SBC35-C398/Setup
v1.0
www.winsystems.com
Page 11
7.8.1 Console
The console argument (
console=ttymxc0,115200n8
) selects the serial device and
protocol for the console output. This variable should not be changed if a console is
desired, and it can be deleted if no console is used.
7.8.2 Video Output
There are three video outputs on the SBC35-C398; one HDMI and two LVDS (Flat
Panel). The two LVDS sources also provide back light support. The desired video
sources and resolutions must be configured using U-Boot environment variables. The
default settings enable the HDMI port with a resolution of 1280x720; the default settings
also enable a single LVDS port with resolution of 1024x600.
Setting the primary display mode:
To set the primary display to HDMI with 1080P60 mode, and the secondary display on
LVDS with XGA mode enter the following:
video=mxcfb0:dev=hdmi, 1920x1080M@60,if=RGB24
video=mxcfb1:dev=ldb,LDB-XGA,if=RGB666
To set the primary display to LVDS with XGA mode, and the secondary display on HDMI
with 1080P60 mode, enter the following:
video=mxcfb0:dev=ldb,LDB-XGA,if=RGB666
video=mxcfb1:dev=hdmi,1920x1080M@60,if=RGB24
7.8.3 Specifying Active Cores
The SBC35-C398Q utilizes the NXP i.MX6Q processor, which has four ARM processor
cores. By default, all four cores are active. You can specify the maximum number of
cores with the environment variable ‘
cpu_count
’.
Normally, Linux will use all available CPU cores. Changing this variable can make kernel
and device driver debugging easier to accomplish. To change the number of CPU cores
in use, enter the following series of commands from the U-Boot command line,
substituting the number of CPUs for
X
:
setenv cpu_count 'maxcpus=
X
'
saveenv
7.8.4 Boot Command and Boot Device
As shipped from the factory, the board is set to boot the Operating System (OS) image
from an SD card. By changing certain U-Boot environment variables, the board can be
directed to boot the OS image from a microSD card, an attached SATA/CFast device, or
over the Ethernet. On startup, U-Boot will look in the environment for a variable named
‘
bootcmd
’. Typically, ‘
bootcmd
’ directs U-Boot to execute commands contained in
another environment variable. For instance, the default ‘
bootcmd
’, which is
