Configuration Field (see Flash Configuration Field Description). The column labelledFlash Configuration Field offset address shows the location of the matching byte in theFlash Configuration Field.Table 45-31. Verify Backdoor Access Key Command FCCOB RequirementsFCCOB Number FCCOB Contents [7:0] Flash Configuration Field Offset Address0 0x45 (VFYKEY)1-3 Not Used4 Key Byte 0 0x0_00035 Key Byte 1 0x0_00026 Key Byte 2 0x0_00017 Key Byte 3 0x0_00008 Key Byte 4 0x0_00079 Key Byte 5 0x0_0006A Key Byte 6 0x0_0005B Key Byte 7 0x0_0004After clearing CCIF to launch the Verify Backdoor Access Key command, the flashmemory module checks the FSEC[KEYEN] bits to verify that this command is enabled.If not enabled, the flash memory module sets the FSTAT[ACCERR] bit and terminates.If the command is enabled, the flash memory module compares the key provided inFCCOB to the backdoor comparison key in the Flash Configuration Field. If thebackdoor keys match, the FSEC[SEC] field is changed to the unsecure state and securityis released. If the backdoor keys do not match, security is not released and all futureattempts to execute the Verify Backdoor Access Key command are immediately abortedand the FSTAT[ACCERR] bit is (again) set to 1 until a reset of the flash memory modulemodule occurs. If the entire 8-byte key is all zeros or all ones, the Verify BackdoorAccess Key command fails with an access error. The CCIF flag is set after the VerifyBackdoor Access Key operation completes.Table 45-32. Verify Backdoor Access Key Command Error HandlingError Condition Error BitThe supplied key is all-0s or all-Fs FSTAT[ACCERR]An incorrect backdoor key is supplied FSTAT[ACCERR]Backdoor key access has not been enabled (see the description of the FSEC register) FSTAT[ACCERR]This command is launched and the backdoor key has mismatched since the last power downreset FSTAT[ACCERR]Functional DescriptionKL27 Sub-Family Reference Manual , Rev. 5, 01/2016926 Freescale Semiconductor, Inc.
