METHOD OF EVENLY USING A PLURALITY OF BLOCKS OF A FLASH MEMORY, AND ASSOCIATED MEMORY DEVICE AND CONTROLLER THEREOF

• US 20100228907A1
• Filed: 09/24/2009
• Published: 09/09/2010
• Est. Priority Date: 03/03/2009
• Status: Active Grant

• Current Assignee: Silicon Motion, Inc. (Silicon Motion)
• Original Assignee: Silicon Motion, Inc. (Silicon Motion)
• Inventors: Shen, Yang-Chih
• Granted Patent: US 8,484,406 B2
• Time in Patent Office: Days
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/7211 Wear leveling
• CPC Class Codes: G11C 16/349 Arrangements for evaluating degradation, retention or wearout, e.g. by counting erase cycles

Abstract

A method of evenly using a plurality of blocks of a Flash memory comprises: providing at least one threshold value, which is utilized for sieving out blocks suitable for use from the plurality of blocks according to erase counts of the plurality of blocks; and by comparing erase counts of at least a portion of the plurality of blocks with the threshold value, sieving out a specific block for use from the plurality of blocks according to a purpose of use. An associated memory device and a controller thereof are also provided, where the controller comprises: a ROM arranged to store a program code, wherein the controller is provided with the at least one threshold value through the program code; and a microprocessor arranged to execute the program code to control the access to the Flash memory. The controller sieves out the specific block according to the purpose of use.

Claims

1. A method of evenly using a plurality of blocks of a Flash memory, the method comprising:

providing at least one threshold value, which is utilized for sieving out blocks suitable for use from the plurality of blocks according to erase counts of the plurality of blocks; and

sieving out a specific block from the plurality of blocks according to a purpose of use by comparing erase counts of at least a portion of the plurality of blocks with the threshold value in order to use the specific block.

2. The method of claim 1, wherein the at least one threshold value comprises a plurality of threshold values.

3. The method of claim 1, wherein the step of sieving out the specific block from the plurality of blocks according to the purpose of use by comparing the erase counts of the portion of the plurality of blocks with the threshold value in order to use the specific block further comprises:

classifying at least a portion of the plurality of blocks by comparing erase counts of at least a portion of the plurality of blocks with the threshold value; and

according to the purpose of use, determining a classification type from which the specific block should be sieved out for use.

4. The method of claim 3, wherein the step of classifying the portion of the plurality of blocks by comparing the erase counts of the portion of the plurality of blocks with the threshold value further comprises:

classifying at least a portion of the plurality of blocks into a first type and a second type, wherein erase counts of blocks of the first type are greater than erase counts of blocks of the second type.

5. The method of claim 1, wherein the step of sieving out the specific block from the plurality of blocks according to the purpose of use by comparing the erase counts of at least the portion of the plurality of blocks with the threshold value in order to use the specific block further comprises:

sorting at least a portion of the plurality of blocks by comparing erase counts of at least a portion of the plurality of blocks with the threshold value; and

according to the purpose of use, determining a sorted portion from which the specific block should be sieved out for use, wherein the sorted portion represents a portion of a sorted result.

6. The method of claim 1, wherein the step of sieving out the specific block from the plurality of blocks according to the purpose of use by comparing the erase counts of the portion of the plurality of blocks with the threshold value in order to use the specific block further comprises:

sieving out the specific block from the plurality of blocks according to the purpose of use by comparing erase counts of all of the plurality of blocks with the threshold value in order to use the specific block.

7. The method of claim 1, further comprising:

dynamically adjusting the threshold value.

8. The method of claim 1, wherein each of the plurality of blocks is a blank block.

9. The method of claim 1, wherein the step of sieving out the specific block from the plurality of blocks according to the purpose of use by comparing the erase counts of the portion of the plurality of blocks with the threshold value in order to use the specific block further comprises:

sieving out a block having an erase count less than others as a temporary block or a file allocation table (FAT) block;

or

sieving out a block having an erase count greater than others as a child block or a new block.

10. A memory device, comprising:

a Flash memory comprising a plurality of blocks; and

a controller for accessing the Flash memory, wherein the controller is provided with at least one threshold value, in order to sieve out blocks suitable for use from the plurality of blocks according to erase counts of the plurality of blocks;

wherein the controller sieves out a specific block from the plurality of blocks according to a purpose of use by comparing erase counts of at least a portion of the plurality of blocks with the threshold value in order to use the specific block.

11. The memory device of claim 10, wherein the at least one threshold value comprises a plurality of threshold values.

12. The memory device of claim 10, wherein the controller classifies at least a portion of the plurality of blocks by comparing erase counts of at least a portion of the plurality of blocks with the threshold value;

and according to the purpose of use, the controller determines a classification type from which the specific block should be sieved out for use.

13. The memory device of claim 12, wherein the controller classifies at least a portion of the plurality of blocks into a first type and a second type, wherein erase counts of blocks of the first type are greater than erase counts of blocks of the second type.

