/*
pin assignments:
9   - R1
10  - R2
11  - R3
12  - R4
*/

int speedValue;

int R1 = 9;

int R2 = 10;

int R3 = 11;

int R4 = 12;

void setup(){
pinMode(R1, OUTPUT);
pinMode(R2, OUTPUT);
pinMode(R3, OUTPUT);
pinMode(R4, OUTPUT);
off();
delay(1000);
}

void loop(){
forward();
delay(3000);
reverse();
delay(3000);
off();
delay(3000);
}


void forward() {
digitalWrite(R1, LOW);
digitalWrite(R2, LOW);
digitalWrite(R4, HIGH);

  // ramp in from min to max in increments of 5 points:
  for(int speedValue = 0 ; speedValue <= 255; speedValue +=5) { 
    // sets the value (range from 0 to 255):
    analogWrite(R3, speedValue);         
    // wait for 30 milliseconds to see the effect    
    delay(30);                            
  } 

  // ramp out from max to min in increments of 5 points:
  for(int speedValue = 255 ; speedValue >= 0; speedValue -=5) { 
    // sets the value (range from 0 to 255):
    analogWrite(R3, speedValue);         
    // wait for 30 milliseconds to see the effect    
    delay(30);                            
  } 


}

void reverse(){
digitalWrite(R2, HIGH);
digitalWrite(R3, LOW);
digitalWrite(R4, LOW);

  // ramp in from min to max in increments of 5 points:
  for(int speedValue = 0 ; speedValue <= 255; speedValue +=5) { 
    // sets the value (range from 0 to 255):
    analogWrite(R1, speedValue);         
    // wait for 30 milliseconds to see the effect    
    delay(30);                            
  } 

  // ramp out from max to min in increments of 5 points:
  for(int speedValue = 255 ; speedValue >= 0; speedValue -=5) { 
    // sets the value (range from 0 to 255):
    analogWrite(R1, speedValue);         
    // wait for 30 milliseconds to see the effect    
    delay(30);                            
  } 

}

void off() {
digitalWrite(R1, LOW);
digitalWrite(R2, HIGH);
digitalWrite(R3, LOW);
digitalWrite(R4, HIGH);
}