27.33.3 Flash Security Register (FTFA_FSEC)This read-only register holds all bits associated with the security of the MCU and flashmemory module.During the reset sequence, the register is loaded with the contents of the flash securitybyte in the Flash Configuration Field located in program flash memory. The flash basisfor the values is signified by X in the reset value.Address: 4002_0000h base + 2h offset = 4002_0002hBit 7 6 5 4 3 2 1 0Read KEYEN MEEN FSLACC SECWriteReset x* x* x* x* x* x* x* x** Notes:x = Undefined at reset.•FTFA_FSEC field descriptionsField Description7–6KEYENBackdoor Key Security EnableThese bits enable and disable backdoor key access to the flash memory module.00 Backdoor key access disabled01 Backdoor key access disabled (preferred KEYEN state to disable backdoor key access)10 Backdoor key access enabled11 Backdoor key access disabled5–4MEENMass Erase Enable BitsEnables and disables mass erase capability of the flash memory module. The state of the MEEN bits isonly relevant when the SEC bits are set to secure outside of NVM Normal Mode. When the SEC field isset to unsecure, the MEEN setting does not matter.00 Mass erase is enabled01 Mass erase is enabled10 Mass erase is disabled11 Mass erase is enabled3–2FSLACCFreescale Failure Analysis Access CodeThese bits enable or disable access to the flash memory contents during returned part failure analysis atFreescale. When SEC is secure and FSLACC is denied, access to the program flash contents is deniedand any failure analysis performed by Freescale factory test must begin with a full erase to unsecure thepart.When access is granted (SEC is unsecure, or SEC is secure and FSLACC is granted), Freescale factorytesting has visibility of the current flash contents. The state of the FSLACC bits is only relevant when theSEC 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 RegistersKL25 Sub-Family Reference Manual, Rev. 3, September 2012428 Freescale Semiconductor, Inc.
