# Bluetooth

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Related articles

- Bluetooth mouse
- Bluetooth keyboard
- Bluetooth headset
- Blueman
- ObexFTP

Bluetooth is a standard for the short-range wireless interconnection of cellular phones, computers, and other electronic devices. In Linux, the canonical implementation of the Bluetooth protocol stack is BlueZ.

## Installation

1. Install the bluez package, providing the Bluetooth protocol stack.
2. Install the bluez-utils package, providing the `bluetoothctl` utility. Alternatively install bluez-utils-compatAUR to additionally have the deprecated BlueZ tools.
3. The generic Bluetooth driver is the `btusb` kernel module. Check whether that module is loaded. If it's not, then load the module.
4. Start/enable `bluetooth.service`.

Note:

- By default the bluetooth daemon will only give out bnep0 devices to users that are a member of the `lp` group. Make sure to add your user to that group if you intend to connect to a bluetooth tether. You can change the group that is required in the file `/usr/share/dbus-1/system.d/bluetooth.conf`.
- Some Bluetooth adapters are bundled with a Wi-Fi card (e.g. Intel Centrino). These require that the Wi-Fi card is firstly enabled (typically a keyboard shortcut on a laptop) in order to make the Bluetooth adapter visible to the kernel.
- Some Bluetooth cards (e.g. Broadcom) conflict with the network adapter. Thus, you need to make sure that your Bluetooth device gets connected before the network service boot.
- Some tools such as hcitool and hciconfig have been deprecated upstream, and are no longer included in bluez-utils. Since these tools will no longer be updated, it is recommended that scripts be updated to avoid using them. If you still desire to use them, install bluez-utils-compatAUR. See FS#53110 and the Bluez mailing list for more information.

### Front-ends

#### Console

- bluetoothctl — Pairing a device from the shell is one of the simplest and most reliable options.

  http://www.bluez.org/ || bluez-utils

Tip: To automate bluetoothctl commands, use `echo -e "command1\ncommand2\n" | bluetoothctl` or `bluetoothctl -- command`.

#### Graphical

The following packages allow for a graphical interface to customize Bluetooth.

- GNOME Bluetooth — GNOME's Bluetooth tool.
  - gnome-bluetooth provides the back-end
  - gnome-shell provides the status monitor applet
  - gnome-control-center provides the configuration front-end GUI that can be accessed by typing Bluetooth on the Activities overview, or with the `gnome-control-center bluetooth` command.
  - You can also launch the `bluetooth-sendto` command directly to send files to a remote device.
  - nautilus-bluetoothAUR adds a "Send via Bluetooth" entry to Nautilus' right-click menu
  - To receive files, open the Bluetooth settings panel; you can only receive whilst the Bluetooth panel is open.
  - To add a Bluetooth entry to the Send To menu in Thunar's file properties menu, see instructions here. (The command that needs to be configured is `bluetooth-sendto %F`).

  https://wiki.gnome.org/Projects/GnomeBluetooth ||

- Bluedevil — KDE's Bluetooth tool. If there is no Bluetooth icon visible in Dolphin and in the system tray, enable it in the system tray options or add a widget. You can configure Bluedevil and detect Bluetooth devices by clicking the icon. An interface is also available from the KDE System Settings.

  https://invent.kde.org/plasma/bluedevil || bluedevil

- Blueberry — Linux Mint's spin-off of GNOME Bluetooth, which works in all desktop environments. Blueberry does not support receiving files through Obex Object Push.

  https://github.com/linuxmint/blueberry || blueberry

- Blueman — A full featured Bluetooth manager.

  https://github.com/blueman-project/blueman || blueman

- ObexFTP — A tool for transferring files to/from any OBEX enabled device.

  http://dev.zuckschwerdt.org/openobex/wiki/ObexFtp || obexftpAUR

## Pairing

Note: Before using the bluetooth device, make sure that it is not blocked by rfkill.

This section describes directly configuring bluez5 via the bluetoothctl CLI, which might not be necessary if you are using an alternative front-end tool (such as GNOME Bluetooth).

