Holly,
More than three months have already passed, but the User's guide has not been updated. Please confirm.
I have analyzed the schematic of the evaluation board, turned on the power, and now I can access the registers.
<URL>
www.ti.com/.../DS90UB928QEVM
<User's guide summary>
EVM User's guide DS90UB928QEVM User's Guide 28 Feb 2013
Makoto