the reset terminal of the microcomputer 4 becomes low level, Will be reset. Then the momentary power failure is released and the power supply voltage is 4.5V.
After returning to the above, the microcomputer 4 reads out the data to be held from the area A of the RAM 5, calculates the checksum thereof, reads the checksum from the area B of the RAM 5, compares both checksums, and further stores the checksum of the RAM 5. Read the inverted data of the data to be held from the area C,
The checksum is calculated and the area D of the RAM 5 is calculated.
The checksum is read from and the two checksums are compared (step S1). Next, it is determined whether the two checksums thus compared are equal to each other (step S2),
If they are equal, data other than the data to be held in the area A of the RAM 5 is initialized (step S3). That is, when the power supply voltage does not drop below the storage holding limit of the RAM 5, for example, 2 V during the momentary power failure, the data in the RAM 5 is not destroyed, and the two sets of checksums are equal. Therefore, if the two sets of checksums are equal to each other, it is determined that the data to be held in the area A has been correctly saved, and that data is not initialized, but the other data is initialized. On the other hand, if it is determined in step S2 that at least one of the two sets of checksums is not equal, then all the data in the RAM 5 is initialized (step S4). That is, when the power supply voltage drops below the storage holding limit of 2V of the RAM 5 during an instantaneous power failure, the data in the RAM 5 has been destroyed, so there is little possibility that the two sets of checksums are equal. Therefore, if at least one of the two sets of checksums is not the same, it is determined that the data to be held in the area A is not correctly stored, and all the data is initialized.

As described above, after the momentary power failure, the data to be held is read from the area A of the RAM 5 to calculate the checksum thereof, and the checksum is read from the area B of the RAM 5 to compare both checksums. , R
The inverted data of the data to be held is read from the area C of the AM5, the checksum thereof is calculated, and the RAM5
The checksum is read out from the area D of No. 2 and the two checksums are compared. If the two checksums compared are equal, the data to be held in the area A of the RAM 5 is not initialized. Even if is reset, the data to be held is not initialized unless the power supply voltage falls below the storage holding limit of the RAM 5 and the data is destroyed. Therefore, the data holding time at the time of momentary power failure can be favorably extended without using special hardware.

That is, as shown in FIG. 4, even if a momentary power failure occurs at time t _{1 and the} power supply voltage drops from 5V to 4.5V at time t ₂ and the microcomputer 4 is reset, the power supply at time t ₃ If the power supply voltage returns to 4.5 V or higher as indicated by the alternate long and short dash line before the voltage drops to 2 V, the data to be held will not be initialized,
The data holding time can be extended by the time t ₃ -t ₂ as compared with the conventional case.

Further, as in the above embodiment, both the checksum of the data to be held and the checksum of the inverted data of the data to be held are calculated and compared with each checksum stored in the RAM 5. By doing so, data destruction can be detected more reliably.

In the above embodiment, both the checksum of the data to be held and the checksum of the inverted data of the data to be held are calculated and compared with each checksum stored in the RAM 5. However, the present invention is not limited to such a configuration, and comparison of checksums of inverted data may be omitted, for example.

[0015]

The present invention is configured as described above, and is a data storage method at the time of a momentary power failure in a remote controller of a water heater having a microcomputer having a RAM for storing data, which is a checksum of data to be held by the microcomputer. Is stored in RAM in advance, and when the power supply voltage of the microcomputer drops below a predetermined voltage due to an instantaneous power failure, the microcomputer is reset, and when the power supply voltage returns to a predetermined voltage or higher, , Read the data to be held stored in the RAM, calculate the checksum, compare the checksum with the checksum stored in the RAM, and hold the contents of the RAM if they match. Initialize data other than the expected data, and if both do not match, R
Since all the contents of AM are initialized, even if the microcomputer is reset during a momentary power failure, the data to be retained must be initialized unless the power supply voltage drops below the memory retention limit of RAM and the data is destroyed. There is no. Therefore, the data holding time at the time of momentary power failure can be favorably extended without using special hardware.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a water heater equipped with a remote controller that employs a data storage method during an instantaneous power failure according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of the contents of RAM.

FIG. 3 is a flowchart illustrating the operation of a microcomputer.

FIG. 4 is an explanatory diagram of changes in the power supply voltage of the microcomputer during an instantaneous power failure.

[Explanation of symbols]

 1 Water heater main body 3 Remote control 4 Microcomputer 5 RAM

Claims (1)

[Claims] 1. A data storage method at the time of an instantaneous power failure in a remote controller of a water heater including a microcomputer having a RAM for storing data, wherein a checksum of data to be held is calculated by the microcomputer and stored in the RAM in advance. The RAM is stored in the RAM by the microcomputer when the power supply voltage of the microcomputer is reset to a predetermined voltage or more after the power supply voltage of the microcomputer drops below a predetermined voltage due to an instantaneous power failure. The data to be held stored in the RAM is read out, its checksum is calculated, and the checksum is compared with the checksum stored in the RAM. Data other than the data to be retained is initialized, and if the two do not match, the entire contents of the RAM are initialized. Data storage method for remote control during momentary power failure.