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=How To Build a Raspberry Pi Bluetooth Speaker=
=How To Build a Raspberry Pi Bluetooth Speaker=


This articles describes how to build a Bluetooth speaker. This article is being actively written.
This articles describes how to build a Bluetooth speaker. This article is being actively written. Currently it is full of bugs but will provide some useful pointers.


=Before You Start=
=Before You Start=
Line 7: Line 7:
* A Raspberry Pi
* A Raspberry Pi
* A Bluetooth USB dongle (if your Pi doesn’t have Bluetooth on board)
* A Bluetooth USB dongle (if your Pi doesn’t have Bluetooth on board)
* An active speaker or sound card and passive speaker(s)
* Sound card and speaker(s)
 
=Article Completion=
# Test everything
# Turn every background task into a service
# More investigation on Bluetooth pairing


=Getting the Speaker(s) Working=
=Getting the Speaker(s) Working=
The audio hardware can range from using the Raspberry Pi's on board audio with an external (active) travel speaker to wiring up an amplifier to some high-end passive speakers.
To get the best results, you'll need an dedicated audio add-on board and matching speakers. Higher end passive speakers need a proper amplifier (e.g. HiFiBerry Amp2 or IQaudIO IQaudIO DigiAMP+).
 
I've used the whole range of IQaudio audio boards with different speakers and headphones. I'd also recommend a dedicated USB Bluetooth dongle (don't get the cheapest versions of these). It is possible to test by using the on-board Bluetooth and the on-board audio with headphones but because of dropped packets, the audio quality isn't great.
 
Once the speakers and audio card are connected to the Raspberry Pi, it's time to install a fresh version of Alpine Linux.  The armv7 version from the [https://alpinelinux.org/downloads/ Downloads] page works on almost all Pis. This Wiki has several articles about installing Alpine on a Raspberry Pi.
 
Enable writing to the boot media:
 
  mount /media/mmcblk0p1 -o rw,remount
 
Then, either enable the on board sound:
 
  echo "dtparam=audio=on" >> /media/mmcblk0p1/usercfg.txt
 
or your sound card (e.g. IQaudIO):
 
  echo "dtoverlay=iqaudio-dacplus,unmute_amp" >> /media/mmcblk0p1/usercfg.txt
 
reboot.
 
Follow [[ALSA|these instructions]] to enable ALSA. In summary:
 
  apk add {{pkg|alsa-utils|arch=a*}} {{pkg|alsa-utils-doc|arch=a*}} {{pkg|alsa-lib|arch=a*}} {{pkg|alsaconf|arch=a*}} # the required software for sound
  aplay -l # should display a List of PLAYBACK Hardware Devices
 
In my case my list is:
 
  **** List of PLAYBACK Hardware Devices ****
  card 0: Headphones [bcm2835 Headphones], device 0: bcm2835 Headphones [bcm2835 Headphones]
    Subdevices: 8/8
    Subdevice #0: subdevice #0
    Subdevice #1: subdevice #1
    Subdevice #2: subdevice #2
    Subdevice #3: subdevice #3
    Subdevice #4: subdevice #4
    Subdevice #5: subdevice #5
    Subdevice #6: subdevice #6
 
Before you play anything from your speakers, I recommend turnong down the volume.
 
  amixer
 
displays a list of "simple controls." For my headphones and the on-board sound, the output looks like this:
 
  Simple mixer control 'Headphone',0
    Capabilities: pvolume pvolume-joined pswitch pswitch-joined
    Playback channels: Mono
    Limits: Playback -10239 - 400
    Mono: Playback 0 [96%] [0.00dB] [on]
 
In this case, there is only 1 control, 'Headphone', so I issue this command to lower the maximum volume to a comfortable level. (50%)
 
  amixer sset Headphone 50%
 
The IQaudIO DAC that I use has a much larger set of controls. I issued this command to set the volume:
 
  amixer sset 'Digital' 50 # quotes may be required if there are spaces in the control name
 
Note: there can be several interlinked controls, some of which are muted by defualt. ALSA (and other audio software on Linux) is notoriously under-documented, try `man amixer` for more information. Sometimes it is easier to use a more visual control to change the configuration:
 
  alsamixer
 
Finally, if you issue this command:
 
  speaker-test -t wav -c 2
 
Then you should hear "Front Left, Front Right" repeating from your chosen speakers. Now it's time to setup Bluetooth. Don't forget to save your changes (lbu commit).
 
=Bluetooth=
I used [[Raspberry Pi 3 - Setting Up Bluetooth|Raspberry Pi 3 - Setting Up Bluetooth]] as a reference with some slight modifications as I am using a Pi 4.
 
