DX.com sells some Bluetooth 3.0 modules carrying Broadcom BCM20730 as the core (link). According to the datasheet attached to this Geekhack post, it scans the matrix of a keyboard automatically. The chip also supports an external optical mouse, IR encoding/decoding, and other undocumented features as the datasheet is preliminary. The BCM20730 is used in a wide range of Chinese Bluetooth keyboards found on eBay and was pretty huge a few years ago, which I think was an advertisement campaign led by Broadcom to publicize their chip.
Working on the ThinkClamp project at the time, I got myself 2 of them, did some research and have some breakout boards made. Here’s the Gerber if you like to use Elecrow to manufacture them; their 5×10 cm for $11 deal is particularly awesome! I got the breakout board about a week ago. Here’s how it looks with everything soldered. For testing purposes, only the UART pins, GND and 3V3 pins are needed to be soldered. TP-BCM730 Schematic for reference.
According to the datasheet and various other sources, Broadcom Bluetool is used to configure these modules. Broadcom is highly secretive I’ve come to know. They keep their development resources tight and controlled via confidential agreements with their customers. Unfortunately, an older version of Bluetool got uploaded. Now I have no idea what’s the current version of Bluetool to say that the version I found is old, but given that there are only 2 COM ports accessible and the old-looking user interface, it’s safe to say that this piece of software was written in the Windows XP era.
Using this testing guide (attached in post) for what I think is another BCM20730 development board and a USB-to-UART converter, I attempted to send commands to the DX module. For most of the time, the RESET command works and a value of ‘Success 0x0′ is replied. However, for all other commands, the module fails to reply.
As I do not have a USB-SPI converter to try to use the chip’s SPI functionality, for me, this module has proved to be potentially useful for invested ones but absolutely useless without clear guidance for usage. So unless you have the tools, good documentation and time to work this module, don’t bother with it.
Update: Finally got some data from these modules I think it was just pure luck that this happens. Despite all connections were soldered properly and letting using the same setup all the time, this happens to be a one-time lucky event. TP-BCM730 log