Citation
BibTEX
@misc { npapadopoulos_zexmte_bt-506_in_debian,
author = "Nikolaos Papadopoulos",
title = "ZEXMTE BT-506 in Debian",
howpublished = "\url{https://www.4rknova.com/blog/2023/04/22/zexmte-bluetooth-debian}",
month = "04",
year = "2023",
}
IEEE
[1] N. Papadopoulos, "ZEXMTE BT-506 in Debian",
https://www.4rknova.com, 2023. [Online].
Available: \url{https://www.4rknova.com/blog/2023/04/22/zexmte-bluetooth-debian}.
[Accessed: 01-03-2025].
I recently purchased a ZEXMTE BT-506 bluetooth dongle from amazon to use in a Debian Linux server.
Installation
This dongle uses a Realtek RTL8761B chipset. A quick check using apt suggests that the required firmware is included in the firmware-realtek package.
% apt show firmware-realtek | grep RTL8761B * Realtek RTL8761B Bluetooth config (rtl_bt/rtl8761b_config.bin) * Realtek RTL8761B Bluetooth firmware (rtl_bt/rtl8761b_fw.bin) * Realtek RTL8761BU Bluetooth config (rtl_bt/rtl8761bu_config.bin) * Realtek RTL8761BU Bluetooth firmware (rtl_bt/rtl8761bu_fw.bin)
Unfortunately after installation, the system was still failing to load the firmware. A quick inspection of /lib/firmware/rtl_bt also confirmed that the relevant files were missing. The solution was to copy the files manually. I used the linux kernel archives as a source.
$ cd /lib/firmware/rtl_bt $ sudo wget https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/plain/rtl_bt/rtl8761bu_config.bin $ sudo wget https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/plain/rtl_bt/rtl8761bu_fw.bin
Power management issues
While using the device, I’ve noticed that it occasionally becomes unresponsive after an unspecified time of operation. Some quick online research reveals that this issue is associated with USB autosuspension. My understanding is that this is a common issue due to the majority of vendors not implementing support for this feature correctly.
One workaround, if the Linux kernel is compiled with usbcore embedded, is to set the usbcore.autosuspend option to -1. This works for Debian and Ubuntu.
If the Grub bootloader is used, modify the “GRUB_CMDLINE_LINUX_DEFAULT” entry in /etc/default/grub to add that option.
GRUB_CMDLINE_LINUX_DEFAULT="quiet usbcore.autosuspend=-1"
Then update grub.
$ sudo update-grub`
After a reboot, the configuration can easily be verified.
$ cat /sys/module/usbcore/parameters/autosuspend -1