This is how I got a Bluetooth low energy (BLE)
adapter to work on a Linux laptop running Ubuntu 12.04.
First, as suggested by several websites, I created the file /etc/modprobe.d/trust-btusb.conf with the following contents:
install usb:v0A5Cp21E8d*dc*dsc*dp*ic*isc*ip* /sbin/modprobe btusb; echo 0a5c 21e8 > /sys/bus/usb/drivers/btusb/new_id
After having restarted the computer and inserted the adapter, dmesg told me the following:
Bluetooth: can't load firmware, may not work correctly
To get the proper firmware, I downloaded the Windows 8 driver (18187_02.exe) from http://www.trust.com/18187
. The driver files can be extracted from the .exe with "unrar x 18187_02.exe".
Then I looked for the vendor id (0x0a5c) and product id (0x21e8) in the various .inf files, and found this in 18187_02/Win32/bcbtums-win7x86-brcm.inf:
%BRCM20702.DeviceDesc%=RAMUSB21E8, USB\VID_0A5C&PID_21E8 ; 20702A1 dongles
Further down in the inf file there is a RAMUSB21E8 section which contains the following line:
The .hex "RAM Patch" file can be found in 18187_02/Win32/. Before it can be used with btusb, it needs to be converted to hcd format. This can be done with hex2hcd
. Finally, the hcd file needs to be moved/copied to /lib/firmware/fw-0a5c_21e8.hcd. Here are the steps to get and compile hex2hcd:
$ git clone https://github.com/jessesung/hex2hcd.git
$ cd hex2hcd/
The resulting executable can be used to convert the .hex firmware file to .hcd, which is then copied to the right destination:
$ ./hex2hcd BCM20702A1_001.002.014.0187.0188.hex BCM20702A1_001.002.014.0187.0188.hcd
$ sudo cp -p BCM20702A1_001.002.014.0187.0188.hcd /lib/firmware/fw-0a5c_21e8.hcd
$ sudo chown root:root /lib/firmware/fw-0a5c_21e8.hcd
The adapter can now be used:
$ sudo hcitool -i hci1 lescan
- The first step is no longer necessary with Ubuntu 14.04, I directly receive the "may not work" message.
- I was able to extract the firmware from 18187_05.exe (latest W8 driver) using this command: "7z x 18187_05.exe"
- The correct .hex file is BCM20702A1_001.002.014.0449.0515.hex