Bozhidar Dryanovski

Arduino: With USB Joystick

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Wow, I found an old Joystick and guess what ? I decide to control the Arduino robot with it. First I try to do it with Ruby, but it was very hard to find a example of that. I found a lib called, joystick but it field when I try to compiled it. The last time when someone supported it was in 2003.

I have some experience with Python and decide to try with it.

We will use python to act as adapter between the Arduino and the USB Joystick.

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import sys
import serial

# Read devices
pipe = open('/dev/input/js0','r')                # USB Joystick 
ser = serial.Serial('/dev/ttyACM1', 9600)        # Arduino Serial 

action = []
spacing = 0
while 1:

  # Decode the information from the Joystick

  for character in pipe.read(1):

      action += ['%02X' % ord(character)]
      if len(action) == 8:

          num = int(action[5], 16) # Translate back to integer form

# We could map any key on the joystick.
          if action[6] == '01': # Button
              if action[4] == '01':
                  print 'press button: ' + action[7]
              else:
                  print 'release button: ' + action[7]

# Left D-Pad 
          elif action[7] == '01': # D-pad up/down
              if action[4] == 'FF': ser.write('2')
              elif action[4] == '01': ser.write('1')
              else: ser.write('5')

# Right D-Pad
          elif action[7] == '02': # Right Joystick up/ down
              if num >= 128:
                  ser.write('3')
              elif num <= 127 \
              and num != 0:
                  ser.write('4')
              else:
                  ser.write('6')
          action = []

Now when we have the middleware, We have to map all the keys to the robot.

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// Motor A
#define leftSpeedPin    16   // Left motor speed control, to PWM_A
#define leftDir1        14   // Left motor direction 1, to AIn1
#define leftDir2        15   // Left motor direction 2, to AIn2

// Motor B
#define rightDir1        17  // Right motor direction 1, to BIn1
#define rightDir2        18 // Right motor direction 2, to BIn2
#define rightSpeedPin    19  // Right motor speed control, to PWM_B 

// setup

void setup() {
  int motorSpeed;                   // From 0->255, slow->fast.

  // Set motor direction pins as outputs.
  pinMode(leftDir1, OUTPUT);
  pinMode(leftDir2, OUTPUT);
  pinMode(rightDir1, OUTPUT);
  pinMode(rightDir2, OUTPUT);

  // Serial 
  Serial.begin(9600);
  Serial.println("Robot ready for mission:");

}

// Loop all day long...

void loop() {

  // Listen for incoming messages 
  if (Serial.available() > 0 )  {
    char command = Serial.read();

    // Motor A
    if(command == '1') { fmotor('A'); }
    if(command == '2') { bmotor('A'); }
    if(command == '5') { stopmotor('A'); }
    // Motor B
    if(command == '3') { fmotor('B'); }
    if(command == '4') { bmotor('B'); }
    if(command == '6') { stopmotor('B'); }

    // Debug
    Serial.println(command);
  }
}

/* *********************************************************
 *
 * Functions 
 *
 * *********************************************************/

// Go go go...

void fmotor(char motor) {

  if (motor == 'A') {
    digitalWrite(leftSpeedPin, HIGH);
    digitalWrite(leftDir1, HIGH);
    digitalWrite(leftDir2, LOW);
    analogWrite(leftSpeedPin, 200);
  }

  if (motor == 'B') {
    digitalWrite(rightSpeedPin, HIGH);
    digitalWrite(rightDir1, HIGH);
    digitalWrite(rightDir2, LOW);
    analogWrite(rightSpeedPin, 200);
  }
}

// Run motor backword

void bmotor(char motor) {

  if (motor == 'A') {

    digitalWrite(leftSpeedPin, HIGH);
    digitalWrite(leftDir1, LOW);
    digitalWrite(leftDir2, HIGH);
    analogWrite(leftSpeedPin, 200);
  }

  if (motor == 'B') {
    digitalWrite(rightSpeedPin, HIGH);
    digitalWrite(rightDir1, LOW);
    digitalWrite(rightDir2, HIGH);
    analogWrite(rightSpeedPin, 200);
  }
}

// Ohoy, stop all motoros!

void stopmotor(char motor) {
  if (motor == 'A') {
    digitalWrite(leftSpeedPin, LOW);
    digitalWrite(leftDir1, LOW);
    digitalWrite(leftDir2, LOW);
  }
  if (motor == 'B') {
    digitalWrite(rightSpeedPin, LOW);
    digitalWrite(rightDir1, LOW);
    digitalWrite(rightDir2, LOW);
  }
}

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