1.4 Customizing the ROM Code Boot Sequence

All Microchip MPU 32-bit devices featuring an OTP controller (OTPC), such as SAM9X60, SAM9X7 Series, SAMA7G5 Series and SAMA7D6 Series devices, use a boot configuration packet to overwrite the default boot sequence.

The BCP can be written into either the real or the emulated OTP memory matrix. To switch between the two, set the emulation bit in the Boot Sequence Controller Configuration Register (BSC_CR). Check the SAM-BA tool documentation for details on how to switch to Emulation mode or revert to Real mode.

The following flowchart shows the boot configuration loading step for Microchip 32-bit MPU devices using a Boot Configuration Packet (BCP) to store the boot sequence.

Figure 1-3. Boot Configuration Loading

The boot configuration packet is used to:

enable only project-specific boot interfaces,
set a specific boot sequence order,
configure the ROM code console serial port,
permanently disable JTAG debug access when required,
permanently disable the ROM code monitor when required.