Kontron SMARC-sA3874i - Manual (Page 75)

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User’s Guide
8 ULP-COM sA3874i Boot Brief
8.1 ULP-COM sA3874i Boot Up Sequence
The following steps define the ULP-COM sA3874i boot process at a high level:
1. The power supplies on the module will be up and stable at the required voltage level after powering-on
the system.
2. System level hardware executes the power-up sequence. This sequence ends when system level hardware
releases SYS_RESET_N.
3. The boot ROM on the TI Cortex A8 SoC begins executing and programs the on-chip I/O controllers to
access the secondary boot device.
4. Secondary boot device will be selected based on the external boot device selection jumpers which are
provided on the ULP-COM carrier board. Details are provided in the section 8.2 BOOT Selection .
5. The boot ROM on the TI Cortex A8 device fetches the Boot Configuration Table (BCT) and boot loader
from the secondary boot device.
6. If the BCT and boot loader are fetched successfully, boot ROM on the TI Cortex A8 device yields to the
boot loader. (Otherwise, boot ROM on the TI Cortex A8 device enters USB recovery mode.)
Note: The ULP-COM sA3874i uses U-Boot boot loader.
7. The boot loader configures processor, memories and essential peripherals into known and usable state.
8. The boot loader then loads the kernel image and jump to kernel.
9. The kernel sets up the processor and all peripherals as per configuration.
10. Kernel starts various kernel daemons and processes.
11. Finally kernel loads the file system and OS desktop.
Kontron has described the ULP-COM sA3874i boot sequence in the “Booting ULP-COM” white paper available in the
EMD Section (
http://emdcustomersection.kontron.com ). This is an interesting and insightful read. Kontron
encourages users to read this document and learn how to enable the power of this architecture.