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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  • Are you trying to connect the usb pins directly to the bluetooth module? Because that won't work. You need to connect to the tx/rx pins directly. If you use the ground radio with the usb connector you have to somehow bypass the usb-part and connect to the correct pins directly.

    As I happen to try and do the same thing just now, I'd also be very interested in the pinout for the ground modules.

    Have a bt-telemetry bridge running successfully but would like to free up the air module I use and instead use one of the (now) superfluous ground-modules instead, but can't figure out where the tx/rx pins are. Tried to find them on my air-module (since it's using the same pcb) using an ohm-meter, but could only find rx, but not tx.

  • I'm in the process of trying to set up one of these but having problems with the usb wiring. I have the ground radio with the USB male connector and want to plug that into a female USB cut from an OTG lead but cant get the wiring right. When the radio is plugged into the computer I get a negative feed from the casing of the plug but not when plugged into the socket fed from the b/t bridge module.

  • The link above now works

  • Hi Guys,

    I successfully tested a bridge that i set up using an android device hosting the telemetry module and an app called mavcell.

    I wrote about it on this blog post.

    The blog post is still waiting approval. Incase the url changes, I will update accordingly.


  • Which tablets have you tested this with? I am most interested if it works with Samsung Galaxy Tab 3 7" that does not support USB OTG.
  • In my ideal world, a little box like this, that I could plug my normal 3DR USB base station radio into would be ideal.   I'm not even sure that can be done.   Bluetooth -> USB -> Serial...    For that I'd pay $75ish on the high end, to support a kickstarter, etc.  

    The solution you've proposed, if it came out of the box plug and play with BT stuff and 3DR radio and battery, is worth $100~120 kickstarter to me.   

  • Thanks Richard... much appreciated... I will test that.... I have to setup the test bench when i get a chance to work that out... I was going to go out and get an Android Tablet for this... but I read somewhere a IOS version... in Beta Testing and not released to public yet... i might hold out for that... thanks again.


  • If it does not work at the first try, don't forget to try to switch the tx and Rx lines. Sometimes, the pinout-descriptions are missleading. Sometimes "Tx" means output, but on some modules "Tx" is input, so "connect to Tx".

    One of my china radios has this kind of labeling. I had to connect Tx with Tx and Rx with Rx to get it work.

  • Thanks, I am going to test bypassing the FTDI / USB adapter and just connect to the tx/rx/5v/gnd pins... see what happens there... fingers crossed... from the looks of it, the USB board with FTDI is attached to the original Telemetry Radio.

  • @LTMNO

    As Richard indicated it is this telemetry set here:

    I'm not sure if there's an equivalent in 915mhz. I'm sure if you hunt around you'd find something.  I bought a separate USB version to plug into my PC and you can have both the PC and the tablet connected and receiving telemetry at the same time if you want.

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