mcf51jf128 Freescale Semiconductor, Inc, mcf51jf128 Datasheet - Page 502

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

Memory Map and Registers
23.34.7 Data Flash Protection Register (FTFL_FDPROT)
The FDPROT register defines which data flash regions are protected against program and
erase operations. Protected Flash regions cannot have their content changed; that is, these
regions cannot be programmed and cannot be erased by any FTFL command.
Unprotected regions can be changed by both program and erase operations.
Address: FTFL_FDPROT is FFFF_84E0h base + 14h offset = FFFF_84F4h
* Notes:
•
502
x = Undefined at reset.
DPROT
Reset
Field
Read
7–0
Write
Bit
Data Flash Region Protect
Individual data flash regions can be protected from program and erase operations by setting the
associated DPROT bit. Each DPROT bit protects one-eighth of the partitioned data flash memory space.
The granularity of data flash protection cannot be less than the data flash sector size. If an unused
DPROT bit is set, the Erase all Blocks command does not execute and the FSTAT[FPVIOL] flag is set.
In NVM Normal mode: The protection can only be increased, meaning 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 FDPROT 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 FDPROT register are writable without restriction. Unprotected areas
can be protected and protected areas can be unprotected.
Restriction: The user must never write to the FDPROT register while a command is running (CCIF=0).
Reset: During the reset sequence, the FDPROT register is loaded with the contents of the data flash
protection byte in the Flash Configuration Field located in program flash memory. The flash basis for the
reset values is signified by X in the register diagram. To change the data flash protection that will be
loaded during the reset sequence, unprotect the sector of program flash that contains the Flash
Configuration Field. Then, erase and reprogram the data flash protection byte.
Trying to alter data with the program and erase commands in any protected area in the data flash memory
results in a protection violation error and sets the FSTAT[FPVIOL] bit. A full block erase of the data flash
memory (see the Erase Flash Block command description) is not possible if the data flash memory
contains any protected region or if the FlexNVM block has been partitioned for EEPROM.
0
1
x*
7
Data Flash region is protected
Data Flash region is not protected
x*
6
MCF51JF128 Reference Manual, Rev. 2, 03/2011
FTFL_FDPROT field descriptions
x*
5
Preliminary
x*
4
DPROT
Description
x*
3
x*
2
Freescale Semiconductor, Inc.
x*
1
x*
0