Methods for Accessing a Storage Unit of a Flash Memory and Apparatuses using the Same

• US 20150058700A1
• Filed: 07/15/2014
• Published: 02/26/2015
• Est. Priority Date: 08/23/2013
• Status: Active Grant

• Current Assignee: Silicon Motion, Inc. (Silicon Motion)
• Original Assignee: Silicon Motion, Inc. (Silicon Motion)
• Inventors: Yang, Tsung-Chieh, Shen, Yang-Chih, Hsu, Sheng-I
• Granted Patent: US 9,411,686 B2
• Time in Patent Office: Days
• US Class Current: 714/773
• CPC Class Codes: G06F 11/1012 using codes or arrangements adapted for a specific type of error G06F11/1048 takes precedence
• CPC Class Codes: G06F 11/108 Parity data distribution in semiconductor storages, e.g. in SSD
• CPC Class Codes: G06F 2211/109 Sector level checksum or ECC, i.e. sector or stripe level checksum or ECC in addition to the RAID parity calculation

Abstract

An embodiment of a method for accessing a storage unit of a flash memory, performed by a processing unit, includes at least the following steps. After all messages within a RAID (Redundant Array of Independent Disk) group are programmed, it is determined whether a vertical ECC (Error Correction Code) within the RAID group has been generated. The processing unit directs a DMA (Direct Memory Access) controller to obtain the vertical ECC from a DRAM (Dynamic Random Access Memory) and store the vertical ECC to a buffer when the vertical ECC within the RAID group has been generated, thereby enabling the vertical ECC to be programmed to the storage unit.

Claims

1. A method for accessing a storage unit of a flash memory, performed by a processing unit, comprising:

after all messages within a RAID (Redundant Array of Independent Disk) group are programmed, determining whether a vertical ECC (Error Correction Code) within the RAID group has been generated; and

directing a DMA (Direct Memory Access) controller to obtain the vertical ECC from a DRAM (Dynamic Random Access Memory) and store the vertical ECC to a buffer when the vertical ECC within the RAID group has been generated, thereby enabling the vertical ECC to be programmed to the storage unit.

2. The method of claim 1, wherein storage unit comprises a plurality of TLCs (Triple-Level Cells), and the vertical ECC is generated during a first run of programming for the vertical ECC.

3. The method of claim 1, further comprising:

directing a RAID-encoding unit to output the vertical ECC to the buffer when the vertical ECC within the RAID group has not been generated, thereby enabling the vertical ECC to be programmed to the storage unit.

4. The method of claim 3, further comprising:

before the vertical ECC is output from the RAID-encoding unit to the buffer, controlling a multiplexer to couple the RAID-encoding unit to the buffer; and

after the vertical ECC is output from the RAID-encoding unit to the buffer, controlling the multiplexer to couple the DRAM to the buffer.

5. The method of claim 3, further comprising:

directing the DMA controller to obtain the vertical ECC from the RAID-encoding unit and store the vertical ECC to the DRAM when the vertical ECC within the RAID group has not been generated.

6. The method of claim 1, wherein the vertical ECC is generated by a RAID-encoding unit according to the messages within the RAID group.

7. A method for accessing a storage unit of a flash memory, performed by a processing unit, comprising:

after all messages within a RAID (Redundant Array of Independent Disk) group are programmed, determining whether a vertical ECC (Error Correction Code) within the RAID group has been generated;

directing a RAID-encoding unit to output the vertical ECC to the buffer when the vertical ECC within the RAID group has not been generated, thereby enabling the vertical ECC to be programmed to the storage unit; and

directing a DMA (Direct Memory Access) controller to obtain the vertical ECC from the RAID-encoding unit and store the vertical ECC to a DRAM (Dynamic Random Access Memory) when the vertical ECC within the RAID group has not been generated.

8. The method of claim 7, further comprising:

before the vertical ECC is output from the RAID-encoding unit to the buffer, controlling a multiplexer to couple the RAID-encoding unit to the buffer; and

after the vertical ECC is output from the RAID-encoding unit to the buffer, controlling the multiplexer to couple the DRAM to the buffer.

9. The method of claim 7, wherein storage unit comprises a plurality of TLCs (Triple-Level Cells), and each TLC stores three bits of information.

10. An apparatus for accessing a storage unit of a flash memory, comprising:

a DMA (Direct Memory Access) controller;

a buffer; and

a processing unit, coupled to the DMA controller, after all messages within a RAID (Redundant Array of Independent Disk) group are programmed, determining whether a vertical ECC (Error Correction Code) within the RAID group has been generated; and

directing the DMA controller to obtain the vertical ECC from a DRAM (Dynamic Random Access Memory) and store the vertical ECC to the buffer when the vertical ECC within the RAID group has been generated, thereby enabling the vertical ECC to be programmed to the storage unit.

12. The apparatus of claim 10, further comprising:

a RAID-encoding unit,

wherein the processing unit directs the RAID-encoding unit to output the vertical ECC to the buffer when the vertical ECC within the RAID group has not been generated, thereby enabling the vertical ECC to be programmed to the storage unit.

13. The apparatus of claim 12, further comprising:

a multiplexer,

wherein the processing unit controls the multiplexer to couple the RAID-encoding unit to the buffer before the vertical ECC is output from the RAID-encoding unit to the buffer, and controls the multiplexer to couple the DRAM to the buffer after the vertical ECC is output from the RAID-encoding unit to the buffer.

14. The apparatus of claim 10, wherein the processing unit directs the DMA controller to obtain the vertical ECC from a RAID-encoding unit and store the vertical ECC to the DRAM when the vertical ECC within the RAID group has not been generated.

15. The apparatus of claim 10, wherein the vertical ECC is generated by a RAID-encoding unit according to the messages within the RAID group.

11. The apparatus of claim 11, wherein storage unit comprises a plurality of TLCs (Triple-Level Cells), and the vertical ECC is generated during a first run of programming for the vertical ECC.