Introduction: Raspberry Pi Wireless Bluetooth Audio FM Radio Transmitter
Use your raspberry pi to wirelessly stream music directly from your phone to your radio! Fantastic to get music to your car stereo.
This instructable draws on information from two other instructables, and fills in the gaps to make them work together. All of the steps to complete your Wireless Bluetooth Audio FM Radio Transmitter will be listed here, but more (specific) information about each piece can be found in these instructables:
- Turn your Raspberry Pi into a Wireless Portable Bluetooth Audio System A2DP
- Raspberry Pi Radio Transmitter
Also many thanks to the Imperial College Robotics Society, for the pifm software.
Step 1: The Prerequisites
The parts (to make it work):
- Raspberry Pi with power supply (any model, but A+ or B+ are recommended)
- At least 2GB micro SD card with Raspian on it
- You'll need to burn the image to the SD card
- For windows, use a handy utility such as Win32DiskImager
- For mac, there's instructions here
- Bluetooth A2DP dongle (something like this)
- Antenna
- Just a length of wire will do (30cm - 75cm), attached to GPIO 4
The extra parts (needed only to complete the installation)
- Ethernet cable (and internet access)
- USB keyboard (or ssh)
- HDMI display and cable (or ssh)
Before you plug the SD card into your pi, plug it into your computer. Open up the drive, and find the config.txt file. Uncomment the following lines. This will allow us to force audio to be played through the HDMI output, rather than the stereo jack, which is necessary for the pi to stream music from bluetooth to the fm transmitter (without which you'd just get a loud, screechy noise on both the audio jack and on your radio).
hdmi_force_hotplug=1 hdmi_drive=2
Step 2: The Software
Plug the SD card (with OS image) into your pi, plug in the USB keyboard, the ethernet cable, connect it to the display, and power it up.
If it asks for login credentials, the default username is pi and the default password is raspberry.
Proceed with downloading the necessary software by executing the following commands:
sudo apt-get upgrade
sudo apt-get install bluez pulseaudio-module-bluetooth python-gobject python-gobject-2 bluez-tools sudo apt-get install sox libsox-fmt-all cd /home/pi; mkdir fm; cd fm wget http://www.icrobotics.co.uk/wiki/images/c/c3/Pifm.tar.gztar -zxvf Pifm.tar.gz
Step 3: The Configuration
Make the following modifications
Add our user pi to the Pulse audio group
sudo usermod –a –G lp pi
Audio configuration settings
sudo nano /etc/bluetooth/audio.conf
Add the following text under
[General]:
Enable=Source,Sink,Media,Socket
Pulse settings
sudo nano /etc/pulse/daemon.conf
Comment this line by adding a semicolon
; speex-float-3
Add these lines
resample-method = trivial
exit-idle-time = -1
Bluetooth configuration
sudo nano /etc/bluetooth/main.conf
Modify these lines to customize your bluetooth device name and class
Name = nameyourbluetoothdevicehere
Class = 0x20041C
Bluetooth configuration of your device
sudo nano /var/lib/bluetooth/<bluetooth mac address>/config
Modify these lines to customize your bluetooth device name and class
(Note, the class may reset on reboot. Don't worry too much about it)
name nameyourbluetoothdevicehere
class 0x20041C
Input rules
sudo nano /etc/udev/rules.d/99-input.rules
Add this line
KERNEL=="input[0-9]*", RUN+="/usr/lib/udev/bluetooth"
Device initialization (auto-login)
sudo nano /etc/inittab
Modify the following line to look like this
(was something like this) 1:2345:respawn:/sbin/getty --noclear 38400 tty1
1:2345:respawn:/bin/login -f pi tty1 </dev/tty1 >/dev/tty1 2>&1
== OPTIONAL ==
Increase the audio quality of the fm transmitter
sudo nano /home/pi/fm/pifm.c
Find and modify the following lines
QUALITY=15 SQUALITY=20
Then recompile
cd /home/pi/fm; mv pifm pifm_bak;
g++ -O3 -o pifm pifm.c
Step 4: The Scripts
Create the following scripts
sudo nano /usr/lib/udev/bluetooth Type this all into the empty editor, then save Note and adjust the radio frequency and volume to your preference #!/bin/bash AUDIOSINK="alsa_output.platform-bcm2835_AUD0.0.analog-stereo" ACTION=$(expr "$ACTION" : "\([a-zA-Z]\+\).*") echo "Executing bluetooth script...|$ACTION|" >> /var/log/bluetooth_dev if [ "$ACTION" = "add" ] then # Turn off BT discover mode before connecting existing BT device to audio hciconfig hci0 noscan # Turn off BT auto connect if it is still running sudo killall bluetooth-auto # set the audio output to the hdmi amixer cset numid=3 2 # Set volume level to 100 percent amixer set Master 100% # Set sink volume to 125% pacmd set-sink-volume 0 0x12500 for dev in $(find /sys/devices/virtual/input/ -name input*) do if [ -f "$dev/name" ] then mac=$(cat "$dev/name") # Add this mac address to list of trusted addresses TRUST=$(grep "$mac" /usr/lib/udev/bluetooth-trust) if [ -z "$TRUST" ] then echo "Adding $mac to trusted addresses" >> /var/log/bluetooth_dev echo $mac >> /usr/lib/udev/bluetooth-trust fi mac_underscore=$(cat "$dev/name" | sed 's/:/_/g') bluez_dev=bluez_source.$mac_underscore # Set source volume to 125% pacmd set-source-volume $bluez_dev 0x12500 sleep 1 CONFIRM=`sudo -u pi pactl list short | grep $bluez_dev` if [ ! -z "$CONFIRM" ] then echo "Setting bluez_source to: $bluez_dev" >> /var/log/bluetooth_dev echo pactl load-module module-loopback source=$bluez_dev sink=$AUDIOSINK rate=44100 adjust_time=0 >> /var/log/bluetooth_dev sudo -u pi pactl load-module module-loopback source=$bluez_dev sink=$AUDIOSINK rate=44100 adjust_time=0 >> /var/log/bluetooth_dev echo "Killing any existing radio connections" >> /var/log/bluetooth_dev sudo killall pifm >> /var/log/bluetooth_dev echo "Connecting bluetooth output to radio input, playing on 87.7" >> /var/log/bluetooth_dev # Using $AUDIOSINK instead of 0 here doesn't seem to work, not sure why echo pacat -r -d 0 --latency-msec=50 | sox -t raw -r 44100 -e signed-integer -b 16 -c 2 - -t wav - gain -l 10 | sudo /home/pi/fm/pifm - 87.9 44100 stereo >> /var/log/bluetooth_dev sudo -u pi pacat -r -d 0 --latency-msec=50 | sudo -u pi sox -t raw -r 44100 -e signed-integer -b 16 -c 2 - -t wav - gain -l 10 | sudo /home/pi/fm/pifm - 87.7 44100 stereo >> /var/log/bluetooth_dev fi fi done fi if [ "$ACTION" = "remove" ] then # Turn on bluetooth discovery if device disconnects sudo hciconfig hci0 piscan # Turn on bluetooth auto discovery sudo /usr/lib/udev/bluetooth-auto & fi Finally, grant appropriate permissions to the script sudo chmod 774 /usr/lib/udev/bluetooth
sudo nano /usr/lib/udev/bluetooth-auto Type this all into the empty editor, then save #!/bin/bash while [ true ] do sleep 1 echo "Scanning for trusted devices" >> /var/log/bluetooth_dev for mac in $(sudo hcitool scan | grep ":" | awk '{print $1}') do trust=$(grep "$mac" /usr/lib/udev/bluetooth-trust) if [ ! -z "$trust" ] then _BT_ADAPTER=`dbus-send --system --print-reply --dest=org.bluez / org.bluez.Manager.DefaultAdapter|awk '/object path/ {print $3}'` BT_ADAPTER=${_BT_ADAPTER//\"/} mac_underscore=$(cat "$mac" | sed 's/:/_/g') echo "Connecting to device at: $mac" >> /var/log/bluetooth_dev sudo dbus-send --print-reply --system --dest=org.bluez $BT_ADAPTER/dev_$mac_underscore org.bluez.AudioSource.Connect >> /var/log/bluetooth_dev exit 0 fi done done Finally, grant appropriate permissions to the script, and create the trust file sudo chmod 774 /usr/lib/udev/bluetooth-auto sudo touch /usr/lib/udev/bluetooth-trust
sudo nano /etc/init.d/bluetooth-agent Type this all into the empty editor, then save #!/bin/sh #/etc/init.d/bluetooth-agent ### BEGIN INIT INFO # Provides: bluetooth-agent # Required-Start: $remote_fs $syslog bluetooth pulseaudio # Required-Stop: $remote_fs $syslog # Default-Start: 2 3 4 5 # Default-Stop: 0 1 6 # Short-Description: Makes Bluetooth discoverable and connectable to 0000 # Description: Start Bluetooth-Agent at boot time. ### END INIT INFO USER=root HOME=/root export USER HOME case "$1" in start) echo "initializing pulseaudio" sudo pactl info echo "setting bluetooth discoverable" sudo hciconfig hci0 piscan start-stop-daemon -S -x /usr/bin/bluetooth-agent -c pi -b -- 0000 echo "bluetooth-agent started pw: 0000" sudo /usr/lib/udev/bluetooth-auto & echo "bluetooth-auto-discovery started" sudo /home/pi/fm/pifm /home/pi/fm/silence 87.7 44100 stereo echo "pifm started at 87.7, playing silence" ;; stop) echo "Stopping bluetooth-agent" start-stop-daemon -K -x /usr/bin/bluetooth-agent ;; *) echo "Usage: /etc/init.d/bluetooth-agent {start|stop}" exit 1 ;; esac exit 0 Finally, create the silence file, grant appropriate permissions to the script, and add it to the list of programs that run on startup sudo touch /home/pi/fm/silence sudo chmod 755 /etc/init.d/bluetooth-agent sudo update-rc.d bluetooth-agent defaults
Step 5: Enjoy
That's it. Restart your pi - either by just disconnecting and reconnecting the power supply, or by running the command:
sudo reboot
Disconnect the keyboard, display, and ethernet cable. You no longer need these.
You should see the pi as a bluetooth device to which you can connect. After connecting the first time, the pi will add your phone to its list of trusted devices. Each time the pi powers up, it will attempt to automatically connect to nearby trusted devices. Likewise, if you move out of bluetooth range, the pi will attempt to reconnect when you're back in range.
Begin playing music, send it to the pi, and tune your radio to your chosen frequency (default 87.7).