Bluetooth to telemetry bridge

Build Log
1

If you wanted to have a convenient way to connect your PC/Android/IOS device to your radio telemetry gear with no wires then a Bluetooth bridge is a convenient way to do this. The basic idea is that telemetry is transmitted through the 3DR radio modules, but then on the ground it is relayed to a Bluetooth module which will transmit/receive the telemetry data wireless to your phone/PC/tablet.

There has been a recent kickstarter campaign for this device, which is a great idea, and looks like a great product but I think its abit on the steep side ($189 for full kit or $139 with no 3DR modules) So if you want to build one on the cheap read on!

Parts List

I estimate this to cost around £40 but will get the exact cost once complete.

  • Bluetooth TTL Module - £10
  • FTDI USB device to configure bluetooth module - £5
  • 3DR 433mhz Radio Module - £10
  • Voltage Regulator / UBEC - £4
  • Battery (2s 500mah will be great) - £10
  • Switch (to turn it off and on easily) (optional)
  • Project Box to house everything (optional)
  • USB charger (optional)

Configuring the bluetooth module

The bluetooth modules that we sell come with a defualt baud rate of 115200, since the 3DR radios run at a telemetry baud rate of 57600 we will need to change the bluetooth baud to match.

You will need to connect your Bluetooth module to your FTDI USB and connect to it via a serial monitor (I use the arduino IDE)

If you down have arduino you can download it here.

You will now need to connect your bluetooth module to the FTDI. Connect the 5V and ground between the Bluetooth module and FTDI. Now connect RX from FTDI to TX on Bluetooth, and TX from FTDI to RX on bluetooth.

Now plug in the FTDI to your computers USB port. After a few seconds it should be installed. Now open arduino and on the Tools menu, go to Serial Port and select the corresponding COM port that matches the FTDI board (usualy the largest number).

Arduino-USB-serial-port-selection-497x596.jpg497×596 111 KB

Now press Ctrl+shift+M to open the serial monitor, you can also open it from the Tools menu. On the bottom corner of this window make sure you have selected the correct baud rate. I for the bluetooth module I am using its default is 115200.

Using AT commands you will need to set the correct baud rate on the Bluetooth module.

Enter the following into the serial monitor window.

AT

Should respond with OK if everything is connected properly.
Now to change the baud rate to 56700 type the following command

AT+BAUD7

You should get a response saying OK57600

That it, the module is now ready to use on the bluetooth telemetry bridge

Connecting it all together

You will just need to connect both the radio module and bluetooth module to your 5V power supply and ground. Then the RX from the bluetooth module will connect to the radio module TX, and TX on bluetooth will connect to radio RX.

Bluetooth-Telemetry-Bridge-Arducopter.jpg1249×665 263 KB

For now I just did a hack job using a ESC as a 5V supply, using a breadboard to share power between the Telemetry and BT module as shown below.

Bluetooth-Telemetry Bridge.jpg900×662 229 KB

Connecting to the bluetooth Telemetry bridge

Now that everything is connected, you will just need to connect to the bluetooth module with your phone/tablet and you will begin to receive telemetry from your arducopter/arduplane. One thing that you should first check is that the two 3DR radio modules have been correctly setup and are both running at 57600 baud (default) and are both on teh same NetID.

Turn on your arducopter/arduplane and you should see the LED on the 3DR telemetry module light up as a solid green showing that they are both connected.

Now you will need to connect to the bluetooth module with your tablet/phone. The device name is CRIUS_BT with a pair code of 0000

BT.JPG837×627 73.6 KB

Now you just need to change the connection settings in andropilot/droidplanner to be bluetooth and everything should work!

Bluetooth-Telemetry Bridge1.jpg949×711 91.6 KB

Whats Next?

Now I just need to do some propper flight testing with this to see how it works. Assuming its still all ok I will work on makign things much neater and also look into adding a switch and possibly a USB charger or something, perhaps via a custom PCB.

If anyone has some comments or suggestions, or needs help please let me know!

1 Like
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I’ve ordered up the bits I need, so I’ll be doing some testing next week sometime.

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I’d be interested to know how this turns out. Eventually I was thinking of doing the same for my setup :smile:

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Just as an update, if you are not too keen to build your own we are now selling the Event38 Bluetooth Bridge from the kickstarter campaign if you are looking for a nice setup.

Despite the price compared to building your own, it does come in a very neat case with integrated battery and charger, as well as a 3DR radio module built in. So now you have the option of building your own or using a ready built one!

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any way you can post the actual connection diagram or picture with out the bread board. I want to be sure i connect everything correctly. Thanks in advance. Or you can send it to aviation@vergonet.net

cant wait to be able to use my galaxy tab 2 10.1 finally!!

Have all my parts on the way!!

