JP5332800B2 - Storage device - Google Patents

Description

The present invention relates to a memory device having a flash memory.

  For example, Patent Document 1 discloses a method for writing data to a flash memory having a plurality of blocks as a unit for collectively erasing data and each block including a plurality of records (also referred to as pages) which are data write / read areas. The method is known.

  In this data writing method, when there is an empty (data not stored) record in the writing target block that is the target of the writing process, new data is added in order from the unstored record at the address next to the written record. . When data is stored in all records, only valid record data is temporarily stored in the RAM, and all data in the write target block is erased. Then, for the write target block that has been emptied by erasing the data, the valid data temporarily stored in the RAM is rewritten from the first record, and in order from the unrecorded record at the next address of the rewritten record, New data is added.

JP 2000-243093 A

  On the other hand, as another data writing method, when data is stored in all records in the writing target block, only valid record data is copied to a free block in a free state different from the above block. Conceivable. In this case, the block to which the data is copied is set as a new write target block, and in this block, new data is added in order from the unrecorded record at the address next to the record to which the data is copied, and the copy source All the data in this block is erased to become an empty block, and is prepared for the next data migration.

  However, in any of the above-described methods, when data is written in all records in the write target block, the data of the valid record is separated from the write target block such as RAM or another block. And erasing all data in the original block to generate a free block. Therefore, for example, when all the records in the writing target block are in a writing state (a state where there is no empty record) in the middle of data writing, an erasing operation of the data occurs regardless of the data writing in progress. The write operation is interrupted, resulting in a long write time.

  In addition, since the application (control software for controlling the electronic device) does not know when the data is copied and the original block data is erased, the data can be copied and the original block at an unexpected timing. If the data is erased, there is a possibility that a predetermined process based on the execution of the application cannot be executed.

In view of the above problems, and an object thereof is to provide a storage peripherals that can suppress a delay in data writing time associated with data copy and the original block data erase.

In order to achieve the above object, according to the first aspect of the present invention, the CPU and the storage area are divided into a plurality of blocks, the data can be erased in units of blocks, the blocks include a plurality of records, Flash memory capable of writing data , driver software stored in ROM as a program executed by the CPU, which is a program executed by the CPU with respect to the flash memory, and application software which is a program for controlling electronic devices The CPU executes the driver software on the basis of the instruction on the application software side to execute the process of writing the data of the application software in the unstored record of the block corresponding to the application software. By running the driver software, data The data writing state in the block is detected at a timing different from the writing, and the CPU executes the driver software so that the detected writing state matches the data migration condition corresponding to the predetermined writing state set in advance. In such a case, the application software is notified that it is time to transfer only valid record data of the corresponding block records to a storage medium different from the block, and the CPU executes the application software. When the notification is received and the migration condition of the corresponding application software is met, the data migration is permitted to the driver software side, and the CPU receives the permission by executing the driver software and records the block. Copy only valid record data to the storage medium. Together, characterized by erasing the data of the data copy source block.

In the present invention, the data writing state in the block is detected at a timing different from the writing, and when the detected writing state matches the data migration condition, the application software corresponding to the matched block is transferred to another storage medium. Notify that it is timing. As a result, the application software side can grasp in advance the timing at which data migration is necessary at a timing different from writing, that is, before writing.

When the notification is received and the application software migration condition is satisfied, the application software issues a data migration instruction (data migration request). Based on this request, a process of copying only valid record data of the corresponding block to a storage medium different from the block and erasing the data of the data copy source block is performed. In this way, the data migration process can be performed at a timing that satisfies the migration condition for each application software . That is, the timing for performing data migration processing, it is possible to manually set in the application software side.

As described above, according to the present invention, it is possible to suppress the data migration process from being executed during the writing operation. That is, it is possible to suppress a delay in data writing time associated with the data migration process. Further, an unintended write time delay can be avoided. The present invention is particularly effective for writing data of application software with severe restrictions on write time.

As described in claim 2, the storage medium is a free block different from the data copy source block, and the CPU executes the driver software to copy the valid record data to the copy destination. the block as a block for writing data corresponding to the application software, the unstored record of the blocks, may add new data.

