HOWTO Use `pulseaudio` with a Fe-Pi Stereo Sound Card and Fldigi/Direwolf

Version: 20200528
Author: Steve Magnuson, AG7GN

This is a variation of the Split Channels documentation for DRAWS/UDRC by mcdermj at NW Digital Radio, expanded, adapted and modified for use with the Nexus DR-X/DigiLink and Fe-Pi audio.

1. Prerequisites

Raspberry Pi 3B or 3B+. I have not tested with a model 4B, but it should work.
Fe-Pi Audio Z Version 2 sound card
WB7FHC Budd Churchward's excellent DigiLink (REV C or later) or Nexus DR-X board, or equivalent GPIO controlled PTT
Raspbian Stretch or Buster OS. This procedure has not been tested on other distributions, and some instructions are OS-specific.
OPTIONAL: Speakers attached to Pi's built-in audio jack if you want to monitor the radio's TX and/or RX on the Pi's speakers
Familiarity with the Pi's Terminal application, basic LINUX commands and the use of sudo
Familiarity with any Linux text editor

This procedure assumes the operating user is pi and pi's home directory is $HOME and that user pi has sudo privileges (the default). Adjust as necessary if this is not the case.

2. Configuration Procedure

NOTE: If you are using the Hampi image, the majority of the following setup is already done for you.

2.0 Modify `/boot/cmdline.txt`

The release of Rasbian Buster stable kernel 4.19.118-v7+ (Raspbian package raspberrypi-kernel/testing,now 1.20200512-2 armhf) introduced some changes in how the sound interfaces are handled. These changes break the Fldigi alerts and TX/RX monitor features.

Fortunately, the fix is simple: Append this text to the end of the line in /boot/cmdline.txt and reboot. This is ONLY needed when using raspbian-kernel 1.20200512-2 or later.

snd-bcm2835.enable_compat_alsa=1 snd-bcm2835.enable_hdmi=0 snd-bcm2835.enable_headphones=0

You must reboot after making this change.

2.1 Install `pulseaudio`

pulseaudio is installed by default in Raspbian Stretch and Buster. Just to make sure it is, open a terminal, then run:

sudo apt update && sudo apt install pulseaudio

2.2 Determine the sound card name

Open a terminal and run arecord -l as shown in this example:

pi@mypi:~ $ arecord -l 
card 1: Audio [Fe-Pi Audio], device 0: Fe-Pi HiFi
sgtl5000-0 [] Subdevices: 0/1 Subdevice #0: subdevice #0

The card name is "Audio" in this example. Use the name that's after "card 1:" and before the text in square brackets. For Fe-Pi, it'll be "Audio"

2.3 Back up any existing `/etc/asound.conf` file

Case 1: There is no existing /etc/asound.conf file. Example:

  pi@mypi:~ $ ls /etc/asound.conf 
  ls: cannot access '/etc/asound.conf': No
  such file or directory

...no file, so nothing to back up.

Case 2: There is an existing file.

  pi@mypi:~ $ ls /etc/asound.conf
  /etc/asound.conf

...back it up. Run:

  sudo cp /etc/asound.conf /etc/asound.conf.original

2.4 Create/modify `/etc/asound.conf`

This step will make the virtual audio interfaces we create in pulseaudio available to applications that can't use pulseaudio directly, like Direwolf. These appear to other applications as ALSA devices.

As sudo, edit or create /etc/asound.conf in a text editor. It should contain only the following lines.

pcm.fepi-capture-left {
  type pulse
  device "fepi-capture-left"
}
pcm.fepi-playback-left {
  type pulse
  device "fepi-playback-left"
}
pcm.fepi-capture-right {
  type pulse
  device "fepi-capture-right"
}
pcm.fepi-playback-right {
  type pulse
  device "fepi-playback-right"
}
pcm.system-audio-playback {
  type pulse
  device "system-audio-playback"
}

2.5 Modify `/etc/pulse/default.pa`

The changes to this file will set up the Fe-Pi left and right channels and tell pulseaudio to use the NULL audio source (no input audio) and the Pi's built-in sound card for the audio sink (output) by default.

