User manual

Design Considerations
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described in this chapter, or in secure boot mode. How the secure boot mode can be
enabled and how the chip operates in this mode is provided in an application by Atmel®,
which is only available under NDA. Please contact taskit support, if you want to employ
the secure bootloader.
The ROM code first samples the BMS signal, if it is low, it will boot from NOR flash
connected to NCS0 of the external bus. If it is high it tries to retrieve valid code from
external memories. The sequence is shown in the following diagram
The standard boot sequence can be altered by writing to the boot sequence controller
(BSC) at address 0xFFFF FE54. This has the effect of speeding up the boot process or to
avoid having relevant pins driven during the boot process. The boot configuration register
is battery-backed and thus the state is preserved during reboots, if a battery is connected.
Otherwise it is reset to the default value (0X0).