Raspberry Pi 4
 
  apk add {{pkg|bluez|arch=a*}}
  btattach -B /dev/ttyAMA0 -P bcm -S 3000000 &
  # btattach -B /dev/ttyAMA0 -P bcm -S 115200 -N & # Pi 3 - not tested by me
  rc-service bluetooth start
 
edit {{Path|/etc/mdev.conf}} and enable bluetooth. This is done by uncommenting the the line and change the <code>btattach</code> to work with Pi 4.
 
{{cat|/etc/mdev.conf|<nowiki>...
# rpi bluetooth
ttyAMA0 root:tty 660 @btattach -B /dev/ttyAMA0 -P bcm -S 3000000 &
...</nowiki>}}
 
Changes to {{Path|/etc/bluetooth/main.conf}}
 
  Name = Pi-Bluetooth-Speaker  # This is what you'll see when connecting
  Class = 0x41C                # Adding audio playback and recording to this Bluetooth device
  DiscoverableTimeout = 0      # Always discoverable
  AlwaysPairable = true        # Always pairable
  PairableTimeout = 0          # no time limit
  AutoEnable=true              # starts Bluetooth when Linux 'sees' the Bluetooth device at boot
 
Ensure that Bluetooth is started at boot:
 
  rc-update add bluetooth
 
Bluetooth's state, including paired devices, in held in {{Path|/var/lib/bluetooth}} so you'll need to add this to `lbu` state:
 
  lbu include /var/lib/bluetooth
  lbu commit && reboot
 
Manual device pairing
 
  bluetoothctl
 
  [bluetooth]# discoverable on
  [agent] Confirm passkey 627133 (yes/no): yes
  [agent] Authorize service 0000110e-0000-1000-8000-00805f9b34fb (yes/no): yes
 
Device pairing:
 
  apk add {{pkg|python3|arch=a*}} {{pkg|py3-dbus|arch=a*}} {{pkg|py3-gobject3|arch=a*}}


I'm testing this using Raspberry Pi's excellent IQaudio DigiAMP+ board with a pair bookshelf speakers and an old (active) travel speaker using the on board audio.
Getting this to work currently involves running the bluez-simple-agent after having edited it to always return sucessful. You'll need to comment out some lines (by adding "#" at the beginning):


Once the speaker(s), and possibly amplifier, are wired into the Pi, it's time to install a fresh version of Alpine Linux.  The armv7 version from the [https://alpinelinux.org/downloads/ Downloads] page works on almost all Pis.
  vi /usr/bin/bluez-simple-agent


=Doing Something Title=
  #import bluezutils
Write the steps of how to do something in this section.
If possible, show an example first, then tell your readers the steps.
Break this procedure into separate procedures to avoid more than
about 7-9 steps per procedure.


INSERT GREAT EXAMPLE HERE
        def RequestConfirmation(self, device, passkey):
                #print("RequestConfirmation (%s, %06d)" % (device, passkey))
                #confirm = ask("Confirm passkey (yes/no): ")
                #if (confirm == "yes"):
                set_trusted(device)       
                return       
                #raise Rejected("Passkey doesn't match")


#Answer the following three questions, at least in your head.
And then running the revised agent in the background, and pair your devices:
##What do I explain how to do?
 
##How do I do that?
  bluez-simple-agent &
##What do HOWTO readers already know about doing that?
  lbu include /usr/bin/bluez-simple-agent
#Write up a good example. This ensures you can do it.
  lbu commit
#Write up the steps to do it.
 
#Write the background info/prerequisites readers need.
Notes: [https://www.kynetics.com/docs/2018/pairing_agents_bluez/ Pairing Agents in BlueZ stack]
#Write the summary.
[https://stackoverflow.com/questions/59214524/since-bluez-5-48-iphones-require-pairing-when-connecting-on-a-ble-gap-periphera Since Bluez 5.48, iPhones require pairing when connecting on a BLE GAP peripheral, why?]
#Clean up your work.
[https://gist.github.com/mill1000/74c7473ee3b4a5b13f6325e9994ff84c Headless A2DP Audio Streaming on Raspbian Stretch ]
#Revise, revise, revise.
 
