Datasheet
Table 4-16. EEPROM protection address range (continued)
DPS[2:0] Global address range Protected size
011 0x3100 – 0x317F 128 bytes
100 0x3100 – 0x319F 160 bytes
101 0x3100 – 0x31BF 192 bytes
110 0x3100 – 0x31DF 224 bytes
111 0x3100 – 0x31FF 256 bytes
All possible flash protection scenarios are shown in Figure 4-6. Although the protection
scheme is loaded from the flash memory at global address 0xFF7C during the reset
sequence, it can be changed by the user.
4.5.2.7 Security
The flash and EEPROM module provides security information to the MCU. The flash
security state is defined by the NVM_FSEC[SEC] bits. During reset, the flash module
initializes the NVM_FSEC register using data read from the security byte of the flash and
EEPROM configuration field at global address 0xFF7F. The security state out of reset
can be permanently changed by programming the security byte, assuming that the MCU
is starting from a mode where the necessary flash and EEPROM erase and program
commands are available and that the upper region of the flash is unprotected. If the flash
security byte is successfully programmed, its new value will take affect after the next
MCU reset.
The following subsections describe these security-related subjects:
• Unsecuring the MCU using backdoor key access
• Unsecuring the MCU using BDM
• Mode and security effects on flash and EEPROM command availability
4.5.2.7.1 Unsecuring the MCU using backdoor key access
The MCU may be unsecured by using the backdoor key access feature which requires
knowledge of the contents of the backdoor keys, which are four 16-bit words
programmed at addresses 0xFF70–0xFF77. If the KEYEN[1:0] bits are in the enabled
state, the verify backdoor access key command – see Verify backdoor access key
command, allows the user to present four prospective keys for comparison to the keys
stored in the flash and EEPROM memory via the memory controller. If the keys
presented in the verify backdoor access key command match the backdoor keys stored in
Chapter 4 Memory map
MC9S08PA60 Reference Manual, Rev. 1, 9/2012
Freescale Semiconductor, Inc. 87