MC9S12P128 Datasheet, PDF (434/564 Pages) Freescale Semiconductor, Inc – S12 Microcontrollers

128 KByte Flash Module (S12FTMRC128K1V1)
phrase containing the Flash security byte during the reset sequence, all bits in the FSEC register will be
set to leave the Flash module in a secured state with backdoor key access disabled.
Table 13-8. FSEC Field Descriptions
Field
Description
7–6
Backdoor Key Security Enable Bits — The KEYEN[1:0] bits define the enabling of backdoor key access to the
KEYEN[1:0] Flash module as shown in Table 13-9.
5–2
Reserved Nonvolatile Bits — The RNV bits should remain in the erased state for future enhancements.
RNV[5:2}
1–0
Flash Security Bits — The SEC[1:0] bits define the security state of the MCU as shown in Table 13-10. If the
SEC[1:0] Flash module is unsecured using backdoor key access, the SEC bits are forced to 10.
Table 13-9. Flash KEYEN States
KEYEN[1:0]
Status of Backdoor Key Access
00
DISABLED
01
DISABLED⁽¹⁾
10
ENABLED
11
DISABLED
1. Preferred KEYEN state to disable backdoor key access.
Table 13-10. Flash Security States
SEC[1:0]
Status of Security
00
SECURED
01
SECURED⁽¹⁾
10
UNSECURED
11
SECURED
1. Preferred SEC state to set MCU to secured state.
The security function in the Flash module is described in Section 13.5.
13.3.2.3 Flash CCOB Index Register (FCCOBIX)
The FCCOBIX register is used to index the FCCOB register for Flash memory operations.
Offset Module Base + 0x0002
7
6
5
4
3
2
1
0
R
0
0
0
0
0
W
CCOBIX[2:0]
Reset
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 13-7. FCCOB Index Register (FCCOBIX)
CCOBIX bits are readable and writable while remaining bits read 0 and are not writable.
S12P-Family Reference Manual, Rev. 1.12
434
Freescale Semiconductor