Boot Sources; Fopt Boot Options - NXP Semiconductors freescale KV4 Series Reference Manual

Table of Contents

• Private peripheral bus

This section describes the boot sequence, including sources and options.

10.3.1 Boot sources

This device only supports booting from internal flash. Any secondary boot must go

through an initialization sequence in flash.

The flash option register (FOPT) in the flash memory module 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 FOPT register bits to configure the device at reset as shown in the

following table.

Freescale Semiconductor, Inc.

Table 10-2. Flash Option Register Bit Definitions

Reserved for future expansion.

Select initialization speed on POR, VLLSx, and any system reset.

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.

Fast Initialization.The Flash has faster recoveries at the expense of higher current

during these times.

Reserved for future expansion.

Enable/disable control for the NMI function.

NMI interrupts are always blocked. The associated pin continues to default to NMI

pin controls with internal pullup enabled.

NMI pin/interrupts reset default to enabled.

Table continues on the next page...

KV4x Reference Manual, Rev. 2, 02/2015

Chapter 10 Reset and Boot