Kazu,
Can you try the things described in the below wiki page and also the video inside it:
http://processors.wiki.ti.com/index.php/U-boot_Debug_in_CCSv5 -> http://software-dl.ti.com/sdo/sdo_apps_public_sw/CCSv5/Demos/u-boot_debug_autonomous/u-boot_debug_autonomous.html
This video is for DM816x device, but I think DM816x u-boot is more close to DM814x u-boot than AM335x u-boot.
Regards,
Pavel