JP2010176200A - Flash memory operation protective device and flash memory operation protective method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flash memory operation protective device and a flash memory operation protective method to protect access from a driver to a flash memory. <P>SOLUTION: Specific one (block D 10 in this example) of a plurality of blocks 7-10 in a flash memory 6 provided as data deletion units is used as a fixed block 10 not to be used for rotation. A product eigenvalue 14 and an initial value 15 are stored in the fixed block 10 as initial operation information indispensable for starting an application 11. When the driver 13 loses an access destination due to power reset or the like, the product eigenvalue 14 and the initial value 15 stored in the fixed block 10 are written in the rotation block, and the driver 13 is started by the data to continue operation of the driver 13. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a flash memory which is a kind of non-volatile data rewritable memory, and more particularly to an operation protection device and an operation protection method therefor.

  2. Description of the Related Art Conventionally, various memories are mounted as storage destinations of various data necessary for operation in a computer that comprehensively manages the operations of apparatuses and devices. As one type of this memory, for example, a non-volatile memory is used as a memory capable of electrically erasing and writing various data, and for example, a flash memory (Flash Read Only Memory: as shown in FIG. 6) is used. 81) is widely used. The flash memory 81 is constructed by an aggregate of blocks 82 to 85 having a plurality of memory areas (four from A to D in FIG. 6) as data write destinations, and data can be erased for each block unit. These blocks 82 to 85 are also referred to as erase blocks because they are data erasure units. Data reading / writing with respect to the flash memory 81 is managed by a driver 87 that operates according to a command from the application 86.

  By the way, EEPROM (Electrically Erasable PROM) and SRAM (Static Random Access Memory), which are other memory types than the flash memory 81, have an overwrite function capable of sequentially writing data on the same address, so that data has already been written. Even if a data write command is issued to this address, data can be sequentially written to this address. However, the above-described flash memory 81 has a characteristic that, when new data is written to an address where data has been written, this operation cannot be executed unless the entire block is erased once. There is.

  Therefore, in this type of flash memory 81, when writing data, the blocks 82 to 85 of A to D are rotated and used as shown in FIGS. At this time, when new data is first written to the flash memory 81, the driver 87 sequentially writes data in the empty area of the used block (A block 82 in FIG. 7) as shown in FIG. When there is no more free space in the A block 82, as shown in FIG. 8, the latest value in each data (ID1 to ID3 in FIG. 8) is copied to the B block 83 which is the next used block. 83 is used as a new data writing destination, and data writing is performed by sequentially repeating this operation each time there is no empty area in the used block. In addition, data is erased from a used block whose free area has run out before the next rotation.

JP 2008-243347 A

  By the way, for example, when the power supply of the computer fluctuates due to an external factor or the like and the power supply is temporarily reset, as shown in FIG. 9, for example, the driver 87 holds the operation information, that is, A to D. Of the blocks 82 to 85, there is a case where all the various information indicating which block is currently used and which data in the used block is the latest value may be taken. Therefore, when the power is supplied again to the computer after this resetting, even if the driver 87 takes an operation of re-accessing the flash memory 81, the operation state before the power is turned off cannot be grasped. In some cases, the operation to be executed is stopped without being recognized, and the application 86 cannot be operated.

  An object of the present invention is to provide a flash memory operation protection device and a flash memory operation protection method capable of protecting a driver's access to the flash memory.

  In order to solve the above problems, in the present invention, when a flash memory is used as a rewritable nonvolatile memory and a driver writes data to the flash memory by a write command from an application, the memory of the flash memory In a flash memory operation protection device that reads and writes data while sequentially using a plurality of blocks that are data erasure units while constructing an area, and used for the rotation among the plurality of blocks A monitoring block for monitoring whether there is an abnormality with respect to the access of the driver to the flash memory, a fixed block in which minimum operation information necessary for operating the application is written, Check the abnormality with monitoring means The initial execution information written in the fixed block is newly written in the block, and the driver is operated according to the initial operation information, thereby providing protection execution means for continuing the access. .