The exact procedure depends on the devices involved and their input functionality. What follows is a general outline of pairing a device using `bluetoothctl`.

Start the `bluetoothctl` interactive command. Input `help` to get a list of available commands.

1. (optional) Select a default controller with `select MAC_address`.
2. Enter `power on` to turn the power to the controller on. It is off by default and will turn off again each reboot, see #Auto power-on after boot.
3. Enter `devices` to get the MAC Address of the device with which to pair.
4. Enter device discovery mode with `scan on` command if device is not yet on the list.
5. Turn the agent on with `agent on` or choose a specific agent: if you press tab twice after `agent` you should see a list of available agents. A bluetooth agent is what manages the Bluetooth 'pairing code'. It can either respond to a 'pairing code' coming in, or can send one out. The `default-agent` should be appropriate in most cases.[1]
6. Enter `pair MAC_address` to do the pairing (tab completion works).
7. If using a device without a PIN, one may need to manually trust the device before it can reconnect successfully. Enter `trust MAC_address` to do so.
8. Enter `connect MAC_address` to establish a connection.

An example session may look this way:

    # bluetoothctl

    [NEW] Controller 00:10:20:30:40:50 pi [default]

    [bluetooth]# agent KeyboardOnly

    Agent registered

    [bluetooth]# default-agent

    Default agent request successful

    [bluetooth]# power on

    Changing power on succeeded
    [CHG] Controller 00:10:20:30:40:50 Powered: yes

    [bluetooth]# scan on

    Discovery started
    [CHG] Controller 00:10:20:30:40:50 Discovering: yes
    [NEW] Device 00:12:34:56:78:90 myLino
    [CHG] Device 00:12:34:56:78:90 LegacyPairing: yes

    [bluetooth]# pair 00:12:34:56:78:90

    Attempting to pair with 00:12:34:56:78:90
    [CHG] Device 00:12:34:56:78:90 Connected: yes
    [CHG] Device 00:12:34:56:78:90 Connected: no
    [CHG] Device 00:12:34:56:78:90 Connected: yes
    Request PIN code
    [agent] Enter PIN code: 1234
    [CHG] Device 00:12:34:56:78:90 Paired: yes
    Pairing successful
    [CHG] Device 00:12:34:56:78:90 Connected: no

    [bluetooth]# connect 00:12:34:56:78:90

    Attempting to connect to 00:12:34:56:78:90
    [CHG] Device 00:12:34:56:78:90 Connected: yes
    Connection successful

### Dual boot pairing

To pair devices on dual boot setups you need to change the pairing keys manually on your Linux install, so that they match in both systems.

#### Setup

To do this, first pair your device on your Arch Linux install. Then reboot into the other OS and pair the device. Now you need to extract the pairing keys, but first switch off the bluetooth devices to prevent any connection attempts.

#### For Windows

This article or section is out of date.

Reason: In recent versions of Windows 10 (as of 2021) the link keys are no longer present in that location, and cannot be found anywhere else. (Discuss in Talk:Bluetooth#)
Note: If your Windows partition is encrypted with Bitlocker, you won't be able to access it from Linux using chntpw.

Reboot into Arch. Install chntpw. Mount your windows system drive.

    $ cd /path/to/windows/system/Windows/System32/config
    $ chntpw -e SYSTEM

Inside the `chntpw` environment, run

    > cd ControlSet001\Services\BTHPORT\Parameters\Keys

Note: Your path might start with `CurrentControlSet` on an older Windows install.

Then get your Bluetooth adapter's MAC address and enter its folder

    > ls
    > cd your-device's-mac-address

Do the same for your paired devices:

    > ls

    Node has 0 subkeys and 1 values
    size  type        value name    [value if type DWORD]
    16    REG_BINARY <123456789876>

Now get your device's key through `hex`:

    > hex 123456789876

    :00000 XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX (some other chars)

The "XX"s are the pairing key. Make note of which keys map to which MAC addresses.

