DIY Bluetooth Telemetry Bridge
If you want to connect your ArduCopter flight controller with DroidPlanner, you can use either a Bluetooth or a 433MHz Telemetry module. By using Bluetooth, you don’t need to attach a module to your smartphone. But the range is not so good, as on 433Mhz. So how to get the best range without attaching modules to your phone?
By using a Bluetooth bridge. How it transmits the data: Pixhawk –> 433Mhz Transmitter –> 433Mhz Receiver –>Bluetooth Module –> Smartphone.
433Mhz Telemetry Kit or one 433Mhz Air Module and one Receiver module (HM-TRP 100mW)
3.7V LiPo Battery
4 tiny cables
Both the HC-05 Bluetooth and HM-TRP 433Mhz modules work on 3.3V. My HC-05 Bluetooth module has integrated voltage regulator and can be used without problems with a 3.7V LiPo Battery.
If you already have a 433Mhz Kit from 3DRobotics or HobbyKing unsolder the HM-TRP module from the receiver module (the one with the USB Plug). Or find bare HM-TRP module (datasheet).
How to do it:
First both modules should use the same baud rate for communication. The standard for the 3DR Robotics module is 57600. So you need to change the baud rate of the Bluetooth module. Then take 4 tiny cables and solder the pins from the HM-TRP module to the pins of the Bluetooth module as described:
5V HM-TRP Module – 5V Bluetooth Module (before last Pin on the left side)
GND HM-TRP Module – GND Bluetooth Module (last Pin on the left side)
TX HM-TRP Module – RX Bluetooth Module (2 Pin on the left side)
RX HM-TRP Module – TX Bluetooth Module (1 Pin on the left side)
A bit tricky is to solder the antenna to the tiny module. First remove the plastic black cover. Then cut the coax cable and remove the PVC shield. Take the metal shielding and without cutting it, form it as a cable and solder it to the GND Pin of the HM-TRP module. The tiny cable under the shielding layer is the cable for the Antenna. Solder this one to the ANT Pin of the HM-TRP module.
I used hot glue to place the HM-TRP 433Mhz module on the backside of the Bluetooth module. It looks better and is more compact. Connect the Bluetooth module to the 3.7V battery and your Bluetooth Telemetry Bridge is ready.