Audio-USB

The phyCORE-i.MX7 development kit provides audio over USB2.0 (X9). This guide will demonstrate how to connect and use a USB headset for audio and microphone support.

Requirements

Logitech H570e headset
CAT5e cable (comes included with the development kit)
Network switch connected to a DHCP enabled network

Hardware Setup

Plug the headset into the USB2.0 (X9) connector.

After the device is connected, you should see Linux console output similar to the below:

Expected Output

root@phyboard-zeta-imx7d-1:~# usb 1-1: new full-speed USB device number 6 using ci_hdrc
usb 1-1: Warning! Unlikely big volume range (=4125), cval->res is probably wrong.
usb 1-1: [11] FU [Sidetone Playback Volume] ch = 1, val = 0/4125/1
input: Logitech Inc Logitech H570e Stereo as /devices/soc0/soc/30800000.aips-bus/30b10000.usb/ci_hdrc.0/usb1/1-1/1-1:1.3/0003:046D:0A56.0005/input/input6
hid-generic 0003:046D:0A56.0005: input: USB HID v1.11 Device [Logitech Inc Logictech H570e Stereo] on usb-ci_hdrc.0-1/input3

Verify that the device was connected.

Target (Linux)

lsusb

Expected Output

root@phyboard-zeta-imx7d-1:~# lsusb
Bus 001 Device 006: ID 046d:0a56 Logitech, Inc.
Bus 001 Device 001: ID 1d6b:0002 Linux 5.15.71-bsp-yocto-nxp-i.mx7-pd23.1.0 ehci_hcd EHCI Host Controller

Next, connect an Ethernet cable from X8 on the development kit carrier board to a network switch that is connected to a DHCP-enabled network.

Playing Audio

Copy an audio file onto the develoment kit.

This example will use the wget command, which requires a network connection. Discover more mediums that can assist in copying files by following the guide Copying Files to the Device.
Target (Linux)
```
wget https://www2.cs.uic.edu/~i101/SoundFiles/ImperialMarch60.wav
```

Play the audio file.

Target (Linux)

aplay ImperialMarch60.wav

Expected Output

root@phyboard-zeta-imx7d-1:~# aplay ImperialMarch60.wav
Playing WAVE 'ImperialMarch60.wav' : Signed 16 bit Little Endian, Rate 22050 Hz, Mono

Recording Audio

Use ‘arecord’ to record audio using the microphone on the headset. The following command will record audio from the microphone for 10 seconds and save it to testrecord.wav.
Target (Linux)
```
arecord -d 10 -f cd -t wav testrecord.wav
```
Use the following to play the file.
Target (Linux)
```
aplay testrecord.wav
```

Audio Mixer Settings

Control volume and various other audio setting using the ALSA soundcard driver’s ‘amixer’ or ‘alsamixer’ commands.
Target (Linux)
```
alsamixer
```

A GUI interface will pop up. This can be navigated using arrow keys.

Tip

Click on the link for more information about alsamixer: https://linux.die.net/man/1/alsamixer