  According to this configuration, a predetermined block of a plurality of blocks that the flash memory has as a memory area is used as a fixed block that is not used for data read / write rotation, and the minimum initial operation information necessary for operating the application is obtained. Write in this fixed block. Then, when the driver accesses the flash memory, the monitoring means monitors the presence or absence of the access abnormality, and when the access abnormality is confirmed, the initial operation information is read from the fixed block and written to the rotation block. The driver is operated based on the initial operation information. For this reason, even if the driver's power supply is temporarily turned off due to voltage fluctuations such as power reset, and the driver cannot recognize the next operation, the driver knows the next operation based on the initial operation information written in the fixed block. This makes it difficult for the driver to lose track of the access destination and stop. Therefore, even if the driver is reset due to such voltage fluctuations, it becomes possible to protect the driver's access to the flash memory.

The gist of the present invention is that the initial operation information is a fixed value that is not rewritten when the flash memory is used.
According to this configuration, there is no situation where the initial operation information is rewritten to an incorrect value when the flash memory is used, so that the value of the initial operation information can be made highly reliable.

  In the present invention, when a flash memory is used as a data rewritable nonvolatile memory and a driver writes data to the flash memory in accordance with a write command from an application, a plurality of data erasing units for constructing a memory area of the flash memory In the operation protection method of the flash memory that executes the writing while rotating the blocks in order, the blocks that are not used for the rotation among the plurality of blocks are provided as fixed blocks, and the application is operated. The minimum necessary initial operation information is written to the fixed block, and monitoring means is used to monitor whether there is an abnormality in access to the flash memory, and when the abnormality occurs, the fixed block is written to the fixed block. Initial operation Is newly written distribution to the block by operating the driver by the initial operation information, and summarized in that to continue the access.

  According to the present invention, it is possible to protect driver access to the flash memory.

The perspective view which shows the external appearance of the driver's seat in a vehicle in one Embodiment. The block diagram which shows schematic structure including the software configuration of a computer. The block diagram which shows the coping operation which a computer takes when access abnormality generate | occur | produces. Explanatory drawing which shows the state in which the data of a fixed block are written in a rotation block when access abnormality generate | occur | produces. The block diagram explaining the effect which the computer shown in this example has. The block diagram which shows schematic structure of the computer in the past. Explanatory drawing which shows operation | movement when writing data in the block of flash memory. Explanatory drawing which shows operation | movement when erasing data from the block of flash memory. Explanatory drawing which shows a state when malfunction occurs in access by reset etc. FIG.

Hereinafter, an embodiment of a flash memory operation protection device and a flash memory operation protection method embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, the vehicle 1 is provided with a steering angle detection device 3 that detects the steering angle of the steering wheel 2. The steering angle detection device 3 includes a steering angle sensor 4 as a sensor component (for example, a magnetic sensor) of the device 3 and a computer 5 as a control unit of the steering angle detection device 3. The computer 5 calculates the steering angle of the steering wheel 2 based on the sensor output value acquired from the steering angle sensor 4, and uses the calculated steering angle (calculated steering angle value) to other in-vehicle devices that need it. Output via a LAN (Local Area Network).

  As shown in FIG. 2, the computer 5 is provided with a flash memory (Flash ROM) 6 as a memory for writing various data. The flash memory 6 is a kind of nonvolatile memory capable of rewriting data in its own memory area. As described in the background art, the flash memory 6 is divided into a plurality of data erasing units (in this example, 4 to 4). Block) 7-10. That is, this type of flash memory 6 is a memory having a characteristic that data erasure can be executed only in block units, although data written in its own memory area can be rewritten. The blocks 7 to 10 have the same storage capacity by equally dividing the memory area of the flash memory 6. Further, these blocks 7 to 10 of A to D constitute a block.

