12.1.1 Description

The system always boots from the ROM memory at address 0x0.

The ROM code is a boot program contained in the embedded ROM. It is also called “Bootloader”.

By default, the chip starts in Standard Boot mode. To know how to enable the Secure Boot mode, see 12.2 Secure Boot Strategy.

Note: JTAG access is disabled during execution of the ROM code sequence. It is re-enabled when jumping into SRAM when a valid code has been found on an external Non-Volatile Memory (NVM) at the same time the ROM memory is hidden. If no valid boot has been found on an external NVM, the ROM code enables the USB connection and one UART serial port, starts the standard SAM-BA^® Monitor, locks access to the ROM memory and re-enables the JTAG connection.