Arduino ambient temperature display

TempDisplay.ino

/**
 * Simple Ambient temperature display.
 *
 * Will display the temperature in both Fahrenheit and Celsius and
 * adjust the backlight color depending on the temperature.
 *
 * If the temperature range is between 61F and 67F, the display will be
 * green.  Above and it will be red, below is blue.
 *
 * More information is available here: 
 * http://analogmachines.com/blog/2012/01/30/ambient-temperature-display/
 *
 * This is for use with the Adafruit RGB backlight positive LCD
 * (http://www.adafruit.com/products/398) and uses example code from
 * their tutorial for changing the backlight color (http://www.ladyada.net/learn/lcd/charlcd.html).
 */

#include <LiquidCrystal.h>
#include <Wire.h> 

#define TEMP_PIN 0

#define REDLITE 3
#define GREENLITE 5
#define BLUELITE 6

#define numSamples 5
 
// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);
 
// you can change the overall brightness by range 0 -> 255
int brightness = 255;

float samples[numSamples];

void setup() {
  lcd.begin(16, 2);  
  Serial.begin(9600);
  brightness = 255;
  
  // init samples
  for (int i=0; i< numSamples; i++) {
    samples[i] = _getTempReading();
  }
}
 
void loop() {
  float temperatureC = getAvgTempReading();
  float temperatureF = (temperatureC * 9.0 / 5.0) + 32.0;

  lcd.setCursor(0,0);
  lcd.print(temperatureF);
  lcd.print(" F");
  lcd.setCursor(0,1);
  lcd.print(temperatureC);
  lcd.print(" C");

  if (temperatureF < 61) {
    setBacklight(0, 0, 255);
  } else if (temperatureF > 67) {
    setBacklight(255, 0, 0);
  } else {
    setBacklight(0, 255, 0);
  }
 
  delay(1000);
}


float _getTempReading() {
  int reading = analogRead(TEMP_PIN);
  float voltage = (reading * 5.0) / 1024;
  return (voltage - 0.5) * 100;
}

unsigned int counter = 0;
float getAvgTempReading() {
  samples[counter++ % numSamples] = _getTempReading();
  int i=0;
  float sum = 0;
  for (i=0; i< numSamples; i++) {
    sum+=samples[i];
  }
  
  return sum/numSamples;
}

 
void setBacklight(uint8_t r, uint8_t g, uint8_t b) {
  // normalize the red LED - its brighter than the rest!
  r = map(r, 0, 255, 0, 100);
  g = map(g, 0, 255, 0, 150);
 
  r = map(r, 0, 255, 0, brightness);
  g = map(g, 0, 255, 0, brightness);
  b = map(b, 0, 255, 0, brightness);
 
  // common anode so invert!
  r = map(r, 0, 255, 255, 0);
  g = map(g, 0, 255, 255, 0);
  b = map(b, 0, 255, 255, 0);
  analogWrite(REDLITE, r);
  analogWrite(GREENLITE, g);
  analogWrite(BLUELITE, b);
}