=bluez-alsa=
At the time of writing this article, bluez-alsa is only found in the community repositories, so you need to edit your repository list:
 
  vi /etc/apk/repositories
 
remove the "#" from the community repository, mine is:
 
  https://uk.alpinelinux.org/alpine/v3.14/community
 
This is the final stretch.  We've got bluetooth working and now we want to link bluetooth to the speakers
 
  apk add bluez-alsa bluez-alsa-utils
  rc-update add bluealsa
  rc-service start bluealsa
  bluealsa-aplay &
 
[https://github.com/Arkq/bluez-alsa Bluetooth Audio ALSA Backend]
[https://github.com/Arkq/bluez-alsa/tree/master/doc bluez-alsa doc]
[https://manpages.debian.org/unstable/bluez-alsa-utils/bluealsa.8.en.html man bluealsa]
[https://manpages.debian.org/unstable/bluez-alsa-utils/bluealsa-aplay.1.en.html man bluealsa-aplay]
[https://panther.kapsi.fi/posts/2018-11-17_linux_bluetooth_audio Bluetooth audio in Linux: ALSA and LDAC]


=See Also=
=See Also=
Line 42: Line 183:
* Pimoroni's [https://shop.pimoroni.com/products/audio-amp-shim-3w-mono-amp Audio Amp SHIM (3W Mono Amp)] and [https://shop.pimoroni.com/products/mini-speaker-4-3w Mini Speaker 4Ω (3W)]
* Pimoroni's [https://shop.pimoroni.com/products/audio-amp-shim-3w-mono-amp Audio Amp SHIM (3W Mono Amp)] and [https://shop.pimoroni.com/products/mini-speaker-4-3w Mini Speaker 4Ω (3W)]
* The Pi Hut offers this [https://thepihut.com/products/adafruit-i2s-3w-stereo-speaker-bonnet-for-raspberry-pi Adafruit I2S 3W Stereo Speaker Bonnet for Raspberry Pi (Mini Kit)] and the [https://thepihut.com/products/stereo-enclosed-speaker-set-3w-4-ohm Stereo Enclosed Speaker Set - 3W 4 Ohm]
* The Pi Hut offers this [https://thepihut.com/products/adafruit-i2s-3w-stereo-speaker-bonnet-for-raspberry-pi Adafruit I2S 3W Stereo Speaker Bonnet for Raspberry Pi (Mini Kit)] and the [https://thepihut.com/products/stereo-enclosed-speaker-set-3w-4-ohm Stereo Enclosed Speaker Set - 3W 4 Ohm]
[[Category:ARM]]
[[Category:Raspberry]]
[[Category:Sound]]

Latest revision as of 13:22, 10 January 2024

How To Build a Raspberry Pi Bluetooth Speaker

This articles describes how to build a Bluetooth speaker. This article is being actively written. Currently it is full of bugs but will provide some useful pointers.

Before You Start

You’ll need:

  • A Raspberry Pi
  • A Bluetooth USB dongle (if your Pi doesn’t have Bluetooth on board)
  • Sound card and speaker(s)

Article Completion

  1. Test everything
  2. Turn every background task into a service
  3. More investigation on Bluetooth pairing

Getting the Speaker(s) Working

To get the best results, you'll need an dedicated audio add-on board and matching speakers. Higher end passive speakers need a proper amplifier (e.g. HiFiBerry Amp2 or IQaudIO IQaudIO DigiAMP+).

I've used the whole range of IQaudio audio boards with different speakers and headphones. I'd also recommend a dedicated USB Bluetooth dongle (don't get the cheapest versions of these). It is possible to test by using the on-board Bluetooth and the on-board audio with headphones but because of dropped packets, the audio quality isn't great.

Once the speakers and audio card are connected to the Raspberry Pi, it's time to install a fresh version of Alpine Linux. The armv7 version from the Downloads page works on almost all Pis. This Wiki has several articles about installing Alpine on a Raspberry Pi.

Enable writing to the boot media:

 mount /media/mmcblk0p1 -o rw,remount

Then, either enable the on board sound:

 echo "dtparam=audio=on" >> /media/mmcblk0p1/usercfg.txt

or your sound card (e.g. IQaudIO):

 echo "dtoverlay=iqaudio-dacplus,unmute_amp" >> /media/mmcblk0p1/usercfg.txt

reboot.

Follow these instructions to enable ALSA. In summary:

 apk add alsa-utils alsa-utils-doc alsa-lib alsaconf # the required software for sound
 aplay -l # should display a List of PLAYBACK Hardware Devices

In my case my list is:

 **** List of PLAYBACK Hardware Devices ****
 card 0: Headphones [bcm2835 Headphones], device 0: bcm2835 Headphones [bcm2835 Headphones]
   Subdevices: 8/8
   Subdevice #0: subdevice #0
   Subdevice #1: subdevice #1
   Subdevice #2: subdevice #2
   Subdevice #3: subdevice #3
   Subdevice #4: subdevice #4
   Subdevice #5: subdevice #5
   Subdevice #6: subdevice #6

