7.1 Boot Process

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 “First level bootloader”. The SAMA5D2 can be configured to run a Standard Boot mode or a Secure Boot mode. More information on how the Secure Boot mode can be enabled, and how the chip operates in this mode, is provided in the document SAMA5D2x Secure Boot Strategy. To obtain this application note and additional information about the secure boot and related tools, contact a Microchip sales representative.

By default, the chip starts in Standard Boot Mode.

The ROM code standard sequence is executed as follows:
  • Basic chip initialization: crystal or external clock frequency detection.
  • Attempt to retrieve a valid code from external non-volatile memories (NVM).
  • Execution of a monitor called SAM-BA® Monitor, in case no valid application has been found on any NVM (1).
Note:
  1. This may be the case during the first start-up or after an NVM erase or when a "boot disable jumper" is used on the memory Chip Select, in order to force an update.