The DDC Core when implemented has the sine output of the DDS connected to the I channel, and the cosine output connected to the Q channel.
This is not explained in the documentation.
This may be counter-intuitive to people who are using the core. Often, the cosine is assumed to be associated with the I channel, sine with the Q channel.
For certain applications, it is important to be aware which way the core is connected.
The work-around for designs that require these connections reversed is simply to connect the I channel coming out of the DDC Core to the Q channel in the rest of the design, and similarly the Q channel to the I portion of the design. The filters and remaining paths after the mixer in the DDC Core will be identical.