Custom audio "cape" with mic - DTO?

Hi all,

Bit of a strange question… We are working on something which uses a tlv320 in the same layout as the audio cape, with one difference, we have added an electret mic. So our board has line out left/right, line in left/right and also mic in.

Apart from changing the i2c bus everything else is the same. With a modded overlay (addressing the right i2c bus) output and line input work as expected. However, the mic is not powered as no bias is being provided. Also the Alsa mixer does not mention the mic anywhere.

My assumption is that I need to modify the device tree overlay to tell the driver that we have a mic present (I’m rather new to audio and dto’s, so forgive me if I’m talking rubbish).

Could anyone point me in the right direction to getting this mic working?

Thanks in advance!


In addition, my engineer tells me we are using MIC3L which is not used on the audio cape. Thats what I need to get working…

“However, the mic is not powered as no bias is being provided”

If the micro is powered by a PIN, you have to tell the cape manager through the dtbo to power the micro .


The bias is provided by the codec afaik