In the present invention, it is provided with a data writing block and at least one free block for copying, and when data migration processing is performed, the copy destination block is made a data writing block corresponding to the application software , A block from which data at the copy source has been erased is designated as a free block for copying. When data is written, new data is added to an unstored record with respect to a copy destination block, that is, a new data write block, so that a delay in write time can be suppressed.

  In addition, since valid record data is copied to an empty block different from the data copy source block, the copied data can be retained even if an instantaneous interruption (power supply momentarily drops) or the like occurs. Even when a large-capacity RAM cannot be secured in terms of space, a delay in writing time can be suppressed. In particular, it is suitable for in-vehicle applications in which space restrictions are stricter than those of consumer and the use conditions are severe.

Meanwhile storage, as described in claim 3, comprising a RAM of the storage medium, CPU by executing the driver software, to block erasing the data, from the head of the plurality of records, in the RAM thereby sequentially rewriting the data valid records, data valid records in the unstored record rewriting blocks, may add new data. According to this, since valid record data is temporarily stored in the RAM, an empty block is not required as in the second aspect of the present invention.

It is a block diagram which shows schematic structure of the electronic controller which applied the memory | storage device which concerns on 1st Embodiment. It is a figure which shows schematic structure of a flash memory. It is a conceptual diagram of a data migration process and a data write process, (a) shows a comparative example, (b) shows the first embodiment. It is a flowchart explaining a data transfer process. It is a schematic diagram which shows a data transfer process, (a) shows before data transfer process, (b) shows after data transfer process. It is a flowchart which shows the data migration process which concerns on 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a block diagram illustrating a schematic configuration of an electronic control device to which the storage device according to the first embodiment is applied. FIG. 2 is a diagram showing a schematic configuration of the flash memory.

  As shown in FIG. 1, the ECU 10 includes a main control unit composed of a CPU (Central Processing Unit) 11, and executes control processing of electronic equipment mounted on the vehicle by executing predetermined application software by the main control unit. The CPU 11, the ROM 12, the RAM 13, the flash memory 14, and the input / output unit (I / O port) 15 are composed of a microprocessor connected by a bus. In the present embodiment, the ECU 10 is configured as a body system ECU that controls the body system of the automobile. In the present embodiment, the CPU 11 also has a controller function for controlling access to the flash memory 14.

  The ROM 12 stores various programs executed by the CPU 11 at the time of startup, for example, and includes the driver software 20 of the flash memory 14 and the application software 21 described above as these programs.

  Flash driver software 20 (hereinafter simply referred to as driver software 20) is a program executed by the CPU 11 for the flash memory 14. On the other hand, the application software 21 is a program that realizes a body function that is a function related to operation of each part of the vehicle by a vehicle user. Here, the body functions include, for example, control associated with opening / closing of a door, control associated with opening / closing of a window, control associated with turning on / off of a light switch, control of a wireless door lock mechanism employed in a keyless entry method, etc. Such as control.

  The RAM 13 is used as a work area for various calculations executed by the CPU 11 in accordance with each program stored in the ROM 12, and an individual work area is secured for each program. In the present embodiment, as an example, the RAM 13 includes an address conversion table (mapping table) indicating a correspondence relationship between a physical address and a logical address, which will be described later, as the work area. Thus, since the address conversion table is stored in the RAM 13, when the power is turned on, the flash memory 14 is accessed and the address conversion table is recovered.

  As is well known, the flash memory 14 is a non-volatile storage element made of a semiconductor, and is a part that stores setting data corresponding to each program described above. In the present embodiment, various system data used by the CPU 11 are also stored. The storage area of the flash memory 14 has a plurality of blocks (block 0 to block n) having a predetermined fixed length, for example, as shown in FIG. In the flash memory 14, data cannot be overwritten as is well known, and the block described above is a unit for batch erasure. Also, physical addresses 0 to n are assigned corresponding to each block. In this embodiment, the capacity of one block is about several kB.

