/* HID Joystick Mouse Example
   by: Jim Lindblom
   date: 1/12/2012
   license: MIT License - Feel free to use this code for any purpose.
   No restrictions. Just keep this license if you go on to use this
   code in your future endeavors! Reuse and share.
 
   This is very simplistic code that allows you to turn the 
   SparkFun Thumb Joystick (http://www.sparkfun.com/products/9032)
   into an HID Keyboard. Send up/down/left/right arrow keystrokes
   using the joystick. The select button on the joystick is set up
   as the 'P' (pause) button. 
   
   I wrote it to play free PacMan online!
   http://www.freepacman.org/
 */
#define	KEY_RIGHT	0x4F  // Right arrow
#define	KEY_LEFT	0x50  // Left arrow
#define	KEY_DOWN	0x51  // Down arrow
#define	KEY_UP	        0x52  // Up arrow

int horzPin = A0;  // Analog output of horizontal joystick pin
int vertPin = A1;  // Analog output of vertical joystick pin
int selPin = 9;  // select button pin of joystick

int vertZero, horzZero;  // Stores the initial value of each axis, usually around 512
int vertValue, horzValue;  // Stores current analog output of each axis
const int threshold = 200;  // Higher sensitivity value = slower mouse

void sendKey(byte key, byte modifiers = 0);

void setup()
{
  pinMode(horzPin, INPUT);  // Set both analog pins as inputs
  pinMode(vertPin, INPUT);
  pinMode(selPin, INPUT);  // set button select pin as input
  digitalWrite(selPin, HIGH);  // Pull button select pin high
  delay(1000);  // short delay to let outputs settle
  vertZero = analogRead(vertPin);  // get the initial values
  horzZero = analogRead(horzPin);  // Joystick should be in neutral position when reading these

}

void loop()
{
  vertValue = analogRead(vertPin) - vertZero;  // read vertical offset
  horzValue = analogRead(horzPin) - horzZero;  // read horizontal offset
  
  if (vertValue > threshold)
    sendKey(KEY_DOWN);
  else if (vertValue < -threshold)
    sendKey(KEY_UP);
  
  if (horzValue > threshold)
    sendKey(KEY_RIGHT);
  else if (horzValue < -threshold)
    sendKey(KEY_LEFT);
  
  if (!digitalRead(selPin))
    Keyboard.write('P');
}

void sendKey(byte key, byte modifiers)
{
  KeyReport report = {0};  // Create an empty KeyReport
  
  /* First send a report with the keys and modifiers pressed */
  report.keys[0] = key;  // set the KeyReport to key
  report.modifiers = modifiers;  // set the KeyReport's modifiers
  report.reserved = 1;
  Keyboard.sendReport(&report);  // send the KeyReport
  
  /* Now we've got to send a report with nothing pressed */
  for (int i=0; i<6; i++)
    report.keys[i] = 0;  // clear out the keys
  report.modifiers = 0x00;  // clear out the modifires
  report.reserved = 0;
  Keyboard.sendReport(&report);  // send the empty key report
}