DiWa Corona Belt - Enforce Social Distancing

// DiWa Corona Belt
// March 25, 2020

int TriggerPin = 8; // Digital 8 -> HC-SR04 Trigger
int EchoPin = 9;    // Digital 9 -> HC-SR04 Echo
// HC-SR04 Vcc -> 5V, GNG -> GND
#include "FastLED.h"

#define ANZAHL_LEDS 26
#define LED_PIN 2
CRGB leds[ANZAHL_LEDS];

void setup()
{
  Serial.begin(9600);
  FastLED.addLeds<NEOPIXEL, LED_PIN>(leds, ANZAHL_LEDS);
  for (int i = 0; i < ANZAHL_LEDS; i++) {
    leds[i] = CRGB::Black;
    FastLED.show();
  }
  delay (5000);
}

void loop()
{
  // establish variables for duration of the ping,
  // and the distance result in inches and centimeters:
  long duration, cm;

  // The PING))) is triggered by a HIGH pulse of 2 or more microseconds.
  // Give a short LOW pulse beforehand to ensure a clean HIGH pulse:
  pinMode(TriggerPin, OUTPUT);
  digitalWrite(TriggerPin, LOW);
  delayMicroseconds(2);
  digitalWrite(TriggerPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(TriggerPin, LOW);

  // The same pin is used to read the signal from the PING))): a HIGH
  // pulse whose duration is the time (in microseconds) from the sending
  // of the ping to the reception of its echo off of an object.
  pinMode(EchoPin, INPUT);
  duration = pulseIn(EchoPin, HIGH);

  // convert the time into a distance
  cm = microsecondsToCentimeters(duration);
  if (cm <= 500)
  {
    Serial.print(cm);
    Serial.println("cm");
  }
  else Serial.println("Ungueltige Messung ! Entfernung groesser als 5 Meter !!!");
  delay(100);
  
  if (cm < 150 && cm > 10){
    for (int blinken = 0; blinken <3; blinken++){
      for (int i = 0; i < ANZAHL_LEDS; i++) {
        leds[i] = CRGB::Red;
        FastLED.show();
      }
      tone(6, 400); // …spiele diesen Ton...
      delay(300); //…und zwar für eine Sekunde...
      noTone(6); // Ton abschalten
      for (int i = 0; i < ANZAHL_LEDS; i++) {
        leds[i] = CRGB::Black;
        FastLED.show();
      }
      tone(6, 700); // …spiele diesen Ton...
      delay(300); //…und zwar für eine Sekunde...
      noTone(6); // Ton abschalten
    }  
    cm = 0;  
  }
}

long microsecondsToCentimeters(long microseconds)
{
  // The speed of sound is 340 m/s or 29 microseconds per centimeter.
  // The ping travels out and back, so to find the distance of the
  // object we take half of the distance travelled.
  return microseconds / 29 / 2;
}