SGTL5000 Audio adapter board - headphone out as input

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mercwut

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Shot in the dark here, but would it be possible to use the headphone output jack as a LINE input?

Looking at the board I was thinking jumper the L/R vias next to the headphone jack to the LINE IN L/R pins and then mute the headphone output as described on page 38 of the spec sheet below. Seems a bit over my head to figure out if this would work or not, and since it's not a big deal if I can do this I don't want to fry anything trying without asking.
https://www.pjrc.com/teensy/SGTL5000.pdf
 
I ended up doing what I was talking about in my previous post and then just cut the original traces. My project didn't need the headphone output so it wasn't a big deal for me to do it.
 
Yup, cutting the traces so it's no long connected to the headphone amp AND jumpering the test pads over to the line in pins will do it.

By default, the SGTL5000 code turns on the headphone amp. I've never tried configuring the chip to not turn on the amp. I'm not sure if that's even possible, and if it is, I don't know whether the unused amp pins would be a high impedance that wouldn't interfere with an input signal.

To try such a thing, you'd definitely need to edit the SGTL5000 code in the audio library, to configure the chip differently. If anyone does try this, please post a followup with anything learned.

Cutting the traces is probably much simpler.
 
Well, reading the datasheet, there might be an issue with the headphone ground pin. It is connected to HPVGND, which, according to the datasheet (pg. 3) is NOT a real ground and may not be connected to it. So, if you cut the traces, I would recommend cutting HPVGND as well.
 
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