Datasheet

Chapter 2 128 Kbyte Flash Module (FTS128K1V1)
MC9S12E128 Data Sheet, Rev. 1.07
92 Freescale Semiconductor
The security function in the Flash module is described in Section 2.4.3, “Flash Module Security”.
2.3.2.3 RESERVED1
This register is reserved for factory testing and is not accessible to the user.
All bits read 0 and are not writable.
Table 2-4. FSEC Field Descriptions
Field Description
7–6
KEYEN[1:0]
Backdoor Key Security Enable Bits — The KEYEN[1:0] bits define the enabling of the backdoor key access
to the Flash module as shown in Table 2-5.
5–2
NV[5:2]
Nonvolatile Flag Bits — The NV[5:2] bits are available to the user as nonvolatile flags.
1–0
SEC[1:0]
Flash Security Bits — The SEC[1:0] bits define the security state of the MCU as shown in Table 2-6. If the Flash
module is unsecured using backdoor key access, the SEC[1:0] bits are forced to 1:0.
Table 2-5. Flash KEYEN States
KEYEN[1:0] Status of Backdoor Key Access
00 DISABLED
01
1
1
Preferred KEYEN state to disable Backdoor Key Access.
DISABLED
10 ENABLED
11 DISABLED
Table 2-6. Flash Security States
SEC[1:0] Status of Security
00 Secured
01
1
1
Preferred SEC state to set MCU to secured state.
Secured
10 Unsecured
11 Secured
Module Base + 0x0002
76543210
R00000000
W
Reset 00000000
= Unimplemented or Reserved
Figure 2-6. RESERVED1