NeoPixel measuring stick using an ultrasonic distance sensor

NeoPixel_MeasuringStick.ino

// Measuring Stick
// Light up neopixel strip proportional to distance sensor reading

#include <Adafruit_NeoPixel.h>
#define LED_PIN    6
#define LED_COUNT 10
Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);

int trigPin = 12;
int echoPin = 13;

void setup() 
  {
  strip.begin();
  strip.setBrightness(127);  // half brightness
  strip.show();

  Serial.begin (9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  }

void loop() 
  {
  int duration, distance, pixelsToLight;
  int ledCount = LED_COUNT;
  float flPixels;
  float maxDistance = 300.0;  // you can adjust this to your situation

  digitalWrite(trigPin, HIGH);
  delayMicroseconds(1000);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = (duration/2) / 29.1;

// emulate a traffic light
  if (distance >= 300 || distance <= 0)
  {
    Serial.println("Out of range");
    strip.setPixelColor(0, 0, 0, 0);
    strip.setPixelColor(1, 0, 0, 0);
    strip.setPixelColor(2, 0, 0, 0); 
    strip.show();
  }

  else 
  {
    Serial.print(distance);
    Serial.println(" cm");

    flPixels = (distance / maxDistance) * ledCount;
    pixelsToLight = flPixels;  // int will truncate to right of decimal

    Serial.print(pixelsToLight);
    Serial.println(" pixels");

    //first clear all pixels
    for(int i=0; i < LED_COUNT; i++)
    {
      strip.setPixelColor(i, 0, 0, 0);
    }

    //light pixels according to distance measured
    for(int i=0; i < pixelsToLight; i++)
    {
      strip.setPixelColor(i, 0, 127, 0);  //this is a green -- you can use any color you like
    }

    strip.show();
  }

  delay(100);
}