NXP Semiconductors KL25 Series - Functional Description

Program flash protection register Flash Configuration Field offset address
FPROT2 0x0009
FPROT3 0x0008
To change the program flash protection that is loaded during the reset sequence,
unprotect the sector of program flash memory that contains the Flash Configuration
Field. Then, reprogram the program flash protection byte.
Address: 4002_0000h base + 10h offset + (1d × i), where i=0d to 3d
Bit 7 6 5 4 3 2 1 0
Read
PROT
Write
Reset
x* x* x* x* x* x* x* x*
* Notes:
x = Undefined at reset.•
FTFA_FPROTn field descriptions
Field Description
7–0
PROT
Program Flash Region Protect
Each program flash region can be protected from program and erase operations by setting the associated
PROT bit.
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 FPROT 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 FPROT are writable without restriction. Unprotected areas can be
protected and protected areas can be unprotected.
Restriction: The user must never write to any FPROT register while a command is running (CCIF=0).
Trying to alter data in any protected area in the program flash memory results in a protection violation
error and sets the FSTAT[FPVIOL] bit. A full block erase of a program flash block is not possible if it
contains any protected region.
Each bit in the 32-bit protection register represents 1/32 of the total program flash except for
configurations where program flash memory is less than 32 Kbytes. For configurations with less than 32
Kbytes of program flash memory, each assigned bit represents 1 Kbyte.
0 Program flash region is protected.
1 Program flash region is not protected
27.4 Functional Description
The following sections describe functional details of the flash memory module.
Functional Description
KL25 Sub-Family Reference Manual, Rev. 3, September 2012
432 Freescale Semiconductor, Inc.