  Each block has a plurality of records (record 0 to record m) as shown in FIG. 2 (illustrated by block 2). Each record has a fixed length and is composed of a data part having a predetermined size and a redundant part. Data is stored in the data portion, and ECC data, various management information (logical address information), and the like are stored in the redundant portion. This record is a unit of writing / reading in the flash memory 14, and physical addresses 0 to m are also assigned to the record. In this embodiment, the capacity of one record is about several tens of B.

  As described above, in the flash memory 14, data is erased in units of blocks, and data writing / reading is performed in units of records. The data sizes of the data erase unit and the data write unit are mutually different. Is different.

  Of the ECU 10, the CPU 11, the flash driver software 20, the RAM 13, and the flash memory 14 stored in the ROM 12 correspond to the storage device described in the claims.

  Next, the concept of data migration processing and data writing processing will be described. FIG. 3 is a conceptual diagram of data migration processing and data writing processing, where (a) shows a comparative example and (b) shows this embodiment. In FIG. 3A, 100 is added to the reference numerals of elements related to the elements shown in FIG. 3A and 3B, the CPU 11 is involved, but is omitted in the figure.

  First, a comparative example (conventional example) will be described. As shown in FIG. 3A, when the user changes the setting value when executing the predetermined application software 121, the CPU writes the data of the changed setting value to the driver software 120 (flash memory 114) side. Request. Then, the CPU executes the driver software 120, and from the beginning of the unstored records in which no data is stored for the write target block of the predetermined physical address corresponding to the application software 121 in the flash memory 114. Processing to write data in order is executed. For example, when all the records of the block to be written are empty, data is written in order from the record with the physical address at the head (0). In addition, the presence or absence of the data writing of a record can be confirmed by the write state confirmation area | region (1st flag) in a redundant part as an example. In the present embodiment, the first flag is set to “0” when data is written, and is set to “1” when data is not written.

  Here, during the data writing, when the CPU executing the driver software 120 detects that all the records of the writing target block are in a written state, that is, in a state where there is no empty record, based on the first flag, for example. The CPU executes a process of copying only valid record data among the data stored in the write target block to a data migration free block corresponding to the application software 121. In addition, a process of erasing all data in the write target block to generate an empty block is executed. The logical address corresponding to the physical address of the original writing target block and the logical address corresponding to the physical address of the original empty block for data migration are then exchanged. That is, the original write target block is set as a new data migration free block, and the original free block is set as a new write target block. As an example, the validity / invalidity of data can be confirmed in the validity confirmation area (second flag) in the redundant portion. In the present embodiment, the second flag is set to “1” when the data is valid, and is set to “0” when the data is invalid.

  When the data migration processing is completed, the CPU that executes the driver software 120 transfers the remaining data in the new write target block, the record at the address next to the record in which the data is copied, that is, the data is not stored. A process of writing data in order from the beginning of the record is executed. When the data writing is completed, the CPU that executes the driver software 120 executes processing for notifying the application software 121 that the writing has been completed.

  As described above, conventionally, when all the records in the write target block are in a write state (a state in which there is no empty record), a data migration process occurs regardless of the data being written. As a result, there is a problem that the data writing time T1 becomes longer.

  Further, since the application software 121 does not know at what timing the data migration process occurs, the writing process is not performed within a predetermined time, and therefore the predetermined process based on the execution of the application software 121 may not be executed. there were.

  On the other hand, in this embodiment, as shown in FIG. 3B, the data migration process is performed at a predetermined timing (a timing different from the data writing timing) when the application software 21 is not executed. That is, before the data writing process, the data migration process is performed in advance as necessary. As a result, during the data writing, all records of the writing target block are in a writing state, and the data migration process is suppressed from occurring accordingly. The data writing time T2 can be made shorter than the above-described writing time T1.

  Further, since the data migration process is performed at an arbitrary timing of the application software 21, it is possible to solve the problem that the predetermined process based on the execution of the application software 21 is not performed at an unintended timing.

  Details of the data migration processing according to this embodiment will be described below. FIG. 4 is a flowchart for explaining data migration processing according to this embodiment. FIG. 5 is a schematic diagram showing the data migration process according to the present embodiment, where (a) shows before the data migration process and (b) shows after the data migration process.

