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by snops 307 days ago
It can, it just needs the two resistors, which is the cheapest possible thing the standards committee could have asked manufacturers to do.

USB-C gets complicated at the high end, but for basic functionality I think the standards committee did a very good job at making the cheapest way to do it the correct way, e.g. a USB-C to 3.5mm audio adaptor can be entirely passive, it just needs the right resistor in it.
2 comments
RobotToaster 307 days ago
Then a lot of phones don't support it, so it took me three attempts to find a usb-c to 3.5mm adapter that didn't have it's own DAC that would work with my phone's FM radio lol
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kevin_thibedeau 307 days ago
Audio Adapter Accessory Mode was deprecated last year so devices using it will be disappearing.
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silisili 307 days ago
Do you mind sharing? I was looking for something like this a couple years ago.
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DoctorOetker 307 days ago
>e.g. a USB-C to 3.5mm audio adaptor can be entirely passive, it just needs the right resistor in it.

How does that work? is each USB-C host port, or downstream USB-C hub port required to contain a stereo DAC? Does the standard impose performance requirements like dynamic range, noise, minimum sample rate,...? Does it also mandate the jack can be used for mic / line-in? Does it similarily stipulate inclusion of an ADC in each port?

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jadamson 307 days ago
It doesn't mandate any of that, it's an optional feature.

The data pins are repurposed for analog audio, so it won't work with hubs. You'd of course need a DAC for output and an ADC for mic input, but the point is to replace a headset jack, so you'd have those already.

https://www.usb.org/sites/default/files/USB%20Type-C%20Spec%... (PDF, page 309)

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