We will use environment variables PULSE_SOURCE and PULSE_SINK when starting Fldigi so that it'll use the Fe-Pi audio interface instead of NULL/built-in-audio-card.

Likewise, we'll specify the left and right virtual interfaces we create in default.pa below in direwolf.conf to point direwolf to the correct radio by referencing the virtual ALSA devices we created in the previous step.

Finally, we'll create the virtual interface system-audio-playback for use within Fldigi for alerts, notifications, and audio monitoring.

As sudo, make a backup of /etc/pulse/default.pa:

cd /etc/pulse 
sudo cp default.pa default.pa.original

As sudo, edit /etc/pulse/default.pa so it looks like the default.pa file in this repository.

2.6 Prevent `pulseaudio` from being the default sound interface

We don't want PulseAudio to be the default audio device. Why? Because we don't want applications that use audio to interfere with the operation of the ham radio applications.

IMPORTANT: I have noticed that when pulseaudio is updated as part of the normal Raspbian updates, /usr/share/alsa/pulse-alsa.conf may be overwritten. Please check this file whenever pulseaudio is updated and make sure that all lines are commented out as described below.

Make a copy of /usr/share/alsa/pulse-alsa.conf:

sudo cp /usr/share/alsa/pulse-alsa.conf /usr/share/alsa/pulse-alsa.conf.original

As sudo, edit /usr/share/alsa/pulse-alsa.conf and comment out all non-empty lines so it looks like this:

# This file is referred to by /usr/share/alsa/pulse.conf to set pulseaudio as
# the default output plugin for applications using alsa when PulseAudio is
# running.

#pcm.!default {
#    type pulse
#    hint {
#        show on
#        description "Playback/recording through the PulseAudio sound server"
#    }
#}

#ctl.!default {
#    type pulse
#}

2.7 Restart `pulseaudio`

For Debian Buster, pulseaudio runs as a user service:

Open a terminal, then run:
```
  systemctl --user restart pulseaudio 
```
For Debian Stretch, pulseaudio runs as a sytem service:

Open a terminal, then run:
```
  pulseaudio -k 
  pulseaudio --start --log-target=syslog
```

3. Scenarios

At this stage, pulseaudio is ready to use on either the left or the right radio or both at once.

Decide how you want to use your radios and Fldigi and Direwolf.
Determine where your radio(s) is/are connected (applies to the Nexus DR-X and DigiLink boards):
- The "Left" radio (uses GPIO 12 for PTT) is plugged in to the left 6-pin miniDIN or the RJ45 jack if configured.
- The "Right" radio (uses GPIO 23 for PTT) is plugged in to the right 6-pin miniDIN or the TRRS jack if configured.
Select your desired scenario from the Scenario sections that follow.

3.1 Scenario 1: I want to use only Fldigi with one radio.

3.1.1 Configure Fldigi (4.1.09 and later)

Open Fldigi, click Configure > Config Dialog. Select Soundcard > Devices.
Check PulseAudio and leave the Server String field empty.
Select Settings and select Converter Medium Sinc Interpolator (best for V/UHF - change as desired)
Select Right channel.
For "Right" connected radios: Check Reverse left/right channels under Transmit Usage and under Receive Usage.
For "Left" connected radios, leave these 2 boxes unchecked.
Select Rig Control > GPIO and set your GPIO to whatever your radio uses:
- "Left" radios: BCM 12, also check the corresponding '= 1 (on)' box
- "Right" radios: BCM 23, also check the corresponding '= 1 (on)' box
Click Save and Close.
Restart Fldigi.

