Ming wrote: > Hacking idea. Am I able to just supply power to a USB Bluetooth > dongle and it will send out the Bluetooth signal?
Possibly. That's a good idea, given you can get dongles for as little as $2: http://article.gmane.org/gmane.org.user-groups.linux.blu.hardware/240/match=bluetooth You should be able to test the idea easily enough. Get one, pair it normally while attached to a host, then try power it from a USB charger, and see if you can still see it. USB Bluetooth dongles are built using a tiny microcontroller, so even if a stock unit doesn't initialize the radio to make it discoverable when powered up, a custom firmware should be able to do so. Here is a message from Nuno Sucena Almeida in the archives talking about custom firmware: http://www.mail-archive.com/[email protected]/msg00250.html I imagine the custom firmware would need to tell the radio to power up once every few minutes, and transmit an "I'm here" and wait for any replies, shutting down the radio if none are received. I doubt the currently available $2 ~ $6 modules work in the 4.0 low energy mode, so the battery you hook up to it may not last very long. Eventually this tech will trickle down to these cheap dongles. The home brew solution may not be very pretty. The USB dongle hot glued to a few lithium coin cells, and maybe a 5V regulator. That does suggest that a knockoff of a Stick-N-Find (say without the speaker and LED) could probably be retailed for under $10. > Write code to constantly search for this particular > profile. I think you'd be looking for a known hardware device address[1] of a previously paired device. A Bluetooth device will broadcast its name, class, and other attributes while in discoverable mode[2], but that won't be unique if you plan to use multiple trackers. Plus, you'd only use discoverable mode for the initial pairing. (I think the power output might even be reduced for security reasons in discoverable mode, which is another reason you wouldn't use it when tracking.) 1. http://en.wikipedia.org/wiki/Bluetooth#Bluetooth_v1.0_and_v1.0B 2. http://en.wikipedia.org/wiki/Bluetooth#Setting_up_connections > The with a raspberry Pi. Sure, any number of devices could be used as the finder. Possibly something as simple as a shell script (wrapping existing BT command line tools) could be used to tell you when a matching device was in-range. If you wanted to get sophisticated, try mounding two Bluetooth dongles on opposite ends of a yard stick, and writing software to interpret the relative signal strength seen by each to determine the direction of your tracker. However, using a cell phone would be more convenient. It wouldn't surprise me at all to learn that someone already created a generic Bluetooth finder app for Android. (There are a ton of oddball apps with hacker appeal available on Android.) It may even be possible to use the Stick-N-Find app, depending on whether they used security keys[3] to authenticate their trackers (and assuming your custom firmware spoofs the device class they expect). 3. http://en.wikipedia.org/wiki/Bluetooth#Security -Tom _______________________________________________ Hardwarehacking mailing list [email protected] http://lists.blu.org/mailman/listinfo/hardwarehacking
