S912XEG384J3VA Datasheet, PDF (999/1324 Pages) Freescale Semiconductor, Inc – MC9S12XEP100 Reference Manual Covers MC9S12XE Family

Chapter 26 384 KByte Flash Module (S12XFTM384K2V1)
state. During the execution of this command (CCIF=0) the user must not write to any Flash module
register. The CCIF flag is set after the Unsecure Flash operation has completed.
Table 26-54. Unsecure Flash Command Error Handling
Register
Error Bit
Error Condition
Set if CCOBIX[2:0] != 000 at command launch
ACCERR Set if a Load Data Field command sequence is currently active
FSTAT
FPVIOL
MGSTAT1
Set if command not available in current mode (see Table 26-30)
Set if any area of the P-Flash memory is protected
Set if any errors have been encountered during the verify operation⁽¹⁾
MGSTAT0
Set if any non-correctable errors have been encountered during the verify
operation¹
FERSTAT
EPVIOLIF Set if any area of the buffer RAM EEE partition is protected
1. As found in the memory map for FTM512K3.
26.4.2.12 Verify Backdoor Access Key Command
The Verify Backdoor Access Key command will only execute if it is enabled by the KEYEN bits in the
FSEC register (see Table 26-11). 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 26-
3). The Verify Backdoor Access Key command must not be executed from the Flash block containing the
backdoor comparison key to avoid code runaway.
Table 26-55. Verify Backdoor Access Key Command FCCOB Requirements
CCOBIX[2:0]
000
001
010
011
100
FCCOB Parameters
0x0C
Key 0
Key 1
Key 2
Key 3
Not required
Upon clearing CCIF to launch the Verify Backdoor Access Key command, the Memory Controller will
check the FSEC KEYEN bits to verify that this command is enabled. If not enabled, the Memory
Controller sets the ACCERR bit in the FSTAT register and terminates. 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 0x7F_FF00, etc. 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 ACCERR) until a reset occurs. The CCIF flag is
set after the Verify Backdoor Access Key operation has completed.
MC9S12XE-Family Reference Manual Rev. 1.25
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