SBC35-C398/Setup
v1.0
www.winsystems.com
Page 7
1/8” phone jacks. The signals available on the cable are Line Out, Headphone, Line In,
and Microphone In. In addition to the analog audio outputs & inputs, the SBC35-C398Q
also supports digital audio on the HDMI video connector. Plugging this connector into a
device with HDMI audio capability allows the board to play audio through the device.
7.5
Startup
As shipped from the factory, the SBC35-C398Q uses the
JP5
jumpers to signal the
i.MX6 ARM processor which device loads the initial boot application. The default device
is on-board SPI-NOR flash, but boot-up can be loaded from the SD card or the microSD
card if desired.
U-Boot is the default boot loader installed on the SBC35-C398. U-Boot has been ported
to the board, and all of the board’s boot peripherals are available for use from within
U-Boot. The boot loader uses environment variables to specify configuration of the
board during startup; the variables also specify the operating system boot device, and
any variables that pass on to the operating system during startup. As shipped from the
factory, U-Boot environment variables are stored in a partition of the SPI-NOR flash.
7.6
Power up
Once the SBC35-C398 powers up, the boot loader starts. U-Boot pauses for three
seconds to allow for aborting the OS boot. If you do not abort the OS boot during the
three-second window, the system loads the WinSystems Linaro distribution of Linux.
The U-Boot OS abort period is programmable - it can be changed by aborting an OS
boot and changing the bootdelay parameters. Please remember to save the changes to
the SPI-NOR flash device after modifying the parameters. If you abort the U-Boot OS
boot by pressing any key during the three-second pause, the U-Boot command prompt
displays as shown in the screen snapshot on the next page.
NOTE
The open source U-Boot project is hosted at http://www.denx.de/wiki/U-Boot. Extensive
U-Boot documentation is available for download from this site.
The image depicted in the figure titled “U-Boot Screen During Startup” on page 36
shows the U-Boot startup screen and OS boot countdown boot screen from an
SBC35-C398 Dual Core or Single Core board.
NOTE
The
“*** Warning - bad CRC…”
message is an indicator that U-Boot is using the
built-in environment variables and not a local copy from SPI-NOR flash. If a variable
were added or modified and the environment saved with the U-Boot
saveenv
command,
this message would not be present.