In a BT5.1 Mouse, you might see this output:

    Node has 0 subkeys and 8 values
      size     type              value name             [value if type DWORD]
        16  3 REG_BINARY         <LTK>
         4  4 REG_DWORD          <KeyLength>               16 [0x10]
         8  b REG_QWORD          <ERand>
         4  4 REG_DWORD          <EDIV>                 37520 [0x9290]
        16  3 REG_BINARY         <IRK>
         8  b REG_QWORD          <Address>
         4  4 REG_DWORD          <AddressType>              1 [0x1]
         4  4 REG_DWORD          <AuthReq>                 45 [0x2d]

We need the `LTK`, `ERand`, and `EDIV` values. `LTK` corrsponds to `LongTermKey.Key`, `ERand` to `Rand`, `EDIV` to `EDiv`. The `ERand` value shound be reversed and converted to decimal. For example:

    > hex LTK
    Value <LTK> of type REG_BINARY (3), data length 16 [0x10]
    :00000  48 4D AF CD 0F 92 22 88 0A 52 9A F4 76 DA 8B 94 HM...."..R..v...
    > hex ERand
    Value <ERand> of type REG_QWORD (b), data length 8 [0x8]
    :00000  63 02 84 B8 5D 40 44 DF                         c...]@D.

Then `LTK` should be `484DAFCD0F9222880A529AF476DA8B94`, `Rand` shound be `16088054540146049635`. `EDiv` should be `37520`.

Note: You can use this python script to do the converting:

    >>> ERand=' 63 02 84 B8 5D 40 44 DF   '
    >>> ERand=list(reversed(ERand.strip().split()))
    >>> int("".join(ERand), 16)
    16088054540146049635

#### For macOS

Boot into macOS, then open a terminal.

- If you are on Sierra or older, run

    $ sudo defaults read /private/var/root/Library/Preferences/blued.plist LinkKeys > ~/bt_keys.txt

- If you are on High Sierra or newer, run

    $ sudo defaults read /private/var/root/Library/Preferences/com.apple.bluetoothd.plist LinkKeys > ~/bt_keys.txt

Copy the `bt_keys.txt` file to a drive that can be read from Arch Linux. Reboot into Arch Linux.

#### Finishing up

Now that you have the keys change user to root, then continue with:

    # cd /var/lib/bluetooth/BT-Adapter-MAC-address

Here you will find folders for each paired bluetooth device. For each device you want to pair with Arch and your dual boot, do the following:

    # cd device-MAC-address

Edit the `info` file and change the key under `[LinkKey]`. E.g.:

    info

    [LinkKey]
    Key=XXXXXXXXXXXXXXX

Note: You will have to make sure that all the letters are in capital case. Remove any spaces.
Note: For older versions of macOS (High Sierra and older) you will have to reverse the key like so:

`98 54 2f aa bb cc dd ee ff gg hh ii jj kk ll mm` becomes `MM LL KK JJ GG FF EE DD CC BB AA 2F 54 98`.

This reversal is not necessary for newer versions of macOS.

Then restart `bluetooth.service` and `pulseaudio` (with `pulseaudio -k && pulseaudio --start`).

You should be able to connect to your device now.

Note: Depending on your bluetooth manager, you may need to perform a full reboot in order to reconnect to the device.

## Configuration

### Auto power-on after boot

By default, the Bluetooth adapter does not power on after a reboot, you need to add the line `AutoEnable=true` in the configuration file `/etc/bluetooth/main.conf` at the bottom in the `[Policy]` section:

    /etc/bluetooth/main.conf

    [Policy]
    AutoEnable=true

### Discoverable on startup

If the device should always be visible and directly connectable:

    /etc/bluetooth/main.conf

    [General]
    DiscoverableTimeout = 0

## Audio

You will typically need to take an additional step to integrate the audio server with bluetooth. This is detailed in the below sections.

See the Bluetooth headset page for more information about bluetooth audio and bluetooth headsets.

### PulseAudio

In order to be able to use audio equipment like bluetooth headphones or speakers, you need to install the additional pulseaudio-bluetooth package. Make sure to restart pulseaudio to make the installation take effect: `pulseaudio -k`. With a default PulseAudio installation you should immediately be able to stream audio from a bluetooth device to your speakers.