  In the flash memory 6 of this example, when data is written, among the blocks 7 to 10 of A to D, the blocks 7 to 9 of A to C are rotated and used as data write destinations. Here, of these three rotation blocks 7 to 9, if the first block to be used is, for example, A block 7, first, various data related to the steering angle detection device 3 are written using A block 7 as the data write destination. Go. The data written in the A block 7 at this time includes, for example, the time (ID1 data) when the engine is started by operating the ignition switch (engine switch) of the vehicle 1 to the ignition on position (IG ON position). The time during which the ignition switch is on (ID2 data), the sensor output value of the steering angle sensor 4 (ID3 data), and the like.

  By the way, when data is written to the flash memory 6, the data cannot be overwritten at the data-written address because the flash memory 6 has a restriction that data erasure is in units of blocks. Therefore, when new write data is received, the flash memory 6 performs an operation of sequentially increasing the received data in the empty area in the A block 7 in use. When the writing area becomes full, the used block is switched to the next used block (in this example, B block 8), and the latest value of each data of ID1 to ID3 is written to the B block 8, while the data is written to the B block. The data write is executed by continuing this operation and repeating this operation every time there is no free area in the block. It should be noted that data erasure is executed for a block in which data writing is full, when there is no free time during which data writing or data reading is not performed, until the next rotation starts.

  As shown in FIG. 2, the computer 5 includes, as software for operating the computer 5, an application 11 which is dedicated software for operating the steering angle detection device 3, and an application 11 and an OS (Operating System). There are provided middleware 12 that functions in an intermediate position and a driver 13 that is software for operating the flash memory 6. The application 11 operates the computer 5 by outputting an operation command to the driver 13 via the middleware 12 based on various information and data input to the application 11. In addition, when there are a plurality of drivers 13, the application 11 can collectively manage these drivers 13.

  When the driver 13 receives an operation command from the application 11 via the middleware 12, the driver 13 operates according to the operation command and executes various processes such as data writing, data reading, and data erasing to the flash memory 6 (blocks 7 to 10). To do. At this time, the driver 13 receives an operation command from the application 11 as a trigger, and executes an operation based on this operation command regardless of the operation state of the application 11 even if the application 11 is executing another operation. Further, the data erasure of the blocks 7 to 10 by the driver 13 is executed when the driver 13 is free when the driver 13 is not writing or reading data as described above.

  In the case of this example, among the blocks 7 to 10 of A to D, the D block 10 is not used as a rotation for writing data, but is used as a fixed block 10 in which predetermined initial operation information is written as a default value. in use. As the initial operation information, a product unique value 14 as an individual product value of the vehicle 1 and an initial value 15 of data (ID1 to ID3) exchanged in the operation process are written. For example, the product specific value 14 includes a vehicle code, a serial number of the vehicle 1, destination information, and the like. The initial value 15 includes “0” as the initial value of the ignition angle, the elapsed time when the ignition is turned on, the steering angle sensor 4, and the like. These product specific value 14 and initial value 15 are the minimum data necessary for the application 11 to operate, and are written in the fixed block 10 on the production line of the vehicle 1 or at the time of product shipment, and are actually used after product shipment. Sometimes it will not be overwritten. The product specific value 14 and the initial value 15 constitute initial operation information.

  Further, the driver 13 is provided with an abnormality occurrence monitoring unit 16 that monitors whether there is an abnormality in which the driver 13 cannot normally access the flash memory 6. The abnormality occurrence monitoring unit 16 of this example confirms whether there is an abnormality by seeing whether the driver 13 has lost sight of the access destination of access to the flash memory 6, for example, despite having accessed the flash memory 6, It is recognized that an abnormality has occurred in access to the flash memory 6 because data cannot be acquired even after a certain period of time. The abnormality occurrence monitoring unit 16 corresponds to a monitoring unit.

