Code for student using Arduino YUN with HC-05 bluetooth module, full-color LED, and DHT module. Copyright © 2015 by K-ways & Joseph.

colerChange.ino

#include <SoftwareSerial.h>
int val = 0;

int redLEDPin = 9;
int greenLEDPin = 10;
int blueLEDPin = 11;

void setup() {
  pinMode(redLEDPin, OUTPUT);
  pinMode(greenLEDPin, OUTPUT);
  pinMode(blueLEDPin, OUTPUT);
  Serial1.begin(9600);    //This is for bluetooth.
  Serial.begin(9600);      //This is for serial monitor.
}
 
void loop() {
  if ( Serial1.available() ) {
    val = Serial1.read();
    Serial.println(val);
  }
  switch ( val ) {
    case '0':
      analogWrite(redLEDPin, ???);
      analogWrite(greenLEDPin, ???);
      analogWrite(blueLEDPin, ???);
      break;
    case '1':
      analogWrite(redLEDPin, ???);
      analogWrite(greenLEDPin, ???);
      analogWrite(blueLEDPin, ???);
      break;
    case '2':
      analogWrite(redLEDPin, ???);
      analogWrite(greenLEDPin, ???);
      analogWrite(blueLEDPin, ???);
      break;
  }
}

ledControl.ino

#include <SoftwareSerial.h>
int val = 0;

void setup()
{
  pinMode(13, OUTPUT);
  digitalWrite(13, LOW);
  Serial1.begin(9600);    //This is for bluetooth.
  Serial.begin(9600);     //This is for serial monitor.
}

void loop()
{
  if(Serial1.available())
  {
    val = Serial1.read();
  }
  
  switch (val)
  {
    case '0':
      digitalWrite(13, LOW);
      break;
    case '1':
      digitalWrite(13, HIGH);
      break;
  }
}

rgbAllcolor.ino

int redLEDPin = 9;
int greenLEDPin = 10;
int blueLEDPin = 11;
int n = 256;
int t = 5;    //This is the time changing to the next color.
 
void setup()
{
  pinMode(redLEDPin, OUTPUT);
  pinMode(greenLEDPin, OUTPUT);
  pinMode(blueLEDPin, OUTPUT);
  
  analogWrite(redLEDPin, 255);
  analogWrite(greenLEDPin, 0);
  analogWrite(blueLEDPin, 0);
}
 
void loop()
{
  upward(greenLEDPin);
  downward(redLEDPin);
  upward(blueLEDPin);
  downward(greenLEDPin);
  upward(redLEDPin);
  downward(blueLEDPin);
}
 
void upward(int p)
{
  for(int i=0; i<256; i++)
  {
    analogWrite(p, i);
    delay(t);
  }
}
 
void downward(int p)
{
  for(int i=255; i>=0; i--)
  {
    analogWrite(p, i);
    delay(t);
  }
}

rgbControl.ino

#include <SoftwareSerial.h>
int redLEDPin = 9;
int greenLEDPin = 10;
int blueLEDPin = 11;
int mode = 0;
int val = 0;

void setup()
{
  pinMode(redLEDPin, OUTPUT);
  pinMode(greenLEDPin, OUTPUT);
  pinMode(blueLEDPin, OUTPUT);
  Serial1.begin(9600);    //This is for bluetooth.
  Serial.begin(9600);      //This is for serial monitor.
}
 
void loop()
{
  if(Serial1.available())
  {
    mode = Serial1.read();
    switch (mode)
    {
      case 'r':
        Serial1.println("Please enter RED amount (from 0-255): ");
        while(1)
        {
          if(Serial1.available())
          {
            val = Serial1.read();
            Serial1.println("OK");
            analogWrite(redLEDPin, val);
            break;
          }
        }
        break;
        
      case 'g':
        Serial1.println("Please enter GREEN amount (from 0-255): ");
        while(1)
        {
          if(Serial1.available())
          {
            val = Serial1.read();
            Serial1.println("OK");
            analogWrite(greenLEDPin, val);
            break;
          }
        }
        break;
        
      case 'b':
        Serial1.println("Please enter BLUE amount (from 0-255): ");
        while(1)
        {
          if(Serial1.available())
          {
            val = Serial1.read();
            Serial1.println("OK");
            analogWrite(blueLEDPin, val);
            break;
          }
        }
        break;
        
      case 'c':
        Serial1.println("Clear!");
        analogWrite(redLEDPin, 0);
        analogWrite(greenLEDPin, 0);
        analogWrite(blueLEDPin, 0);
    }
  }
}

rgbMix.ino

/*
rgbMix for ThreeForOneCourse
*/

int redLEDPin = 9;
int greenLEDPin = 10;
int blueLEDPin = 11;

