Raspberry PI Sound Player

This is a Network Table client that can run on a Raspberry Pi to play audio.

Building

The project uses Gradle. Clone it to your Pi and be build it with the following command:

./gradlew build

Running

The project can easily be run using Gradle. It will run on a Raspberry Pi, but it will also run on Windows (and probably Linux and Mac.) The program takes the following arguments:

• The address of the Network Table server (the robot)

./gradlew run --args="10.70.28.2"

Pi Configuration

Output device

First, make sure you have selected the right audio output device, the default is HDMI audio. To configure audio, right click the speaker icon on the desktop and select the output device. You can also configure it from the terminal (SSH) using sudo raspi-config and selecting System Options > Audio.

Scheduling at startup

Schedule this project to run on startup with systemd.

Create a file with the below contents in the folder /etc/systemd/system.

sudo nano /etc/systemd/system/raspberrysound.service

Add contents like this to the file and save:

[Unit]
Description=Tank Bot Sound
Wants=sound.target
After=sound.target
[Service]
Restart=on-failure
RestartSec=5s
User=pi
Type=simple
RemainAfterExit=no
WorkingDirectory=/home/pi/RaspberrySound
ExecStart=/home/pi/RaspberrySound/gradlew run
[Install]
WantedBy=multi-user.target

Start the service and then check that it starts up with these comands:

sudo systemctl start raspberrysound
journalctl -f -u raspberrysound

If the service was successful enable so it will start automatically when the computer boots up:

sudo systemctl enable raspberrysound.service

Java configuration

You may need to edit the sound.properties file in the Java conf folder. These settings work on a Raspberry Pi B running Raspberry Pi OS (Raspbian):

javax.sound.sampled.Clip=com.sun.media.sound.DirectAudioDeviceProvider
javax.sound.sampled.Port=com.sun.media.sound.PortMixerProvider
javax.sound.sampled.SourceDataLine=com.sun.media.sound.DirectAudioDeviceProvider
javax.sound.sampled.TargetDataLine=com.sun.media.sound.DirectAudioDeviceProvider

This solution was found here.

Using Outline Viewer

In a VS Code with WPILib extensions, press CTRL + SHIFT + P, select WPILib: Start Tool, then select OutlineViewer. This will launch the Outline Viewer where you can see and edit Network Tables.

Make sure Server Mode and the Default Port setting are on, then press OK.

Finally, tart the Pi Audio Player application. The application should connect to the Network Table. Now, in Outline Viewer you can change the Network Table values to trigger events in the player.

Triggering sound from the robot

The robot sets a network table value to trigger playing the audio file.

    private final NetworkTableInstance inst = NetworkTableInstance.getDefault();
    private final NetworkTable table = inst.getTable("audio");
    private final NetworkTableEntry playEntry = table.getEntry("shot");

    public void playGun() {
        playEntry.setBoolean(true);
    }

Raspberry Pi Amp HAT

Documentation for the Amp HAT can be found here: https://www.inno-maker.com/product/hifi-amp-hat/

The overlay needs to be added to the config.txt file, and then a reboot is needed. This can be done with the following commands:

sudo echo "dtoverlay=hifiberry-amp" >> /boot/config.txt
sudo reboot 0

Once the reboot is complete use raspi-config to select the output device (see above).