JPH06131891A - Semiconductor file device - Google Patents

Abstract

PURPOSE:To shorten the average data writing time to a memory for a considerable period from the start of use of the memory and then to increase the access time to the memory. CONSTITUTION:When the detail rewriting frequency of the erasing blocks 22-1, 22-2, etc., are smaller than a hundred thousand, a memory controller 11 updates the rewriting frequency rough data on a control table 21 from the detail rewriting frequency in a carry mode of every ten thousand. Meanwhile the controller 11 updates the rewriting frequency rough data from the detail rewriting frequency in a carry mode of every hundred if the detail rewriting frequency is larger than a hundred thousand. Therefore, the probability of producing a difference larger than the prescribed value between the rewriting frequency rough data can be reduced at an early stage of use of a memory chip 2. Thus the swapping frequency is reduced and the average data writing time is shortened to the erasing blocks.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a flash type EEPRO.
The present invention relates to a semiconductor file device for reading / writing data from / to M, and more particularly to a swapping process for equalizing the number of data writes to each erase block allocated to the flash type EEPROM.

[0002]

2. Description of the Related Art Conventionally, in this type of semiconductor file device,
After converting the logical block address of the data write destination designated by the system side into the physical block address for specifying the erase block assigned to the flash type EEPROM, the data is written to the erase block of the physical block address. However, there is a limit to the number of times data can be written in the flash type EEPROM. Therefore, if the correspondence between the logical block address and the physical block address is fixed, when the number of times of writing data to a certain logical block address exceeds the limit, data is not yet written to other erase blocks. Despite being able to write, the erase block at the physical block address corresponding to the logical block address becomes unwritable, and the number of times of writing data to each erase block of the flash type EEPROM cannot be equalized, and the memory area is effective. It had the drawback that it would not be available.

Therefore, in order to avoid the above-mentioned drawback, when there is another erase block in which the number of times of rewriting data in the erase block of the conventional physical block address exceeds a predetermined number and the number of times of rewriting data is small. , A logical block address corresponding to an erase block in which the number of data rewrites exceeds a predetermined number corresponds to another erase block in which the number of data rewrites is small, and the number of data rewrites is small. Swapping is performed to change the correspondence between the logical block address and the physical block address so that the logical block address corresponding to another erase block corresponds to the erase block in which the number of times of rewriting of the data exceeds a predetermined number. . In performing this swapping, it is necessary to manage the number of data rewrites to each erase block.
Normally, this is done by a management table provided in the flash type EEPROM. The management table manages the number of times of data rewriting of a plurality of erase blocks under its own control, and there are a plurality of such management tables.

The erase block managed by the management table stores the number of times of rewriting data for the block, but the management table lists rough data of the number of times of rewriting data of each erase block under management. Has been saved. Swapping is performed between erase blocks having a predetermined difference in the rough data. At this time, the frequency of the swapping depends on the rule for extracting the rough rewriting frequency data stored in the management table from the detailed rewriting frequency of the data stored in the erase block. For example, in the case of collecting the rough data as the information of ten thousand units of the detailed data and the case of collecting it as the information of thousand units, the latter is more likely to have a difference in the rewrite frequency rough data between the erase blocks. As a result, the frequency of swapping increases, and in the former case, the frequency of swapping decreases vice versa.

However, in the conventional management table, since the rough data is collected from the number of detailed rewrites of the data stored in the erase block according to the same rule from the start to the end of use of the memory, the above-mentioned swapping is performed. It was supposed to be performed at a constant frequency from the start to the end of use. By the way, if swapping is performed on the erase block assigned to the flash EEPROM at the time of data rewriting, the rewritten portion is the “erasure block to be rewritten”, the “erasure block to be swapped”, and Since there are three locations in the “management table”, this takes an extra time than the normal data rewriting process without swapping. Therefore, if the frequency of the above-mentioned swapping is made uniform from the start of use of the memory to the end thereof, the average data write time from the start of use of the memory to the end thereof is always the same. However, if the frequency of the above-described swapping is set low at the beginning of the use of the memory and set so that the frequency of the swapping occurs just before the end of the use of the memory, the frequency of the swapping occurs for a considerable period from the start of the use of the memory. By lowering it, the average time for writing data can be shortened. Depending on the user, the semiconductor file device having such a setting may be more convenient to use, but in the past, as described above, only the same average data writing time can be obtained from the start to the end of use of the memory. .

[0006]

In the conventional semiconductor file device, swapping for rearranging the logical block address and the physical block address is performed based on the rewriting frequency rough data of the erase block managed by the management table. It is being appreciated. However, in the above-mentioned swapping in the conventional semiconductor file device, since the frequency of occurrence of the swapping is uniform from the start to the end of the memory, the average time of writing data to the memory from the start to the end of use of the memory is the same. , The write average time cannot be changed with the lapse of the use time of the memory.
There is a drawback that the semiconductor file device is not easy to use.

