From 7b849be00e4c02d821ceb8857cb5856b0b9163a8 Mon Sep 17 00:00:00 2001
From: Andrea Bondavalli <56439183+bondagit@users.noreply.github.com>
Date: Sun, 13 Sep 2020 11:25:00 +0200
Subject: [PATCH] Update USB_GADGET.md

---
 USB_GADGET.md | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

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 ##
 <a name="kernel_config"></a>
@@ -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 ##
 <a name="usb_transmitter"></a>
@@ -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.