Data processor with flash memory, and method for accessing flash memory

• US 20100011155A1
• Filed: 07/06/2009
• Published: 01/14/2010
• Est. Priority Date: 07/11/2008
• Status: Active Grant

• Current Assignee: Renesas Electronics Corporation
• Original Assignee: NEC Electronics Corporation (Renesas Electronics Corporation)
• Inventors: Kitagawa, Katsuhisa
• Granted Patent: US 8,327,064 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 2212/1016 Performance improvement
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A data processor includes a flash memory that stores a plurality of types of data therein, a random access memory that stores record data information therein, and a controller that can access the flash memory and the RAM. The record data information indicates a head address in the flash memory and a data length corresponding to latest data of each of the plurality of types of data. The controller reads, from the flash memory, the latest data of a type of a reading target among the plurality of types of data, with reference to the record data information.

Claims

1. A data processor, comprising:

a flash memory that stores a plurality of types of data therein;

a random access memory (RAM) that stores record data information therein; and

a controller that can access the flash memory and the RAM,

wherein the record data information indicates a head address in the flash memory and a data length corresponding to latest data of each of the plurality of types of data, and

wherein the controller reads, from the flash memory, the latest data of a type of a reading target among the plurality of types of data, with reference to the record data information.

2. The data processor according to claim 1,

wherein the latest data of each of the plurality of types of data is additionally written to the flash memory without existing data of a same type being overwritten therewith.

3. The data processor according to claim 1,

wherein the controller writes new data to a free space in the flash memory without overwriting existing data when writing new data to the flash memory.

4. The data processor according to claim 3,

wherein the RAM further stores therein free space information indicating a head address of the free space in the flash memory, and

wherein the controller writes the new data to a head of the free space with reference to the free space information.

5. The data processor according to claim 4,

wherein the controller updates the record data information and the free space information on the basis of a writing destination and a data length of the new data after writing the new data.

6. The data processor according to claim 4,

wherein the flash memory comprises:

a first block including the free space; and

a second block subsequent to the first block,

wherein the controller updates the head address of the free space, which is indicated by the free space information, to a head address of the free space in the second block, when the free space in the first block is insufficient to write the new data.

20. A product, comprising the data processor according to claim 1.

7. A data processor, comprising:

a flash memory;

a RAM that stores therein free space information indicating a head address of a free space in the flash memory; and

a controller that can access the flash memory and the RAM,

wherein the controller writes new data to a head of the free space with reference to the free space information, when writing the new data to the flash memory.

8. The data processor according to claim 7,

wherein the controller updates the free space information on the basis of a writing destination and a data length of the new data after writing the new data.

9. The data processor according to claim 7,

wherein the flash memory comprises:

a first block including the free space; and

a second block subsequent to the first block,

wherein the controller updates the head address of the free space, which is indicated by the free space information, to a head address of the free space in the second block, when the free space in the first block is insufficient to write the new data.

10. A method of accessing a flash memory, comprising:

reading latest data for each identifier from the flash memory;

creating record data including a head address in the flash memory and a data length in response to each of the read latest data;

storing the record data into a random access memory (RAM), with respect to each of the identifier;

acquiring an identifier of a reading target;

reading the record data corresponding to the identifier of the reading target from the RAM; and

reading data of the reading target from the flash memory based on the read record data.

11. The method according to claim 10,

wherein the flash memory includes a plurality of blocks, and each block has a status flag,

wherein the reading of the latest data comprises:

searching the status flag from a last block toward a head block in the flash memory; and

identifying a block having a status flag indicative that the latest data is included therein, as a last available block.

12. The method according to claim 11,

wherein data stored in the block of the flash memory includes the identifier, a data main body, and an end flag,

wherein the reading of the latest data further comprises:

searching the end flag of the data from the end address of the last available block toward the head address thereof;

identifying a space following the end flag firstly detected as a head of a free space;

creating a free space information indicating a free space head address based on the identified head of the free space; and

storing the free space information into the RAM.

13. The method according to claim 11,

wherein data stored in the block of the flash memory includes the identifier and a data main body,

wherein the reading of the latest data further comprises:

reading the data from an end address of the last available block toward a head address thereof; and

identifying the read data as the latest data corresponding to a new identifier, when the data with a new identifier ID is read.

14. The method according to claim 10,

wherein the flash memory includes a plurality of blocks, and each block has a status flag,

wherein the reading data of the reading target comprises:

confirming the status flag of a reading target block storing the reading data; and

cancelling a reading operation to execute an abnormal condition processing, when the status flag indicative that the latest data is included therein is not confirmed.

15. The method according to claim 12, further comprising:

acquiring the free space information from the RAM; and

writing new data to the head of the free space with reference to the read free space information.

16. The method according to claim 15,

wherein the writing comprises:

confirming the status flag of a writing target block for writing the new data; and

cancelling a writing operation to execute an abnormal condition processing, when the status flag indicative that the latest data is included therein is not confirmed.

17. The method according to claim 15, further comprising:

creating a new record data including a head address in the flash memory and a data length in response to the new data, when the record data corresponding to the identifier of the new data is not stored in the RAM; and

storing the new record data into the RAM, with respect to the identifier of the new data.

18. The method according to claim 15, further comprising:

creating an updating record data including a head address in the flash memory and a data length in response to the new data, when the record data corresponding to the identifier of the new data is stored in the RAM; and

updating the record data corresponding to the identifier of the new data in the RAM, with the updating record data.

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

detecting a maximum identifier number of the identifier corresponding to the latest data; and

storing the detected maximum identifier number as a maximum identifier information into the RAM.