/* This sketch simply drives the robot forward, then backward, attempting a straight line using PWM
   * This will reveal any inconsistencies between motor speeds as they should both turn at the same speed.
   * This works with both motors turning in unison, with the positive of each motor on the chip end of the motor connectors.
   * pin 12 goes to IN1, pin 8 goes to IN3. pin 12 & 8 are FORWARD when high and 9 & 13 LOW. 
   * see hookup image in lesson, I have the RIGHT motor going to MOTOR B
   */

void setup() {
  // put your setup code here, to run once:
  pinMode (13, OUTPUT);
  pinMode (12, OUTPUT);
  pinMode (11, OUTPUT);
  pinMode (10, OUTPUT);
  pinMode (9, OUTPUT);
  pinMode (8, OUTPUT);
  
}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite (12, HIGH);
  digitalWrite (13, LOW);
  digitalWrite (8, HIGH);
  digitalWrite (9, LOW);
  //turn on the motors for one second
  analogWrite (11, 125);
  analogWrite (10, 125);
  delay (1500);
  //turn off the motors for one-half second
  analogWrite (11, 0);
  analogWrite (10, 0);
  delay (1000);
  digitalWrite (12, LOW);
  digitalWrite (13, HIGH);
  digitalWrite (8, LOW);
  digitalWrite (9, HIGH);
  //turn on the motors for one second
  analogWrite (11, 125);
  analogWrite (10, 125);
  delay (1500);
  //turn off the motors for one-half second
  analogWrite (11, 0);
  analogWrite (10, 0);
  delay (1000);
  
}