  Further, the driver 13 operates using the initial operation information (product specific value 14 and initial value 15) of the fixed block 10 when the abnormality occurrence monitoring unit 16 confirms the abnormality, so that the driver 13 is a flash memory. A protection processing unit 17 is provided to ensure that access to 6 is possible. The protection processing unit 17 corresponds to protection execution means. Further, the abnormality occurrence monitoring unit 16 and the protection processing unit 17 are functionally generated when the CPU of the computer 5 operates in accordance with a program, and this is illustrated in a block diagram in FIG.

  Next, after the computer 5 (driver 13) of this example is turned on, an example of operation when the computer 5 takes a reset state due to, for example, temporary voltage fluctuation will be described with reference to FIGS.

  When the ignition switch is operated to the ignition-on position, the computer 5 receives power from the in-vehicle battery, and the operation state is switched from the stopped state to the activated state. The driver 13 then starts the time when the ignition switch is turned on (ID1 data), the elapsed time after the ignition switch is turned on (ID2 data), and the sensor output value (ID3 data) received from the steering angle sensor 4 thereafter. Is written into the flash memory 6. In this example, since the A block 7 is set as a block to be used first among the blocks 7 to 10 of A to D, first, these data are written from the A block 7 first.

  By the way, when the ignition switch is operated, for example, from the ignition on position to the engine start position, the voltage supplied to the computer 5 fluctuates due to the switching of the switch contact of the ignition switch in this operation process. The supplied power may be temporarily turned off and the power may be reset. At this time, the voltage is temporarily not supplied to the computer 5 due to the momentary power-off, and when the voltage returns to the original level, the power is supplied to the computer 5 again, and the computer 5 returns to the activated state. Take action to do.

  In this situation, as described in the background art, the driver 13 does not have a function of sequentially holding various information before the power is turned off. The driver 13 loses sight of various information before the power is turned off, such as which block was used before the power was turned off, and which address of the used block was accessed. In this case, after the power is turned on again, the driver 13 cannot execute the access to the block that has been used so far, and in some cases, the data written in the blocks 7 to 9 is lost. As a result, the data written in the blocks 7 to 9 may be lost.

  However, in this example, as shown in FIG. 3, the abnormality occurrence monitoring unit 16 determines whether the driver 13 has lost sight of the destination for accessing the flash memory 6 when the power is turned on (power is turned on again). By checking whether or not there is an access abnormality. It should be noted that the abnormality occurrence monitoring unit 16 of this example confirms whether there is an access abnormality by checking whether the driver 13 actually accesses the flash memory 6 and can read data during a predetermined time. Then, if the abnormality occurrence monitoring unit 16 can normally read the data from the blocks 7 to 9 within a predetermined time, the abnormality occurrence monitoring unit 16 recognizes that no abnormality has occurred in the access of the driver 13, and on the other hand, the block does not stop even after a predetermined time. If the data of 7 to 9 cannot be read normally, it is recognized that an abnormality has occurred in the access of the driver 13. The abnormality occurrence monitoring unit 16 confirms the presence / absence of the access abnormality and outputs the confirmation result to the protection processing unit 17.

  When the protection processing unit 17 receives the confirmation result from the abnormality occurrence monitoring unit 16 and this is a notification that there is no abnormality, the protection processing unit 17 can restart the power supply even if the computer 5 is temporarily turned off due to a power reset. The inserted driver 13 recognizes that the access destination of the flash memory 6 can be held. Therefore, at this time, since the driver 13 can access the blocks 7 to 9 as usual, the access can be made, so the protection processing unit 17 does not take any special measures and Various processes such as data writing, data reading, and data erasing to the blocks 7 to 9 are executed by the driver 13 along the normal operation.

  On the other hand, when the protection processing unit 17 receives the monitoring result from the abnormality occurrence monitoring unit 16, if this is a notification that there is an abnormality, an abnormality occurs in the access to the flash memory 6 by the driver 13, and the driver 13 flashes. It is recognized that the access destination of the memory 6 has been lost. At this time, in some cases, the data of the rotation blocks 7 to 9 among the blocks 7 to 10 of A to D may be lost due to the power reset, but the D block 10 is fixed so that the value is not rewritten. Since the block 10 is used, even if the data of the rotation blocks 7 to 9 are temporarily skipped by the power reset, the data group written in the fixed block 10 is maintained.

