Doesn’t seem to now (Ubuntu 20.04), is the hardware capable of reading TRRS buttons on a wired headset?
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I am curious about this question and would like to have a definitive answer as well.
This is an interesting question. So I thought I’d dig a little. Unfortunately, it looks the ALC269 audio DAC used doesn’t support detection of analog headphone buttons. This is for the FWL13’s built-in 3.5mm jack.
Note: The ALC269 does not support impedance sensing. Read as 0’s
Those buttons are implemented by momentarily shorting the mic pin to gnd through a resistor. Different resistor value for the different buttons. So detection in hardware is done through impedance sensing on the mic pin.
Now, I’ve seen some people mention that it might be possible to impliment detection in software, but not sure if anyone has done it. When the hardware doesn’t support detecting those buttons you usually hear a click over the mic when you press them. I’ve never listened close but I saw someone suggest that you can hear the difference in different buttons. I think on devices with hardware detection, the chip mutes the mic at the moment of detection, starting fast enough that the click isn’t heard.
I haven’t looked at the audio DAC in the audio expansion card yet. Just the FWL13 built-in one.
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