Bluetooth Controlled Bot

const int i = 7;
const int in1 = 4;
const int in2 = 5;
const int in3 = 10;
const int in4 = 11;
const int in5 = 12;
unsigned long d;

void setup() {
  pinMode(i, INPUT);
  pinMode(in1, OUTPUT);
  pinMode(in2, OUTPUT);
  pinMode(in3, OUTPUT);
  pinMode(in4, OUTPUT);
  pinMode(in5, OUTPUT);
  Serial.begin(57600);
}
void loop() {
  d = pulseIn(i, HIGH);

  if(22000 <= d && d <= 24000) {
    forwards();
  }
  else if(10000 <= d && d <= 12000) {
    backwards();
  }
  else if(5000 <= d && d <= 7000) {
    left();
  }
  else if(4400 <= d && d <= 4999) {
    right();
  }
  else if(3000 <= d && d <= 4300) {
    digitalWrite(in5, LOW);
    OFF();
  }
  else {
    digitalWrite(in5, HIGH);
    OFF();
  }
}
void forwards() {
  digitalWrite(in1, LOW);
  digitalWrite(in2, HIGH);
  digitalWrite(in3, LOW);
  digitalWrite(in4, HIGH);
}
void backwards() {
  digitalWrite(in1, HIGH);
  digitalWrite(in2, LOW);
  digitalWrite(in3, HIGH);
  digitalWrite(in4, LOW);
}
void left() {
  digitalWrite(in1, HIGH);
  digitalWrite(in2, LOW);
  digitalWrite(in3, LOW);
  digitalWrite(in4, HIGH);
}
void right() {
  digitalWrite(in1, LOW);
  digitalWrite(in2, HIGH);
  digitalWrite(in3, HIGH);
  digitalWrite(in4, LOW);
}
void OFF() {
  digitalWrite(in1, LOW);
  digitalWrite(in2, LOW);
  digitalWrite(in3, LOW);
  digitalWrite(in4, LOW);
}