If you have a system-wide PulseAudio setup make sure the user running the daemon (usually `pulse`) is in the `lp` group and you load the bluetooth modules in your PulseAudio config:

    /etc/pulse/system.pa

    ...
    load-module module-bluetooth-policy
    load-module module-bluetooth-discover
    ...

### PipeWire

PipeWire as of v0.3.19 enables its Bluetooth support by default, see bluetooth.

### ALSA

Note: Bluez5 has dropped direct integration for ALSA and supports PulseAudio only. Follow the instructions below if you cannot or do not want to use PulseAudio.

First, ensure that your bluetooth audio device is correctly paired and connected to the system.

Then, install bluez-alsa-gitAUR, start (and enable) the `bluealsa` service, and add your user to the `audio` group.

Run the following command to check if everything is working as intended (replace `XX:XX:XX:XX:XX:XX` and `FILE.wav` below):

    $ aplay -D bluealsa:SRV=org.bluealsa,DEV=XX:XX:XX:XX:XX:XX,PROFILE=a2dp FILE.wav

Finally, add the following lines to your `~/.asoundrc`:

    ~/.asoundrc

    defaults.bluealsa {
        service "org.bluealsa"
        device "XX:XX:XX:XX:XX:XX"
        profile "a2dp"
    }

You can now use the `bluealsa` device to reach your bluetooth audio device. Volume management is conducted normally via `alsamixer` with the option `-D bluealsa`.

## Bluetooth serial

To get bluetooth serial communication working on Bluetooth-to-Serial modules (HC-05, HC-06) do the following steps:

Pair your bluetooth device using `bluetoothctl` as described above.

Install bluez-rfcommAUR and bluez-utils-compatAUR, as they provide certain functionality which is missing from newer tools.

Bind paired device MAC address to tty terminal:

    # rfcomm bind rfcomm0 MAC_address_of_bluetooth_device

Now you can open `/dev/rfcomm0` for serial communication:

    picocom /dev/rfcomm0 -b 115200

## Troubleshooting

This article or section is out of date.

Reason: Replace hciconfig with newer commands. (Discuss in Talk:Bluetooth#)

### Debugging

In order to debug, first stop `bluetooth.service`.

And then start it with the `-d` parameter:

    # /usr/lib/bluetooth/bluetoothd -n -d

Another option is via the `btmon` tool.

### Deprecated BlueZ tools

Eight BlueZ tools were deprecated and removed from bluez-utils, although not all of them were superseded by newer tools. The bluez-utils-compatAUR package provides an alternative version of bluez-utils with the deprecated tools.

Deprecated tool | Most likely replacement
--- | ---
gatttool | btgatt-client, D-Bus Gatt API
hciattach | btattach
hciconfig | btmgmt (and bluetoothctl?)
hcidump | btmon (and btsnoop)
hcitool | missing, D-Bus Device API available
rfcomm | missing, implement with D-Bus Profile1 API?
ciptool
sdptool | missing, functionality seems to be scattered over different D-Bus objects: Profile, Advertising, and the UUIDs arrays in device and adapter.

### gnome-bluetooth

If you see this when trying to enable receiving files in bluetooth-properties:

    Bluetooth OBEX start failed: Invalid path
    Bluetooth FTP start failed: Invalid path

Then make sure that the XDG user directories exist.

### Bluetooth USB Dongle

If you are using a USB dongle, you should check that your Bluetooth dongle is recognized. You can do that by running `journalctl -f` as root when you have plugged in the USB dongle (or inspecting `/var/log/messages.log`). It should look something like the following (look out for hci):

    Feb 20 15:00:24 hostname kernel: [ 2661.349823] usb 4-1: new full-speed USB device number 3 using uhci_hcd
    Feb 20 15:00:24 hostname bluetoothd[4568]: HCI dev 0 registered
    Feb 20 15:00:24 hostname bluetoothd[4568]: Listening for HCI events on hci0
    Feb 20 15:00:25 hostname bluetoothd[4568]: HCI dev 0 up
    Feb 20 15:00:25 hostname bluetoothd[4568]: Adapter /org/bluez/4568/hci0 has been enabled

