Ultimate LRS provide a long range RC and fast telemetry link.
You can use :
- A laptop connected to the ULRS with an FTDI (USB) cable or via bluetooth
- An Android device running Tower app, connected via USB (USB OTG cable + FTDI cable) or via bluetooth.
Bluetooth is a good solution because you’ll get rid of any cable to your RC TX. And every laptop, smartphone or tablet has a bluetooth module, so you can run Tower or Mission Planner on it, see your plane/quad on the map, see the artificial horizon, change parameters, select waypoints etc.
However bluetooth is less reliable than a cable, and can disconnect from time to time.
Step by step instructions
Also check instructions provided by rcgroups user aethertop here, which are more detailed than below.
Bluetooth module one-time configuration
ULRS will be connected via a small bluetooth module that can be found for example on ebay. A bluetooth link is very similar to a serial link, that’s why the bluetooth module will be connected on the serial port of the ULRS module.
HC05 or HC06 modules
Notice that the configuration or HC-06 modules is be slightly different but there are many tutorials on internet about this.
The first thing to do is to tell the bluetooth module the baudrate to use. This is a one-time operation, that the module will save in eeprom and remember forever.
Some modules are working at 3.3V, some are working at 5V, and some can select their voltage. It’s recommended to use a BT module that matches the voltage of your ULRS board.
Else, consider using a voltage shifter such as this one.
To configure the baudrate of the BT module, it must be put in a special mode that will make him receptive to special commands that we’ll send on the serial port.
This operation must only be done once per module, and will then be retained forever.
Enter configuration mode
This is done by connecting the ‘KEY‘ pin to VCC before powering up the module:
The module is then in configuration mode, and its LED will flash slowly (every 2 seconds).
Then connect with a terminal (or Arduino environment) at 38400 bauds, this is the default baudrate when the BT module is in configuration mode.
3. Type “AT” without the quotes, the module should answer “OK“. (On my module it answers continuously “OK” until CTRL-C is pressed.)
4. Type “AT+UART:57600,0,0“, the module should answer “OK“.
Notice that some modules require to use “=” rather than “:“, which would give “AT+UART=57600,0,0“.
You’re done !
Connecting to “Tower”
Tower is a ground control software, equivalent to Mission Planner for Android devices. Almost any ground control software will work, because ULRS will simply transfer transparently any serial data it receives from the flight controller, and the bluetooth module will do the same. It’s really similar to having connected a long cable between the flight controller (APM or similar) and the ground station software (Mission Planner or similar).
On the next power up (without the ‘Key’ wire) the BT module will run at 57600 bauds.
- Connect your BT module to your ULRS TX.Be careful that some BT modules have a different pinout, here is the connection to ULRS for the BT module referenced above :
2. Install Tower from Google Play (free software)
3. Click on ‘Settings’ (click on the icon with 3 horizontal lines on top left, and then you’ll see a menu with Settings on the bottom)
4. Choose Connection type : bluetooth. Notice that no baudrate has to be configured in Tower when using a bluetooth connection.
5. Click on Connect (main screen bottom left)
That’s it !
Using ULRS CC with Bluetooth
The initial COM ports detection of ULRS CC freezes when BT is powered on on a PC. Here’s a workaround.