6. Debug Message

VAB-600 Linux BSP supports debugging with RS232 port. The RS232 client software (such as putty) should configure the parameters as follows:

COM speed：115200
COM parity： NONE
COM data： 8
COM stop-bit：1

Use picocom or another terminal emulator on the HOST PC to open the console:

picocom -b 115200 /dev/ttyS0

If the picocom is not installed, use apt-get to install it:

apt-get install picocom

After successfully connecting to VAB-600 through RS232 line, you can enter the u-boot console and try modifying the u-boot parameters for various configurations, such as changing display resolution and so on.

6.1. Enter U-Boot environment

VAB-600 Linux platform can stop booting to enter u-boot environment. The u-boot will initiate hardware at an earlier stage by those parameters.

The u-boot will wait 3 seconds to stop booting after power on by pressing any key. When booting comes to a halt, the sign WMT # will pop up on terminal screen.

U-Boot is similar to a tiny operation system that has its own commands. Some important commands and parameters are described here.

Print online help:

WMT # help

Change display U-boot logo resolution:

WMT # setenv wmt.display.param 4:6:1:1280:1024:60

Save changed parameters:

WMT # saveenv

6.2. Default u-boot parameters

The default u-boot parameters are configured in the following file:

/update_package/bspinst/bspinst.cfg

The bspinst.cfg file structure has four segments:

1. Scenario: board model and boot method
2. Common: general setting
3. Target (board models): specific setting for each target
4. Routine: parameters of boot method

Its content will be parsed and stored into the on-board storage device during installation procedure described in Boot from eMMC.