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Getting the Trust 18187 Bluetooth 4.0 USB adapter (0a5c:21e8) to work with Linux

Posted by crox on
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:
HKR,,%RAMPatchFileName%,0x00000, "BCM20702A1_001.002.014.0187.0188.hex"

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/
$ make

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


Update, 2014-09-08:
  • 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

raspbmc - getting rid of iptables

Posted by crox on
I don't need a firewall on my Raspberry PI which runs XMBC (raspbmc distribution) - it's in a dedicated subnet behind a firewall. Furthermore, there are several reports of iptables having an impact on the performance of network playback, causing buffering issues (although I didn't do any benchmark myself).

I modified /etc/network/if-up.d/secure-rmc by adding "exit 0" right at the beginning like this:
#!/bin/bash

exit 0

dec_to_bin() {
...

And then I ran:
apt-get remove iptables

This was followed by a reboot.

nb: the secure-rmc file appears to be a raspbmc addition, and it could probably just be deleted instead.

Enabling IPv6 Privacy Extensions on all interfaces (Ubuntu Linux, may work for other distros too)

Posted by crox on
According to the Wikipedia IPv6 article, Privacy extensions are, except for the Windows platform and Mac OS X since 10.7 as well as iOS since version 4.3, not enabled by default.

In theory, one can enable the IPv6 Privacy Extensions on all interfaces at once using sysctl like this:
sudo sysctl net.ipv6.conf.all.use_tempaddr=2

However, this currently doesn't work as expected, so I'm using this one-liner in /etc/rc.local:
for IF in `/bin/ls /proc/sys/net/ipv6/conf/*/use_tempaddr` ; do echo 2 > $IF ; done

This also sets "use_tempaddr" for "default", which means it should also apply to interfaces added to the system afterwards.

A simple check to verify that the new configuration is working: ipv6-test.com will print your MAC address when available...

See also: Linux Kernel Bug 11655