3.1.2 Locate and edit your `fldigi.desktop` file

Open the /usr/local/share/applications/fldigi.desktop file in an editor (as sudo) and change the Exec= line as follows, then save the file and exit the editor:
```
 Exec=sh -c 'PULSE_SINK=fepi-playback PULSE_SOURCE=fepi-capture fldigi'
```
Reload the menu items. Run this command in a terminal (this step may not be necessary):
```
 lxpanelctl restart
```
[Re]start Fldigi from the menu.

3.2 Scenario 2: I want to use only Direwolf with one radio.

3.2.1 Configure Direwolf

In your direwolf.conf file (usually located in your home folder or in /etc), change the ADEVICE line to look like this:

ADEVICE fepi-capture-? fepi-playback-?

where ? = left or right depending on where your radio is plugged in to the Nexus DR-X/DigiLink.

Also change the PTT line to

PTT GPIO y

where y = 12 for the left radio or 23 for the right radio.

3.2.2 Restart Direwolf using whatever script you use to operate Direwolf.

3.3 Scenario 3: I want to run Fldigi on the {right or left} radio and Direwolf on the {left or right} radio at the same time.

Note that if Direwolf is on the Left radio, then Fldigi must be on the Right radio or vice-versa. Fldigi and Direwolf cannot both use the same radio at the same time.

3.3.1 Follow the directions in Scenarios 1 and 2.

3.4 Scenario 4: I want to run 2 Fldigi applications at the same time, one for a "Right" radio and one for a "Left" radio.

Attention Flmsg users: It is possible but somewhat complicated to run 2 instances of Flmsg, one associated with the left Fldigi and one with the right. I recommend keeping things as simple as possible: If you want to use Flmsg, make sure only one instance of Fldigi is running.

The Hampi image comes already set up to do run and Flmsg "Left" and Flmsg "Right" corresponding to Fldigi Left and Right.

3.4.1 Make copies of the Fldigi configuration folder.

Open a terminal, then run:

cd ~
cp -r .fldigi/ .fldigi-left/
cp -r .fldigi/ .fldigi-right/

3.4.2 Locate your `fldigi.desktop` file.

SECTION DELETED

3.4.3 Make new menu entries for each radio.

Example: Say your 2 radios are a Kenwood (on the left) and an Alinco (on the right), then run:

 cd /usr/local/share/applications/
 sudo cp fldigi.desktop fldigi-kenwood.desktop 
 sudo cp fldigi.desktop fldigi-alinco.desktop 
 sudo mv fldigi.desktop fldigi.desktop.disabled

Edit (as sudo) the fldigi-kenwood.desktop file, changing the Exec= and Name= lines as follows:

 Exec=sh -c 'PULSE_SINK=fepi-playback PULSE_SOURCE=fepi-capture fldigi --config-dir=$HOME/.fldigi-left -title "Kenwood fldigi"' 
 Name[en_US]=Fldigi - Kenwood

Edit (as sudo) the fldigi-alinco.desktop file, changing the Exec= and Name= lines as follows:

 Exec=sh -c 'PULSE_SINK=fepi-playback PULSE_SOURCE=fepi-capture fldigi --config-dir=$HOME/.fldigi-right -title "Alinco fldigi"' 
 Name[en_US]=Fldigi - Alinco

Reload the menu. Run this command in a terminal (this step may not be necessary):
```
 lxpanelctl restart
```

You should now see 2 Fldigi entries in your menu.

Run ONE (only run one at a time during setup!) of the new Fldigi menu items and set up the sound card and Rig control settings as described in Scenario 1. Close that instance of Fldigi and repeat for the second Fldigi menu item.
Now you can run both the Alinco and Kenwood Fldigis at the same time.

4. Adjust audio settings

4.1 Start `alsamixer`

Open a terminal and run:

alsamixer

Use the arrow keys to select the control. Notes on using alsamixer:

The default card reported by alsamixer should be the Pi's built-in card (bcm2835 ALSA).
Some controls are in stereo. The up and down arrows change the levels of both left channels (for the left radio) and right (for the right radio).

