mcf51jf128 Freescale Semiconductor, Inc, mcf51jf128 Datasheet - Page 503

• Manufacturer Part Number: mcf51jf128
• Description: Mcf51jf128 Reference Manual
• Manufacturer: Freescale Semiconductor, Inc

23.34.8 EEPROM Protection Register (FTFL_FEPROT)
The FEPROT register defines which EEPROM regions of the FlexRAM are protected
against program and erase operations. Protected EEPROM regions cannot have their
content changed by writing to it. Unprotected regions can be changed by writing to the
FlexRAM.
Address: FTFL_FEPROT is FFFF_84E0h base + 15h offset = FFFF_84F5h
* Notes:
•
Freescale Semiconductor, Inc.
x = Undefined at reset.
EPROT
Reset
Field
Read
7–0
Write
Bit
EEPROM Region Protect
Individual EEPROM regions can be protected from alteration by setting the associated EPROT bit. The
EPROT bits are not used when the FlexNVM Partition Code is set to data flash only. When the FlexNVM
Partition Code is set to data flash and EEPROM or EEPROM only, each EPROT bit covers one-eighth of
the configured EEPROM data (see the EEPROM Data Set Size parameter description).
In NVM Normal mode: The protection can only be increased. This means that currently-unprotected
memory can be protected, but currently-protected memory cannot be unprotected. Since unprotected
regions are marked with a 1 and protected regions use a 0, only writes changing 1s to 0s are accepted.
This 1-to-0 transition check is performed on a bit-by-bit basis. Those FEPROT bits with 1-to-0 transitions
are accepted while all bits with 0-to-1 transitions are ignored.
In NVM Special mode: All bits of the FEPROT register are writable without restriction. Unprotected areas
can be protected and protected areas can be unprotected.
Restriction: Never write to the FEPROT register while a command is running (CCIF=0).
Reset: During the reset sequence, the FEPROT register is loaded with the contents of the FlexRAM
protection byte in the Flash Configuration Field located in program flash. The flash basis for the reset
values is signified by X in the register diagram. To change the EEPROM protection that will be loaded
during the reset sequence, the sector of program flash that contains the Flash Configuration Field must be
unprotected; then the EEPROM protection byte must be erased and reprogrammed.
Trying to alter data by writing to any protected area in the EEPROM results in a protection violation error
and sets the FPVIOL bit in the FSTAT register.
0
1
x*
7
EEPROM region is protected
EEPROM region is not protected
x*
6
MCF51JF128 Reference Manual, Rev. 2, 03/2011
FTFL_FEPROT field descriptions
x*
5
Preliminary
x*
4
EPROT
Description
x*
3
Chapter 23 Flash Memory Module (FTFL)
x*
2
x*
1
x*
0
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