pybluez-examples

Example Bluetooth tasks using the Python PyBluez module. Tested using BlueZ 5 with Python 2.7 and:

Raspberry Pi 2 with CSR bluetooth 4.0 USB adapter
Raspberry Pi 3 (on-board Bluetooth)
laptop with Ubuntu 18.04 / 16.04

Contents

Prereqs
Scan for bluetooth devices from Python
Non-Python Bluetooth examples
- Bluetooth pairing
Notes
Bluetooth connect
Errors
Set Bluetooth speaker as default audio device
References

Prereqs

Note that we use system Python 2.7 for ease of library install (even on Ubuntu 18.04). If you have Anaconda/Miniconda, you can alternatively use conda-forge libraries.

from Terminal:

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

adduser lp $(whoami)

setup Python code:
```
/usr/bin/python2.7 -m pip install -e .
```
check that your Bluetooth devices are not blocked (should say "no"):
```
rfkill list
```

Scan for bluetooth devices from Python

/usr/bin/python2.7 bluetooth_scan.py

If no Bluetooth devices found in the PyBluez device scan, try each of the following:

hcitool scan

and:

bluetoothctl

scan on

If the second way finds devcies but not the first, you may have a chipset issue. I have noted this with Marvell hardware on Ubuntu 18.04. I did not look into a resolve for this, as I usually use other hardware.

If you get error

OSError: No such device

check that there is a Bluetooth adapter available:

hciconfig dev

The bluetooth adapter may need to be enabled:

hciconfig hci0 up

Non-Python Bluetooth examples

These example use Bluez directly from Terminal (without Python)

Bluetooth pairing

using Bluez5 bluetoothctl agent:

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

bluetoothctl       # 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 error

Creating device failed: org.bluez.Error.AuthenticationRejected: Authentication Rejected

then edit /etc/bin/bluez-simple-agent, changing "KeyboardDisplay" to "DisplayYesNo"

Also try:

bluez-test-device trusted <speaker uuid> yes

If connected but lacking sound, try editing ~/.asoundrc, pasting 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"
}

Bluetooth connect

hcitool cc <uuid>

I sometimes saw in Ubuntu that it disconnects after a second, maybe because system bluetooth menu is overriding with "off"?

Errors

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

apt install bluez-alsa

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

edit /etc/bluetooth/audio.conf, pasting in:

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

AutoConnect=true
SCORouting=PCM

then:
```
service bluetooth restart
```

Set 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/

pablocarle/pybluez-examples

pybluez-examples