Therefore, the present invention eliminates the above-mentioned drawbacks, shortens the average time for writing data to the memory for a considerable period from the start of use of the memory, and speeds up access to the memory. It is intended to provide a file device.

[0008]

The present invention is a flash type E
When a carry of the number of times of rewriting data to the erase block allocated in the EPROM occurs in a predetermined unit, the separately managed coarse data of the number of times of rewriting of the erase block is updated, and the data write target erase is performed. In a semiconductor file device that performs swapping between these erase blocks when there is an erase block having a coarse number of rewrite times smaller than the above-mentioned coarse number of rewrite times of the block, in the semiconductor file device, A configuration is provided that includes a control unit that changes a unit of carry of the rewriting frequency when updating the rewriting frequency rough data according to the rewriting frequency.

[0009]

In the semiconductor file device of the present invention, the control means changes the carry unit of the number of rewriting when updating the rough rewriting frequency data according to the number of rewriting of data to the erase block. For example, if the number of times data is rewritten to the erase block is less than 100,000, the carry unit is 10,000 units, and if it is 100,000 or more, the carry unit is 100 units. At the beginning of the start of use of the memory, the average number of times of data writing is shortened by making it difficult for a predetermined number of differences or more to be made between the rough rewriting frequency data of each erase block and reducing the frequency of swapping.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a semiconductor file device of the present invention. Reference numeral 1 denotes a controller unit that controls reading and writing data from and to the memory chip 2, and includes a memory management controller 11, an R / W control unit 12, and a memory 1.
Have three. 2 is a flash-type EEPROM memory chip, which includes a management table 21 and an erase block 22-
1 to 22-2 and the like are assigned. The management table 21 manages the number of times of data rewriting of the erase blocks 22-1 and 22-2. Further, although there are a plurality of management tables and erase blocks managed by each management table, here, as a representative, the management table 21 and the erase blocks 22-
1 to 22-2 are shown.

Next, the operation of this embodiment will be described. When the write data and the logical block address that is the write destination are sent from the system side, the memory management controller 11 of the controller unit 1 converts the logical block address into a physical block address and then causes the R / W control unit 12 to operate. The erase block having the physical block address of the data write destination is accessed through the memory chip 2 to read the number of detailed rewrites in the erase block. Next, when the memory management controller 11 adds 1 to the read number of detailed rewrites, rough data of the number of rewrites of this erase block is stored in the management table that manages this erase block. 2 for rewriting frequency rough data
Whether or not it is greater than the above is determined by accessing the management table 21 via the R / W control unit 12. As a result, when the coarse data of the number of times of rewriting is small and there is no erase block having a difference of 2 or more, the memory management controller 11 again performs R
The data is written to the erase block at the physical block address via the / W control unit 12, the number of detailed rewrites of the erase block is incremented by 1, and the process is terminated.

By the way, the memory management controller 11 uses, for example, the erase block 22-1 or 2 in the memory chip 2.
When the number of data rewrites of 2-2 is updated, a process of changing the corresponding rough data of the number of rewrites in the management table 21 is performed according to the rule shown in FIG. That is, the memory management controller 11 sets the detailed rewrite frequency indicating the data rewrite frequency of the erase block set in the memory 13 shown in FIG. 2, and the rewrite frequency rough data extracted from the detailed rewrite frequency. Whenever it is necessary to refer to the table data indicating the correspondence relation of (3), the rewriting frequency rough data in the management table 21 is updated each time data is rewritten into the erase block. In FIG. 2, until the number of detailed rewrites on the erase block side reaches 100,000, each time the number of detailed rewrites is carried by tens of thousands, the rewrite count rough data is incremented by +1. The coarse frequency data is updated. That is, the number of detailed rewrites on the erase block side in FIG.
During the period 9, the corresponding rewriting frequency rough data is 0,
While the detailed rewriting frequency is from 10,000 to 19999, the rewriting frequency rough data is 1, and so on. But,
When the number of detailed rewritings on the erase block side is 100,000 or more, the rough rewriting frequency data is updated by a method of incrementing the coarse rewriting frequency data by +1 every time the number of detailed rewritings is carried by 100. To be done.

As described above, the memory management controller 1
After 1 has once written the rough rewrite frequency data of the erase block in the management table 21, only when there is a difference of 2 or more as described above between the rewrite frequency rough data of the management table 21, the erase block And the difference between the rough data on which the swapping is performed is
It is constant from the start of use to the end of use.

Now, the operation when the controller 1 of FIG. 1 is instructed by the system to write data to the logical block address 3112 will be described. The memory management controller 11 converts the logical block address 3112 from the correspondence table of the logical block address and the physical block address in the memory 13 into the physical block address of 31415, and then, through the R / W control unit 12, the physical block The erase block 22-1 corresponding to the address 31415 is accessed to read the detailed rewrite count 29999. When the memory management controller 11 adds 1 to the number of rewrites 29999, it becomes 30000, so that the rough rewrite count data for the erase block 22-1 of the management table 21 becomes 3. At this time, since the coarse data of the number of times of rewriting of the erase block of the physical block address 58979 is 1, the coarse data of the erase block 22-1 becomes larger than the coarse data of the erase block 22-2 by 2. Swapping will be performed between both erase blocks.

