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Memory map and register definition
11.4.2 Flash Security Register (FTMRH_FSEC)
The FSEC register holds all bits associated with the security of the MCU and NVM
module. All fields in the FSEC register are readable but not writable. During the reset
sequence, the FSEC register is loaded with the contents of the flash security byte in the
flash configuration field located in flash memory.
See
Security
for security function.
Address: 1830h base + 1h offset = 1831h
Bit
7
Read
KEYEN
Write
Reset
x*
* Notes:
•
x = Undefined at reset.
Field
7–6
Backdoor Key Security Enable Bits
KEYEN
The KEYEN[1:0] bits define the enabling of backdoor key access to the flash module.
NOTE: 01 is the preferred KEYEN state to disable backdoor key access.
00
Disabled
01
Disabled
10
Enabled
11
Disabled
5–2
This field is reserved.
Reserved
SEC
Flash Security Bits
Defines the security state of the MCU. If the flash module is unsecured using backdoor key access, the
SEC field is forced to 10.
NOTE: 01 is the preferred SEC state to set MCU to secured state.
00
Secured
01
Secured
10
Unsecured
11
Secured
182
6
5
x*
x*
FTMRH_FSEC field descriptions
MC9S08SU16 Reference Manual, Rev. 5, 4/2017
4
3
Reserved
x*
x*
Description
2
1
SEC
x*
x*
NXP Semiconductors
0
x*
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