Memory management apparatus

• US 8,280,579 B2
• Filed: 09/10/2008
• Issued: 10/02/2012
• Est. Priority Date: 09/14/2007
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Yasue, Motohiro, Suganuma, Takeshi
• Primary Examiner(s): Tran, Khoi
• Assistant Examiner(s): Amin, Bhavesh V
• Application Number:
  US12/207,873
• Publication Number:
  US 20090076681A1
• Time in Patent Office: 1,483 Days
• Field of Search: 726/5
• US Class Current: 701/33.4
• CPC Class Codes: G06F 11/1446 Point-in-time backing up or restoration of persistent data

Abstract

A vehicular memory management apparatus includes in an SRAM a mirror area for mirroring information from a PDTC storage area and an update information storage area for storing update information of the SRAM. When a fault is detected, a DTC is stored in both of the mirror area and a DTC storage area for maintaining consistency between the contents of the two areas, and the update information is updated. After confirming the consistency based on the update information, the information in the mirror area is copied to the PDTC storage area. Further, the information in the PDTC storage area is copied to the mirror area upon determining that the information in the mirror area is deleted based on the update information.

Claims

1. A memory management apparatus for a vehicle that is disposed in a vehicle, the apparatus comprising:

a volatile memory arranged to have a diagnostic trouble code storage area (DTC storage area), a mirror area, and an update information storage area, wherein the volatile memory is configured to be continuously supplied with power;

a nonvolatile memory arranged to have a backup area;

a storage control unit configured to store a detected DTC, wherein the detected DTC is indicative of a fault detected in a predetermined object to be detected in the vehicle, the storage control unit stores the detected DTC in the DTC storage area of the volatile memory, and stores the detected DTC as a permanent diagnostic trouble code (PDTC) in the backup area of the nonvolatile memory and in the mirror area of the volatile memory, the storage control unit is further configured to store an update information indicative of a data update status of the volatile memory in the update information storage area; and

a recovering unit configured to update information in one of the mirror area and the backup area by a predetermined recovery process that is based on the update information stored in the update information storage area, so that PDTC information in the mirror area and PDTC information in the backup area are identical.

2. The memory management apparatus of claim 1, wherein

the recovering unit is further configured to execute a first recovery process to copy the PDTC in the mirror area to the backup area, the recovering unit executes the first recovery process when the update information indicates that information in the mirror area and the DTC storage area are updated, and

the recovering unit is further configured to execute a second recovery process to copy the PDTC in the backup area to the mirror area, wherein the recovering unit executes the second recovery process when the update information indicates that information in at least one of the mirror area and the DTC storage area is not updated.

3. The memory management apparatus of claim 2, wherein

when the update information indicates that the information in at least one of the mirror area and the DTC storage area is not updated, the recovering unit determines whether or not a latest DTC in a storage period that is stored in one of the mirror area and the DTC storage area is also stored in another area based on the information in the mirror area and the DTC storage area, and when it is determined that the latest DTC is stored in the other area, the recovering unit is further configured to execute, the first recovery process in place of the second recovery process.

4. The memory management apparatus of claim 1, wherein

the nonvolatile memory is further arranged to have a second update information storage area,

the volatile memory is further arranged to include a clear history storage area to hold a clear history information, the clear history information indicates that predetermined information in the volatile memory is deleted,

the storage control unit is further configured to store the update information in the second update information storage area of the nonvolatile memory, and

when it is determined that the predetermined information in the volatile memory has been deleted on the basis of the clear history information, the recovering unit executes the first or the second recovery process based on the update information stored in the second update information storage area.

5. The memory management apparatus of claim 1, wherein

the volatile memory is further arranged to include a plurality of mirror areas,

the storage control unit is further configured to store the PDTC into each of the mirror areas, and

the memory management apparatus further comprises an abnormality detecting unit configured to compare the PDTC in the mirror areas with the PDTC in the back-up area, and to detect an abnormality when information do not match.

6. The memory management apparatus of claim 1, wherein

the nonvolatile memory is further arranged to include a plurality of backup areas,

the storage control unit is further configured to store the PDTC into each of the backup areas, and

the memory management apparatus further comprises a storage abnormality detecting unit configured to compare the PDTC in the back-up areas with the PDTC in the mirror area, and to detect an abnormality when information do not match.

