METHOD FOR RECOGNIZING A POWER FAILURE IN A DATA MEMORY AND RECOVERING THE DATA MEMORY

• US 20090158089A1
• Filed: 12/12/2006
• Published: 06/18/2009
• Est. Priority Date: 12/20/2005
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Aue, Axel
• Granted Patent: US 8,074,120 B2
• Time in Patent Office: Days
• US Class Current: 714/15
• CPC Class Codes: G06F 11/10 Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's
• CPC Class Codes: G11C 11/4074 Power supply or voltage generation circuits, e.g. bias voltage generators, substrate voltage generators, back-up power, power control circuits
• CPC Class Codes: G11C 11/4096 Input/output [I/O] data management or control circuits, e.g. reading or writing circuits, I/O drivers or bit-line switches
• CPC Class Codes: G11C 5/143 Detection of memory cassette insertion or removal; Continuity checks of supply or ground lines; Detection of supply variations, interruptions or levels G11C5/148 takes precedence; Switching between alternative supplies G11C5/141 takes precedence
• CPC Class Codes: G11C 7/1006 Data managing, e.g. manipulating data before writing or reading out, data bus switches or control circuits therefor

Abstract

To detect a power failure in a volatile data memory containing useful data units and test data units associated with the useful data units, the associated test data unit is also read when the useful data unit is read-accessed, and a decision is made as to whether the useful data unit is corrupted based on the test data unit. A power failure is identified when at least two read useful data units within a predefined number of successive read accesses are found to be corrupted.

Claims

1-7. -7. (canceled)

8. A method for detecting a power failure in a volatile data memory containing useful data units and test data units associated with the useful data units, comprising:

reading the associated test data unit when the useful data unit is read-accessed;

deciding, based on the test data unit, whether the useful data unit is corrupted; and

identifying a power failure when at least two read useful data units within a predefined number of successive read accesses are found to be corrupted.

9. The method as recited in claim 8, wherein the test data unit associated with each useful data unit is a parity bit.

10. The method as recited in claim 8, wherein a useful data unit found to be corrupted is corrected based on the test data unit when the finding does not result in identification of a power failure.

11. A method for recovering a volatile data memory, comprising:

detecting a power failure;

discarding the useful data units from at least a portion of the volatile data memory; and

recovering the useful data units from a source outside the volatile memory.

12. The method as recited in claim 11, wherein the useful data units are recovered, at least in part, by recomputation based on measured data.

13. The method as recited in claim 11, wherein the useful data units are recovered, at least in part, by transferral from a nonvolatile memory.

14. The method as recited in claim 11, wherein useful data units which have not been found to be corrupted are also recovered.