  When the protection processing unit 17 confirms that an abnormality has occurred in the access to the flash memory 6 by the driver 13, as shown in FIG. 3, the product unique value 14 that the vehicle 1 (steering angle detection device 3) has from the fixed block 10 and The initial value 15 such as ID1 to ID3 is read, and the read data at this time is written at the head of the A block 7 set to be used first as shown in FIG. . When data is written, if data remains in the A block 7, an erasing process is executed on the A block 7 to empty the A block 7, and then data for recovery is written. Execute.

  As a result, the driver 13 reads the product specific value 14 and the initial value 15 that are newly written in the A block 7 that is used first when the power is turned on even if the used block and the access destination address before the power-off are not known due to the power reset. Thus, it is possible to grasp the operation to be executed when the power is turned on again. Therefore, even if the driver 13 loses sight of the access destination to the flash memory 6 due to the power reset, the driver 13 continues to execute the operation although it is from the default value (initial operation information) such as the product specific value 14 and the initial value 15. It becomes possible.

  In this example, even if an access abnormality occurs in which the driver 13 loses sight of the access destination of the flash memory 6 due to a power reset, the product specific value 14 stored in the fixed block 10 that holds various data as fixed values, The initial value 15 is newly written in the rotation blocks 7 to 9, and the driver 13 is made aware of the next operation by this data group. For this reason, even if the driver 13 loses sight of the access destination due to the power reset, the driver 13 can continue to execute the next operation with the product specific value 14 and the initial value 15. Therefore, when the power supply reset occurs, it is difficult for the driver 13 to stop without knowing the next operation, thereby preventing the application 11 from being abnormally stopped.

According to the configuration of the present embodiment, the following effects can be obtained.
(1) One of the plurality of blocks 7 to 10 of the flash memory 6 (D block 10 in this example) is used as a fixed block 10 that is not used for rotation, and the application 11 is operated on the fixed block 10. The product specific value 14 and the initial value 15 are stored as the minimum initial operation information required for the operation. When the driver 13 loses track of the access destination due to power reset or the like, the product specific value 14 and the initial value 15 stored in the fixed block 10 are written to the rotation blocks 7 to 9, and the driver 13 is continuously operated by these data. . Therefore, even if the computer 5 once activated is reset, the driver 13 can grasp the access destination, so that the situation in which the operation of the driver 13 is stopped can be made difficult to occur. If the operation of the driver 13 can be ensured in this way, the operation of the application 11 is hardly stopped.

  (2) As a storage destination of the product specific value 14 and the initial value 15, one of a plurality of blocks 7 to 10 included in the flash memory 6 as described in the embodiment is set as the fixed block 10 and is used as the storage destination. For example, as shown in FIG. 5, it is assumed that an EEPROM (Electrically Erasable PROM) 21 is separately provided and stored therein. However, in this case, since the driver 22 for the EEPROM 21 must be prepared separately, a total of two drivers 13 and 22 are required, and there is a problem that data management becomes complicated accordingly. In this case, since only one driver 13 is required for this type of driver, the above-described problem of data management is not considered. If the EEPROM 21 is not required as in this example, the memory capacity required for the ROM can be reduced accordingly.

  (3) As shown in FIG. 5, when the EEPROM 21 is used as the storage destination of the product unique value 14 and the initial value 15, the data of the product unique value 14 and the initial value 15 read from the EEPROM 21 are temporarily passed through the middleware 12. Therefore, there is a problem that extra data processing time is required for the data transfer through the middleware 12 in the data transfer. However, in the case of this example, since the process is completed within one driver 13, the data processing speed of the product specific value 14 and the initial value 15 can be increased by the amount not via the middleware 12.

