PXD10RM Datasheet, PDF (635/1332 Pages) Freescale Semiconductor, Inc – PXD10 Microcontroller

17.3.9.1 Modify Protection
The Flash Modify Protection information is stored in non-volatile Flash cells located in the Test Flash. This
information is read once during the Flash initialization phase following the exit 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 non-volatile Modify Protection registers can be programmed through a normal Double Word
Program operation at the related locations in Test Flash.
The non-volatile Modify Protection registers cannot be erased.
• The Non-volatile Modify Protection Registers are physically located in Test Flash 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 (Low/Mid Address Space Block Lock Register) or HBL (High
Address Space Block Lock Register) registers.
An alternate means to enable software locking for blocks of Low Address Space only is through the SLL
(Secondary Low/Mid Address Space Block Lock Register).
All these registers have a non-volatile image stored in Test Flash (NVLML, NVHBL, NVSLL), so that the
locking information is kept on reset.
On delivery the Test Flash non-volatile image is at all ‘1’s, meaning all sectors are locked.
By programming the non-volatile locations in Test Flash the selected sectors can be unlocked.
Being the Test Flash One Time Programmable (i.e. not erasable), once unlocked the sectors cannot be
locked again.
Of course, on the contrary, all the volatile registers can be written at 0 or 1 at any time, therefore the user
application can lock and unlock sectors when desired.
17.3.9.2 Censored Mode
The 80K Flash Macrocell does not contain a Shadow Sector and all the associated features to manage the
Censored Mode. These must therefore be managed by the associated Code Flash Macrocell embedded in
the same SoC.
Freescale Semiconductor
PXD10 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
17-85