  This data migration processing is executed at a timing different from the timing of writing data (and reading timing) to the flash memory 14 with the ECU 10 powered on. As shown in FIG. 4, first, the write state of the write target block is detected (step 10). This step 10 corresponds to the first step described in the claims. Specifically, the CPU 11 executes the driver software 20 and detects the write state of the write target block at a timing different from the data write timing (and read timing). That is, the CPU 11 that executes the driver software 20 corresponds to a writing state detection unit. In this detection of the write state, up to which record is written among all the records constituting the block to be written, how much of all the records are in the write state, and which of the all records are free records Detect if there is any remaining.

  The detection target of the writing state may be all writing target blocks corresponding to each application software 21 or one writing target block corresponding to predetermined application software 21. The detection timing may be any timing when none of the application software 21 is executed. For example, it can be performed immediately after the data writing process of the application software 21 is completed, or after a predetermined time has elapsed since completion. It can also be determined based on a signal from a sensor or the like.

  The method for detecting the writing state is not particularly limited. For example, a detection method based on the first flag described above, or a detection method based on a logical address corresponding to the physical address of the last record in a write state (alert is given when data is written to a record at a predetermined physical address) Etc. can be applied.

  Then, the CPU 11 determines whether or not the detected writing state matches the data migration condition based on the program of the driver software 20 (step 11). This data migration condition is set in advance corresponding to a state in which a predetermined number of empty records remain in the write target block.

  Here, in the example shown in FIG. 5A, as a block corresponding to predetermined application software 21 (for example, application software 2), a block 4 that is a write target block and a block 5 that is a free block for data migration are included. Each block has seven records. In block 4, the state in which data is written in the fifth record is the data migration condition. That is, in the example shown in FIG. 5A, the write state of the block 4 that is the write target block is exactly in a state that matches the data migration condition. In FIG. 5A, data (a, ddd, xx) of three records among the five records written with data is valid, and data (b, abc) of two records are invalid. Yes.

  If the data migration condition is not met in step 11, the write status (empty record) of the block to be written has a margin, and the data migration process at this timing is terminated. On the other hand, if the data migration condition is met, based on the program of the driver software 20, the CPU 11 notifies the corresponding application software 21 that the data migration condition is met, in other words, data migration is to be performed. (Step 12). That is, the CPU 11 that executes the driver software 20 corresponds to notification means.

  The notification method is not particularly limited. In this embodiment, as an example, based on the program of the driver software 20, the CPU 11 executes a process of writing the determination result in a predetermined area (third flag) of the RAM 13. Specifically, “1” is set if the data migration condition is met, and “0” is set if the data migration condition is not met. Further, after writing to the RAM 13, the CPU 11 executes the application software 21 and executes a process of checking the third flag of the RAM 13. When the third flag is “1”, the corresponding application software 21 is notified that the data migration condition is met. The above corresponds to the second step described in the claims.

  When the CPU 11 knows that the write target block is in a state to be transferred while the application software 21 is in an execution state, the CPU 11 determines whether or not the transfer condition of the application software 21 is satisfied (step 13). This transition condition is appropriately set for each application software 21.

  If the migration condition of the corresponding application software 21 is not satisfied in step 13, the data migration process at this timing is terminated. On the other hand, if the migration condition of the corresponding application software 21 is satisfied, the CPU 11 requests the data migration processing from the driver software 20 (flash memory 14) side based on the program of the application software 21 (step 14). That is, the CPU 11 that executes the application software 21 corresponds to a permission unit. Then, the CPU 11 executes the driver software 20, and only the valid record data among the data stored in the write target block at the predetermined address corresponding to the application software 21 in the flash memory 14 is applied to the application software 21. A process of copying to an empty block for data migration corresponding to is executed (step 15). In addition, a process of erasing all data in the writing target block to generate an empty block is executed (step 16). That is, the CPU 11 that executes the driver software 20 corresponds to data migration means. Further, in accordance with this processing, a process of exchanging the logical address corresponding to the physical address of the original writing target block and the logical address corresponding to the physical address of the original empty block for data migration is executed. That is, the original write target block is set as a new data migration free block, and the original free block is set as a new write target block. The validity / invalidity of the data can be confirmed by, for example, the validity confirmation area (second flag) in the redundant part as described above. The above corresponds to the third step described in the claims.

