16.5.3 Boot ROM Operating Modes
The Boot ROM operation is logically divided into the following four modes, each serving a
distinct purpose during the device startup and debug process:
- Boot mode: This is the default mode entered immediately after any type of reset. In this mode, the Boot ROM performs system initialization, fuse integrity checks, and attempts to boot the device using the user-configured settings.
- Interactive mode (IMODE): The
Boot ROM enters interactive mode under the following conditions:
- A boot failure occurs, for example due to fuse integrity check failure or invalid configuration.
- A debugger explicitly requests entry into IMODE to perform advanced operations.
In this mode, users can perform these tasks:
- Full chip erase
- Device locking (setting DAL = 0)
- CFM integrity checks on CFM, PFM, ROM, SRAM
- Mission Mode: This mode allows the device to begin execution from the first mutable application executable stored at 0x0800_0000 in the Boot Flash Memory region (BFM). The device remains in mission mode until the device is reset due to any reason. Once the device is reset, the device goes into Boot mode.
Note: Interactive mode is specifically designed to enable the host
debugger to offer additional debug features.