NXP Semiconductors MC9S12G - Page 768

16 KByte Flash Module (S12FTMRG16K1V1)
MC9S12G Family Reference Manual Rev.1.27
770 NXP Semiconductors
The FPROT register, described in Section 24.3.2.9, can be set to protect regions in the Flash memory from
accidental program or erase. Two separate memory regions, one growing downward from global address
0x3_FFFF in the Flash memory (called the higher region), and the remaining addresses in the Flash
memory, can be activated for protection. The Flash memory addresses covered by these protectable
regions are shown in the P-Flash memory map. The higher address region is mainly targeted to hold the
boot loader code since it covers the vector space. Default protection settings as well as security information
that allows the MCU to restrict access to the Flash module are stored in the Flash configuration field as
described in Table 24-4.
Figure 24-2. P-Flash Memory Map
Table 24-4. Flash Configuration Field
Global Address
Size
(Bytes)
Description
0x3_FF00-0x3_FF07 8
Backdoor Comparison Key
Refer to Section 24.4.6.11, “Verify Backdoor Access Key Command,” and
Section 24.5.1, “Unsecuring the MCU using Backdoor Key Access”
0x3_FF08-0x3_FF0B
1
1
0x3FF08-0x3_FF0F form a Flash phrase and must be programmed in a single command write sequence. Each byte in
the 0x3_FF08 - 0x3_FF0B reserved field should be programmed to 0xFF.
4 Reserved
0x3_FF0C
1
1
P-Flash Protection byte
.
Refer to Section 24.3.2.9, “P-Flash Protection Register (FPROT)”
0x3_FF0D
1
1
EEPROM Protection byte
.
Refer to Section 24.3.2.10, “EEPROM Protection Register (EEPROT)”
0x3_FF0E
1
1
Flash Nonvolatile byte
Refer to Section 24.3.2.16, “Flash Option Register (FOPT)”
0x3_FF0F
1
1
Flash Security byte
Refer to Section 24.3.2.2, “Flash Security Register (FSEC)”
Flash Configuration Field
P-Flash START = 0x3_C000
P-Flash END = 0x3_FFFF
0x3_F800
0x3_F000
0x3_E000
Flash Protected/Unprotected Higher Region
2, 4, 8, 16 Kbytes
16 bytes (0x3_FF00 - 0x3_FF0F)
Protection
Protection
Movable End
Fixed End