6.4.4 Boot Failure Signal

The Boot ROM provides a mechanism to indicate boot failure through a user-configurable Boot Failure Signal, enabled via the Boot External Notification I/O Pin (BOOT_GPIOSEL) fuse located in the Boot Configuration (BOOTCFG) fuse.

Users can select a specific I/O pin to serve as the fault indicator for their application. If a boot failure occurs (e.g., due to a fuse integrity check failure or invalid configuration), the Boot ROM asserts the selected I/O pin to signal the fault condition.

Note: By default, the Boot Failure Signal is disabled (BOOT_GPIOSEL = NONE). To enable this feature, users must program the BOOT_GPIOSEL fuse with a valid I/O selection. Refer to the BOOTCFG - Boot Configuration Fuse and Pinout chapters for details on available I/O options.

Important: Once the Boot ROM transfers control to the first mutable application code, it no longer manages or controls the fault signal pin. The application is responsible for any further de-assertion of the signal and configuration of the pin.