Alternative version of the zigzag example using motor control functions

This is an alternative version of the zigzag example program from the RoboSlam workshop. It encapsulates the code that sets the motor control pins in handy reusable functions:

• forward()
• reverse()
• turnleft()
• turnright()
• stoprobot()

//
// RoboSlam example: Better Zigzag with functions
//

// the setup routine runs once when you press reset:
void setup()
{
  // Digital output for LED
  pinMode(2, OUTPUT);

  // Digital outputs for left motor
  pinMode(3, OUTPUT);
  pinMode(4, OUTPUT);

  // Digital outputs for right motor
  pinMode(7, OUTPUT);
  pinMode(8, OUTPUT);
}

// the loop routine runs over and over again forever:
void loop()
{
  forward();    // forward for 2000ms
  delay(2000);
  
  turnleft();   // turn left for 1000ms
  delay(1000);  
  
  forward();    // forward for 2000ms
  delay(2000);
  
  turnright();  // turn right for 1000ms
  delay(1000);  
}

void forward()
{
  digitalWrite(3, HIGH); // Left motor forward
  digitalWrite(4, LOW);
  digitalWrite(7, HIGH); // Right motor forward
  digitalWrite(8, LOW);
}

void reverse()
{
  digitalWrite(3, LOW);  // Left motor forward
  digitalWrite(4, HIGH);
  digitalWrite(7, LOW);  // Right motor forward
  digitalWrite(8, HIGH);
}

void turnleft()
{
  digitalWrite(3, LOW);  // Left motor reverse
  digitalWrite(4, HIGH);
  digitalWrite(7, HIGH); // Right motor forward
  digitalWrite(8, LOW);
}

void turnright()
{
  digitalWrite(3, HIGH); // Left motor forward
  digitalWrite(4, LOW);
  digitalWrite(7, LOW);  // Right motor reverse
  digitalWrite(8, HIGH);
}

void stoprobot()
{
  digitalWrite(3, LOW); // Left motor stop
  digitalWrite(4, LOW);
  digitalWrite(7, LOW); // Right motor stop
  digitalWrite(8, LOW);
}