Arduino(ATmega32u4) Joystick firmware

First of all, this project uses the ArduinoJoystickLibrary, available at https://github.com/MHeironimus/ArduinoJoystickLibrary.

This firmware aims to add a bit more of control to the values read and sent to the computer.

To this end, this firmware offers the following functionality:

• 10bit (0 to 1023) precision, from the Pro micro's ADC.
• Persistent Calibration
• Custom Curves
• Filtering
• Analog stick to HAT switch conversion (is a bit old)

Beware that you will need to alter the source code in order to configure it. As this project is compiled, it is a bit laborious to make a "configurator", so you will have to change some lines in the code to customize it to your input configuration, as well as your curves and filtering likings.

Configuration (really more like a customization)

To customize this firmware to you setup, search the Joystick.ino for the <CUSTOM> comments.

There you wil find more information on how to add, remove or change those entries.

In the sections below you will find information about what each functionality configuration, but for information on what to edit and where to edit, please search the .ino file.

Setting up buttons

Search for <BUTTON>.

This is the one that should change the most. The only configuration needed is the array of button pins. There you should insert all the pins that correspond to buttons in your arduino. The order will determine the order they appear at the computer (e.g. if the fist button of the array is pin 4, then in the computer the button 1 will be controlled by pin 4 of the arduino).

Setting up axes

Search for <AXIS>.

The axes are set the same way as the buttons, but you also have to specify the number of axes present. Just add the pins corresponding to you axes to the array of axes pins and set the AXES_ARRAY_SIZE to the number of pins you entered.

Setting up custom curves

Search for <CURVE>.

The curves used are Bézier Curves, so to configure it you will need to inform 4 numbers from 0 to 1023.

There is a good website that I use to tune curves: cubic-bezier.com by Lea Verou. There you can see how the curve will respond to the input value.

To export a curve just multiply the values shown in the site by 1023 and put them, in order, in the two center points of the bézier.

Example:

// Site curve: cubic-bezier(0,.9,1,.1)
// Approximated multiplied values: 0, 900, 1, 100
// Line of code:
calibration_data.curves[0] = Bezier(Point(0, 0), Point(0, 900), Point(1023, 100), Point(1023, 1023));
// Site curve: cubic-bezier(.31,.91,.6,.15)
// Approximated multiplied values: 310, 910, 600, 150
// Line of code:
calibration_data.curves[0] = Bezier(Point(0, 0), Point(310, 910), Point(600, 150), Point(1023, 1023));

The two outer values define a cap for the axis range.

Setting up hat conversion

Search for <HAT>.

To use axes as a hat switch, first add your axes as normal axes.

Then at the end of the .ino file, uncomment the section to use HAT as DIGITAL. Then adjust the index of each axis according to your axes_pins array.

Calibration

The procedure to calibrate the joystick is easier to be done the first time with a serial monitor. But it can be done without one too.

The calibration just needs to be done the first time you change some axis. After that the max and min values will be stored in the EEPROM. If you want to recalibrate it, just follow the normal calibration procedure.

Without serial monitor

1. As you plug the joystick, hold your designated calibration button until the Tx Rx LEDs in the board turn off;
2. Move all your axes to their full extension both ways;
3. Hold the calibration button for 1 second to finish calibration.

With serial monitor

1. As you plug the joystick, you will see this message:

=================================
Joystick Initializing - baud 9600
=================================

Hold calibration button to force calibration...
##################################################

2. Hold your designated calibration button, before the bar stops filling up, until the this message appears:

Force calibration
Release calibration button to proceed...

3. Release your designated calibration button and this message appears repeatedly:

Move axes now
========= Calibrating =========
Axis: 0 - Raw Value: 172
Axis: 1 - Raw Value: 150
Axis: 2 - Raw Value: 187
===============================
Hold calibration button to finish...

4. Move all your axes to their full extension both ways;

5. Hold the calibration button for 1 second to finish calibration.

Structure

.
├── Bezier.cpp        // Source file for the curves. You'll probably never touch this file.
├── Bezier.hpp        // Neither this one.
├── FlightStick.ino   // This is the main file. Here you will make all the changes needed.
├── LICENSE
└── README.md         // You are here.

Compiling and flashing

To use this project you will need the Arduino IDE installed.

Install the ArduinoJoystickLibrary.

Put the contents of this folder inside a folder called Joystick, as this enables you to import it into arduino IDE as a sketch.

Make the modifications needed to the main file.

Upload it to the arduino.