Makes an Arduino robot pace back and forth.

sentry.cpp

int MOTOR_A_BRAKE = 9;
int MOTOR_A_SPEED = 3;
int MOTOR_A_DIR   = 12;

int MOTOR_B_BRAKE = 8;
int MOTOR_B_SPEED = 11;
int MOTOR_B_DIR   = 13;

void setup() {                
  pinMode(MOTOR_A_SPEED, OUTPUT);
  pinMode(MOTOR_A_BRAKE, OUTPUT); 
  pinMode(MOTOR_A_DIR, OUTPUT);
  pinMode(MOTOR_B_SPEED, OUTPUT);
  pinMode(MOTOR_B_BRAKE, OUTPUT); 
  pinMode(MOTOR_B_DIR, OUTPUT);

  digitalWrite(MOTOR_A_BRAKE, LOW);  // disable the brake
  digitalWrite(MOTOR_B_BRAKE, LOW);  // disable the brake
  
  digitalWrite(MOTOR_A_DIR, LOW);   // move forward
  digitalWrite(MOTOR_B_DIR, HIGH);   // move forward
  // note that you could also change the direction by screwing the motor wires in differently
}

// the loop routine runs over and over again forever:
void loop() {
  analogWrite(MOTOR_A_SPEED, 255); // full speed 
  analogWrite(MOTOR_B_SPEED, 255); // full speed
  delay(1000);
  analogWrite(MOTOR_A_SPEED, 255); // keep going
  analogWrite(MOTOR_B_SPEED, 0); // stop so the robot will turn
  delay(1000);
}