Information

The device can be in single chip (default) or serial flash programming mode (EzPort).
While in single chip mode the device can be in run or various low power modes
mentioned in Power mode transitions.
Table 6-2. Mode select decoding
EzPort chip select (EZP_CS) Description
0 Serial flash programming mode (EzPort)
1 Single chip (default)
6.3.3 FOPT boot options
The flash option register (FOPT) in flash memory module (FTFL) 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 user can
reprogram the option byte in flash to change the FOPT values that are used for
subsequent resets. For more details on programming the option byte, refer to the flash
memory chapter.
The MCU uses the FTFL_FOPT register bits to configure the device at reset as shown in
the following table.
Table 6-3. Flash Option Register (FTFL_FOPT) Bit Definitions
Bit
Num
Field Value Definition
7-3 Reserved Reserved for future expansion.
2 NMI_DIS 0 NMI interrupts are always blocked. The associated pin continues to default to NMI
pin controls with internal pullup enabled.
1 NMI pin/interrupts reset default to enabled.
1 EZPORT_DIS 0 EzPort operation is disabled. The device always boots to normal CPU execution
and the state of EZP_CS signal during reset is ignored. This option avoids
inadvertent resets into EzPort mode if the EZP_CS/NMI pin is used for its NMI
function.
1 EzPort operation is enabled. The state of EZP_CS pin during reset determines if
device enters EzPort mode.
Table continues on the next page...
Boot
K20 Sub-Family Reference Manual, Rev. 2, Feb 2012
162 Freescale Semiconductor, Inc.