3D Robotics


[UPDATE: We now sell a Bluetooth set that has all this pre-setup for you. If you get that, no need to read further!]. We're going to be adding Bluetooth connectivity to more 3DR products in the coming months, but there's no need to wait. Right now you can add Bluetooth connectivity yourself with cheap third-party bluetooth modules. Connecting the APM and Pixhawk via Bluetooth is a great way to do basic setup and mission planning with your laptop (Mac, PC or Linux) or Android phone or tablet, without the need to carry and connect a 3DR radio and OTG cable.  You’re limited to Bluetooth range (about 50m), but for wireless setup before launch, this works fine.  Mission Planner (Windows), APM Planner (Mac, Windows, Linux), DroidPlanner and AndroPilot (both Android) all support Bluetooth connectivity.


This tutorial will show you how to connect two kinds of commonly available Bluetooth modules (shown above) to APM or Pixhawk.

The process consists of three steps: 

  1. Configuring the modules so they’re running at 57600 baud
  2. Physically connecting the modules to APM/Pixhawk
  3. Connect via BT to your Android device or laptop and a GCS app (pair the module with your device)


Option 1: Setup with RN-42 and RN-41 Bluetooth modules


Connect the module with an XtreamBee adapter board and this cable





You can use any serial terminal program (the terminal in the Arduino IDE is shown), but there are a few things you need to do:

  1. You must enter command mode within 60 seconds of powering up the board
  2. The board can’t be already wirelessly paired with a device (such as your phone or tablet)
  3. The default baud rate is usually 115200. We need to change that to 57600 baud. But for the first connection, to get the command prompt for this change, we’re going to start at 115200.
  4. To get to command mode, you need to select “No line ending” in your terminal program, then enter “$$$” [enter]. After that, the terminal program needs to be in “Newline”  mode, as shown below. Crazy, but that’s the way Roving Networks set it up. Now you know!

First, ensure that your terminal baud rate is at 115200 and “No line endings” is selected. Then plug in your module and within 30 seconds type “$$$” [enter]. You should get the return message “CMD”.


Once you have that, switch your terminal program to “Newline” for the rest of the commands.


Now you can enter commands. To switch to a 57600k baud rate the command would be "SU,57" (A full list of commands is here, although you won’t need them for this change). Once you reboot the board, that baud change will take effect.


Congrats, you’re done! Now you’re ready to use it with APM/Pixhawk. See the bottom of the post for instructions on how to use the GCS apps with Bluetooth.




Option 2: Setup with cheap ($10) HC-05 Arduino Bluetooth Module


Full instructions are here, but the basics are below:


 You can make your own cable by swapping some wires in the standard 3DR telem-to-Xbee adapter cable. For clarity’s sake, I’ve used some color-coded wires above to show what goes where.


Here’s a neater cable that I’ve made with some regular breakaway header pins:



This same custom cable will allow you to plug it into a regular FTDI cable (shown below) so you can change the configuration of the Bluetooth board to switch the default baud rate from 9600 baud to 57600 baud.


Once you’ve plugged the board into your FTDI cable and plugged that into your computer, it will show up in your computer as a serial port. The LED on the board should be blinking red, not blue. You should NOT wirelessly pair the Bluetooth model with any device at this point; if it the LED is blue that means that it’s paired with something, so if that’s the case make sure that you unpair it first.  At that point you can use any serial terminal to communicate with the Bluetooth module. For the sake of this demo, we’ll use the serial terminal built into Arduino.


First, select the port assigned to your FTDI cable (it probably won’t be 26, as shown below, and on a Mac it may show us as “tty-usbserial”):


Ensure that the serial terminal baud rate is set for 9600 baud and “No line ending”, as shown.

Type AT [return]. The board should return “OK”.  That means that all is well and you’re talking to the board. If you don’t get a return, check your wiring and make sure that the Bluetooth board is showing a blinking red LED (powered on) and is not blue (paired with something).  


Now we can change the baud rate to 57600. The command for that is “AT+BAUD7 [return]”, as shown. If this is a success, it will report back “OK57600”, as shown below. If so, you’re done! Unplug the board and you’re ready to use it with APM/Pixhawk.



Now that you have your module working, you just need to pair with your device. On Android, this is the Bluetooth settings. Set your device to "discoverable" and you'll see the module show up. Then pair it. If it asks for a code, type "1234". 

Once it's paired you can connect with either Android app: DroidPlanner 2 and Andropilot. On Andropilot, there's a button marked "Bluetooth" on the main screen. On DroidPlanner, go to the settings menu (top left) and under "Telemetry Connection Type" select Bluetooth and the module you've paired with it. 

Both of these modules work great with either app!



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  • Hi anybody,
    I've tried this many times but after successful pairing with my mobile phone the droid planner always say connection lost, no mavlink data. My Baud rate is 57000.
    Any captions?
  • Here is my home made BT-Telemetery bridge, hope you guys like it:


  • Developer

    Has anyone tried the RN-41 or RN-42? I have been testing APM Planner 2.0 with RN-41 today. This is my findings.

    The XtremeBee adapter from 3DR it will work as Chris described*. If you are using this adapter from Sparkfun you will need to remove the FETs and Pull-Up resistors used in level conversion, and wire DIN to IN and DOUT to OUT.* Otherwise the logic levels are not working.

    When using this with OSX, i turned of the authentication on pairing. OSX wasn't showing the PIN entry dialog. You can set authentication to off by using the command SA,0. I'll do some more testing and see if I can find a solution for this with automatic pairing using PIN 0000

    If anybody is stuck please PM me and I can help ( and it helps me find any potential issues with AP2).

    *Unless I find a solderless solution. the issue is that the data signals are 0V to 3.3V even with the Vcc being 5V and needing the regulator on-board

  • You could skip the interim cable on the second option and just shift the pins in molex connector to correct position, then plug the Molex directly into the HC-05.

  • Hi, is it currently possible to decrease the baud on droid planner to 9200 or at least 19200?
  • Also I think it's the CTS wire that for some reason get skipped hence the 5 pin


  • I'm not positive but I think this is what you need or is this the cable you referance?


  • I purchased the XtreamBee adapter board, RN-42, and the DF13 5 pin cable.  However I'm attempting to connect it to a Pixhawk but both Telemetry ports are DF13 6 pin. how do I use the "3DR Radio adapter cable for APM 2.5" on my pixhawk?

  • I just realized I posted a link to this thread IN this tread. ha That's what happens when you have 15 pages open in your browser. :]

  • You could likely rig up a Bluetooth Bridge to run a RFD900 inside. It might get tight mechanically to fit it in there though, and routing the antennas out would be a little tougher. As some have stated earlier you can just run an RFD900 on your aircraft and use the 915MHz BTB which is compatible.. that will give you 3.5 to 4.5km range. Looks like there's a lot of interest in a longer range version of the BTB so maybe we'll try to get an RFD900 to fit inside and make that an option in the future!

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