I have a design that is a few years old using the AD9880. When I designed the board we did not have any customers interested in audio so we simply connected the SPDIF and I2S signal to our FPGA. We never tested the audio to see if it worked. We now have a customer interested in using the audio on the board. When I set up all of the registers to enable audio I get nothing on either the SPDIF or I2S. I don't even get the LRCLK. Register 5B shows a 4. 5B should be 0 for DVI and 1 for HDMI. This would show up in the register as an 8. This would indicate that the AD9880 thinks my source is DVI rather than HDMI. Since DVI has no audio that could explain why I get no audio out.
The question is "why does the AD9880 think I have a DVI source connected instead of HDMI". And, "how do I fix this". Can anyone please help.