JP2001273198A - Data writing device and data destruction detection device - Google Patents

Abstract

(57) [Problem] In a conventional data writing device and a data destruction detection device, there is a problem that data destruction cannot be detected due to destruction of a parity bit string. To provide a data writing device and a data destruction detection device which can be detected. A parity writing unit calculates a parity bit string based on input data, and a parity inversion unit inverts the parity bit string and stores the inverted parity bit string in a memory. The parity inversion unit 25 inverts the written parity bit string, the parity calculation unit 23 calculates the parity bit string from the current data, and the comparison unit 24 compares the calculation results of the parity inversion unit 25 and the parity calculation unit 23. This is a data destruction detection device that detects data destruction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data writing device and a data destruction detecting device for detecting data destruction on a memory, and more particularly to improvement of detection accuracy.

[0002]

2. Description of the Related Art In recent years, software and parameters required for processing by many embedded microcomputers are recorded in a nonvolatile memory such as an electrically programmable ROM (EPROM). This EPROM records each bit of data by a transistor, and controls the on / off of the transistor by injecting electrons into a floating gate to store bits. This EPROM
Regarding the principle and operation of storage retention of non-volatile memory,
The details are described on pages 256 to 258 of “Iwanami Koza Microelectronics 1 Microelectronics Device I” by Sugano et al., Published by Iwanami Shoten in 1985, and will not be described in detail here.

A conventional data writing device and data destruction detecting device will be described with reference to FIGS. As shown in FIG. 4, a conventional data writing device 10 includes an EPROM
The memory 1 stores data and parity bits calculated based on the data. The memory 1 basically includes a buffer 11, a parity calculation unit 12, and a writing unit 13. The conventional data destruction detection device 20 reads data from the memory 1 as shown in FIG. 5 and outputs the data and information of a comparison result indicating the presence or absence of destruction. It basically comprises a unit 21, a buffer 22, a parity operation unit 23, and a comparison unit 24.

Here, the buffer 11 holds the input data to be written. The parity operation unit 12
Each bit to be written stored in the buffer 11 is added, and the lower n bits (n is 1 or more) of the addition result are extracted and output as a parity bit string. The writing unit 13
In response to the input of the parity bit string, data to be written is acquired from the buffer 11 and stored together with the parity bit string. The stored result is as shown in FIG. 6A shows the case where n = 1, and FIG. 6B shows the case where n = 2.

On the other hand, the reading unit 2 of the data destruction detecting device 20
1 reads the data to be read from the memory 1, separates the data portion and the parity bit string portion, and outputs them to the buffer 22 and the comparison unit 24, respectively. The buffer 22
It receives and holds the data portion from the reading unit 21. The parity calculator 23 calculates an n-bit parity bit string of the data stored in the buffer 22. Comparison section 24
Compares the parity bit sequence read from the memory 1 input from the reading unit 21 with the parity bit sequence based on the data currently stored in the memory 1 input from the parity operation unit 23, and compares the comparison result. Is output.

The conventional data writing device 10 calculates a parity bit string of input data, and stores the data and the parity bit string in the memory 1. Where E
Regarding the data stored in the memory 1 such as a PROM, if the data “0” is a state where electrons are not stored in the floating gate and the data “1” is a state where electrons are stored in the floating gate, the electrons in the floating gate are deteriorated due to aging. A part of the data bits may be changed from “1” to “0” due to discharge (charge loss) (this is called data destruction). On the other hand, the probability that electrons are injected into the floating gate and change from “0” to “1” is very low in probability.

The data "00100" shown in FIG.
It is assumed that the lower third bit of “10111” changes from “1” to “0” and becomes “0010010011”.

Then, the reading section 21 of the conventional data destruction detecting device 20 outputs "0010010011" as a data portion, and outputs the parity bit "1" (when n = 1) or "01" (when n = 2). ) Is output. On the other hand, the parity bit calculated by the parity calculation unit 23 based on the data portion read by the reading unit 21 is “0” when n = 1 and “00” when n = 2. Therefore,
The comparison unit 24 detects that these values are different, and notifies the user that data corruption has occurred as a result of the comparison.

[0009]

However, in the above-described conventional data writing device and data destruction detecting device, n =
In the case of 1, when data destruction of two bits occurs, detection becomes impossible. Even when n = 2, for example, in the case of FIG.
When it changes to “1” and the lower bit of the parity bit string changes to “0” and becomes “00”, the read parity bit string and the parity bit string calculated based on the read data are one. There was a problem that detection was impossible.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a data writing device and a data destruction detecting device capable of reliably detecting data destruction of a plurality of bits.

