The sequences outlined in this section can vary depending on the BIOS version, operating system setting, device state when sequence is initiated and the specific expansion board hosting the compute module. While deemed accurate, material presented is not absolute for all configurations.
Once power on is initiated, the platform resets devices, energizes power supplies on the expansion board and begins to execute the firmware (BIOS) code.
The BIOS will perform additional housekeeping and configuration tasks before turning control over to the boot loader on the target boot device, as set within the BIOS menu system.
Power On from Mechanical Off
Under most conditions, the expansion board included in the development kit will begin the boot process when an acceptable power source is connected. This happens because VSYS (module power) line is connected to the VDC_IN line on the expansion board. Alternate expansion board design can allow VSYS to be energized without the platform running.
Depending on platform configuration, depressing the power button can initiate the boot sequence. See Buttons Jumpers and LEDs
for more information on hardware based power control.
Power Off via Hardware Button
When the platform is energized, holding the power button for longer then 10 seconds will trigger a power down. Depending on configuration, it might be required to disconnect and reconnect the DC power source to initiate the power on sequence.
Reset via Hardware Button
When the platform is energized, depressing the power button for 2 seconds will trigger a cold-reboot. This is a controlled power down and immediate reboot.