MPC5604B/C Microcontroller Reference Manual, Rev. 8
Freescale Semiconductor 713
When some flash memory sectors are used to perform an Eeprom Emulation, it is reccomended for safety
reasons to reserve at least 3 sectors to this purpose.
27.6.3.4.1 All ‘1’s No Error
The All ‘1’s No Error Algorithm detects as valid any Double Word read on a just erased sector (all the 72
bits are ‘1’s).
This option allows to perform a Blank Check after a Sector Erase operation.
27.6.3.5 Protection strategy
Two kinds of protection are available: Modify Protection to avoid unwanted program/erase in flash
memory sectors and Censored Mode to avoid piracy.
27.6.3.5.1 Modify protection
The flash memory Modify Protection information is stored in nonvolatile flash memory cells located in
the TestFlash. This information is read once during the flash memory initialization phase following the
exiting from Reset and is stored in volatile registers that act as actuators.
The reset state of all the volatile modify protection registers is the protected state.
All the nonvolatile modify protection registers can be programmed through a normal Double Word
Program operation at the related locations in TestFlash.
The nonvolatile modify protection registers cannot be erased.
• The nonvolatile Modify Protection Registers are physically located in TestFlash their bits can be
programmed to ‘0’ only once and they can no more be restored to ‘1’.
• The Volatile Modify Protection Registers are Read/Write registers which bits can be written at ‘0’
or ‘1’ by the user application.
A software mechanism is provided to independently lock/unlock each Low, Mid and High Address Space
Block against program and erase.
Software locking is done through the LML register.
An alternate means to enable software locking for blocks of Low Address Space only is through the SLL.
All these registers have a nonvolatile image stored in TestFlash (NVLML, NVSLL), so that the locking
information is kept on reset.
0x0000_0000_FFFF_FFFF 0xFF
0xFFFF_0000_0000_0000 0xFF
0x0000_FFFF_0000_0000 0xFF
0x0000_0000_0000_0000 0xFF
Table 27-55. Bit manipulation: Double words with the same ECC value (continued)
Double word ECC all ‘1’s no error
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