[0011]

According to a first aspect of the present invention, there is provided a data writing apparatus for writing data on a memory, wherein a parity is provided for data to be written. A first operation unit for operating a bit string, a second operation unit for inverting each bit of the operated parity bit string, and a writing unit for writing the inverted parity bit string on the memory together with data to be written; And an insertion part.

[0012] Further, the invention according to claim 2 for solving the problem of the above-mentioned conventional example is capable of preventing data on a memory from being destroyed.
A data corruption detection device for detecting using a parity bit string stored on the memory together with the data, wherein the parity bit string is a result of inversion of a parity bit string based on data targeted for corruption detection at the time of writing data. An inversion operation unit that performs an inversion operation on each bit of the parity bit string that is an inversion operation result; a parity operation unit that calculates a parity bit string of current data on the memory; the inversion operation unit; And a detection unit that detects data destruction by comparing the calculation results of (1) and (2).

According to a third aspect of the present invention, there is provided a data corruption detecting apparatus for detecting data corruption in a memory using a parity bit string stored in the memory together with the data. The apparatus, wherein the parity bit string is a result of inversion of a parity bit string based on data to be destroyed detected at the time of writing data, and a parity calculation unit that calculates a parity bit string based on current data on the memory. An inversion operation unit that inverts each bit of the parity bit string based on current data, and a detection unit that detects data destruction by comparing the parity bit string on the memory with the operation result of the inversion operation unit. It is characterized by:

[0014]

Embodiments of the present invention will be described with reference to the drawings. A data writing device 30 according to an embodiment of the present invention writes data and a parity bit string into a memory 1, and as shown in FIG. 1, a buffer 11 and a parity operation unit as a first operation unit. 12 and
Writing unit 13 and parity inverting unit 14 as a second arithmetic unit
It is basically composed of The data destruction detection device 40 according to the present embodiment reads data from the memory 1 and outputs the data and information of a comparison result indicating whether or not the data is destructed. As shown in FIG. 21
, Buffer 22, parity operation unit 23, and comparison unit 2
4 and a parity inverting unit 25 as an inverting operation unit. The components having the same configuration as the conventional one are denoted by the same reference numerals, and the detailed description is omitted.

Here, when it is desired to detect an m-bit error, the parity bit string is set to m bits. Specifically, a case where m = 2 will be specifically described below.

The parity inverting unit 14 is a parity operating unit 1
Each bit of the parity bit string input from 2 is inverted and output to the writing unit 13. Specifically, the parity operation unit 12
If the parity bit string input from is "01", these bits are inverted to "10" and the inverted parity bit string is output.

Similarly, the parity inverting section 25 of the data destruction detecting apparatus 40 inverts each bit of the parity bit string input from the reading section 21 and outputs the inverted bit to the comparing section 24.

Next, the operation of the data writing device 30 and the data destruction detecting device 40 according to the embodiment of the present invention will be described. In the following description, an adjustment parameter (VSC (Vehicle Stability Control) related to the steerability of a vehicle, which is set in consideration of the characteristics of each vehicle in an automobile, will be described.
l) Parameters and the like are stored in the EPROM as an example.

Parameters calculated according to the characteristics of each vehicle at the time of shipment of the vehicle are input as data to the data writing device 30 of the present embodiment. In the following description, it is assumed that this data is “0010010111”. The data writing device 30 receives the data, holds the data in the buffer 11, the parity calculation unit 12 calculates a 2-bit parity bit string "01" based on the data, and the parity inversion unit 14 inverts the data. Is output to the writing unit 13 as “10”. Then, the writing unit 13 writes the data held in the buffer 11 and the parity bit string output by the parity inversion unit 14 into the memory 1. At this time, “00100101” is stored in the memory 1 as shown in FIG.
11 and a parity bit string of “10” are stored.

While the vehicle is running, the data is read out by the data destruction detection device 40 of the present embodiment, and the presence or absence of data destruction is verified. That is, in a state where the data is not destroyed, the reading unit 21
The data read in and stored in the buffer 22 is
Since it is “0010010111”, the parity bit string output from the parity operation unit 23 is “01”. On the other hand, since the parity bit string “10” output from the reading unit 21 is inverted by the parity inverting unit 25 and the result is “01”, it is detected that they match and the data is not destroyed.

On the other hand, as shown in FIG. 3B, when one bit is missing from the data portion (the location of the missing bit is indicated by an arrow), the second bit from the lowermost bit is, for example, "0010010101". If the value has changed from “1” to “0”, the output of the parity operation unit 23 becomes “0”.
0 ", and the output of the parity inverting unit 25 is" 01 ". Therefore, these values do not match, and the comparing unit 24 detects that the data has been destroyed, outputs the result, and outputs the result. Will not be used.

