diff --git a/USB_GADGET.md b/USB_GADGET.md index d853537..92056d4 100644 --- a/USB_GADGET.md +++ b/USB_GADGET.md @@ -4,7 +4,7 @@ This document describes how to use the AES67 Daemon on a board to operate as AES The board doesn't need to have an audio codec but a USB client or OTG connector that is able to operate in device mode. -Eventually you will connect your card to your PC (*Windows* / *Linux* / *MAC*) via USB and use the PC as a player or recorder and the card to relay audio from USB to Ethernet and vice versa. +Eventually you will connect your card to your PC ( *Windows* / *Linux* / *MAC* ) via USB and use the PC as a player or recorder and the card to relay audio from USB to Ethernet and vice versa. ## Kernel configuration ## @@ -44,6 +44,13 @@ On the PC new audio input and output devices show up. The name assigned to these depend on the OS. On *Windows* a new speaker and microphone named *AC interface* get configured. +**_NOTE:_** +If the USB gadget module loads but the USB audio device doesn't show up check in the kernel ring buffer for the following message: + + udc-core: couldn't find an available UDC - added [g_audio] to list of pending drivers + +This means you have other USB gadgets currently active (for example g_serial). +To proceed disable the automatic load of these modules and configure *g_audio* instead. ## AES67 USB Transmitter ## @@ -51,7 +58,7 @@ Before starting make sure that the [AES67 daemon basic setup](DEVICES.ms#daemon_ On the board run the following command to relay the audio from the USB to the AES67 Source: - sudo nice -n -10 ./alsaloop -c 2 -r 48000 -f S16_LE -C plughw:UAC1Gadget -P plughw:RAVENNA + sudo nice -n -10 alsaloop -c 2 -r 48000 -f S16_LE -C plughw:UAC1Gadget -P plughw:RAVENNA On the PC start the audio playback on the new device. **_NOTE:_** The *ALSA RAVENNA driver* will perform the format conversion from *S16\_LE* to the *Source* format. @@ -63,7 +70,7 @@ You also need to configure a new stereo *Sink* on the daemon. On the board run the following command to relay the audio from AES67 Sink to the USB: - sudo nice -n -10 ./alsaloop -c 2 -r 48000 -f S16\_LE -C plughw:RAVENNA -P plughw:UAC1Gadget + sudo nice -n -10 alsaloop -c 2 -r 48000 -f S16_LE -C plughw:RAVENNA -P plughw:UAC1Gadget On the PC start the audio recording on the new device. **_NOTE:_** The *ALSA RAVENNA driver* will perform the format conversion from *S16\_LE* to the *Sink* format.