14. The memory device of claim 10, wherein the controller sorts at least a portion of the plurality of blocks by comparing erase counts of at least a portion of the plurality of blocks with the threshold value;

and according to the purpose of use, the controller determines a sorted portion from which the specific block should be sieved out for use, wherein the sorted portion represents a portion of a sorted result.

15. The memory device of claim 10, wherein the controller sieves out the specific block from the plurality of blocks according to the purpose of use by comparing erase counts of all of the plurality of blocks with the threshold value in order to use the specific block.

16. The memory device of claim 10, wherein the controller dynamically adjusts the threshold value.

17. The memory device of claim 10, wherein each of the plurality of blocks is a blank block.

18. The memory device of claim 10, wherein the controller sieves out a block having an erase count less than others as a temporary block or a file allocation table (FAT) block;

or the controller sieves out a block having an erase count greater than others as a child block or a new block.

19. A controller of a memory device, the controller being utilized for accessing a Flash memory comprising a plurality of blocks, the controller comprising:

a read only memory (ROM) arranged to store a program code, wherein the controller is provided with at least one threshold value through the program code, in order to sieve out blocks suitable for use from the plurality of blocks according to erase counts of the plurality of blocks; and

a microprocessor arranged to execute the program code to control the access to the Flash memory;

wherein the controller that executes the program code by utilizing the microprocessor sieves out a specific block from the plurality of blocks according to a purpose of use by comparing erase counts of at least a portion of the plurality of blocks with the threshold value in order to use the specific block.

20. The controller of claim 19, wherein the at least one threshold value comprises a plurality of threshold values.

21. The controller of claim 19, wherein the controller that executes the program code by utilizing the microprocessor classifies at least a portion of the plurality of blocks by comparing erase counts of at least a portion of the plurality of blocks with the threshold value;

and according to the purpose of use, the controller that executes the program code by utilizing the microprocessor determines a classification type from which the specific block should be sieved out for use.

22. The controller of claim 21, wherein the controller that executes the program code by utilizing the microprocessor classifies at least a portion of the plurality of blocks into a first type and a second type, wherein erase counts of blocks of the first type are greater than erase counts of blocks of the second type.

23. The controller of claim 19, wherein the controller that executes the program code by utilizing the microprocessor sorts at least a portion of the plurality of blocks by comparing erase counts of at least a portion of the plurality of blocks with the threshold value;

and according to the purpose of use, the controller that executes the program code by utilizing the microprocessor determines a sorted portion from which the specific block should be sieved out for use, wherein the sorted portion represents a portion of a sorted result.

24. The controller of claim 19, wherein the controller that executes the program code by utilizing the microprocessor sieves out the specific block from the plurality of blocks according to the purpose of use by comparing erase counts of all of the plurality of blocks with the threshold value in order to use the specific block.

25. The controller of claim 19, wherein the controller that executes the program code by utilizing the microprocessor dynamically adjusts the threshold value.

26. The controller of claim 19, wherein each of the plurality of blocks is a blank block.

27. The controller of claim 19, wherein the controller that executes the program code by utilizing the microprocessor sieves out a block having an erase count less than others as a temporary block or a file allocation table (FAT) block;

or the controller that executes the program code by utilizing the microprocessor sieves out a block having an erase count greater than others as a child block or a new block.

28. A method of evenly using a plurality of blocks of a Flash memory, the Flash memory being erased in units of blocks, the method comprising:

classifying the plurality of blocks into a data region or a spare region, wherein the blocks in the spare region are blank blocks;

recording at least one erase count of at least one block of the spare region; and

popping a spare block from the spare region according to the recorded erase count and one of a plurality of purposes of use in order to use the spare block.

29. The method of claim 28, wherein the step of popping the spare block from the spare region according to the recorded erase count and one of the plurality of purposes of use in order to use the spare block further comprises:

classifying at least one block of the spare region according to the recorded erase count and at least one threshold value; and

popping the spare block according to the purpose of use and a classified result in order to use the spare block.

30. The method of claim 28, wherein the step of popping the spare block from the spare region according to the recorded erase count and one of the plurality of purposes of use in order to use the spare block further comprises:

sorting a plurality of blocks of the spare region according to the recorded erase count and at least one threshold value; and

popping the spare block from the spare region according to the purpose of use and a sorted result in order to use the spare block.

31. The method of claim 28, wherein the plurality of purposes of use comprises:

popping at least one block from the spare region as a temporary block, a file allocation table (FAT) block, a child block, or a new block for a purpose of writing.

32. The method of claim 31, wherein the step of popping the spare block from the spare region according to the recorded erase count and one of the plurality of purposes of use in order to use the spare block further comprises:

popping a block having an erase count less than others from the spare region as a temporary block or a FAT block;

or

popping a block having an erase count greater than others from the spare region as a child block or a new block.