MEMORY MANAGEMENT APPARATUS

• US 20090076681A1
• Filed: 09/10/2008
• Published: 03/19/2009
• Est. Priority Date: 09/14/2007
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Yasue, Motohiro, Suganuma, Takeshi
• Granted Patent: US 8,280,579 B2
• Time in Patent Office: Days
• US Class Current: 701/35
• 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, which is mounted on the vehicle, comprising:

a volatile memory to which power source is continuously supplied and having a diagnostic trouble code storage area for storing and holding a diagnostic trouble code;

a nonvolatile memory having a backup area for storing the same code as the diagnostic trouble code; and

a storage control unit, when a fault is detected in a predetermined object to be detected in the vehicle, for storing the diagnostic trouble code indicative of the detected fault as a determined diagnostic trouble code into the diagnostic trouble code storage area, and storing the determined diagnostic trouble code configured to be stored in the backup area from among the determined diagnostic trouble codes into the backup area as a permanent diagnostic trouble code,

wherein the volatile memory further includes a mirror area for storing same information as information in the backup area and an update information storage area for storing update information indicative of a data update status in the volatile memory,

the storage control unit further stores the same code as the permanent diagnostic trouble code into the mirror area, and stores the update information into the update information storage area, and

a recovering unit is provided, for updating information in one of the mirror area and the backup area by a predetermined recovering process on a basis of the update information stored in the update information storage area so that the information in the mirror area and the information in the backup area match with each other.

2. The memory management apparatus according to claim 1, wherein

the recovering unit executes, as the recovering process, a first process of copying the information in the mirror area into the backup area when it is determined on the basis of the update information that the information in both of the mirror area and the diagnostic trouble code storage area is updated, and executes, as the recovering process, a second process of copying the information in the backup area into the mirror area when it is determined on the basis of the update information that the information in at least one of the mirror area and the diagnostic trouble code storage area is not updated.

3. The memory management apparatus according to claim 2, wherein

when it is determined on the basis of the update information that the information in at least one of the mirror area and the diagnostic trouble code storage area is not updated, the recovering unit determines whether or not a latest diagnostic trouble code in a storage period in one of the mirror area and the diagnostic trouble code storage area is stored also in an other area on the basis of the information in the mirror area and the diagnostic trouble code storage area, and when it is determined that the latest diagnostic trouble code is stored in the other area, the recovering unit executes, as the recovering process, the first process in place of the second process.

4. The memory management apparatus according to claim 1, wherein

the nonvolatile memory has a storage area for storing the update information as a second update information storage area,

the volatile memory has a clear history storage area for storing clear history information showing that predetermined information in the volatile memory is deleted,

the storage control unit stores the update information in the second update information storage area, 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 recovering process on the basis of the update information stored in the second update information storage area.

5. The memory management apparatus according to claim 1, wherein

the volatile memory has a plurality of mirror areas,

the storage control unit stores the same code as the permanent diagnostic trouble code into each of the plurality of mirror areas, and

an abnormality detecting unit is provided, for comparing the information in the plurality of mirror areas and the backup area with each other and detecting an abnormality when compared information do not match.

6. The memory management apparatus according to claim 1, wherein

the nonvolatile memory has a plurality of backup areas,

the storage control unit stores the permanent diagnostic trouble code into each of the plurality of backup areas, and

a storage abnormality detecting unit is provided, for comparing the information in the mirror area and the plurality of backup areas with each other and detecting an abnormality when compared information do not match.

7. A memory management apparatus for a vehicle, which is mounted on the vehicle, comprising:

a volatile memory to which power source is always supplied and having a diagnostic trouble code storage area for storing and holding a diagnostic trouble code;

a nonvolatile memory having a backup area for storing the same code as the diagnostic trouble code; and

a storage control unit, when a fault is detected in a predetermined object to be detected in the vehicle, for storing the diagnostic trouble code indicative of the detected fault as a determined diagnostic trouble code into the diagnostic trouble code storage area, and storing a determined diagnostic trouble code configured to be stored in the backup area from among the determined diagnostic trouble codes into the backup area as a permanent diagnostic trouble code,

wherein the volatile memory further comprises a mirror area for storing same information as the information in the backup area,

the storage control unit performs process of, when a fault is detected, storing the determined diagnostic trouble code indicative of the detected fault into the mirror area, storing the determined diagnostic trouble code in the diagnostic trouble code storage area, storing the determined diagnostic trouble code as the permanent diagnostic trouble code into the backup area, and further performs process of, as a recovery process, when it is determined on a basis of information in the mirror area, the diagnostic trouble code storage area, and the backup area that the information in the mirror area and the information in the backup area do not match with each other and a latest determined diagnostic trouble code identified as a latest code among the determined diagnostic trouble codes in the mirror area is stored in the diagnostic trouble code storage area, storing the latest code into the backup area, and, when it is determined that the information in the mirror area and the information in the backup area do not match with each other and the latest code in the mirror area is not stored in the diagnostic trouble code storage area, storing the latest code in both of the diagnostic trouble code storage area and the backup area.

8. The memory management apparatus according to claim 7, wherein

the mirror area has a plurality of storage areas for respectively storing same code as a replica of an object code to be stored for each of the object codes, and

the storage control unit stores the determined diagnostic trouble code, for each of the determined diagnostic trouble codes to be stored as the object code, into each of the plurality of the storage areas in the mirror area, recognizes a code matching in a majority of the plurality of storage areas in the mirror area as a regular determined diagnostic trouble code, executes the recovering process, and further rewrites the code being different from the regular determined diagnostic trouble code in the storage area with the regular determined diagnostic trouble code.

9. The memory management apparatus according to claim 7, wherein

information indicative of a battery removal history in the vehicle is stored at least in the volatile memory, and

when a removal of the battery is determined on a basis of information indicative of the removal history, the storage control unit copies information in the backup area to the mirror area instead of performing the recovering process.