What is missing
The device-side UAC function presents a stereo speaker with feedback (CFG_TUD_AUDIO_ENABLE_EP_OUT, USBIF_AUDIO_SPEAKER_STEREO_FB_DESCRIPTOR). There is no isochronous IN endpoint, so a board cannot present as a USB microphone or a full-duplex sound card.
Why it matters
Host-side capture works (host_uac_read, usbif.uac_audio.input, proven with a commercial USB mic). The reverse pairing — an S3 or a PC capturing from a PyDevices board — cannot exist until the device side grows a mic stream. The examples catalog therefore has usb_mic.py (host capture) but no device-side capture counterpart.
Evidence
src/usbif_tusb_ext.h: CFG_TUD_AUDIO_ENABLE_EP_OUT (1) only; speaker descriptor only- No
CFG_TUD_AUDIO_ENABLE_EP_IN / TX path in the module
Not claiming
Host UAC capture is fine. This issue is device-role mic only.
What is missing
The device-side UAC function presents a stereo speaker with feedback (
CFG_TUD_AUDIO_ENABLE_EP_OUT,USBIF_AUDIO_SPEAKER_STEREO_FB_DESCRIPTOR). There is no isochronous IN endpoint, so a board cannot present as a USB microphone or a full-duplex sound card.Why it matters
Host-side capture works (
host_uac_read,usbif.uac_audio.input, proven with a commercial USB mic). The reverse pairing — an S3 or a PC capturing from a PyDevices board — cannot exist until the device side grows a mic stream. The examples catalog therefore hasusb_mic.py(host capture) but no device-side capture counterpart.Evidence
src/usbif_tusb_ext.h:CFG_TUD_AUDIO_ENABLE_EP_OUT (1)only; speaker descriptor onlyCFG_TUD_AUDIO_ENABLE_EP_IN/ TX path in the moduleNot claiming
Host UAC capture is fine. This issue is device-role mic only.