Therefore, the memory management controller 11 uses the R
After temporarily pulling up the data written in the erase block 22-2 to be swapped via the / W control unit 12, while writing this into the erase block 22-1 via the R / W control unit 12, This erase block 22-1
After adding 1 to the number of detailed rewriting of the data, the data to be written this time is erased via the R / W control unit 12 to the erase block 22-
In addition to writing to 2, the number of detailed rewrites of this erase block 22-2 is incremented by 1. Next, the memory management controller 11 rewrites the correspondence relationship between the logical block address and the physical block address of the management table 21 via the R / W control unit 12 according to the swapping, and then the rough data of the number of rewritings, After rewriting the addresses of both the swapping targets to the rough data of the updated write count of the erase block 22-1 which originally tried to write the current data, the process is ended.

FIG. 3 is a flowchart showing the operation of the memory management controller 11 of the controller unit 1 at the time of writing data. First, in step 301, the memory management controller 11 reads the number of detailed rewrites of the data rewrite target erase block in the memory chip 2, adds 1 and then in step 302, the detailed rewrite before adding 1 It is determined whether the number of times is 100,000 or more, and if so, the process proceeds to step 303, and if not, step 3
Go to 04. In step 304, it is determined whether or not the digit is increased by ten thousand when adding 1 to the number of detailed rewriting. If the digit is not increased, the process proceeds to step 307. If the digit is increased, the process proceeds to step 305. On the other hand, in the case of proceeding to step 303, it is determined whether or not the digit is increased by a unit of 100 by adding 1 to the number of detailed rewriting, and if not, step 3
If the digit goes up, go to step 305.
In step 305, it is determined whether or not there is an erase block having a coarse rewrite count data whose difference is 2 or less with respect to the coarse rewrite count data of the erase block to be written with data.
If not, the process proceeds to step 307, and if there is, the process proceeds to step 306. When the process proceeds to step 307, a normal write process for writing data in the erase block to be rewritten is performed, and the process ends. Step 30
When the process proceeds to 6, the data is written in the swapped target erase block while the swapping process is performed between the data rewrite target erase block and the corresponding erase block, and the data of each part associated with the swapping is rewritten. After that, the process ends.

According to this embodiment, when the number of detailed rewritings of the erase block in the memory chip 2 is less than 100,000, the detailed rewritings are collected in the management table 21 every time the number of detailed rewritings is increased by ten thousand. The rough rewriting frequency rough data is incremented by +1 so that the detailed rewriting frequency of the erase block is 10
In the case of ten thousand times or more, each time the detailed rewriting frequency is carried by one hundred, the rewriting frequency rough data collected in the management table 21 is incremented by +1. Therefore, the rewriting frequency rough data in the management table 21 is incremented. The difference between the two is only slow until the number of data rewrites to the erase block exceeds 100,000. Therefore, the frequency of swapping is reduced for a considerable period from the start of use of the memory chip 2, and the average is averaged. The number of times of data rewriting can be shortened, and the access to the memory chip 2 of the controller unit 1 can be speeded up. In addition, since swapping is also performed on each erase block in the memory chip 2, the prescribed number of rewriting times of each erase block expires at about the same time, enabling uniform use in the memory chip 2.

In addition to the swapping method described in the above embodiment, the rewriting frequency rough data in the management table 21 is 1
For erase blocks of 0 or less, swapping is not performed even if there is another erase block whose rewriting count rough data is 2 or more, and it is only a swapped target. It is possible to reduce the frequency with which swapping occurs. In this case, the rough rewrite frequency data is used for prioritizing the erase blocks that have been swapped.

[0019]

As described above, according to the semiconductor file device of the present invention, the memory is used for a considerable period of time from the start of use.
By shortening the average time to write data to the memory,
It is possible to speed up access to the memory.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a semiconductor file device of the present invention.

FIG. 2 is a diagram showing an example of a rule for extracting rewriting frequency rough data to be collected in a management table from the detailed rewriting frequency stored in an erase block.

FIG. 3 is a flowchart showing an operation of the memory management controller shown in FIG. 1 when writing data.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Controller part 2 ... Memory chip 11 ... Memory management controller 12 ... R / W control part 13 ... Memory 21 ... Management table 22-1 to 22-2 ... Erase block

Claims (1)

[Claims] 1. When a carry of the number of times of rewriting data to the erase block allocated in the flash type EEPROM occurs in a predetermined unit, the separately managed coarse data of the number of rewriting of the erase block is updated. In a semiconductor file device that performs swapping between erase blocks when there is an erase block having a coarse rewrite count data that is smaller than the coarse rewrite count data of the data write target erase block by a predetermined number or more, A semiconductor file device comprising: a control unit that changes a unit of carry of the rewrite count when updating the rough rewrite count data according to the data rewrite count in the erase block.