TI PCM2902C S/PDIF input

[florian911]

Hello,

I built an USB-Headphone-Amplifier using the PCM2902C which is working quite nicely but I also want to use the SPDIF-functionality. SPDIF out works, but I can not get SPDIF in to work. I am using a Cliff FC684208R receiver.

What I have tested:
-different sources (Creative Sound Blaster X-Fi Surround 5.1 Pro, Creative Sound Blaster E5, Wiim Pro)
-16 bit and 44,1kHz and 48kHz stereo
-built a second prototype (in case of soldering problems)

In the following you can see (sorry, a real screenshot was not possible, USB-interface of the oscilloscope didnt work):
-CH1 (yellow): SPDIF out on PCB1 (connected via USB to a PC)
-CH2 (green): SPDIF in on PCB2 (connected via optical cable to PCB1)

So there is a signal arriving at SPDIF in on PCB2 but I can hear no sound (also there is no chance to switch the input afaik, it should do this automatically).
Do you have any ideas?

Thanks a lot!

 

[phofman]

I may not understand your intention correctly, but the chip datasheet does not show any monitor feature SPDIF-in -> analog/SPDIF out. The SPDIF-in and ADC seem to be connected to the USB input endpoint, sending captured data to the PC only.
Also the block diagram does not show any work with the recovered SPDIF clock, apart of filling the FIFO for EP-IN for async transfer over USB.

 

[rsavas]

That’s correct, no spdif in to analog output, only spdif in to USB output.
I have used the spdif out to spdif in as a way to do loopback. It a neat way to record or capture audio streams!

 

[florian911]

Ok thank you, than I didnt look at the datasheet careful enough..
At least I can use the IC for conversion USB-->SPDIF, so I will start some research for a DAC IC, wanted to replace the one of the PCM2902 anyway