6.3.2 FOPT boot options
The Flash Option (FOPT) register in the Flash Memory module (FTFA_FOPT) allows
the user to customize the operation of the MCU at boot time. The register contains read-
only bits that are loaded from the NVM's option byte in the flash configuration field. The
default setting for all values in the FTFA_FOPT register is logic 1 since it is copied from
the option byte residing in flash, which has all bits as logic 1 in the flash erased state. To
configure for alternate settings, program the appropriate bits in the NVM option byte.
The new settings will take effect on subsequent POR, VLLSx recoveries, and any system
reset. For more details on programming the option byte, see the flash memory chapter.
The MCU uses the FTFA_FOPT register bits to configure the device at reset as shown in
the following table.
Table 6-2. Flash Option Register (FTFA_FOPT) bit definitions
Bit
Num
Field
Value
Definition
7-6
Reserved
Reserved for future expansion.
5
FAST_INIT
Selects initialization speed on POR, VLLSx, and any system reset .
0
Slower initialization: The flash initialization will be slower with the benefit of
reduced average current during this time. The duration of the recovery will be
controlled by the clock divider selection determined by the LPBOOT setting.
1
Fast Initialization: The flash has faster recoveries at the expense of higher current
during these times.
3
RESET_PIN_CFG
Enables/disables control for the RESET pin.
0
RESET_b pin is disabled following a POR and cannot be enabled as reset
function. When this option is selected, there could be a short period of contention
during a POR ramp where the device drives the pinout low prior to establishing the
setting of this option and releasing the reset function on the pin.
This bit is preserved through system resets and low-power modes. When
RESET_b pin function is disabled, it cannot be used as a source for low-power
mode wake-up.
NOTE: When the reset pin has been disabled and security has been enabled by
means of the FSEC register, a mass erase can be performed only by
setting both the Mass Erase and System Reset Request fields in the
MDM-AP register.
1
RESET_b pin is dedicated. The port is configured with pullup enabled, open drain,
passive filter enabled.
2
NMI_DIS
Enables/disables control for the NMI function.
0
NMI interrupts are always blocked. The associated pin continues to default to
NMI_b pin controls with internal pullup enabled. When NMI_b pin function is
disabled, it cannot be used as a source for low-power mode wake-up.
1
NMI_b pin/interrupts reset default to enabled.
1
Reserved
Reserved for future expansion.
Table continues on the next page...
Boot
KL02 Sub-Family Reference Manual, Rev. 2.1, July 2013
102
Freescale Semiconductor, Inc.