Boot ROM

The Boot ROM allows to ensure the integrity of the device at boot.

The Boot ROM features Boot Interactive mode, which allows the user to perform several actions on the device, such as NVM areas integrity check and chip erase via a debugger connection.

Unless a debugger is connected and places the Boot ROM in Boot Interactive mode, the CPU will jump to the Flash memory, loading the Program Counter (PC) and Stack Pointer (SP) values, and will start fetching Flash user code.

Note: Before jumping to the Flash, the Boot ROM resets the first 2kB of SRAM. The Clocks remain unchanged.

In addition, the SAM L11 Boot ROM has extra security features, such as device integrity checks, memories/peripherals security attributions, and secure boot, which can be executed before jumping to the Flash in Secure state.

For security reasons, while the Boot ROM is executing, no debug is possible except when entering a specific Boot ROM mode called CPU Park mode.