NXP Semiconductors KL25 Series - Freescale Semiconductor, Inc

27.33.3 Flash Security Register (FTFA_FSEC)
This read-only register holds all bits associated with the security of the MCU and flash
memory module.
During the reset sequence, the register is loaded with the contents of the flash security
byte in the Flash Configuration Field located in program flash memory. The flash basis
for the values is signified by X in the reset value.
Address: 4002_0000h base + 2h offset = 4002_0002h
Bit 7 6 5 4 3 2 1 0
Read KEYEN MEEN FSLACC SEC
Write
Reset
x* x* x* x* x* x* x* x*
* Notes:
x = Undefined at reset.•
FTFA_FSEC field descriptions
Field Description
7–6
KEYEN
Backdoor Key Security Enable
These bits enable and disable backdoor key access to the flash memory module.
00 Backdoor key access disabled
01 Backdoor key access disabled (preferred KEYEN state to disable backdoor key access)
10 Backdoor key access enabled
11 Backdoor key access disabled
5–4
MEEN
Mass Erase Enable Bits
Enables and disables mass erase capability of the flash memory module. The state of the MEEN bits is
only relevant when the SEC bits are set to secure outside of NVM Normal Mode. When the SEC field is
set to unsecure, the MEEN setting does not matter.
00 Mass erase is enabled
01 Mass erase is enabled
10 Mass erase is disabled
11 Mass erase is enabled
3–2
FSLACC
Freescale Failure Analysis Access Code
These bits enable or disable access to the flash memory contents during returned part failure analysis at
Freescale. When SEC is secure and FSLACC is denied, access to the program flash contents is denied
and any failure analysis performed by Freescale factory test must begin with a full erase to unsecure the
part.
When access is granted (SEC is unsecure, or SEC is secure and FSLACC is granted), Freescale factory
testing has visibility of the current flash contents. The state of the FSLACC bits is only relevant when the
SEC bits are set to secure. When the SEC field is set to unsecure, the FSLACC setting does not matter.
Table continues on the next page...
Memory Map and Registers
KL25 Sub-Family Reference Manual, Rev. 3, September 2012
428 Freescale Semiconductor, Inc.