  FIG. 5B shows a state where step 16 is completed, that is, a state where data migration is completed. In FIG. 5B, the valid data is copied to the block 5 which was an empty block before data migration, and the block 5 becomes a new write target block, and the data of the block 4 which was the write target block before data migration. Are deleted, and the block 4 becomes a new empty block for data migration.

  Thus, when the data migration process is completed, the CPU 11 executing the driver software 20 executes a process of notifying the application software 21 that the data migration process is completed (step 17).

  Therefore, when the application software 21 corresponding to the blocks 4 and 5 is executed and data is newly written (added), the data stored in the record of the block 5 is stored as shown in FIG. Data is written sequentially from the beginning (fourth record) of the records that have not been recorded.

  Next, the effect of the characteristic part which concerns on this embodiment is demonstrated. In this embodiment, the data write state of the write target block is detected at a timing different from the data write. If the detected writing state matches the data migration condition corresponding to the predetermined writing state set in advance, the CPU 11 that is the execution means of the application software 21 corresponding to the matching writing target block is notified to the matching writing target. It is notified that it is time to transfer only valid data in the block to a storage medium different from the block (in this embodiment, an empty block corresponding to the application software 21). Therefore, the application software 21 can recognize in advance that the corresponding write target block is in a write state in which data is to be migrated, that is, at a timing different from that of writing, that is, before writing.

  When the notification is received and the migration condition of the corresponding application software 21 is satisfied, the CPU 11 that executes the application software 21 issues a data migration request. Then, based on this request, the valid data of the matched write target block is copied to a free block different from the block, and the data of the data copy source block is erased. Therefore, the data migration process can be performed at a timing that satisfies the migration conditions set appropriately for each application software 21.

  From the above, according to the data processing method of the flash memory 14 and the storage device (including the ECU 10) to which the method is applied according to the present embodiment, the data migration process is executed during the writing operation. Can be suppressed. That is, it is possible to suppress a delay in data writing time associated with the data migration process. Further, an unintended write time delay can be avoided. In other words, the data migration process can be performed at an arbitrary timing according to the application software 21 (preferred timing of each application software 21). Therefore, it is effective for writing data of the application software 21 that has particularly severe restrictions on the writing time.

  In the present embodiment, the flash memory 14 includes a write target block for data writing and at least one free block for copying for each application software 21, and when data migration processing is executed, copying is performed. The previous block is set as a new write target block, and the block from which the data at the copy source is erased is set as a new free block for copying. When data is written, new data is added to an unstored record with respect to a copy destination block, that is, a new data write target block. As described above, since the valid data is copied to the empty block corresponding to the application software 21, the copied data can be retained even if an instantaneous interruption occurs. Moreover, even when it is not possible to secure a large-capacity RAM 13 in terms of space, a delay in writing time can be suppressed. Therefore, it is particularly suitable for in-vehicle applications where space restrictions are severe and usage conditions are severe compared to consumer.

  In the present embodiment, the example in which the data migration process at this timing is terminated when the migration condition of the corresponding application software 21 is not satisfied in step 13 indicating the data migration process. However, for example, the determination in step 13 may be repeated until a predetermined time elapses, and after the predetermined time elapses, the data migration processing at this timing may be terminated. Alternatively, the determination in step 13 may be repeated up to a predetermined number of times, and the data migration process at this timing may be terminated after repeating the predetermined number of times.

(Second Embodiment)
Next, a second embodiment of the present invention will be described based on FIG. FIG. 6 is a flowchart showing data migration processing according to the second embodiment.

  The flash memory data processing (data migration processing) method according to the present embodiment and the configuration of the ECU including the storage device to which the method is applied are often in common with those according to the first embodiment. Detailed explanations of the parts are omitted, and different parts are explained mainly.

  In the data migration process of the flash memory 14 according to the present embodiment, the request for the data migration process shown in the first embodiment (see FIG. 4) up to the request for the data migration process in step 24 shown in FIG. 6 (step 14). Is consistent with. Further, the configuration of the ECU 10 is substantially the same as that of the first embodiment, and the difference is that the flash memory 14 does not have an empty block for data migration used for data migration processing.

