Realtek RTL8761B is a USB Bluetooth 5.0 dongle chip made by Realtek. It is identified by lsusb as
0bda:8771 Realtek Semiconductor Corp. Most of the cheaper BT 5.0 dongles, like the C-TECH BTD-01, use this chip.
The RTL8791B dongle chip has been supported by the
CONFIG_BT_RTL) driver since Linux 5.8.
You will need to upgrade your kernel to 5.8+ if you have an older kernel and you want to use this dongle.
CONFIG_BT_RTL is not listed as its own item in
menuconfig in Linux 5.11, which can be a bit confusing. You should choose ▸ ▸ ▸ and the two options both named in that same menu (
BT_HCIUART_RTL). You will then find that
BT_RTL is enabled if you press / and search for .
The driver requires firmware. The firmware package shipped with most GNU/Linux distributions tend to just provide a
/lib/firmware/rtl_bt/rtl8761a_fw.bin file for the RTL8761A model.
The firmware files for the RTL8761B can be acquired from the github.com/Realtek-OpenSource/android_hardware_realtek firmware repository using these links:
These firmware files need to be copied and renamed to:
It does not matter which location you copy the firmware files to on most distributions. Fedora and many others have a symbolic link from
/usr/lib (making them the same folder).
Robert Síbek has written a tutorial with screenshots for the C-TECH BTD-01 dongle (actually the RTL8761B chip) specific to Ubuntu 20.10.