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PCM2707: Minimal test circuit

Carlos Moreno1
Intellectual 550 points

Part Number: PCM2707

Before committing to more elaborate designs, I'm trying to give it a quick try.  In particular, I want to see if there are any surprises with Linux recognizing the device (mostly interested in Ubuntu).

If I want to start by just to seeing the device appear on the "Sound Settings" dialog, regardless of being able to hear the actual sound, I guess that the absolutely minimal setup would be just connecting the 12MHz crystal and the four USB pins to the corresponding four pins in the PCM2707?  (that would be:  Vbus to pin 24, D+ to pin 23, D- to pin 22, GND connected to pin 20 -- DGND)

Literally, just that --- *all* of the other pins unconnected.  Should this activate the USB device and show up in the host's "Sound Settings" dialog?  (again, my question is not:  does this work well?  the question is:  should this work at all?)

I just tried it and it's not showing up on the Ubuntu 14.04 "Sound Settings" dialog.  (disclaimer:  I know I could simply try adding the missing components and connections and see;  but the prototype setup makes it a bit hard to solder in components, so I figured I'd ask for some hints/pointers to help me minimize changes for a quick test)

Thanks,
Carlos
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  • 0
    TI__Guru 57800 points

    Hi, Carlos,

    In general, we recommend to follow as close as possible the schematics from the datasheet. This device requires some hardware pins to be connected in order to establish certain operating modes, so It is recommended to make sure all the configuration pins, decoupling points, grounds and power supplies for the device are properly connected.

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer