pybluez-examples

Example Bluetooth tasks using the Python PyBluez module. Tested on Raspberry Pi 2 with CSR bluetooth 4.0 USB adapter & Bluez 5

Contents

• Prereqs
• Scanning for bluetooth devices from Python
• one-time pairing
• Notes
• to connect
• Errors
• Picking the Bluetooth speaker as default audio device
• References

Prereqs

apt install libbluetooth-dev bluez bluez-hcidump  libboost-python-dev libboost-thread-dev libglib2.0-dev

pip install pybluez gattlib

sudo adduser lp $(whoami)
sudo reboot

Scanning for bluetooth devices from Python

using pybluez:

python blueztools.py

If you get OSError: No such device you may not be finding your bluetooth adapter. Try enabling it via:

sudo hciconfig hci0 up

one-time pairing

optional commands commented out, with Bluez 5, we use the bluetoothctl agent:

#sudo hciconfig hci0 up   #enables bt on computer
#hcitool scan  # gets UUID of devices in pairing mode
#hcitool dev # get BT adapter uuid

bluetoothctl -a  #starts interactive prompt
scan on          #scans for UUID of device (BT and BLE) in pairing mode
pair uuid        # where "uuid" is what you found with scan
trust uuid
connect uuid    # after pairing, this is how you connect in the future

Notes

If you get the message "Creating device failed: org.bluez.Error.AuthenticationRejected: Authentication Rejected", then:

sudo nano /etc/bin/bluez-simple-agent

and change "KeyboardDisplay" to "DisplayYesNo" (thanks to http://www.wolfteck.com/projects/raspi/iphone/)

Also try:

bluez-test-device trusted <speaker uuid> yes

If connected but lacking sound try:

nano ~/.asoundrc

paste in:

pcm.btspkr {
   type plug
   slave {
       pcm {
           type bluetooth
           device "AA:BB:CC:DD:EE:FF"
           profile "auto"
       }
   }
   hint {
       show on
       description "BT Speaker"
   }
}
ctl.btspkr {
  type bluetooth
}

pcm.btspkr_softvol
{
   type softvol
   slave.pcm "btspkr"
   control.name "Bluetooth"
   control.card 0
}

# Using bluetooth as default :
pcm.!default {
    type plug
    slave.pcm "btspkr_softvol"
}

(thanks https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=570468)

to connect

(note, in ubuntu it disconnects after a second, maybe because system bluetooth menu is overriding with "off":

sudo hcitool cc <uuid>

Errors

Cannot open shared library /usr/lib/arm-linux-gnueabihf/alsa-lib/libasound_module_pcm_bluetooth.so:

sudo apt-get install bluez-alsa

bt_audio_service_open: connect() failed: Connection refused (111):

sudo nano /etc/bluetooth/audio.conf

paste in:

[general]
Enable=Sink,Source,Socket
Disable=Media

AutoConnect=true
SCORouting=PCM

then:

sudo service bluetooth restart

Picking the Bluetooth speaker as default audio device

First test it works with:

mpg321 -a bluetooth  myfile.mp3

or:

mplayer -ao alsa:device=bluetooth myfile.mp3

Then, list your audio ALSA devices with:

aplay -L

and you can use:

alsamixer

References

https://bitbucket.org/OscarAcena/pygattlib

https://wiki.archlinux.org/index.php/bluetooth_keyboard

https://github.com/oz123/dude/blob/master/bin/speakersswitcher.sh

http://blog.scphillips.com/2013/01/sound-configuration-on-raspberry-pi-with-alsa/

https://wiki.debian.org/Bluetooth/Alsa

http://www.raspberrypi.org/forums/viewtopic.php?f=63&t=92900

http://samtuke.com/2014/10/manually-pair-bluetooth-devices-on-linux-via-cli-nfc-workaround/

http://www.correderajorge.es/bluetooth-on-raspberry-audio-streaming/

http://www.ioncannon.net/linux/1570/bluetooth-4-0-le-on-raspberry-pi-with-bluez-5-x/

https://gist.github.com/dustywilson/8267078

http://www.correlatedcontent.com/blog/bluetooth-keyboard-on-the-raspberry-pi/