Paring and Using Bluetooth Devices on Arch Linux

Taha Azzaoui - 2018.10.30

Intro

Bluetooth is one of those things that’s always been a pain to set up in Linux. This is partly because of the Bluetooth stack and how it interacts with the kernel. The architecture is essentially split between user and kernel space, where the kernel takes care of things like low level protocols (RFCOMM), security, and hardware drivers leaving the central daemon, blutoothd and command line agent bluetoothctl up in user space. For more on how this it works, check out the source code here: https://github.com/torvalds/linux/tree/master/drivers/bluetooth

Getting the client

  1. Since BlueZ is the de facto Bluetooth protocol stack in Linux, we’ll start by grabbing that

    sudo pacman -S bluez bluez-utils

  2. Next, we’ll need a Bluetooth client. Blueman is pretty minimal and easy to use, so we’ll go with that

    sudo pacman -S blueman

Kernel Support

I’m assuming we’re configuring Bluetooth on a laptop with a built in radio. In this case, the driver should be automatically loaded. In case you’re using a USB Bluetooth dongle, you can manually load the driver as follows:

sudo modprobe btusb

Configuring the Client

  1. Start the Bluetooth service

    sudo systemctl start bluetooth.service

    Note that if you wish to start the service on boot up, you can enable it as well

    sudo systemctl enable bluetooth.service

  2. Start the client

    bluetoothctl

    You’ll then be greeted with a prompt. We’ll interact with it as follows

    [bluetooth]# power on

    [bluetooth]# agent on

    [bluetooth]# default-agent

    Now we’ll scan for a device. Be sure to put your Bluetooth device in pairing mode.

    [bluetooth]# scan on

    Output: [NEW] Device 00:18:09:9B:A1:DD MDR-XB650BT

    Now copy the MAC Address of the device and pair with it as follows

    [bluetooth]# pair 00:18:09:9B:A1:DD

    Once we’re paired with the device, we can connect to it like so

    [bluetooth]# connect 00:1D:43:6D:03:26

    Once we’re connected, we can turn off scanning mode and quit the program

    [bluetooth]# scan off

    [bluetooth]# exit

A Note on Sound Quality

Many people complain about poor sound quality when using Bluetooth headsets. This is usually a problem with high fidelity playback. To solve this problem simply switch to A2DP instead as follows

List the audio cards on your system

pacmd list-cards

Make note of the card number of your Bluetooth device and substitute it in the command below to make the switch

pacmd set-card-profile <card #> a2dpsink

Finally, make sure the device is recognized

pacmd set-sink-volume 0 0