Pressing Q or E increases the left or right channel (radio) level respectively.

Pressing Z or C decreases the left or right channel (radio) level respectively.
Press F6 and select 1 Fe-Pi Audio from the list. For the Fe-Pi, these levels are good starting points:

Headphone: 00
Headphone Mux: DAC
Headphone Playback ZC: 00
PCM: 89 (left), 89 (right)
Lineout: 100 (left), 100 (right)
Mic: 0
Mic: 0
Capture: 13 (left), 13 (right)
Capture Attenuate Switch: 00
Capture Mux: LINE_IN
Capture ZC: 00
AVC: MM
AVC Hard Limiter: MM

Leave the remaining settings as-is.

You will want to open alsamixer while running Fldigi and/or direwolf and adjust these settings on the 1 Fe-Pi Audio device as needed:

Capture (for audio coming from the radio into the Pi - radio RX)
PCM (for audio coming from the Pi to the radio - radio TX)

Once you're happy with your audio settings, press Esc to exit alsamixer.
Save Audio Settings (usually not required)

These audio settings should save automatically, but for good measure you can store them again by running:
```
 sudo alsactl store
```
If you want to save different audio level settings for different scenarios, you can run this command to save the settings (choose your own file name/location):
```
 sudo alsactl --file ~/mysoundsettings1.state store
```
...and this command to restore those settings:
```
 sudo alsactl --file ~/mysoundsettings1.state restore
```

5. (Optional) Monitor Radio's TX and/or RX audio on Pi's Speakers

If you have speakers connected to the Pi, you can configure pulseaudio to monitor the audio to and/or from the radio

The Pi's built-in sound interface can output audio to the audio jack on the board. This is the Analog output. It can also send audio to HDMI-attached monitors that have built-in speakers. This is the HDMI output. To toggle between Analog and HDMI, right-click on the speaker icon on the menu bar. Move your mouse over Audio Outputs. Another menu should pop out showing Analog and HDMI. Select the one appropriate for your setup.

To adjust the level of the audio on your Pi's speakers, use the speaker's volume knob if it has one. The speaker icon in the upper right of the Pi desktop also controls the Pi's speaker volume.

Another way is to adjust the volume in alsamixer (0 bcm2835 ALSA device) or clicking the Raspberry icon on the desktop, select Preferences > Audio Device Settings. Select the bcm2835 ALSA sound card, and adjust the slider to your liking. You may have to click the Select Controls... button to enable the slider.

5.1 Control TX and/or RX monitoring control from the command line

These terminal commands will enable and disable monitoring of the radio's TX and RX on the Pi's speakers. None, one or both of these monitors can be run at the same time.

TX monitoring

  pactl load-module module-loopback source="fepi-playback.monitor" sink="system-audio-playback"

RX monitoring

  pactl load-module module-loopback source="fepi-capture" sink="system-audio-playback"

Stop all monitoring
```
  pactl unload-module module-loopback
```

Make sure your speakers are attached (Ananlog or HDMI) and your have Analog or HDMI output selected and the volume is set correctly.

5.2 (Optional) Make some menu items to control RX and TX monitoring

You can create menu items to control RX and TX monitoring by placing the above commands in a .desktop file. You may need to modify Categories= in the files described below depending on how you have your Raspberry Pi menus set up so that they appear in the correct top level menu.

