I have purchased DM816x EVM recently. I am not able to use XDS510USB with this EVM. The same emulator I am able to use with DM648 board. Are there any issues in using XDS510USB with DM816x EVM? I knew there are some issues with stellaris EVM. See below link.
http://processors.wiki.ti.com/index.php/JTAG_configuration_for_CCS_and_Stellaris#External_Emulator_Connection
Best Regards
JK