Memory and method for checking reading errors thereof

• US 7,925,960 B2
• Filed: 03/26/2007
• Issued: 04/12/2011
• Est. Priority Date: 11/07/2006
• Status: Active Grant

• Current Assignee: Macronix International Co., Ltd.
• Original Assignee: Macronix International Co., Ltd.
• Inventors: Hung, Chun-Hsiung, Ho, Wen-Chiao, Chang, Kuen-Long, Chang, Chin-Hung
• Primary Examiner(s): Torres; Joseph D
• Application Number:
  US11/727,256
• Publication Number:
  US 20080109697A1
• Time in Patent Office: 1,478 Days
• Field of Search: 714/773, 714/763, 714/819
• US Class Current: 714/773
• CPC Class Codes: G06F 11/1068 in sector programmable memories, e.g. flash disk G06F11/1072 takes precedence
• CPC Class Codes: H03M 13/03 Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words
• CPC Class Codes: H03M 13/13 Linear codes
• CPC Class Codes: H03M 13/3776 using a re-encoding step during the decoding process

Abstract

A method for checking reading errors of a memory includes receiving a first data fragment and accordingly generating a first ECC and a first count index; writing the first data fragment, the first ECC and the first count index into a memory; reading the first data fragment from the memory as a second data fragment, generating a second ECC and second count index according to the second data fragment; determining whether the first count index and second count index are equal; determining whether the first ECC and the second ECC are equal; and outputting the second data fragment when the first count index is equal to the second count index and the first ECC is equal to the second ECC.

Claims

1. A method for checking reading errors of a memory, comprising:

receiving a first data fragment;

generating a first error correction code (ECC) and a first count index according to the first data fragment, wherein the first count index is corresponding to a quantity of one kind of binary value in the first data fragment;

writing the first data fragment, the first error correction code and the first count index into a memory;

reading the first data fragment from the memory as a second data fragment;

generating a second error correction code and a second count index according to the second data fragment;

determining whether the first count index and the second count index are equal;

determine whether the first error correction code and the second error correction code are equal; and

outputting the second data fragment when the first count index and the second count index are equal, and the first error correction code and the second error correction code are equal.

2. The method according to claim 1, wherein the binary value is 1.

3. The method according to claim 2, wherein the memory is a single-level-cell (SLC) flash memory.

4. The method according to claim 2, wherein the memory is a multi-level-cell (MLC) flash memory.

5. The method according to claim 1, wherein the binary value is 0.

6. The method according to claim 1, wherein the memory is a non-volatile memory.

7. The method according to claim 1, wherein the first count index is obtained by using an n-bit counter, and n is a positive integer.

8. The method according to claim 7, wherein the method for checking reading errors of a memory can determine the second data fragment has n bit errors at most as compared to the first data fragment.

9. The method according to claim 7, further comprising:

if the first count index is not equal to the second count index and the first count index differs from the second count index by 1, correcting the second data fragment to be the first data fragment by using the second correction code, and outputting the second data fragment.

10. The method according to claim 9, wherein if the first count index differs from the second count index by 1, the second data fragment has 1 bit error as compared to the first data fragment.

11. The method according to claim 7, further comprising:

if the first count index is not equal to the second count index and the first count index differs from the second count index by x, correcting the second data fragment to be the first data fragment by using the second correction code, and outputting the second data fragment, wherein x is a positive integer and less than a positive integer m.

12. The method according to claim 11, wherein if the first count index differs from the second count index by x, the second data fragment has x bits error as compared to the first data fragment.

13. The method according to claim 7, further comprising:

if the first count index is not equal to the second count index and the first count index differs from the second count index by m, changing a reference current of the memory in the reading operation; and

reading again the first data fragment from the memory to be the second data fragment;

wherein m is a positive integer larger than 1 and smaller than or equal to n.

14. The method according to claim 13, wherein if the first count index is larger than the second count index by m, reducing the reference current and if the first count index is smaller than the second count index by m, increasing the reference current.

15. The method according to claim 13, wherein if the first count index differs from the second count index by m, the second data fragment has m bit errors as compared to the first data fragment.

16. A memory, comprising:

a memory-cell array, for receiving and storing a first data fragment, reading the first data fragment from the memory-cell array to be a second data fragment;

an error correction circuit, for generating a first error correction code (ECC) according to the first data fragment and generating a second error correction code according to the second data fragment; and

an n-bit counter, for generating a first count index and a second count index, wherein the first count index and the second count index are respectively corresponding to a quantity of one kind of binary value occurred in the first data fragment and a quantity of one kind of binary value occurred in the second data fragment, and n is a positive integer;

wherein the memory determines whether the second data fragment is equal to the first data fragment according to the first count index, the second count index, the first error correction code and the second error correction code;

wherein when the second data fragment has y bit errors as compared to the first data fragment, the memory corrects the second data fragment to be the first data fragment and outputs the second data fragment, and y is a positive integer smaller or equal to n.

17. The memory according to claim 16, is a non-volatile memory.

18. The memory according to claim 17, is a single-level-cell flash memory.

19. The memory according to claim 17, a multi-level-cell flash memory.

20. The memory according to claim 16, wherein if the first count index differs from the second count index by 1, the memory corrects the second data fragment to be the first data fragment by using the second correction code, and outputs the second data fragment.

21. The memory according to claim 20, wherein if the first count index differs from the second count index by 1, the second data fragment has 1 bit error as compared to the first data fragment.

22. The memory according to claim 16, wherein if the first count index differs from the second count index by m, the memory changes a reference current of the reading operation to read again the first data fragment from the memory to be the second data fragment, wherein m is a positive integer larger than 1 and smaller than or equal to n.

23. The memory according to claim 22, wherein if the first count index is larger than the second count index by m, the memory reduces the reference current and if the first count index is smaller than the second count index by m, the memory increases the reference current.

24. The memory according to claim 22, wherein if the first count index differs from the second count index by m, the second data fragment has m bit errors as compared to the first data fragment.

25. The method according to claim 16, further comprising:

if the first count index is not equal to the second count index and the first count index differs from the second count index by x, correcting the second data fragment to be the first data fragment by using the second correction code, and outputting the second data fragment, wherein x is a positive integer and less than m.

26. The method according to claim 25, wherein if the first count index differs from the second count index by x, the second data fragment has x bits error as compared to the first data fragment.