Datasheet

retained following power cycling. Once the register contents are committed, the only way to restore
the factory default values is to perform the sequence described in “Recovering a "Locked"
Microcontroller” on page 223.
All of the FMPREn and USER_REGn registers, in addition to the BOOTCFG register can be
committed in non-volatile memory. The FMPREn, FMPPEn, and USER_REGn registers can be
tested before being committed; the BOOTCFG register cannot. To program the BOOTCFG register,
the value must be written into the Flash Memory Data (FMD) register before it is committed. The
BOOTCFG configuration cannot be tried and verified before committing to non-volatile memory.
Important: All Flash memory resident registers can only have bits changed from 1 to 0 by user
programming. The FMPREn and BOOTCFG registers can be committed multiple times,
but the USER_REGn registers can only be committed once, after the entire register
has been set to 1s. After being committed, the USER_REGn registers can only be
returned to their factory default values of all 1s by performing the sequence described
in “Recovering a "Locked" Microcontroller” on page 223. The mass erase of the main
Flash memory array caused by the sequence is performed prior to restoring these
registers.
Table 8-3 on page 644 provides the FMA address required for commitment of each of the registers
and the source of the data to be written when the FMC register is written with a key value of 0xA442
or the PEKEY value of the FLPEKEY register. The key value used is determined by the KEY bit in
the BOOTCFG register at reset. If the KEY value is 0x0, the PEKEY value in the FLPEKEY register
is used for commits in the FMC/FMC2 register. If the KEY value is 0x1, the value 0xA442 is used
as the WRKEY in the FMC/FMC2 register. If the After writing the COMT bit, the user may poll the FMC
register to wait for the commit operation to complete.
Table 8-3. User-Programmable Flash Memory Resident Registers
Data SourceFMA ValueRegister to be Committed
FMPRE00x0000.0000FMPRE0
FMPRE10x0000.0002FMPRE1
FMPRE20x0000.0004FMPRE2
FMPRE30x0000.0006FMPRE3
FMPRE40x0000.0008FMPRE4
FMPRE50x0000.000AFMPRE5
FMPRE60x0000.000CFMPRE6
FMPRE70x0000.000EFMPRE7
FMPRE80x0000.0010FMPRE8
FMPRE90x0000.0012FMPRE9
FMPRE100x0000.0014FMPRE10
FMPRE110x0000.0016FMPRE11
FMPRE120x0000.0018FMPRE12
FMPRE130x0000.001AFMPRE13
FMPRE140x0000.001CFMPRE14
FMPRE150x0000.001EFMPRE15
FMPPE00x0000.0001FMPPE0
FMPPE10x0000.0003FMPPE1
FMPPE20x0000.0005FMPPE2
FMPPE30x0000.0007FMPPE3
December 13, 2013644
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Internal Memory