7. The memory management apparatus of claim 1, wherein

the update information is provided as an updating state to indicate a predetermined code is being stored in the mirror area and the DTC storage area, and is provided as an update enable state to indicate a state in which the update state is complete, and

the storage control unit is further configured to store the update information as the updating state in the update information storage area before the detected DTC is stored in the mirror area and the DTC storage area, and to store the update information as the update enable state after the detected DTC is stored in the mirror area and the DTC storage area.

8. The memory management apparatus of claim 7, wherein

the update information is further provided as a no-update to indicate a state in which the mirror area and the DTC storage area are not updated after the mirror area and the back up area are in a matching state,

the recovering unit is further configured to execute a first recovery process to copy the PDTC in the mirror area to the backup area, when the update information in the update information storage area is provided as the update enable state, and

the storage control unit is further configured to store the update information as the no-update in the update information storage area after the first recovery process is complete.

9. The memory management apparatus of claim 8, wherein

the recovering unit is further configured to execute a second recovery process to copy the PDTC in the backup area to the mirror area, when the update information indicates that information in at least one of the mirror area and the diagnostic trouble code storage area is not updated.

10. The memory management apparatus of claim 9, wherein

when the update information indicates that the information in at least one of the mirror area and the DTC storage area is not updated, the recovering unit determines whether or not a latest DTC in a storage period that is stored in one of the mirror area and the DTC storage area is also stored in another area based on the information in the mirror area and the DTC storage area, and when it is determined that the latest DTC is stored in the other area, the recovering unit is further configured to execute the first recovery process in place of the second recovery process.

11. A memory management apparatus for a vehicle that is disposed in a vehicle, the apparatus comprising:

a volatile memory configured to have a diagnostic trouble code storage area (DTC storage area), a mirror area, and an update information storage area, the volatile memory being configured to be continuously supplied with power;

a nonvolatile memory configured to have a backup area; and

a processor configured to;

store a detected DTC, the detected DTC being indicative of a fault detected in a predetermined object to be detected in the vehicle, so that the detected DTC is stored in the DTC storage area of the volatile memory, and the detected DTC is stored as a permanent diagnostic trouble code (PDTC) in the backup area of the nonvolatile memory and in the mirror area of the volatile memory;

store an update information indicative of a data update status of the volatile memory in the update information storage area; and

update information in one of the mirror area and the backup area by a predetermined recovery process that is based on the update information stored in the update information storage area, so that PDTC information in the mirror area and PDTC information in the backup area are identical.

12. The memory management apparatus of claim 11, wherein the processor is configured to:

execute a first recovery process to copy the PDTC in the mirror area to the backup area when the update information indicates that information in the mirror area and the DTC storage area are updated; and

execute a second recovery process to copy the PDTC in the backup area to the mirror area when the update information indicates that information in at least one of the mirror area and the DTC storage area is not updated.

13. The memory management apparatus of claim 11, wherein

the nonvolatile memory is further configured to have a second update information storage area,

the volatile memory is further configured to include a clear history storage area to hold a clear history information, wherein the clear history information indicates that predetermined information in the volatile memory is deleted,

the processor is further configured to store the update information in the second update information storage area of the nonvolatile memory, and

when it is determined that the predetermined information in the volatile memory has been deleted on the basis of the clear history information, the processor executes the first or the second recovery process based on the update information stored in the second update information storage area.

14. The memory management apparatus of claim 11, wherein

the volatile memory is further configured to include a plurality of mirror areas,

the processor is further configured to store the PDTC into each of the mirror areas, and

the memory management apparatus further comprises an abnormality detector is configured to compare the PDTC in the mirror areas with the PDTC in the back-up area, and to detect an abnormality when information do not match.

15. The memory management apparatus of claim 11, wherein

the nonvolatile memory is further configured to include a plurality of backup areas,

the processor is further configured to store the PDTC into each of the backup areas, and

the memory management apparatus further comprises a storage abnormality detector configured to compare the PDTC in the back-up areas with the PDTC in the mirror area, and to detect an abnormality when information do not match.

16. The memory management apparatus of claim 11, wherein

the update information is provided as an updating state to indicate a predetermined code is being stored in the mirror area and the DTC storage area, and is provided as an update enable state to indicate a state in which the update state is complete, and

the processor is further configured to store the update information as the updating state in the update information storage area before the detected DTC is stored in the mirror area and the DTC storage area, and to store the update information as the update enable state after the detected DTC is stored in the mirror area and the DTC storage area.