Tablet Ground Station via Bluetooth Telemetry Bridge

We've been experimenting more and more with tablet ground stations here at Event 38 and have had a lot of success using the DroidPlanner app. The software has been working well for us but we found our ground station setup was really cluttered, the opposite of what we were going for when switching to tablets. My main complaint was having the ground side telemetry radio dangling from my phone or tablet. Not only was it a hassle and prone to coming unplugged, it was also hard to keep it in a good position for radio reception.

Following Arthur Benemann's instructions, we set up a bluetooth bridge that would let us at least set the radio down and move freely with the ground station tablet. A huge improvement, no doubt, but still a little rough around the edges, even needing power from a laptop. So we added a nice case and a single cell LiPo battery to power it all. This worked even better, and looked pretty nice as well!

2013-10-16 15.36.09

It still had some power management issues but it worked well enough for our purposes. At this point we're thinking about running a Kickstarter campaign to run a production scale build of these but we'd like to get some feedback from potential users before we solidify the specs. I'd appreciate any/all comments on what kind of features you'd like to see on something like this, if any, besides the telemetry bridge to Bluetooth. Right now we're planning on including the following:

  • Internal LiPo battery, rechargeable by USB
  • Battery status LEDs
  • 433 and 915MHz variants to be compatible with any 3DR Radio
  • ~20m Bluetooth range
  • ~1km telemetry range
  • 5-6 hours battery life
  • A durable plastic enclosure

Is there anything else we should consider adding to improve the functionality or usability? Do you think this would be priced fairly at $139? Let us know what you think!

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  • Love that setup, Jack!

  • Developer


    There was no space to mount the radio directly on the back of the antenna?

    Anyway, nice idea!

  • @LTMNO

    I've got the same. It is a version without the USB FTDI Chip on it but with a separate USB-RS232 adapter cable.

  • Jack, great idea... for those of us that have mod'd the radios with all the fixings.. whats one more... my problem is finding enough room in there with all the other upgrades I have done.  Did your 3dr Radio originally have the USB attachment on it? Or is this a different Transmitter?

  • Nice project......


  • Here's some photos showing my 9x with the 3dr radio to bluetooth bridge integrated inside. This has the same functionality of the box proposed by Jeff without the need to carry arond another box/battery. There's a bunch of other mods in here but you should be able to pick it out.  The bluetooth module and the 3dr radio are powered off the 5v from the regulator on the top PCB on the transmitter front.  The 3dr aerial goes out through the Thr. Cut switch hole.  This switch has been hot glued inside the case (not used). The 5v gets powered up when the transmitter is turned on.  I've considered setting up a switch to turn the bridge on and off but I use it pretty much all the time and it doesn't appear to drain a lot out of the battery. Only potential issue is the load on the 5v reg but no problems there so far!

    I think this is a great set up as I don't have to carry another box around, charge another battery or have the 3dr radio module hanging off my tablet. Bluetooth range is never a problem because I always have the transmitter and tablet with me.





  • Developer


    Please try that, and report any problems to the DP forum so that we can help.

    Still uncommon that they did not implement a device selection.

    I implemented it, I'm sorry for not doing it that way. It's mostly because I don't have bluetooth on my device, so I had to do a fast implementation to fill the user's needs (I borrowed a phone). You can read more about it here:

    If you want to give a try to implementing the device selection everyone (that uses DP and Bluetooth) would be happy :)

  • Thanks, Arthur. Now, at least I know, how DP determinates which BT device to use.

    I'll try to unpair all other devices and see if it works then.

    Still uncommon that they did not implement a device selection.

  • Developer


    About Bluetooth on DP: Basically DP connects to the first serial bluetooth adpater that your phone is paired to. Here is the part of the source that handles that:

    One problem that we already debuged/solved on the DP forum is that one guys was not able to use the bluetooth option. The problem happened because he had his car paired to it's device, and the car also showed up as a serial device. So when DP tried to connect the first thing it saw was the car, and failed to connect.

    So at least for the first run try to un-pair  from every bluetooth device, and then connect only to the serial module.

  • I tried to build the same with an HC-07 bluetooth module, but I have 2 problems:

    1.) If you access the bluetooth COM-port in MS Windows, it takes a few seconds ti establish the connection. Mission Planner seems to timeout too early and will not connect.

    2.) Droid Planner on Android: I have no idea how to connect. (like others might have too) I have several bluetooth devices paired with my tablet (headset, stereo, car, ...) How does Droid Planner know which paired bluetooth device to choose to make a connection.

    As soon as I hit "connect", it instantly says "connected,disconnected".

    Does the bluetooth device have to have a special name to get recognised by Droid Planner?

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