Before you play anything from your speakers, I recommend turnong down the volume.

 amixer

displays a list of "simple controls." For my headphones and the on-board sound, the output looks like this:

 Simple mixer control 'Headphone',0
   Capabilities: pvolume pvolume-joined pswitch pswitch-joined
   Playback channels: Mono
   Limits: Playback -10239 - 400
   Mono: Playback 0 [96%] [0.00dB] [on]

In this case, there is only 1 control, 'Headphone', so I issue this command to lower the maximum volume to a comfortable level. (50%)

 amixer sset Headphone 50%

The IQaudIO DAC that I use has a much larger set of controls. I issued this command to set the volume:

 amixer sset 'Digital' 50 # quotes may be required if there are spaces in the control name

Note: there can be several interlinked controls, some of which are muted by defualt. ALSA (and other audio software on Linux) is notoriously under-documented, try `man amixer` for more information. Sometimes it is easier to use a more visual control to change the configuration:

 alsamixer

Finally, if you issue this command:

 speaker-test -t wav -c 2

Then you should hear "Front Left, Front Right" repeating from your chosen speakers. Now it's time to setup Bluetooth. Don't forget to save your changes (lbu commit).

Bluetooth

I used Raspberry Pi 3 - Setting Up Bluetooth as a reference with some slight modifications as I am using a Pi 4.

Raspberry Pi 4

 apk add bluez
 btattach -B /dev/ttyAMA0 -P bcm -S 3000000 &
 # btattach -B /dev/ttyAMA0 -P bcm -S 115200 -N & # Pi 3 - not tested by me
 rc-service bluetooth start

edit /etc/mdev.conf and enable bluetooth. This is done by uncommenting the the line and change the btattach to work with Pi 4.

Contents of /etc/mdev.conf

... # rpi bluetooth ttyAMA0 root:tty 660 @btattach -B /dev/ttyAMA0 -P bcm -S 3000000 & ...

Changes to /etc/bluetooth/main.conf

 Name = Pi-Bluetooth-Speaker   # This is what you'll see when connecting 
 Class = 0x41C                 # Adding audio playback and recording to this Bluetooth device
 DiscoverableTimeout = 0       # Always discoverable
 AlwaysPairable = true         # Always pairable
 PairableTimeout = 0           # no time limit
 AutoEnable=true               # starts Bluetooth when Linux 'sees' the Bluetooth device at boot

Ensure that Bluetooth is started at boot:

 rc-update add bluetooth

Bluetooth's state, including paired devices, in held in /var/lib/bluetooth so you'll need to add this to `lbu` state:

 lbu include /var/lib/bluetooth
 lbu commit && reboot

Manual device pairing

 bluetoothctl
 [bluetooth]# discoverable on
 [agent] Confirm passkey 627133 (yes/no): yes
 [agent] Authorize service 0000110e-0000-1000-8000-00805f9b34fb (yes/no): yes

Device pairing:

 apk add python3 py3-dbus py3-gobject3

Getting this to work currently involves running the bluez-simple-agent after having edited it to always return sucessful. You'll need to comment out some lines (by adding "#" at the beginning):

 vi /usr/bin/bluez-simple-agent
 #import bluezutils
       def RequestConfirmation(self, device, passkey):
               #print("RequestConfirmation (%s, %06d)" % (device, passkey))
               #confirm = ask("Confirm passkey (yes/no): ")
               #if (confirm == "yes"):
               set_trusted(device)        
               return        
               #raise Rejected("Passkey doesn't match")

And then running the revised agent in the background, and pair your devices:

 bluez-simple-agent &
 lbu include /usr/bin/bluez-simple-agent
 lbu commit

Notes: Pairing Agents in BlueZ stack Since Bluez 5.48, iPhones require pairing when connecting on a BLE GAP peripheral, why? Headless A2DP Audio Streaming on Raspbian Stretch

bluez-alsa

At the time of writing this article, bluez-alsa is only found in the community repositories, so you need to edit your repository list:

 vi /etc/apk/repositories

remove the "#" from the community repository, mine is:

 https://uk.alpinelinux.org/alpine/v3.14/community

This is the final stretch. We've got bluetooth working and now we want to link bluetooth to the speakers

 apk add bluez-alsa bluez-alsa-utils
 rc-update add bluealsa
 rc-service start bluealsa
 bluealsa-aplay &

Bluetooth Audio ALSA Backend bluez-alsa doc man bluealsa man bluealsa-aplay Bluetooth audio in Linux: ALSA and LDAC

See Also

Raspberry Pi's blog on How to play sound and make noise with your Raspberry P

There are lots of speaker and amplifier options: