Freescale Semiconductor MC9S12ZVM series, Reference Manual

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Chapter 19 128 KB Flash Module (S12ZFTMRZ128K512V2)
MC9S12ZVM Family Reference Manual Rev. 1.3
698 Freescale Semiconductor
The security function in the Flash module is described in Section 19.5 .
19.3.2.3 Flash CCOB Index Register (FCCOBIX)
The FCCOBIX register is used to indicate the amount of parameters loaded into the FCCOB registers for
Flash memory operations.
CCOBIX bits are readable and writable while remaining bits read 0 and are not writable.
Table 19-9. FSEC Field Descriptions
Field Description
7–6
KEYEN[1:0]
Backdoor Key Security Enable Bits — The KEYEN[1:0] bits define the enabling of backdoor key access to the
Flash module as shown in
Table 19-10 .
5–2
RNV[5:2]
Reserved Nonvolatile Bits — The RNV bits should remain in the erased state for future enhancements.
1–0
SEC[1:0]
Flash Security Bits — The SEC[1:0] bits define the security state of the MCU as shown in Table 19-11 . If the
Flash module is unsecured using backdoor key access, the SEC bits are forced to 10.
Table 19-10. Flash KEYEN States
KEYEN[1:0] Status of Backdoor Key Access
00 DISABLED
01 DISABLED
(1)
1. Preferred KEYEN state to disable backdoor key access.
10 ENABLED
11 DISABLED
Table 19-11. Flash Security States
SEC[1:0] Status of Security
00 SECURED
01 SECURED
(1)
1. Preferred SEC state to set MCU to secured state.
10 UNSECURED
11 SECURED
Offset Module Base + 0x0002
7 6 5 4 3 2 1 0
R 0 0 0 0 0
CCOBIX[2:0]
W
Reset 0 0 0 0 0 0 0 0
= Unimplemented or Reserved
Figure 19-7. FCCOB Index Register (FCCOBIX)