If you only get the first two lines, you may see that it found the device but you need to bring it up. Example:

    # btmgmt

    [mgmt]# info

    Index list with 1 item
    hci0:	Primary controller
    	addr 00:1A:7D:DA:71:10 version 6 manufacturer 10 class 0x000000
    	supported settings: powered connectable fast-connectable discoverable bondable link-security ssp br/edr hs le advertising secure-conn debug-keys privacy static-addr
    	current settings: connectable discoverable bondable ssp br/edr le secure-conn
    	name Mozart
    	short name

    [mgmt]# select hci0

    Selected index 0

    [hci0]# power up

    hci0 Set Powered complete, settings: powered connectable discoverable bondable ssp br/edr le secure-conn

    [hci0]# info

    hci0:	Primary controller
    	addr 00:1A:7D:DA:71:10 version 6 manufacturer 10 class 0x1c0104
    	supported settings: powered connectable fast-connectable discoverable bondable link-security ssp br/edr hs le advertising secure-conn debug-keys privacy static-addr
    	current settings: powered connectable discoverable bondable ssp br/edr le secure-conn

Or

    # bluetoothctl

    [bluetooth]# show

    Controller 00:1A:7D:DA:71:10 (public)
    	Name: Mozart
    	Alias: Mozart
    	Class: 0x0000095c
    	Powered: no
    	Discoverable: yes
    	Pairable: yes

    [bluetooth]# power on

    [CHG] Controller 00:1A:7D:DA:71:10 Class: 0x001c0104
    Changing power on succeeded
    [CHG] Controller 00:1A:7D:DA:71:10 Powered: yes

    [bluetooth]# show

    Controller 00:1A:7D:DA:71:10 (public)
    	Name: Mozart
    	Alias: Mozart
    	Class: 0x001c0104
    	Powered: yes
    	Discoverable: yes
    	Pairable: yes

To verify that the device was detected you can use `btmgmt` which is part of the `bluez-utils`. You can get a list of available devices and their identifiers and their MAC address by issuing:

    $ btmgmt info

    Index list with 1 item
    hci0:	Primary controller
    	addr 00:1A:7D:DA:71:10 version 6 manufacturer 10 class 0x1c0104
    	supported settings: powered connectable fast-connectable discoverable bondable link-security ssp br/edr hs le advertising secure-conn debug-keys privacy static-addr
    	current settings: powered connectable discoverable bondable ssp br/edr le secure-conn

It is possible to check the Bluetooth version as mapped to the HCI version according to the table in the official specification. For example, in the previous output, HCI version 6 is Bluetooth version 4.0.

More detailed information about the device can be retrieved by using the deprecated `hciconfig`. (bluez-utils-compatAUR)

    $ hciconfig -a hci0

    hci0:   Type: USB
            BD Address: 00:1B:DC:0F:DB:40 ACL MTU: 310:10 SCO MTU: 64:8
            UP RUNNING PSCAN ISCAN
            RX bytes:1226 acl:0 sco:0 events:27 errors:0
            TX bytes:351 acl:0 sco:0 commands:26 errors:0
            Features: 0xff 0xff 0x8f 0xfe 0x9b 0xf9 0x00 0x80
            Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3
            Link policy: RSWITCH HOLD SNIFF PARK
            Link mode: SLAVE ACCEPT
            Name: 'BlueZ (0)'
            Class: 0x000100
            Service Classes: Unspecified
            Device Class: Computer, Uncategorized
            HCI Ver: 2.0 (0x3) HCI Rev: 0xc5c LMP Ver: 2.0 (0x3) LMP Subver: 0xc5c
            Manufacturer: Cambridge Silicon Radio (10)

#### Audio devices start to skip at short distance from dongle

If other devices share the same USB host, they can interrupt communication with audio devices. Make sure it is the only device attached to its bus. For example:

    $ lsusb

    Bus 002 Device 002: ID 0a12:0001 Cambridge Silicon Radio, Ltd Bluetooth Dongle (HCI mode)
    Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
    Bus 001 Device 004: ID 048d:1345 Integrated Technology Express, Inc. Multi Cardreader
    Bus 001 Device 003: ID 0424:a700 Standard Microsystems Corp. 2 Port Hub
    Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
    Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

#### CSR Dongle 0a12:0001

The device `ID 0a12:0001 Cambridge Silicon Radio, Ltd Bluetooth Dongle (HCI mode)` has a regression bug, and currently only works in the kernel version ≤ 3.9.11. There is a patch available for newer versions. For more information, see Kernel Bug 60824.

