Chapter 19 Flash Module (S12ZFTMRZ)MC9S12ZVMB Family Reference Manual Rev. 1.3658 NXP Semiconductors4.). The Verify Backdoor Access Key command must not be executed from the Flash block containing thebackdoor comparison key to avoid code runaway.Upon clearing CCIF to launch the Verify Backdoor Access Key command, the Memory Controller willcheck the FSEC KEYEN bits to verify that this command is enabled. If not enabled, the MemoryController sets the ACCERR bit in the FSTAT register and terminates. If the command is enabled, theMemory Controller compares the key provided in FCCOB to the backdoor comparison key in the Flashconfiguration field with Key 0 compared to 0xFF_FE00, etc. If the backdoor keys match, security will bereleased. If the backdoor keys do not match, security is not released and all future attempts to execute theVerify Backdoor Access Key command are aborted (set ACCERR) until a reset occurs. The CCIF flag isset after the Verify Backdoor Access Key operation has completed.19.4.7.12 Set User Margin Level CommandThe Set User Margin Level command causes the Memory Controller to set the margin level for future readoperations of the P-Flash or EEPROM block.Table 19-54. Verify Backdoor Access Key Command FCCOB RequirementsRegister FCCOB ParametersFCCOB0 0x0C Not requiredFCCOB1 Key 0FCCOB2 Key 1FCCOB3 Key 2FCCOB4 Key 3Table 19-55. Verify Backdoor Access Key Command Error HandlingRegister Error Bit Error ConditionFSTATACCERRSet if CCOBIX[2:0] != 100 at command launchSet if an incorrect backdoor key is suppliedSet if backdoor key access has not been enabled (KEYEN[1:0] != 10, seeSection 19.3.2.2)Set if the backdoor key has mismatched since the last resetFPVIOL NoneMGSTAT1 NoneMGSTAT0 NoneTable 19-56. Set User Margin Level Command FCCOB RequirementsRegister FCCOB ParametersFCCOB0 0x0D Global address [23:16] to identify FlashblockFCCOB1 Global address [15:0] to identify Flash blockFCCOB2 Margin level setting.
