Tag Archives: re-purpose - Page 2

Breathing life in old laptop Bluetooth module (GUBTCR42M)

Some days ago colleague of mine gave me his old broken laptop for parts / components. One of the recovered components was the Bluetooth module, which had the GUBTCR42M marking on it. At a closer look on the wiring there were only 5 wires coming out from the module and connecting to the main board. This made me think maybe can be reused (thinking about SPI or USB connection), so I started to look for information about the module.

I’ve eventually found some data here and there, and even the datasheet somewhere on a forum. From the datasheet:

The GUBTCR42M is designed to provide Bluetooth function on a small form factor. The Bluetooth function is based on CSR BC04-ROM chipset Bluetooth System, which implements the full speed class 2 Bluetooth operations with full 7 slave piconet support. The interface of GUBTCR42M to host system is USB and full compliant with USB ver.2.0

Also the pinout:

1 3V ~ +5V Positive supply for whole module
2 GND Ground Pin
3 USB_D- USB Data Minus
4 USB_D+ USB Data Plus
5 LED BT Activity LED indicator
6 Reserved
BT Active indicator output to inform WLAN NIC. Host side should keep it NC if not supported.
7 Reserved
WLAN Active indicator output to from WLAN NIC. Host side should keep it NC if not supported.
8 BT_ON# Active LOW to enable Bluetooth function. High to disable function

Using this pinout table, the following pins are actually accessible:

From an old broken card reader I got a small USB cable with connector, and the Internet solved the problem with the pinout based on wire color:

After I connected the two together, and also connected the BT_ON# to GND, I’ve connected it to the computer’s USB port. The device was successfully detected and configured on my linux desktop:

asd@gg ~ $ lsusb 
   .... devices ....
Bus 003 Device 013: ID 0a12:0001 Cambridge Silicon Radio, Ltd Bluetooth Dongle (HCI mode)
   ...  devices ....

Happy hacking! 🙂