void setup() {
  pinMode(redLEDPin, OUTPUT);
  pinMode(greenLEDPin, OUTPUT);
  pinMode(blueLEDPin, OUTPUT);  
}

void loop() {
  //Color1
  analogWrite(redLEDPin, ???);
  analogWrite(greenLEDPin, ???);
  analogWrite(blueLEDPin, ???);  
  delay(1000);
  //Color2
  analogWrite(redLEDPin, ???);
  analogWrite(greenLEDPin, ???);
  analogWrite(blueLEDPin, ???);  
  delay(1000);
  //Color3
  analogWrite(redLEDPin, ???);
  analogWrite(greenLEDPin, ???);
  analogWrite(blueLEDPin, ???);  
  delay(1000);
}

rgbSwitch.ino

int redLEDPin = 9;
int greenLEDPin = 10;
int blueLEDPin = 11;

void setup() {
  pinMode(redLEDPin, OUTPUT);
  pinMode(greenLEDPin, OUTPUT);
  pinMode(blueLEDPin, OUTPUT);  
}

void loop() {
  //Red  (255,0,0)
  analogWrite(redLEDPin, 255);
  analogWrite(greenLEDPin, 0);
  analogWrite(blueLEDPin, 0);  
  delay(1000);
  //Green  (0,255,0)
  analogWrite(redLEDPin, 0);
  analogWrite(greenLEDPin, 255);
  analogWrite(blueLEDPin, 0);  
  delay(1000);
  //Blue  (0,0,255)
  analogWrite(redLEDPin, 0);
  analogWrite(greenLEDPin, 0);
  analogWrite(blueLEDPin, 255);  
  delay(1000);
}

sensor2all.ino

#include <SoftwareSerial.h>
#include "DHT.h"
#define DHTPIN A3     // what pin we're connected to
#define DHTTYPE DHT11   // DHT 11 
DHT dht(DHTPIN, DHTTYPE);

int redLEDPin = 9
int greenLEDPin = 10;
int blueLEDPin = 11;

int mode = 0;

void setup() {
  Serial.begin(9600); 
  Serial1.begin(9600);
  Serial1.println("DHT11 Connecting successfully!");
  pinMode(redLEDPin, OUTPUT);
  pinMode(greenLEDPin, OUTPUT);
  pinMode(blueLEDPin, OUTPUT); 
  pinMode(A5,OUTPUT);
  pinMode(A4,OUTPUT);
  digitalWrite(A5,LOW);
  digitalWrite(A4,HIGH);
  dht.begin();
}

void loop() {
  delay(2000);

  float h = dht.readHumidity();

  float t = dht.readTemperature();

  float f = dht.readTemperature(true);
  
  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(t) || isnan(f)) {
    Serial1.println("Failed to read from DHT sensor!");
    return;
  }

  if (t > 30 && h <= 50 && mode != 1) {
    //Red  (255,0,0)
    analogWrite(redLEDPin, 255);
    analogWrite(greenLEDPin, 0);
    analogWrite(blueLEDPin, 0); 
    Serial1.println("It's too hot !");
    mode = 1;
  }
  if (t <= 30 && h > 50 && mode != 2) {
    //Blue  (0,0,255)
    analogWrite(redLEDPin, 0);
    analogWrite(greenLEDPin, 0);
    analogWrite(blueLEDPin, 255);    
    Serial1.println("It's so humid !");
    mode = 2;
  }
  if (t > 30 && h > 50 && mode != 3) {
    //purple  (255,0,255)
    analogWrite(redLEDPin, 255);
    analogWrite(greenLEDPin, 0);
    analogWrite(blueLEDPin, 255); 
    Serial1.println("It's both hot and humid !");
    mode = 3;
  }
  if (t <= 30 && h <= 50 && mode != 4) {
    //Green  (0,255,0)
    analogWrite(redLEDPin, 0);
    analogWrite(greenLEDPin, 255);
    analogWrite(blueLEDPin, 0); 
    Serial1.println("It's comfortable now ~");
    mode = 4;
  }
  
  float hi = dht.computeHeatIndex(f, h);
}

sensor2monitor.ino

#include <SoftwareSerial.h>
#include "DHT.h"

#define DHTPIN A3     // what pin we're connected to
#define DHTTYPE DHT11   // DHT 11 

// Initialize DHT sensor for normal 16mhz Arduino
DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(9600); 
  Serial.println("DHT11 Connecting successfully!");
  pinMode(A4,OUTPUT);
  pinMode(A5,OUTPUT);
  digitalWrite(A5,LOW);
  digitalWrite(A4,HIGH);
  dht.begin();
}

void loop() {
  // Wait a few seconds between measurements.
  delay(2000);

