REALTEK RTL8761B/BU USB Bluetooth adapter

Trying to get my 8.22.3 release of Dietpi, running on Pi Zero WH to use this USB BLE 5 adapter rather than the on board Bluetooth 4.
Using dtoverlay = disable_bt seems to remove the on board adapter and the USB adapter is detected and reported as running and configured. Unfortunately no devices can be detected (using Bluez 5.66).
I have test with my app, and standalone bluetoothctl.
Lots of stuff about the firmware not loading on older kernels due to name issues but I see nothing about firmware in dmesg.
Anybody got this device working?

Looks like btusb.c is missing an entry for the specific rtl8761b series USB device on my kernel (5.10.103+)

as follows :-

{ USB_DEVICE(0x2550, 0x8761), .driver_info = BTUSB_REALTEK | BTUSB_WIDEBAND_SPEECH }

Was added in 5.15.32 , 5.16.18 , 5.17.2 and 5.18 onwards.

I guess you are still running Debain Bullseye??

Can you share some more information on your device


  • DietPi version | cat /boot/dietpi/.version
  • Distro version | echo $G_DISTRO_NAME $G_RASPBIAN
  • Kernel version | uname -a
  • Architecture | dpkg --print-architecture
  • SBC model | echo $G_HW_MODEL_NAME or (EG: RPi3)

I’m running the latest Bookworm 8.22.3 - updated in place from Buster then Bullseye.


bookworm 1

Linux DietPi 5.10.103+ #1529 … armv6l


RPi Zero W (armv6l)

Are you running something like Berryboot? Because your kernel version is too old and should already be 6.x :thinking:

No, just plain old DietPi - it’s a long-standing build - progressively updated for about 3 years …

I have a master image that I burn to SD card then dietpi-update and re-image after.

I remember doing the kernel update manually for the Dirty Pipe vulnerability as per the Blog.

Kernel version and DietPi version are not related. On RPi device, kernel should be updated using apt package manager.

As long as you don’t put kernel package on hold manually, it should update automatically. At least as long as you don’t use any 3rd party bootloader. Did you reboot your system in between?

Can you share

apt update
apt update
Hit:1 bookworm InRelease
Hit:2 bullseye InRelease
Hit:3 bullsyey InRelease
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
12 packages can be upgraded. Run 'apt list --upgradable' to see them.
W: Key is stored in legacy trusted.gpg keyring (/etc/apt/trusted.gpg), see DEPRECIATION section in apt-key(8) for details.
W: Key is stored in legacy trusted.gpg keyring (/etc/apt/trusted.gpg), see DEPRECIATION section in apt-key(8) for details.
W: Key is stored in legacy trusted.gpg keyring (/etc/apt/trusted.gpg), see DEPRECIATION section in apt-key(8) for details.

System has been rebooted many times and the image has been deployed to several devices at once…

can you share following

apt list --upgradable
apt list raspberrypi*
The apt list --upgradable lists the following (I have summarized):

The apt list raspberrypi* gives more interesting results:

raspberrypi-archive-keyring/olstable 2021.1.1+rpt1 all
raspberrypi-bootloader/now 1:1.20230509~buster-1 armhf [installed,local]
raspberrypi-kernel-headers/oldstable 1:1.20230405-1 armhf
raspberrypi-kernel/now 1:1.20230509~buster-1 armhf [installed,local]
raspberrypi-net-mods/oldstable 1.3.4 all
raspberrypi-sys-mods/now 2:20230510-dietpi1 all [installed,local]
raspberrypi-ui-mods/oldstable 1.20230127 armhf

Still Buster kernel? :thinking:

What happen if you to reinstall kernel?

apt update
apt install --reinstall raspberrypi-kernel raspberrypi-bootloader

I’ll try in a bit, just replaying my buster->bullseye update to see if that’s where the problem started (seems likely!)

OK, those reinstalls fail with ‘not possble,it cannot be downloaded.’

can you share the whole output.

In terminal, after reading package files, building dependency tree and reading state information - just three lines:
Reinstallation of raspberrypi-kernel is not possible, it cannot be downloaded.
Reinstallation of raspberyypi-bootloader is not possible, it cannot be downloaded.
0 upgraded, 0 newly Installed, 0 to remove and 12 not upgraded.

let’s check if kenel was set on-hold

apt-mark showhold
dpkg -l | grep "^hi"