Computer Controlled RC Car With Two Arduinos

• Sending Arduino
• Recieving Arduino
• Computer program

#include <VirtualWire.h> //include the required library

void setup()
{
  //Begin the serial connection
  Serial.begin(9600);
  while(!Serial); //Wait till serial connection is ready
  Serial.println("Serial ready"); //Debugging
  //Initialize the IO and ISR
  vw_setup(2000); // Bits per sec
}

void loop()
{
  
  //If serial input is available
  if(Serial.available())
  {
    char input = Serial.read(); //Read input
    send(&input); //Send input via RF transmitter
  } else {  
  }
}

void send (char *message)
{
  vw_send((uint8_t *)message, strlen(message)); //Send the message
  vw_wait_tx(); // Wait until the whole message is gone
}

You can download the complete sketch from here: Simple_send.ino

Wiring the receiving Arduino is a little more complicated.
It requires both the RF receiver and the L293D chip.

The RF receiver:
The pins on the RF receiver labelled GND are ground. DATA OUT is where the received signal will be sent out. VDD is power for the chip and ANT is for the optional antenna.
-Wiring:
The RF receiver is connected separately from the L293D chip. The ground goes to one of the ground ports on the Arduino. The power in goes to the Arduino's 5V output and the DATA OUT should be connected to pin 13 on the Arduino. The antenna can be left loose and later connected to the RC car's antenna.

The L293D chip:
The pins on the L293D chip are shown on the diagram above. EN1 and EN2 are the motor enable pins. They act as a master on/off switch for each motor. IN1,IN2,IN3 and IN4 are the inputs that control the directions of each motor. If IN1 is powered and IN2 is not, the motor on OUT1 and OUT2 will turn one way. Likewise if the inputs are flipped, so too are the outputs and the motor will turn the other way. 0V is ground and +V is power for the chip. +Vmotor is used as a separate power source for the motors.
-Wiring:
The wiring for the l293D chip is not as complicated as it may look. The +V and the +Vmotor pins should be connected to and external power supply. In this project we will end up connecting these to the battery pack from the RC car. The IN1, IN2, IN3 and IN4 pins will be connected to pins 3,4,5 and 6 on the Arduino. The two motor enable pins are connected to pins 9 and 10 on the Arduino. The OUT1 and 2 pins go to one motor and OUT3 and 4 go to the other. It doesn't matter which IN pins go to which pins on the Arduino or which OUT pins go to which leads on the motor as these will be defined in code.

#include <VirtualWire.h> //Include required library

#define FORWARD '8'
#define BACKWARD '5'
#define STOP '0'
#define LEFT '4'
#define RIGHT '6'
#define STRAIGHT '/'


#define TIMEOUT 500UL

int motor1Pin1 = 5;    // pin 2 on L293D is connected to this pin on the Arduino
int motor1Pin2 = 6;    // pin 7 on L293D                  "
int enablePin1 = 9;    // pin 1 on L293D                  "
int motor2Pin1 = 3;    // pin 10 on L293D                 "int motor2Pin2 = 4;    // pin 15 on L293D                 "
int enablePin2 = 10;    // pin 9 on L293D                 "

int motor1Speed = 255; //max speed 255 
int motor2Speed = 255;

unsigned long counter;

void setup() 
{  
    //Set pin modes
    pinMode(motor1Pin1, OUTPUT);
    pinMode(motor1Pin2, OUTPUT);
    pinMode(motor2Pin1, OUTPUT);
    pinMode(motor2Pin2, OUTPUT);
    pinMode(enablePin1, OUTPUT);
    pinMode(enablePin2, OUTPUT);
    
    //Set enablePin to the motors speed
    analogWrite(enablePin1, motor1Speed);
    analogWrite(enablePin2, motor2Speed);
    
    //Begin with motors off
    digitalWrite(motor1Pin1, LOW); 
    digitalWrite(motor1Pin2, LOW);
    digitalWrite(motor2Pin1, LOW); 
    digitalWrite(motor2Pin2, LOW);


    Serial.begin(9600);
    //Initialise the IO and ISR
    vw_set_ptt_inverted(true);    // Required for RX Link Module
    vw_setup(2000);                   // Bits per sec
    vw_set_rx_pin(13);           // We will be receiving on pin 23 (Mega) ie the RX pin from the module connects to this pin. 
    vw_rx_start();                      // Start the receiver 
}

void loop()
{
  //variables for Virtual Wire
  uint8_t buf[VW_MAX_MESSAGE_LEN];
  uint8_t buflen = VW_MAX_MESSAGE_LEN;
  
  //If we got a message from the serial port
  if (Serial.available())
  {
    //Reset the timeout counter
    counter = millis();
    //Drive the requested motor
    drive(Serial.read());
    
    //Otherwise check for a message from the reciever
  } else if (vw_get_message(buf, &buflen)) // check to see if anything has been received
    {
      //Reset timeout counter
      counter = millis();
      int i;
      Serial.println("recieved"); //Debug message
       // Message with a good checksum received.
      