  When the CPU 11 requests the driver software 20 (flash memory 14) to perform data migration processing based on the program of the application software 21 (step 24), the CPU 11 executes the driver software 20 and A process of copying (temporarily saving) valid data of a write target block having a predetermined physical address corresponding to the application software 21 to a corresponding area of the RAM 13 is executed (step 25). In addition, a process of generating an empty block by erasing all data in the write target block is executed (step 26).

  Then, a process of writing the valid data temporarily stored in the RAM 13 in order from the first record, that is, a rewrite process, is executed on the write target block which has been erased and becomes an empty block (step 27). The validity / invalidity of the data can be confirmed by, for example, the validity confirmation area (second flag) in the redundant part as described above. The above corresponds to the fifth step recited in the claims.

  In this way, when the data migration process is completed, the CPU 11 executing the driver software 20 executes a process of notifying the application software 21 that the data migration process is completed (step 28).

  As described in the first embodiment, the flash memory data processing method (data migration processing) method and the ECU 10 including the storage device to which the method is applied are also in the middle of the write operation as described in the first embodiment. Thus, the execution of the data migration process can be suppressed. That is, it is possible to suppress a delay in data writing time associated with the data migration process. Further, an unintended write time delay can be avoided. In other words, the data migration process can be performed at an arbitrary timing according to the application software 21 (preferred timing of each application software 21). Therefore, it is effective for writing data of the application software 21 that has particularly severe restrictions on the writing time.

  In the present embodiment, since valid record data is temporarily stored in the RAM 13, the flash memory 14 can be configured not to require an empty block as a data copy storage medium.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In the present embodiment, an example of a body system ECU that controls the body system of an automobile is shown as the ECU 10 including a storage device to which a data processing (data migration processing) method of a flash memory is applied. However, the use of the ECU 10 is not limited to the above example. Further, the present invention is not limited to in-vehicle use, and can be applied to consumer electronic devices.

  Further, the migration condition of the application software 21 may be set as appropriate. For example, the transition condition may be that the vehicle speed is equal to or higher than a predetermined value or that the light is on. In addition, a data transfer state is displayed (notified) on a display device (for example, a monitor) electrically connected to the CPU 11 via the interface, and data transfer processing is performed by a user (worker) who has seen the data transfer state. The transition condition may be that the requested key operation has been performed.

10 ... Electronic control unit (ECU)
11 ... CPU
12 ... ROM
13 ... RAM
14: Flash memory 21: Application software (application)

Claims (3)

CPU,
A storage area is divided into a plurality of blocks, data can be erased in units of the blocks, the block includes a plurality of records, and a flash memory capable of writing data in units of the records;
Driver software that is stored in ROM as a program executed by the CPU and that is a program executed by the CPU with respect to the flash memory, and application software that is a program for controlling electronic devices.
Based on an instruction of the application software side, the CPU, by executing the driver software, the data of the application software, executes a process of writing the unstored record block corresponding to the application software,
The CPU, by executing the driver software, at different timings from the data writing, to detect the data write state in said block,
The CPU executes the driver software, and when the detected write state matches a data migration condition corresponding to a predetermined write state set in advance, a valid record among the records of the corresponding block only, it has rows notification that the a block is a timing shifts to another storage medium to the application software side of the data,
The CPU, by executing the application software, receives the notification, and, if matches the transition condition of the application software corresponding permits the migration of data to the driver software side,
The CPU executes the driver software, receives the permission, and copies only the valid record data of the block records to the storage medium, and the data of the block of the data copy source storage apparatus characterized by erasing. The storage medium is an empty block different from the block of the data copy source,
The CPU executes the driver software so that the copy destination block to which valid record data has been copied is used as a data write block corresponding to the application software in an unstored record of the block. The storage device according to claim 1 , wherein new data is additionally written. A RAM as the storage medium;
The CPU re-writes data of valid records stored in the RAM in order from the top of the plurality of records to the block from which data has been erased by executing the driver software , and the valid records 2. The storage device according to claim 1 , wherein new data is added to an unstored record of the block in which the data is rewritten.

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