Further, as shown in FIG. 3 (c), when the data portion is missing one bit to become "0010010101" and one bit is missing from the parity bit string and becomes "00" instead of "10", The parity bit string output from the arithmetic unit 23 is “00”, and the parity bit string output from the parity inversion unit 25 is “11” obtained by inverting “00”. The destruction is detected, the result is output, and the data output from the buffer 22 is not used.

Similarly, as shown in FIG. 3 (d), when the parity part is missing by one bit and becomes "00", the parity part is inverted to "11", and the parity bit string "01" calculated from the data part. Does not match, data corruption is detected.

Further, as shown in FIG.
In the case of “10101000”, the parity bit string is “0”.
0 ", and according to the data writing device 30 of the present embodiment," 11 "which is the inverse of this is written. Here, when two bits are destroyed in the parity bit string "11" and changed to "00" as shown in FIG. 3F, the parity operation unit 2 of the data destruction detection device 40 of the present embodiment.
3 outputs “00” and the parity inverting unit 25 outputs “11” which is the inverted parity bit string “00” after the change, so that the comparing unit 24 detects that they do not match, and the data is destroyed. Is detected.

As described above, according to the data writing device and the data destruction detecting device of the present embodiment, by writing m parity bits, data destruction up to m bits can be reliably detected.

In this case, the parity inverting unit 25 inverts the parity bit string output from the reading unit 21 (the parity bit string currently written in the memory 1). The parity bit string written in 1 is output to the comparison section 24 as it is, and the parity inversion section 25 inverts each bit of the parity bit string output from the parity calculation section 23 (parity bit string calculated based on current data). Then, it may be output to the comparison unit 24.

[0027]

According to the first aspect of the present invention, since the data writing device is configured to write the data by inverting the parity bit string, the parity bit string is inverted later, and the operation is performed based on the data at that time. By comparing with the parity bit string, data destruction of the number of bits of the parity bit string can be reliably detected.

According to the second or third aspect of the present invention, there is provided a data destruction detecting device for detecting data destruction based on a parity bit sequence written in reverse and a parity bit sequence calculated based on data. Therefore, data destruction corresponding to the number of bits of the parity bit string can be reliably detected.

[Brief description of the drawings]

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

FIG. 2 is a configuration block diagram of a data destruction detection device according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating an example of data and a parity bit string stored in a memory.

FIG. 4 is a configuration block diagram of a conventional data writing device.

FIG. 5 is a configuration block diagram of a conventional data destruction detection device.

FIG. 6 is an explanatory diagram illustrating an example of data and a parity bit string stored in a memory.

[Description of Signs] 1 Memory, 10, 30 Data writing device, 11, 22
Buffer, 12, 23 parity operation unit, 13 writing unit, 14, 25 parity inversion unit, 20, 40 data destruction detection device, 21 reading unit, 24 comparison unit.

Continuation of the front page F term (reference) 5B001 AA01 AB01 AC04 AD03 AE02 5B018 GA01 HA01 HA12 NA06 QA15 RA02 RA11 RA12 5B025 AD04 AD05 AE08 5L106 AA09 BB02

Claims (3)

[Claims] 1. A data writing device for writing data on a memory, comprising: a first operation unit for operating a parity bit string on data to be written; and inverting each bit of the operated parity bit string. A data writing device, comprising: a second calculation unit; and a writing unit that writes the inverted parity bit string together with data to be written into the memory. 2. A data destruction detection device for detecting destruction of data on a memory using a parity bit string stored on the memory together with the data, wherein the parity bit string detects destruction when writing data. An inversion operation unit that inverts a parity bit string based on the target data and that inverts each bit of the parity bit string that is an inversion operation result; and a parity operation that operates a parity bit string of current data on the memory. A data destruction detection device, comprising: a detection unit that detects data destruction by comparing operation results of the inversion operation unit and the parity operation unit. 3. A data destruction detection device for detecting destruction of data on a memory using a parity bit string stored on the memory together with the data, wherein the parity bit string detects destruction when writing data. A parity calculation unit that calculates a parity bit string based on current data on the memory, and a parity calculation unit that calculates a parity bit string based on current data on the memory; and an inversion calculation that reverses each bit of the parity bit string based on current data. A data destruction detection device, comprising: a detection unit that detects data destruction by comparing a parity bit string on the memory with an operation result of an inversion operation unit.