Create (as sudo) a file called /usr/local/share/applications/radio-monitor-rx.desktop with this text:

[Desktop Entry]
Name=Start RX Monitor
GenericName=Amateur Radio Digital Modem
Comment=Amateur Radio Sound Card Communications
Exec=sh -c 'pactl load-module module-loopback source="fepi-capture" sink="system-audio-playback"'
Icon=fldigi
Terminal=false
Type=Application
Categories=HamRadio;
Path=$HOME

Create (as sudo) a file called /usr/local/share/applications/radio-monitor-tx.desktop with this text:

[Desktop Entry]
Name=Start TX Monitor
GenericName=Amateur Radio Digital Modem
Comment=Amateur Radio Sound Card Communications
Exec=sh -c 'pactl load-module module-loopback source="fepi-playback.monitor" sink="system-audio-playback"'
Icon=fldigi
Terminal=false
Type=Application
Categories=HamRadio;
Path=$HOME

Create (as sudo) a file called /usr/local/share/applications/radio-monitor-stop.desktop with this text:

[Desktop Entry]
Name=Stop TX and RX Monitors
GenericName=Amateur Radio Digital Modem
Comment=Amateur Radio Sound Card Communications
Exec=sh -c 'pactl unload-module module-loopback'
Icon=fldigi
Terminal=false
Type=Application
Categories=HamRadio;
Path=$HOME

Edit the placement of these menu items as desired using the Pi's Main Menu editor (Pi icon > Preferences > Main Menu Editor)

5.3 (Optional) Using Fldigi 4.1.09 (and later) Alerts, Notifications and RX Monitoring

Fldigi version 4.1.09 introduced the ability to control where alerts, notifications and monitoring audio is sent. Obviously, you don't want to send that audio to the radio so having the ability to control where it goes is important.

5.3.1 Fldigi Alerts

Note that Fldigi Alerts won't work for FSQ because it only looks in the signal browser for any text you specify in the alert.

The sound interface used for Alerts and RX Monitoring is set in Configure > Config Dialog > Soundcard > Devices.

In the Alerts/RX Audio section, select system-audio-playback and check Enable Audio Alerts. Click Save and Close.
In the left pane of the Fldigi configuration window, select Alerts to set up your alerts.

All alerts will now play through the Pi's built-in sound interface. Don't forget to select Analog or HDMI output as described earlier.

5.3.2 Fldigi Notifications

Unlike Alerts, Fldigi Notifications can look for text in Fldigi's Receive Messages pane. To set up an audio alert in Fldigi, open Configure > Notifications

Enter your search criteria.

Under Run Program, enter the following:

aplay -D system-audio-playback <path-to-WAV-file>

For example:

aplay -D system-audio-playback /usr/lib/libreoffice/share/gallery/sounds/untie.wav

This will send audio triggered by a Notification to the built-in audio interface. Don't forget to select Analog or HDMI output as described earlier.

You can also use paplay, the PulseAudio player, which can play OGG audio files in addition to WAV files. You can optionally tell paplay what audio sink to use. Example:

	paplay --device=system-audio-playback $HOME/fsq_ag7gn.ogg

Use this command list the audio formats paplay supports:

	paplay --list-file-formats

Both aplay and paplay are installed by default in Raspbian Buster.

5.3.3 Fldigi RX Monitoring

Fldigi has built-in audio monitoring capability. You can toggle RX monitoring on and off and apply filtering to the received audio by going View > Rx Audio Dialog. The audio will be played through the built-in audio interface. Don't forget to select Analog or HDMI output as described earlier.

Name		Name	Last commit message	Last commit date
Latest commit History 17 Commits
.local/share/applications		.local/share/applications
config/pulse		config/pulse
etc		etc
img		img
usr/share/alsa		usr/share/alsa
.gitattributes		.gitattributes
README.md		README.md
fe-pi.version		fe-pi.version
nexus-install		nexus-install

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HOWTO Use pulseaudio with a Fe-Pi Stereo Sound Card and Fldigi/Direwolf

1. Prerequisites

2. Configuration Procedure

2.0 Modify /boot/cmdline.txt

2.1 Install pulseaudio

2.2 Determine the sound card name

2.3 Back up any existing /etc/asound.conf file

2.4 Create/modify /etc/asound.conf

2.5 Modify /etc/pulse/default.pa

2.6 Prevent pulseaudio from being the default sound interface

2.7 Restart pulseaudio