JPS62286142A - Method for detecting breakage of storage contents of volatile memory - Google Patents

Abstract

PURPOSE:To detect the breakage of the storage contents of a volatile memory by checking plural data needed to be stored double out of the control arithmetic data used for control every time a power supply is applied. CONSTITUTION:A main control circuit 3 contains a CPU 31, a ROM 32 and an I/O 33. A power supply 1 is applied to the circuit 3 when a key switch 2 is turned on and the voltage is always applied to the RAM 4 from the power supply 1. The input is received from a sensor via the I/O 33 and the read data is written to a read data store area of the RAM 4. The same value is written to a storing area for control arithmetic data of the RAM 4 as long as the sensor has no abnormality. The switch 2 is turned on for comparison between the read data received from the sensor in a power supply application mode and the data stored in the arithmetic data storing area of the RAM 4. When the coincidence is obtained between both data, it is decided that the power supply of the RAM 4 is never cut off from the preceding OFF mode of the switch 2.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] The present invention provides a volatile memory that detects that the stored contents of a volatile memory in an automobile control device are destroyed due to a power cut, etc. The present invention relates to a method for detecting memory content corruption.

[Prior art]

Conventionally, as a technology in this field, there is
There is one disclosed in Japanese Patent No. 4850. The method for detecting the destruction of the storage contents of volatile memory is to
A specific pattern (for example, 1, 2, 3.5) stored in
numbers, random numbers, etc.) and the specific pattern in the specific pattern storage section in volatile memory (RAM, etc.), and if there is even one discrepancy, clear the entire volatile memory section, and at the same time The contents of the fixed memory are transferred to the pattern storage unit in their entirety. Furthermore, if all of the specific patterns match, the contents of the data storage section are odoriferous, and the data stored in this data storage section is used to
is in control.

[Problem that the invention seeks to solve]

However, in the conventional method described above, since it is necessary to provide a portion in the memory for storing only a specific pattern, there is an inconvenience that the memory capacity cannot be used effectively in a control device equipped with a memory having a small storage capacity.

The present invention has been developed in view of the above-mentioned problems, and the present invention eliminates the above-mentioned problems and uses control data etc. to detect whether or not the stored contents of the volatile memory have been destroyed due to a power cut, etc. An object of the present invention is to provide a content destruction detection method.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention compares and checks a plurality of pieces of control calculation data used for control that need to be stored in duplicate each time the main control circuit is powered on. If even one of the stored data is different, all the data is rewritten and set to a certain value, and if all the data stored twice is the same value,
It is configured so that it can be controlled as is without rewriting data.

[Effect]

As described above, the method for detecting storage content destruction in a volatile memory according to the present invention is applicable to a plurality of pieces of control calculation data used for control that need to be stored in duplicate, each time '@t, R is input. Since the checking method is adopted, there is no need for a storage section to write a specific pattern for checking into the non-volatile memory, and it is possible to detect the destruction of the stored contents of the volatile memory due to a power cut, which makes it possible to use the memory capacity effectively. , you can use a memory with a small storage capacity,
It is possible to reduce the cost of the control device by downsizing the circuit and reducing the number of parts.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a schematic diagram showing a circuit configuration of a control device to which a volatile memory storage content destruction detection method according to the present invention is applied. In the figure, 1 is a power supply, 2 is a key switch,
3 is a main control circuit, and 4 is a volatile memory. The main control circuit 3 includes a central processing unit (CPU) 31 and a non-volatile memory 3.
2 and an input/output interface (Ilo) 33. Further, a random access memory (RAM) is used as the volatile memory 4, and a read only memory (ROM) is used as the nonvolatile memory 32. In the case of an automobile, a storage battery is used as the power source 1, and when the key switch 2 is turned on, the main control circuit 3 is powered on.

Further, a T source voltage is constantly applied to the volatile memory 4 from the power supply 1.

In an automobile control device, input/output interface 3
This is done by the sensor input from 3 or the input signal from the switch, but in order to implement a self-diagnosis function for the sensor input, the read data from the sensor is written to the read data storage area of the volatile memory 4, and the sensor is If there is no abnormality, the same value as the read data is written into the control calculation data storage area of the volatile memory 4.

FIG. 2 is a flowchart showing the procedure for detecting power cutoff. First, turn on the key switch 2 to turn on the power. Next, the number of data N to compare the counter setting value i
Step 101), the data read from the sensor when the power is turned on is compared with the control calculation data stored in the control calculation data storage area of the volatile memory 4, and it is determined whether the two are the same. If they are the same, it means that the power to the volatile memory 4 has not been cut off since the last time the key switch was turned off. ” or all 11 (step 103). When the volatile memory 4 is powered on, the bit pattern of the control calculation data is either all 10's or all 1's.
1j may occur, but when the signal is input from the sensor, the bit pattern of the control calculation data is all 10.
"or 11" means a power outage or short circuit in the sensor, so if all bit patterns are "OJ" or "11"
If yes, then it is determined whether or not N pieces of data have been compared (step 105); if N pieces of data have not been compared, the process returns to step 102 and repeats the process. In step 102, if the control calculation data and the read data do not match, "
-1'' (step 104). In addition, in step 103, if the bit pattern of the control calculation data is all 10'' or all 11'', 1-1'' is similarly subtracted from the counter setting value i (step 1
04). In step 105, it is determined whether the count value i of the counter is equal to the number N of comparison data, and if the count value i is equal to the number N of comparison data, it is determined that the stored contents of the volatile memory 4 have not been destroyed. Then, the process moves to the next step, and if the count value i is not equal to the number N of comparison data, initial data is written into the volatile memory 4 (step 107).

According to the above embodiment, the nonvolatile memory 3 of the main control circuit 3
2, it is possible to detect power cut-off of the volatile memory 4 without the need for a memory section in which a specific pattern is written to detect destruction of the memory contents of the volatile memory 4, and the non-volatile memory 32 can be used effectively. becomes possible.

〔Effect of the invention〕

As explained above, according to the present invention, there is no need to provide a storage unit for writing a specific pattern to the nonvolatile memory, and it is possible to detect destruction of stored contents due to power cutoff of the volatile memory, etc., thereby effectively utilizing the capacity of the nonvolatile memory. In addition, since a non-volatile memory with a small storage capacity can be used, the cost of the control device can be reduced by downsizing the circuit and reducing the number of parts.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a circuit configuration of a control device to which a volatile memory storage content destruction detection method according to the present invention is applied;
FIG. 2 is a flowchart showing the procedure for detecting power cutoff. In the diagram, 1...power supply, 2...key switch, 3...
...control circuit, 4 volatile memory.

Claims (1)

[Claims] In a control device comprising a volatile memory and a main control circuit that includes a nonvolatile memory and performs arithmetic processing according to data from the nonvolatile memory, using specific data written to a plurality of locations in the volatile memory, A volatile memory characterized in that when power is applied to the main control circuit, the plurality of data are compared and it is detected whether or not the stored contents of the volatile memory are destroyed based on whether they match or not. Memory content corruption detection method.