  (4) The initial operation information written in advance in the fixed block 10 is set as a fixed value that is not overwritten at the time of actual use after the product is shipped. For this reason, since there is no situation in which the initial operation information is rewritten to an incorrect value when the product is used, the value of the initial operation information can be made highly reliable.

Note that the embodiment is not limited to the configuration described so far, and may be modified as follows.
The method for detecting an access abnormality is not limited to whether or not the driver 13 has lost sight of the access destination for the flash memory 6. For example, it may be confirmed that the flash memory 6 (blocks 7 to 9) is empty or that data written in the flash memory 6 has been garbled.

The initial operation information is not limited to the product specific value 14 or the initial value 15 described above, and may be any type as long as the driver 13 can know the operation content of the next operation.
The data written in the flash memory 6 is not limited to the ignition on start time, the ignition on execution time, and the sensor value of the steering angle sensor indicated by ID1 to ID3. Anything can be used.

The middleware 12 is not always necessary and may be omitted.
The number of blocks of the flash memory 6 is not limited to a total of four of A to D, and may take other numbers.

The number of the fixed blocks 10 is not necessarily limited to one, and may be two or more as long as the number of the rotation blocks 7 to 9 is small.
The write destination of the initial operation information when the access is abnormal is not necessarily limited to the A block 7, but may be the B block 8 or the C block 9, for example.

  The computer 5 of this example having an access protection function is not limited to being mounted on the steering angle detection device 3 and is particularly limited as long as it includes the computer 5 having the flash memory 6 as a memory. It is not a thing.

Next, technical ideas that can be grasped from the above-described embodiment and other examples will be described below together with their effects.
(1) In Claim 1 or 2, the initial operation information is an initial value of a detection value (measurement value) written in the block. According to this configuration, when the driver accesses the detection value in the flash memory, it is possible to make it difficult to cause a situation where the access stops.

  (2) In Claim 1 or 2, the initial operation information is a product-specific value possessed by each product of the flash memory. According to this configuration, when the driver accesses the product specific value in the flash memory, it is possible to make it difficult to cause a situation where the access stops.

  6 ... Flash memory, 7 ... A block constituting the block, 8 ... B block constituting the block, 9 ... C block constituting the block, 10 D block constituting the 10 block (fixed block), 11 ... Application, 13, DESCRIPTION OF SYMBOLS 22 ... Driver, 14 ... Product specific value which comprises initial operation information, 15 ... Initial value which comprises initial operation information, 16 ... Abnormality generation monitoring part as a monitoring means, 17 ... Protection processing part as a protection execution means.

Claims (3)

When a flash memory is used as a rewritable nonvolatile memory and a driver writes data to the flash memory in response to a write command from an application, a plurality of data erasing units are constructed while building the memory area of the flash memory. In the operation protection device for flash memory that reads and writes data while using the blocks in turn,
Among the plurality of blocks, a fixed block that is not used for the rotation and in which initial operation information necessary for operating the application is written is written.
Monitoring means for monitoring whether there is an abnormality with respect to access of the driver to the flash memory;
Protection execution means for continuing the access by newly writing the initial operation information written in the fixed block to the block and operating the driver based on the initial operation information when the monitoring means confirms the abnormality. And a flash memory operation protection device.   2. The flash memory operation protection device according to claim 1, wherein the initial operation information is a fixed value that is not rewritten when the flash memory is used. When a flash memory is used as a data rewritable nonvolatile memory, and a driver writes data to the flash memory in accordance with a write command from an application, a plurality of blocks of data erasing units that construct the memory area of the flash memory In the operation protection method of the flash memory that executes the writing while rotating and using in order,
A plurality of the blocks that are not used for the rotation are provided as fixed blocks, and initial operation information necessary for operating the application is written to the fixed blocks, and there is an abnormality in access to the flash memory. By monitoring whether or not there is, when the abnormality occurs, the initial operation information written in the fixed block is newly written in the block and the driver is operated by the initial operation information, An operation protection method for a flash memory, characterized by continuing access.

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