### Logitech Bluetooth USB Dongle

There are Logitech dongles (ex. Logitech MX5000) that can work in two modes: Embedded and HCI. In embedded mode dongle emulates a USB device so it seems to your PC that you are using a normal USB mouse/keyoard.

If you hold the little red Button on the USB BT mini-receiver it will enable the other mode. Hold the red button on the BT dongle and plug it into the computer, and after 3-5 seconds of holding the button, the Bluetooth icon will appear in the system tray. Discussion

Alternatively, you can install the bluez-hid2hci package. When you connect your Logitech dongle it will automatically switch.

### hcitool scan: Device not found

- On some laptops (e.g. Dell Studio 15, Lenovo Thinkpad X1) you have to switch the Bluetooth mode from HID to HCI. Install the bluez-hid2hci package, then udev should do this automatically. Alternatively, you can run this command to switch to HCI manually:

    # /usr/lib/udev/hid2hci

- If the device will not show up and you have a Windows operating system on your machine, try booting it and enable the bluetooth adapter from windows.

- Sometimes also this simple command helps:

    # bluetoothctl power on

### bluetoothctl: No default controller available

This error may happen if the device is blocked by rfkill.

It might also happen with some intel cards (such as the 8260) to not be picked up correctly by the bluetooth service. In some cases, using the deprecated bluez-utils-compatAUR in lieu of bluez-utils have reportedly fixed the issue.

This might also be caused by power saving measures, in which case adding the kernel parameter `btusb.enable_autosuspend=n` is a potential solution. See also Red Hat Bugzilla – Bug 1573562.

### systemd: Condition check resulted in Bluetooth service being skipped

`bluetooth.service` only requires the directory `/sys/class/bluetooth` to exist, which should be created by kernel module `bluetooth`, which is only autoloaded by `systemd-udev` if it actually finds a working bluetooth hardware device.

If your `/sys/class/bluetooth` does not exist, check if your kernel bluetooth module is loaded by `lsmod`. If not, and you believe you have a bluetooth device, you can try manually starting them by loading the bluetooth module and restarting `bluetooth.service`.

You should also load your corresponding kernel bluetooth driver when loading the `bluetooth` module, most likely `btusb`, but can also be `btrtl,btintel,btbcm,bnep,btusb` etc.

Check `bluetooth.service`'s unit status to see whether it started.

See also Debian Bug report logs - #853207.

If `bluetooth.service` started successfully, but there is chance that you still cannot use bluetooth normally (e.g. `bluetoothctl` says something like `org.Bluez.Error.NotReady` when you `scan on`). If this happens, try rebooting your computer, and double-check: whether directory `/sys/class/bluetooth` exists; whether `lsmod` includes correct bluetooth modules; log messages in the journal; etc. `systemd-udev` should pickup your bluetooth hardware automatically without manual changes again.

### rfkill unblock: Do not unblock

If your device still soft blocked and you run ConnMan, try this:

    $ connmanctl enable bluetooth

### Computer is not visible

Enable discoverable mode if your computer cannot be discovered from your phone:

    # bluetoothctl discoverable on

Verify that discoverable mode is on:

    # bluetoothctl show

    	Powered: yes
    	Discoverable: yes
    	Pairable: yes

Note: Check `DiscoverableTimeout` and `PairableTimeout` in `/etc/bluetooth/main.conf`.

