gistfile1.txt

//int pwm_a = 10; //PWM control for motor outputs 1 and 2 is on digital pin 10
int pwm_a = 3;  //PWM control for motor outputs 1 and 2 is on digital pin 3
int pwm_b = 11;  //PWM control for motor outputs 3 and 4 is on digital pin 11
int dir_a = 12;  //dir control for motor outputs 1 and 2 is on digital pin 12
int dir_b = 13;  //dir control for motor outputs 3 and 4 is on digital pin 13


void setup()
{
  pinMode(pwm_a, OUTPUT);  //Set control pins to be outputs
  pinMode(pwm_b, OUTPUT);
  pinMode(dir_a, OUTPUT);
  pinMode(dir_b, OUTPUT);
  
  analogWrite(pwm_a, 100);        
  //set both motors to run at (100/255 = 39)% duty cycle (slow)  
  analogWrite(pwm_b, 100);
  
}

void loop()
{
  digitalWrite(dir_a, LOW);  //Set motor direction, 1 low, 2 high
  digitalWrite(dir_b, LOW);  //Set motor direction, 3 high, 4 low
  
  delay(1000);
  
  analogWrite(pwm_a, 255);      
  //set both motors to run at 100% duty cycle (fast)
  analogWrite(pwm_b, 255);
  
  delay(1000);
  
  digitalWrite(dir_a, HIGH);  //Reverse motor direction, 1 high, 2 low
  digitalWrite(dir_b, HIGH);  //Reverse motor direction, 3 low, 4 high
  
  delay(1000);
  
  analogWrite(pwm_a, 100);
  //set both motors to run at (100/255 = 39)% duty cycle   
  analogWrite(pwm_b, 100);
  
  delay(1000);
}