거리에 따라 LED불빛이 변화가 되어야합니다.
 1) 0~1m 까지 LED 1개 ON     2)    ~2m 까지 LED 2개 ON   3)    ~3m 까지 LED 3개 ON
#define triggerPin 8
#define echoPin 9
#define Pin A0
#define CTM 10
     
int distanceThreshold = 0;
     
int cm = 0;
     
void setup() {
Serial.begin(9600);
  
  {
  pinMode(triggerPin, OUTPUT);
  digitalWrite(triggerPin,LOW);
  delayMicroseconds(2);
  digitalWrite(triggerPin,HIGH);
  delayMicroseconds(10);
  digitalWrite(triggerPin,LOW);
  pinMode(echoPin,INPUT);
}
  
  pinMode(2, OUTPUT);
  pinMode(3, OUTPUT);
  pinMode(4, OUTPUT);
  pinMode(5, OUTPUT);
  pinMode(6, OUTPUT);
  pinMode(7, OUTPUT);
  
  
  pinMode(triggerPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(A1, OUTPUT);
  digitalWrite(A1, HIGH);
  pinMode(A2, OUTPUT);
  digitalWrite(A2, LOW);
}
void loop() {
  int dur4, dur3;
  float dis4, dis3;
  digitalWrite(triggerPin, HIGH);
  delayMicroseconds(CTM);
  digitalWrite(triggerPin, LOW);
  dur4 = pulseIn(echoPin, HIGH);
  dis4 = (float) dur4 * 0.017;
  Serial.print(dis4);
  Serial.println(" cm");
  
  pinMode(Pin, OUTPUT);
  digitalWrite(Pin, LOW);
  delayMicroseconds(2);
  pinMode(Pin, OUTPUT);
  digitalWrite(Pin, HIGH);
  delayMicroseconds(CTM);
  digitalWrite(Pin, LOW);
  pinMode(Pin, INPUT);
  
  dur3 = pulseIn(Pin, HIGH);
  dis3 = (float) dur3 * 0.017;
   Serial.print(dis4);
  Serial.println(" cm");
  
  distanceThreshold = 300;
  Serial.print(cm);
  Serial.print("cm, ");
  
if (cm >= distanceThreshold) {
    digitalWrite(2, HIGH);
    digitalWrite(3, HIGH);
    digitalWrite(4, HIGH);
    digitalWrite(5, HIGH);
    digitalWrite(6, HIGH);
    digitalWrite(7, HIGH); 
  
  }
  if (cm < distanceThreshold & distanceThreshold - 100 <= cm) {
    digitalWrite(2, HIGH);
    digitalWrite(3, HIGH);
    digitalWrite(4, LOW);
    digitalWrite(5, HIGH);
    digitalWrite(6, HIGH);
    digitalWrite(7, LOW);
    
  }
    if (cm < distanceThreshold & distanceThreshold - 200 <= cm) {
    digitalWrite(2, HIGH);
    digitalWrite(3, LOW);
    digitalWrite(4, LOW);
    digitalWrite(5, HIGH);
    digitalWrite(6, LOW);
    digitalWrite(7, LOW);
  }  
      
  delay(100);
}
 
 
이렇게 코딩하면 거리측정만 가능하고 LED에 불빛이 안 들어옵니다...