• 8 analog axis supporting values from -32768 to 32767.
• 40 buttons

Background

• Putting an R1 UNO into DFU mode
• Putting an R2 or R3 UNO into DFU mode
• Flashing new firmware to the 8U2/16U2 with dfu-programmer

    /* Arduino USB Joystick HID demo */
    /* Author: Darran Hunt
     * Released into the public domain.
     */

    #define NUM_BUTTONS	40
    #define NUM_AXES	8	       // 8 axes, X, Y, Z, etc

    typedef struct joyReport_t {
	int16_t axis[NUM_AXES];
	uint8_t button[(NUM_BUTTONS+7)/8]; // 8 buttons per byte
    } joyReport_t;

    joyReport_t joyReport;

    void setup() 
    {
	Serial.begin(115200);
	delay(200);

   	for (uint8_t ind=0; ind<8; ind++) {
	    joyReport.axis[ind] = ind*1000;
	}

	for (uint8_t ind=0; ind<sizeof(joyReport.button); ind++) {
	    joyReport.button[ind] = 0;
	}
    }

    // Send an HID report to the USB interface
    void sendJoyReport(struct joyReport_t *report)
    {
	Serial.write((uint8_t *)report, sizeof(joyReport_t));
    }

    // turn a button on
    void setButton(joyReport_t *joy, uint8_t button)
    {
	uint8_t index = button/8;
	uint8_t bit = button - 8*index;

   	joy->button[index] |= 1 << bit;
    }

    // turn a button off
    void clearButton(joyReport_t *joy, uint8_t button)
    {
	uint8_t index = button/8;
	uint8_t bit = button - 8*index;

	joy->button[index] &= ~(1 << bit);
    }

    uint8_t button=0;	// current button
    bool press = true;	// turn buttons on?

    /* Turn each button on in sequence 1 - 40, then off 1 - 40
     * add values to each axis each loop
     */
    void loop() 
    {
	// Turn on a different button each time
	if (press) {
	    setButton(&joyReport, button);
	} else {
	    clearButton(&joyReport, button);
	}

	/* Move all of the axes */
	for (uint8_t ind=0; ind<8; ind++) {
	    joyReport.axis[ind] += 10 * (ind+1);
	}
	sendJoyReport(&joyReport);
	button++;
	if (button >= 40) {
	   button = 0;
	   press = !press;
	}
	delay(100);
    }

Upload the sketch to the Arduino first, then flash Arduino-big-joystick.hex to the 8U2/16U2. Unplug the Arduino and plug it back in, and will look like a joystick to the host and the host will receive the joystick updates from the sketch.

If you want to upload another sketch, flash Arduino-usbserial.hex to the 8U2/16U2 first, unplug the Arduino and plug it back in. You can now upload the sketch.

Downloads

• Put the UNO into DFU mode.
• dfu-prgrammer at90usb82 erase
• dfu-programmer at90usb82 flash --debug 1 Arduino-big-joystick.hex
• dfu-programmer at90usb82 reset
• Unplug the UNO's USB cable for a few seconds and plug it back in

• Put the UNO into DFU mode.
• dfu-prgrammer atmega16u2 erase
• dfu-programmer atmega16u2 flash --debug 1 Arduino-big-joystick.hex
• dfu-programmer atmega16u2 reset
• Unplug the UNO's USB cable for a few seconds and plug it back in

• Put the UNO into DFU mode.
• dfu-prgrammer at90usb82 erase
• dfu-programmer at90usb82 flash --debug 1 Arduino-usbserial.hex
• dfu-programmer at90usb82 reset
• Unplug the UNO's USB cable for a few seconds and plug it back in
• Check that you can still upload a sketch. If you can't upload the sketch (e.g. the usb device hasn't shown up), then put the UNO back into DFU mode and repeat the above procedure using the prebuilt Arduino-usbserial-uno.hex file that is in the Arduino-usbserial directory.

Creating Keyboard HID firmware

• Install avr-binutils. I've got macports installed so this is as simple as running the command "sudo port install avr-binutils". You can install macports from The MacPorts Project.
• Build and install avr-gcc. For this I downloaded gcc-4.5.2 from gcc.gnu.org. To build gcc you'll need to have XCode installed (from developer.apple.com). Do the following to build avr-gcc:
• sudo port install gmp
• sudo port install mpfr
• sudo port install libmpc
• export PATH=/opt/local/bin:/opt/local/sbin:$PATH
• tar xjf gcc-4.5.2.tar.bz2
• cd gcc-4.5.2
• mkdir build
• cd build
• CFLAGS="-g -O2 -I/opt/local/include" LDFLAGS="-L/opt/local/lib" ../configure --prefix=/opt/local --target=avr --with-gcc --with-gnu-as --enable-languages=c,c++ --disable-nls --disable-libssp --with-dwarf2
• make
• sudo make install
• cd ../..
• Build and install avr-libc.
• Download the latest avr-libc source from the AVR-Libc Project, e.g. avr-libc-1.7.1.tar.bz2
• tar xjf avr-libc-1.7.1.tar.bz2
• cd avr-libc-1.7.1
• mkdir build
• cd build
• CFLAGS=-Os ../configure --prefix=/opt/local --build=`../config.guess` --host=avr
• make
• sudo make install
• cd ../..

• If you don't have git installed, use macports to install it now: "sudo port install git".
• Get a copy of the Arduino source code:
• git clone git://github.com/arduino/Arduino.git
• Download a copy of LUFA 100807, unzip it and copy the LUFA subdirectory to the Arduino source tree:
• ftp http://www.fourwalledcubicle.com/files/LUFA/LUFA-100807.zip
• unzip LUFA-100807.zip
• cp -pr LUFA\ 100807/LUFA Arduino/hardware/arduino

• Install libusb-compat: sudo port install libusb-compat
• Download the latest dfu-programmer package from Sourceforge (e.g. 0.5.4) and do the following:
• tar xzf dfu-programmer-0.5.4.tar.gz
• cd dfu-programmer-0.5.4
• ./configure
• make
• sudo make install
• cd ..

Do a test build of Arduino-usbserial