      
      //For each command recieved
      for (i = 0; i < buflen; i++)
      {
          drive(buf[i]); //Drive requested motors
      }
      
      
      //If the counter is greater than the timeout (No signal recieved) then stop the car.
    } else if(millis()-counter >= TIMEOUT) {
      drive(STOP);
      drive(STRAIGHT); 
    }
}

void drive(int dir) {
  //Check which direction is requested (same for below)
  if (dir == FORWARD) {
     Serial.println("Forward");//Used for debugging
     
     //Set motor accordingly (same for below)
     digitalWrite(motor1Pin1, HIGH); 
     digitalWrite(motor1Pin2, LOW);
     
  } else if (dir == BACKWARD) {
    Serial.println("Backward");
     digitalWrite(motor1Pin1, LOW); 
     digitalWrite(motor1Pin2, HIGH); 
  } else if (dir == STOP) {
     Serial.println("Stop");
    digitalWrite(motor1Pin1, LOW); 
    digitalWrite(motor1Pin2, LOW); 
  } else if(dir == STRAIGHT) {
    Serial.println("Straight");
    digitalWrite(motor2Pin1, LOW);
    digitalWrite(motor2Pin2, LOW);
  }else if (dir == LEFT) {
    Serial.println("Left");
    digitalWrite(motor2Pin1, LOW);
    digitalWrite(motor2Pin2, HIGH);
  }else if (dir == RIGHT) {
    Serial.println("Right");
    digitalWrite(motor2Pin1, HIGH);
    digitalWrite(motor2Pin2, LOW);
  }
}

You can download the complete sketch from here: RC_CAr.ino

public class GUI extends JPanel implements ActionListener, KeyListener {

}

	public JButton bFront, bBack, bLeft, bRight; //Define the buttons
	
	StyledDocument instructionsText; //This is used for the instructions
	public JTextPane instructions;	//Also used for instructions
		
	public GUI() {
		
		setLayout(new GridBagLayout()); //Set the layout to Grid Bag
		this.setPreferredSize(new Dimension(400,400));//Set the size of the window
		GridBagConstraints c = new GridBagConstraints();
		c.fill = GridBagConstraints.BOTH;
		c.gridx = 0; //This will be the position of the instructions
		c.gridy = 0;
		
		c.gridwidth = 4; //The instructions will span 4 tiles
		
                //Create the instructions text
		StyledDocument instructionsText = new DefaultStyledDocument();
		Style defaultStyle = instructionsText.getStyle(StyleContext.DEFAULT_STYLE);
		StyleConstants.setAlignment(defaultStyle, StyleConstants.ALIGN_CENTER);
		
		try {
			instructionsText.insertString(0, "Control the car using the keyboard.\n Change the key bindings by clicking the buttons below.", null);
		} catch (BadLocationException e) {
			e.printStackTrace();
		}
		
                //add the text to the pane
		instructions = new JTextPane(instructionsText);
		instructions.setFocusable(false);
		//add the pane to the window
		add(instructions,c);
		
		//Create the forward button (same for others below)
		bFront = new JButton("Forward key: " + KeyEvent.getKeyText(frontKey));
		bFront.setActionCommand("forward");
		bFront.addActionListener(this);
		bFront.setFocusable(false);


		//Set position of the forward button (same for others below)
		c.gridwidth = 1;
		c.gridx = 1;
		c.gridy = 1;
		add(bFront,c);
		
		
		bBack = new JButton("Backward key: " + KeyEvent.getKeyText(backKey));
		bBack.setActionCommand("backward");
		bBack.addActionListener(this);
		bBack.setFocusable(false);
		
		c.gridx = 1;
		c.gridy = 4;
		add(bBack,c);
		
		bLeft = new JButton("Left key: " + KeyEvent.getKeyText(leftKey));
		bLeft.setActionCommand("left");
		bLeft.addActionListener(this);
		bLeft.setFocusable(false);
		
		c.gridx = 0;
		c.gridy = 3;
		add(bLeft,c);
		 
		
		bRight = new JButton("Right key: "+ KeyEvent.getKeyText(rightKey));
		bRight.setActionCommand("right");
		bRight.addActionListener(this);
	    bRight.setFocusable(false);
	    
	    c.gridx = 3;
		c.gridy = 3;
		add(bRight,c);
		
		setFocusable(true);
		addKeyListener(this);


