int AIA = 5;  
int AIB = 6;  
int BIA = 11; 
int BIB =10; 
int trigPin = 12;
int echoPin = 13;

long previousMillis=0;
long interval=1000;

char val;

void setup() {

  pinMode(AIA, OUTPUT); 
  pinMode(AIB, OUTPUT);
  pinMode(BIA, OUTPUT);
  pinMode(BIB, OUTPUT);
  
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);


  Serial.begin(9600);
}




// Fordward action
void go_forward() {
  analogWrite(AIA, 0);
  analogWrite(AIB, 200);
  analogWrite(BIA, 0);
  analogWrite(BIB, 200);
}


// Stop Forward action
void stop_go_forward() {
  analogWrite(AIA, 0);
  analogWrite(AIB, 0);
  analogWrite(BIA, 0);
  analogWrite(BIB, 0);
}


// Reverse action
void go_reverse() {
analogWrite(AIA, 200);
  analogWrite(AIB, 0);
  analogWrite(BIA, 200);
  analogWrite(BIB, 0);


}


// Stop Reverse action
void stop_go_reverse() {
  analogWrite(AIA, 0);
  analogWrite(AIB, 0);
  analogWrite(BIA, 0);
  analogWrite(BIB, 0);
}


// Left action
void go_left() {
  analogWrite(AIA, 0);
  analogWrite(AIB, 150);
  analogWrite(BIA, 0);
  analogWrite(BIB, 0);
}


// Right action
void go_right() {
 analogWrite(AIA, 0);
  analogWrite(AIB, 0);
  analogWrite(BIA, 0);
  analogWrite(BIB, 150);
}


// Stop turn action
void stop_turn() {
analogWrite(AIA, 0);
  analogWrite(AIB, 0);
  analogWrite(BIA, 0);
  analogWrite(BIB, 0);
}


// Stop car
void stop_car() {
  analogWrite(AIA, 0);
  analogWrite(AIB, 0);
  analogWrite(BIA, 0);
  analogWrite(BIB, 0);
}


void performCommand() {
  if (Serial.available()) {
    val = Serial.read();
  }
    if (val == 'f') { // Forward
      go_forward();
    } else if (val == 'z') { // Stop Forward
      stop_go_forward();
    } else if (val == 'b') { // Backward
      go_reverse();
    } else if (val == 'y') { // Stop Backward
      stop_go_reverse();
    } else if (val == 'l') { // Right
      go_right();
    } else if (val == 'r') { // Left
      go_left();
    } else if (val == 'v') { // Stop Turn
      stop_turn();
    } else if (val == 's') { // Stop
      stop_car();
    }
  
}

void medition(){
  long distance, duration;
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  
  duration = pulseIn(echoPin, HIGH);
  distance = (duration/2) / 29.1;

Serial.print(distance);

}

void loop() {
  performCommand();
  unsigned long currentMillis= millis();
 
  if (currentMillis - previousMillis > interval){
    previousMillis=currentMillis;
    medition();
  }
}