USB Bluetooth bridge for Joystick and RC radio

This repo contains two projects;

1. USB Joystick to Bluetooth bridge - for using a USB joystick on, for example, an Android device to play the excellent Picasim RC flight simulator
2. IBUS to USB bridge aka Flysky FS-ia6b receiver IBUS to USB joystick converter - for connecting a Flysky RC transmitter to a laptop to practice RC flying using a simulator. The Flysky radio has an USB cable, but lots more phun without the wire (e.g. sitting on my couch)

Both projects works independantly, but may be used together to play Picasim on an Android phone using a Flysky radio

Credits

The joystick-bt bridge (1) is a remix of EmuBTHID (copied BluetoothHID.py) and Bluetooth GPIO Joystick for Raspberry Pi (sdp_record_joystick_4axis.xml). The HID descriptor file was only modified to allow 4 axis instead of the 2 in the source.

The IBUS-USB bridge (2) uses circuitpython-ibus and example code from Adafruit's Custom HID Devices in CircuitPython

USB Joystick to BT bridge

Below is based on

Ubuntu 20.04
python 3.8

Installation

Create a virtualenv (note for conda users, the version of python in Anaconda repo's is not compiled with the bluetooth extensions for socket and does not work (ymmv) using conda, so sticking to raw virtualenv for now)

python3 -m venv python-env

Activate the virtualenv

source python-env/bin/activate

Install pygame and dbus-python

pip install pygame
pip install dbus-python

Update Bluetooth service

on Ubuntu 20.04, the bluetooth.service needed to be modified to include the input module:

Edit bluetooth.service (location of this file differs by distribution and assumes systemd)

sudo nano /usr/lib/systemd/system/bluetooth.service

and update the ExecStart line in the [service] section to read:

...

[Service]
Type=dbus
BusName=org.bluez
ExecStart=/usr/lib/bluetooth/bluetoothd -P input

...

Once edited and saved, reload the service file, restart the service and check the status:

sudo systemctl daemon-reload
sudo systemctl restart bluetooth.service
sudo systemctl status bluetooth.service

Running

Run within the activated virtualenv as sudo (in order to access dbus)

sudo `which python` joystick_bt_bridge.py

If all went well, you should see something like:

Errors

If you see "Address already in use" - verify that the bluetooth service was updated correctly and restarted and is running

If you get "AttributeError: module 'socket' has no attribute 'AF_BLUETOOTH'", it means the bluetooth extension to socket was not compiled into the version of python being used - notably 'Anaconda' has this problem. Check which python is being used ( which python or try /usr/bin/python directly to verify) and make sure socket.AF_BLUETOOTH is available.

One way to check is to run these commands in python:

>> import socket
>> print(socket.AF_BLUETOOTH)
AddressFamily.AF_BLUETOOTH

As a last resort, you may need to recompile python from source and include the bluetooth extension.

Using

Pair your Android phone to your laptop's bluetooth and once paired, make sure the 'Input Device' service is active in the settings in Android (screenshot of Android 8 on Samsung device):

Once the Android device is connected, the console will show the connection details.

Now fire up PicaSim, enable the joystick and map the inputs as needed.

Installation - IBUS to USB bridge

The IBUS to USB bridge uses CircuitPython and was tested using the Trinket M0 device running CircuitPython 7.0.

To connect to the FS-IA6B IBUS, use the instructions here

Into lib folder on the Trinket, add

• ibus.mpy (cross-compiled)
• adafruit_bus_device (from CircuitPython library bundle)
• adafruit_hid (from CircuitPython library bundle)

Copy the source files from the circuitpython folder onto the device.

The contents of boot.py was used directly from Custom HID Devices in CircuitPython

hid_gamepad.py from the examples shipped with the CircuitPython library bundle

Testing

Once all wired up and ready to use, test using:

jstest --normal /dev/input/js0