Oleh,
I wanted to point you to a Wiki page on the Critical Link support website that previously covered how to get the UART echo StarterWare demo working for the MityDSP-L138 family of modules.
https://support.criticallink.com/redmine/projects/arm9-platforms/wiki/StarterWare
As well Critical Link offers a support forum on that same website which is monitored and responded to directly by our own engineering team.
https://support.criticallink.com/redmine/projects/arm9-platforms/boards
Thank you and we look forward to getting you up and running.