	}

	 public static void main(String[] args) {
		 // TODO Auto-generated method stub
		
		 //Create and show the GUI
		javax.swing.SwingUtilities.invokeLater(new Runnable() {
		 public void run() {
			 createAndShowGUI();			 
	        }
	    });	 
	}
	
	 private static void createAndShowGUI() {
		//Create and set up the window.
		JFrame frame = new JFrame("Arduino RC Car Controller");


		
		frame.setLocationRelativeTo(null);
		//Tell the program to exit when the GUI is closed
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
		
		final GUI gui = new GUI(); //create the GUI
		gui.setOpaque(true); //Set it to visible
		frame.setContentPane(gui); //attach it to the Jframe
				 
		//Display the window.
		frame.pack();
		frame.setVisible(true);
	 }

@Override
//If a button is clicked tell the program to listen for the next key pressed
public void actionPerformed(ActionEvent e) {

	if(e.getActionCommand().equals("forward")) {
		listenKey = 1;
	} else if(e.getActionCommand().equals("backward")) {
		listenKey = 2;
	} else if(e.getActionCommand().equals("left")) {
		listenKey = 3;
	} else if(e.getActionCommand().equals("right")) {
		listenKey = 4;
	}		
}

@Override
public void keyPressed(KeyEvent e) {
	//When a key is pressed
	
	//if not listening for a key change the color of the corresponding button 
	//and save the state of the key
	if(listenKey <= 0)
		if(e.getKeyCode() == frontKey) {
			bFront.setBackground(Color.yellow);
			frontKeyPressed = true;
		} else if(e.getKeyCode() == backKey) {
			bBack.setBackground(Color.yellow);
			backKeyPressed = true;
		} else if(e.getKeyCode() == leftKey) {
			bLeft.setBackground(Color.yellow);
			leftKeyPressed = true;
		} else if(e.getKeyCode() == rightKey) {
			bRight.setBackground(Color.yellow);
			rightKeyPressed = true;
		} 
}

@Override
public void keyReleased(KeyEvent e) {
	//When a key is released
	
	//If we are waiting for a key
	switch(listenKey) {
		
		//Set the control for the requred button
		case 1:
			frontKey = e.getKeyCode();
			bFront.setText("Forward key: " + KeyEvent.getKeyText(frontKey));
			listenKey = 0;
			break;
		
		case 2:
			
			backKey = e.getKeyCode();
			bBack.setText("Backward key: " + KeyEvent.getKeyText(backKey));
			listenKey = 0;
			break;
			
		case 3:
			leftKey = e.getKeyCode();
			bLeft.setText("Left key: " + KeyEvent.getKeyText(leftKey));
			listenKey = 0;
			break;
			
		case 4:
			rightKey = e.getKeyCode();
			bRight.setText("Right key: " + KeyEvent.getKeyText(rightKey));
			listenKey = 0;
			break;
		
			//Otherwise return the button to normal
		default:
			if(e.getKeyCode() == frontKey) {
				bFront.setBackground(null);
				frontKeyPressed = false;
			} else if(e.getKeyCode() == backKey) {
				bBack.setBackground(null);
				backKeyPressed = false;
			} else if(e.getKeyCode() == leftKey) {
				bLeft.setBackground(null);
				leftKeyPressed = false;
			} else if(e.getKeyCode() == rightKey) {
				bRight.setBackground(null);
				rightKeyPressed = false;
			} 
			break;
	
	}
}

Download the class file so far: GUI.java

Thread t=new Thread() {
	public void run() {

		//Attempt to initialize the serial connection
		while(!gui.initialize()) {
			System.out.print("Waiting one second...");
			try {Thread.sleep(1000);} catch (InterruptedException ie) {}
		}
		
		//Send data every 100ms
		while(true) {
			gui.sendData();
			try {Thread.sleep(100);} catch (InterruptedException ie) {}
		}
	}
};
t.start();
System.out.println("Started");

public void sendData(){
	try {
		//If forward key is pressed send forward etc...
		if(frontKeyPressed){
			output.write(FORWARD);
		} else if(backKeyPressed){
			output.write(BACKWARD);
		} else {
			output.write(STOP);
		}
		
		if(leftKeyPressed){
			//If both left and right are pressed the car will go straight
			if(rightKeyPressed)
				output.write(STRAIGHT); 
			else
				output.write(LEFT);
		} else if (rightKeyPressed){
			output.write(RIGHT);
		} else {
			output.write(STRAIGHT);
		}
		
	} catch(Exception e) {
		e.printStackTrace();
	}
}

• If your RC car has any LED lights, try hooking them up to your Arduino too. You could use a photosensitive resistor to detect when it gets dark and turn the lights on accordingly.
• Another cool addition could be to add a wireless camera to see what the car see's while you drive it around.
• For advanced programmers, In addition to a wireless camera try creating a web interface to control your car from anywhere in the world.
• Try adding different sensors to the car and give it some artificial intelligence.