Datasheet

Table 4-39. Unsecure flash command error handling

FSTAT

ACCERR

Set if CCOBIX[2:0] != 000 at command launch

Set if command is not available in current mode (see Table 4-9)

FPVIOL Set if any area of the flash or EEPROM memory is protected

MGSTAT1 Set if any errors have been encountered during the verify operation

MGSTAT0

Set if any non-correctable errors have been encountered during the verify

operation

1. As found in the memory map for NVM

4.5.2.9.11 Verify backdoor access key command

The verify backdoor access key command will execute only if it is enabled by the

NVM_FSEC[KEYEN] bits. The verify backdoor access key command releases security

if user-supplied keys match those stored in the flash security bytes of the flash

configuration field. See Table 4-6 for details. The code that performs verifying backdoor

access command must be running from RAM or EEPROM.

Table 4-40. Verify backdoor access key command FCCOB requirements

CCOBIX[2:0] NVM_FCCOBHI parameters NVM_FCCOBLO parameters

000 0x0C Not required

001 Key 0

010 Key 1

011 Key 2

100 Key 3

Upon clearing NVM_FSTAT[CCIF] to launch the verify backdoor access key command,

the memory controller will check the NVM_FSEC[KEYEN] bits to verify that this

command is enabled. If not enabled, the memory controller sets the

NVM_FSTAT[ACCERR] bit. If the command is enabled, the memory controller

compares the key provided in FCCOB to the backdoor comparison key in the flash

configuration field with Key 0 compared to 0xFF70, and so on. If the backdoor keys

match, security will be released. If the backdoor keys do not match, security is not

released and all future attempts to execute the verify backdoor access key command are

aborted (set NVM_FSTAT[ACCERR]) until a reset occurs. The NVM_FSTAT[CCIF]

flag is set after the verify backdoor access key operation has completed.

Flash and EEPROM

MC9S08PA60 Reference Manual, Rev. 1, 9/2012

100 Freescale Semiconductor, Inc.