If the computer still does not show up, try changing the device class in `/etc/bluetooth/main.conf` as follows:

    # Default device class. Only the major and minor device class bits are
    # considered.
    #Class = 0x000100 # Computer Type (from default config)
    Class = 0x100100 # (Object-Transfer Service & Computer Type)

Note: In some cases, `Class` in `main.conf` gets overridden after device initialization, so set the class directly with `hciconfig hci0 class 100100`.

A user reported that this was the only solution to make their computer visible for their phone. LG TVs (and some others) are discoverable from their audio devices, so using `000414` (the soundbar class) will make such devices appear.

See https://bluetooth-pentest.narod.ru/software/bluetooth_class_of_device-service_generator.html to generate Bluetooth device/service classes.

### Logitech keyboard does not pair

If you do not get the passkey when you try to pair your Logitech keyboard, type the following command:

    # btmgmt ssp off

If after pairing, the keyboard still does not connect, check the output of `hcidump -at`. If the latter indicates repeatedly connections-disconnections like the following message:

       status 0x00 handle 11 reason 0x13
       Reason: Remote User Terminated Connection

then, the only solution for now is to install the old Bluetooth stack[archived page].

### Foxconn / Hon Hai / Lite-On Broadcom device

Some of these devices require the firmware to be flashed into the device at boot. The firmware is not provided but can converted from a Microsoft Windows .hex file into a .hcd using hex2hcd (which is installed with bluez-utils).

In order to get the right .hex file, try searching the device vendor:product code obtained with lsusb, for example:

    ...
    Bus 002 Device 004: ID 04ca:2006 Lite-On Technology Corp. Broadcom BCM43142A0 Bluetooth Device
    ...

or

    Bus 004 Device 004: Id 0489:e031 Foxconn / Hon Hai

Alternatively, boot into Windows (a virtual machine installation will suffice) and get the firmware name from the Device Manager utility. If you want to know the model of your device but cannot see it in lsusb, you might see it in lsusb -v as `iProduct`.

The .hex file can be extracted from the downloaded Windows driver without having to run Windows for it. Download the right driver, for example Bluetooth Widcomm (listed among the drivers for Lifebook P771), which contains the drivers for many Broadcomm devices. In case of Bluetooth Widcomm, the driver is a self-extracting RAR archive, so it can be extracted using unrar x. To find out which of the many .hex files is the right one for you, look in the file `Win32/bcbtums-win7x86-brcm.inf` and search for `[RAMUSBE031.CopyList]`, where `E031` should be replaced with the product code (the second hex number in lsusb) of your device in upper-case. Underneath you should see the file name of the right .hex file.

Once you have the .hcd file, copy it into `/lib/firmware/brcm/BCM.hcd` - this filename is suggested by dmesg and it may change in your case so check your dmesg output in order to verify. Then reload the btusb module:

    # rmmod btusb
    # modprobe btusb

The device should now be available. See BBS#162688 for information on making these changes persistent.

### Intel combined wifi and bluetooth cards

See Wireless network configuration#Bluetooth coexistence.

### Device connects, then disconnects after a few moments

If you see messages like the following in the journal, and your device fails to connect or disconnects shortly after connecting:

    bluetoothd: Unable to get connect data for Headset Voice gateway: getpeername: Transport endpoint is not connected (107)
    bluetoothd: connect error: Connection refused (111)

This may be because you have already paired the device with another operating system using the same bluetooth adapter (e.g., dual-booting). Some devices cannot handle multiple pairings associated with the same MAC address (i.e., bluetooth adapters). Follow instructions on #Dual boot pairing for solving this issue.

### Device does not connect with an error in journal

If you see a message like the following in the journal while trying to connect to a device:

    a2dp-source profile connect failed for 9C:64:40:22:E1:3F: Protocol not available

try installing pulseaudio-bluetooth and restarting PulseAudio. This error can manifest even while using only file transfer.

