Based on the original works of dmpriso github.com.
Adapted for use in the Wifibroadcast system. You can toggle between using WBC to send the axis data to the plane or to use the original Arduino -> PPM module solution.
All you need is a Raspberry Pi, a Linux compatible Joystick and an Arduino board (optional). Plug the Joystick into Raspberry. Connect the Raspberry to the Arduino via USB. The Raspberry will use the devices from joyconfig.ini.
When using the Arduino as output it will generate a 12-Channel 22.5ms PPM signal on Pin 10. Arduino code is based on previous work: https://github.com/ckalpha/Generate-PPM-Signal/
Configuration is done via settings files. These ar given as command line arguments to the application.
You can map axis and buttons to output channels, and define special actions for buttons. Configuration files are INI files. Ini parsing is based on previous work: https://github.com/atomicptr/libini
Install jstest on your raspberry and run
jstest /dev/input/js0
I strongly recommend you to perform a joystick calibration and save the joystick configuration on your system. See the following article for instructions: http://aegidian.org/bb/viewtopic.php?t=12217#p178651
An axis mapping entry consists of the following elements:
[axis2] # "2" is the axis identifier, as seen in jstest
ppm_channel_id=0 # "0" is the PPM channel ID, zero-based
weight=100 # 100% weighting. For reversing, just put a negative value here
expo=30 # 30% expo
offset=10 # 10% offset = subtrim
You may target the same PPM channel ID from multiple axes in order to achieve mixing.
Button actions are defined as follows:
# flightmode: manual
[action_button9] # "9" is the button identifier, from jstest
ppm_channel_id=4 # target PPM channel ID, zero-based
value=-67 # value to be set when button is pressed. Range from -100 to +100%
# Below is a release button action. One can also use it to init default PPM values.
# This one is intended to set the initial flightmode to "manual"
[action_releasebutton9]
ppm_channel_id=4
value=-67
Buttons can be set for trims and subtrims. Trim applies to a stick input, so expo and rate are also applied to the trim. Subtrims are applied to PPM output.
[trim_button15] # Apply trim when button 15 is pressed
axis_id=1 # Target axis ID
step=1 # Trim step, in percent
[subtrim_button20] # This is a subtrim when button 20 is pressed
ppm_channel_id=1 # Target PPM channel ID, zero-based
step=1
Trims are automatically saved and restored. The path of the file generated is: /usr/local/etc/joystick/user_trims.ini TODO: make that customizable via parameter
Some joysticks do report their coolie hat as axis, not as buttons. However the coolie hat might be useful for trimming. You can use an axis to trigger button actions as follows:
[buttonize_axis7] # Axis ID of the coolie hat X or Y axis
low_button_id=34 # Virtual button ID to be triggered when axis is low (left)
high_button_id=35 # Virtual button ID to be triggered when axis is high (right)
I've added a mapping.ini to the source repo which I wrote for the Saitek X-52 Pro Joystick.
Clone the repo
cmake ./
make
Create a mappings.ini and set it up
Simply run ./joystick_ppm_converter with the correct arguments for testing
In order to let the tool automatically run when the raspberry starts up, copy the executable tool to /usr/local/bin/ Then, edit /etc/rc.local and add the following line near the end, but before the exit command:
/usr/local/bin/joystick_ppm_converter >joystick.log &
Restart your raspberry to verify
The project is still at a very early alpha-stage. Most important items to do are:
- Improve file parsing so invalid numbers etc. are catched and proper error messages are emitted
- Create a GUI for editing the configuration
- Integrate the GUI and allow for live updating of configuration