01-08-2021, 06:19 AM
(This post was last modified: 01-08-2021, 07:07 AM by dsimic.
Edit Reason: Wording improvements
)
Please, have a look at my third edit above...
I agree that J2, the audio jack, looks funny. According to the way J2 is depicted, its pins 3 & 5 and 4 & 6 should be shorted when no headphones are connected. How should it be possible for the left channel to work as expected, or at all, is beyond my comprehension.
Furthermore, the audio codec actually receives nothing on its GPIO1 line... The R233 resistor is marked as NC, as well as R234, which somehow slipped by in the earlier analysis.
I'd say that the Pine64 engineers probably originally followed the ES8316 reference design that requires GPIO1 to be the headphones "flag", but the thing refused to work as expected so R233 became NC, which actually makes more sense.
Edit: Corrected the J2 pin numbers above.
I agree that J2, the audio jack, looks funny. According to the way J2 is depicted, its pins 3 & 5 and 4 & 6 should be shorted when no headphones are connected. How should it be possible for the left channel to work as expected, or at all, is beyond my comprehension.
Furthermore, the audio codec actually receives nothing on its GPIO1 line... The R233 resistor is marked as NC, as well as R234, which somehow slipped by in the earlier analysis.
I'd say that the Pine64 engineers probably originally followed the ES8316 reference design that requires GPIO1 to be the headphones "flag", but the thing refused to work as expected so R233 became NC, which actually makes more sense.Edit: Corrected the J2 pin numbers above.