### Device does not show up in scan

Some devices using bluetooth low energy do not appear when scanning with bluetoothctl, for example the Logitech MX Master. The simplest way I have found to connect them is by installing bluez-utils-compatAUR, then start `bluetooth.service` and do:

    # bluetoothctl

    [NEW] Controller (MAC) myhostname [default]

    [bluetooth]# power on

    [CHG] Controller (MAC) Class: 0x0c010c
    Changing power on succeeded
    [CHG] Controller (MAC) Powered: yes

    [bluetooth]# scan on

    Discovery started
    [CHG] Controller (MAC) Discovering: yes

In another terminal:

    # hcitool lescan

Wait until your device shows up, then `Ctrl+c` hcitool. bluetoothctl should now see your device and pair normally.

### Cannot receive transferred files due to symlink

If incoming file transfers fail on an an otherwise functional bluetooth connection, the problem may be due to symlinks in your file transfer path. Logs like this would appear in the journal:

    Jun 18 11:18:13 ember obexd[3338969]: open(/home/me/.cache/obexd/MOC740): Operation not permitted (1)

If the path shown in the error message contains a symlink, then obexd by default will not accept it. The behavior can be overridden on initialization using a drop-in file for the `obex.service` user service:

    ~/.config/systemd/user/obex.service.d/10-symlink.conf

    [Service]
    ExecStart=
    ExecStart=/usr/lib/bluetooth/obexd --symlinks

Then reload the systemd manager configuration of the calling user and restart the `obex.service` user unit.

### Interference between Headphones and Mouse

If you experience audio stuttering while using a bluetooth mouse and keyboard simultaneously, you can try the following as referenced in #23 https://bugs.launchpad.net/ubuntu/+source/bluez/+bug/424215

    # hciconfig hci0 lm ACCEPT,MASTER
    # hciconfig hci0 lp HOLD,SNIFF,PARK

### Bluetooth mouse laggy movements

Try edit the file `/var/lib/bluetooth/XX:XX:XX:XX:XX:XX/YY:YY:YY:YY:YY:YY/info` (`XX:XX:XX:XX:XX:XX` - your Bluetooth adapter MAC-address, `YY:YY:YY:YY:YY:YY` - your mouse MAC-address) and add those lines:

    [ConnectionParameters]
    MinInterval=6
    MaxInterval=9
    Latency=44
    Timeout=216

You can see your local adapter MAC address by running command `hcitool dev`, your can see MAC addresses of currently connected remote devices by running command `hcitool con`

### Adapter disappears after suspend/resume

First, find vendor and product ID of the adapter. For example:

    $ lsusb -tv

    /:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/12p, 480M
        ID 1d6b:0002 Linux Foundation 2.0 root hub
        ...
        |__ Port 3: Dev 3, If 0, Class=Wireless, Driver=btusb, 12M
            ID 8087:0025 Intel Corp.
        |__ Port 3: Dev 3, If 1, Class=Wireless, Driver=btusb, 12M
            ID 8087:0025 Intel Corp.
        ...

In this case, the vendor ID is 8087 and the product ID is 0025.

Then, use usb_modeswitch to reset the adapter:

    # usb_modeswitch -R -v vendor_ID -p product_ID

### Problems with all BLE devices on kernel 5.9+

Starting with v5.9, the kernel Bluetooth stack tries to use link-layer privacy on BLE connections. If the device works after pairing but does not survive a reboot or suspend, it is probably because of this.

To workaround [2] this issue, open `/var/lib/bluetooth/adapter_mac/device_mac/info`, remove the following lines, and restart `bluetooth.service`:

    [IdentityResolvingKey]
    Key=...

See the relevant discussion on the Arch forum.

### Problems with some Bluetooth drivers in kernel 5.10

This section is being considered for removal.

Reason: The issue is supposedly fixed. (Discuss in Talk:Bluetooth#)

Starting with v5.10, some Qualcomm Atheros bluetooth chipset drivers have stopped working with the following error:

    # journalctl --grep=hci0

    Feb 22 18:40:24 user kernel: Bluetooth: hci0: do not support firmware rome 0x31010000

See the relevant bug report on the Linux.org Bugzilla.

You can either rebuild the modules with the applied patches (btusb-210681-fix), or use an old (5.9.x) kernel. This bug was fixed in linux 5.11.arch2-1.

Category:

- Bluetooth

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