Memos From the Cube

New LUFA release coming up – more on that in a week or two. The last LUFA release has doubled the last download record, and is in the mitts of at least 2000 people! That’s not bad for a small, niche hobbyist project. Don’t forget to link me to the projects you use it in, I love seeing what people create with it!

Now, as usual, back on to what I’m doing at the moment. I think this blog is rather useful to me – not only to bore the people who stumble across it, but to motivate me so that I keep having new things to post here. Without some way of announcing what I’m working on, I’d probably just stagnate and watch way to much TV.

Bluetooth! It’s all about Bluetooth! I’ve had some big success over the last two days; I can now connect to it from my phone, and send HID data giving button presses on the keypad. I’d say that’s pretty damned cool, since it means general Bluetooth use is just around the corner for hobbyists. I was going to make my Bluetooth code GPL instead of MIT in order to try to generate licensing revenue, but I think I’ll just keep it as-is and hope some companies license LUFA instead. Lots of things aren’t done yet, like packet fragmentation, service discovery and LUFA initiated connections to other devices, but this shows that it already has practical implementations.

It seems lots of people are interested in the possibility of embedded Bluetooth, as I’ve already got feedback from people testing my extremely-volatile latest SVN revisions of the code. Two things have been pointed out, through both my personal experience, and the testing of others:

1) Cheap Bluetooth dongles really are cheap for a reason. All Bluetooth devices carry a unique device address (BDADDR) which is used to distinguish one device from another – like a MAC address on network cards. I’ve now got three different dongles all which cost me under $5 shipped off eBay which all have the same “unique” address. Nearest I can tell there’s a company in China making these by the millions and saving a milli-cent a piece by not changing the device codes. That’s bloody annoying as while having one such device is fine, two of them make for some very strange connection issues; Windows will give up immediately with a generic error code as soon as it detects that the source and destination BDADDR values are identical.

Since these devices all have a spoofed VID/PID of a well-known Bluetooth dongle manufacturer, it seems the Chinese have also come up with a cheap solution to my VID/PID rant a few weeks ago – just use someone else’s. I can’t fault them for that to be honest since I don’t agree with the USB-IF’s stupid system anyway, but it makes me wonder if they aren’t selling perfect clones of the real company’s silicon and simply don’t realize that the device address has to be unique.

If you get odd error codes when trying to use two cheap adapters, this is probably why.

2) Not all Bluetooth adapters are created equal. Richard and Andrei have both reported that some of their Bluetooth adapters are actually not standard adapters at all – they report as a hub device with a Bluetooth adapter and a HID device attached. Nearest I can tell this is so that the adapter can pair with a dedicated keyboard/mouse wirelessly via Bluetooth and report as a standard Mouse/Keyboard HID device to the host, so that hosts lacking the proper drivers for the Bluetooth dongle aren’t stuck finding a wired keyboard/mouse combo until they are installed. Unfortunately LUFA isn’t hub compatible due to the way the USB AVRs work, so these device are currently off-limits for the demo.