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Hi i will get diagram for you in a couple days as im traveling at the moment and dont have my pc but essentially you just need to connect the tx from bluetooth to rx on telemetry and rx from bluetooth to tx on telemetry. Both modules can be powered from same 5v source.

Otherwise you can also connect the telemtry module directly to your android tablet with an OTG cable.

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I purchased a 12v-5v 850mah converter, will that be enough power for both units.

And since this is for the 3dr telemetry receiver i will be able to use my tablet finally as samsung does not have usb hosting for otg cable to work.

And nothing is needed to be added to the Iris correct?

Noticed they offer bluetooth module now, but i though you cant get farther than 30ft or so without bluetooth lose…?

Anyways if you could send me a schematic that would be superb, i am an aircraft mechanic and would rather wait for replay and error on side of safety!

Thanks a ton!!

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@William_Vergonet I have just updated the first post to include the diagram :smile:

1 Like
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Thanks so much, I got it!!

Works great!
However i do have the new version 3dr telemetry radio and the power goes all the way to the right (in comparison to your pic) on the 6 position connector. But I am also referring to the same type connector shown in the bluetooth picture side. My connectors are reversed as in FTDI is on my bluetooth and mini 6 pin is connected to radio.

THANKS AGAIN!! I can use my tablet and my cell phone now!!!

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Do I need to change settings for this to work? I can connect to Bluetooth but she’s not actually connecting to telemetry. Do I need to change any settings?

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Not sure how your telemetry module has been setup, but as long as its set to the correct baud rate it should work? If you connect to your bluetooth module via a serial monitor you should be able to see what buad rate it is set to, and then you just need to make sure your telemetry modules are set to the same rate (or the other way around).

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Just wondering if there has been much progress with this? I built one, but am having a similar problem to William. If I connect mine to my PC first via USB and connect to mission planner it works, I can then disconnect the usb and connect via android to Bluetooth and it works. However I cant simply connect via Bluetooth in the field without the assist of mission planner getting it started.

Its obvious when it will work too, the telemetry module on the drone with flash its red data light like crazy to say its transmitting. I then can actually unplug both telemetry modules from power/everything and plug them back in and they will work.

So I’ve narrowed it down to something on the PX4 that registers a telemetry connection and enables data transmission.

Any help would be appreciated, is there a setting in mission planner to force telemetry to on?

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Have you tried to first connect to your pixhawk directly via 2 telemetry modules the normal way? As that might be a good place to start to narrow down the problem. At least that way you can narrow down the problem to be either a PX4 setting, or a bad configuration with the telemetry modules.

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Yeah, thats what i was trying to say. PC > telemetry works fine, then if i dont power off the drone i can use Tablet > bluetooth > telemetry and it works well.

However if i dont connect the telemetry with my PC first, i cant use tablet > bluetooth > telemetry. Does that make sense?

Something that the pc sends to the drone enbles the telemetry connection.

I tried using a serial monitor and copying commands sent to the drone though mission planner with no luck.

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Has anyone tried this on an iOS device? There is a product called iDroneLink that does the trick but it costs $99! I appreciate any and all input

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Hi all
New to this but could you Help Got one of your Bluetooth modules (great service)
But having trouble changing Baud rate here is what I get:

  1. connect to orduino ftdi usb
  2. Tools select port / tools select serial monitor
  3. select 115200 baud rate / no line ending
    4.AT command nothing back
  4. Select both NL & CR /same baud rate 1152000
    5.Type AT command get OK back
  5. Type AT+BAUD7 nothing back
    Hope this is clear as totally new to this but if can help with this I must be doing something wrong
    Thank you Grabo
17

The problem might be because the bluetooth module is not connected correctly to your FTDI board, are you making sure RX from bluetooth module is connected to TX on FTDI? etc?

Also on the serial monitor, if you type AT, do you get an OK back?
http://www.dronetrest.com/uploads/db5290/300/a7d25fcc3a4dd93d.JPG
If not maybe your bluetooth module is not currently set at 115200 baud.

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All connected rx Bluetooth tx FTDI if I select 115200 bald rate and NL&CR type AT get answer OK as your screen shot but type AT+BAUD7 nothing comes back just blank hope this is clear

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That is rather strange, I have never had this issue so I am not sure if I can help too much. My only suggestion would be to try running the arduino IDE as admin, and also verify your Bluetooth module is working ok by trying other AT commands? Also if you just power on your bluetooth module are you able to find it with your smartphone?

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OK I have tried powering bt module and it does not show on any of my devices ie iPhone,ipad or my Hudl the only command it seems to reply to is AT but I must have it on 115200 baud rate and on NL&CR it will not respond to any other AT command ie name, pin,the leds on BT module are solid green and steady flashing red and do not change when AT command is sent I have tried 2 ftdi cards and on 2 computers but but why wont it work on no line ending
Gra