  // Reading temperature or humidity takes about 250 milliseconds!
  // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
  float h = dht.readHumidity();
  // Read temperature as Celsius
  float t = dht.readTemperature();
  // Read temperature as Fahrenheit
  float f = dht.readTemperature(true);
  
  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(t) || isnan(f)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }
  
  // Compute heat index
  // Must send in temp in Fahrenheit!
  float hi = dht.computeHeatIndex(f, h);

  Serial.print("Humidity: "); 
  Serial.print(h);
  Serial.print(" % ");
  Serial.print("Temperature: "); 
  Serial.print(t);
  Serial.print(" *C ");
  Serial.print(f);
  Serial.print(" *F ");
  Serial.print("Heat index: ");
  Serial.print(hi);
  Serial.println(" *F");
}

sensor2phone.ino

#include <SoftwareSerial.h>
#include "DHT.h"
#define DHTPIN A3     // what pin we're connected to
#define DHTTYPE DHT11   // DHT 11 
// Initialize DHT sensor for normal 16mhz Arduino
DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(9600); 
  Serial1.begin(9600);
  Serial1.println("DHT11 Connecting successfully!");
  pinMode(A4,OUTPUT);
  pinMode(A5,OUTPUT);
  digitalWrite(A5,LOW);
  digitalWrite(A4,HIGH);
  dht.begin();
}

void loop() {
  // Wait a few seconds between measurements.
  delay(2000);

  // Reading temperature or humidity takes about 250 milliseconds!
  // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
  float h = dht.readHumidity();
  // Read temperature as Celsius
  float t = dht.readTemperature();
  // Read temperature as Fahrenheit
  float f = dht.readTemperature(true);
  
  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(t) || isnan(f)) {
    Serial1.println("Failed to read from DHT sensor!");
    return;
  }
  
  // Compute heat index
  // Must send in temp in Fahrenheit!
  float hi = dht.computeHeatIndex(f, h);

  Serial1.print("Humidity: "); 
  Serial1.print(h);
  Serial1.print(" % ");
  Serial1.print("Temperature: "); 
  Serial1.print(t);
  Serial1.print(" *C ");
  Serial1.print(f);
  Serial1.print(" *F ");
  Serial1.print("Heat index: ");
  Serial1.print(hi);
  Serial1.println(" *F");
}

sensorAlarm.ino

#include <SoftwareSerial.h>
#include "DHT.h"
#define DHTPIN A3     // what pin we're connected to
#define DHTTYPE DHT11   // DHT 11 
DHT dht(DHTPIN, DHTTYPE);

int redLEDPin = 9;
int greenLEDPin = 10;
int blueLEDPin = 11;

void setup() {
  Serial.begin(9600); 
  Serial.println("DHT11 Connecting successfully!");
  pinMode(redLEDPin, OUTPUT);
  pinMode(greenLEDPin, OUTPUT);
  pinMode(blueLEDPin, OUTPUT); 
  pinMode(A5,OUTPUT);
  pinMode(A4,OUTPUT);
  digitalWrite(A5,LOW);
  digitalWrite(A4,HIGH);
  dht.begin();
}

void loop() {
  delay(2000);

  float h = dht.readHumidity();

  float t = dht.readTemperature();

  float f = dht.readTemperature(true);
  
  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(t) || isnan(f)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }

  if (t > 30 && h <= 50) {
    //Red  (255,0,0)
    analogWrite(redLEDPin, 255);
    analogWrite(greenLEDPin, 0);
    analogWrite(blueLEDPin, 0); 
  }
  if (t <= 30 && h > 50) {
    //Blue  (0,0,255)
    analogWrite(redLEDPin, 0);
    analogWrite(greenLEDPin, 0);
    analogWrite(blueLEDPin, 255);    
  }
  if (t > 30 && h > 50) {
    //purple  (255,0,255)
    analogWrite(redLEDPin, 255);
    analogWrite(greenLEDPin, 0);
    analogWrite(blueLEDPin, 255); 
  }
  if (t <= 30 && h <= 50) {
    //Green  (0,255,0)
    analogWrite(redLEDPin, 0);
    analogWrite(greenLEDPin, 255);
    analogWrite(blueLEDPin, 0); 
  }
  
  float hi = dht.computeHeatIndex(f, h);

  Serial.print("Humidity: "); 
  Serial.print(h);
  Serial.print(" % ");
  Serial.print("Temperature: "); 
  Serial.print(t);
  Serial.print(" *C ");
  Serial.print(f);
  Serial.print(" *F ");
  Serial.print("Heat index: ");
  Serial.print(hi);
  Serial.println(" *F");
}

setupAT.ino

/*======================================================================================
Setup your HC-05 bluetooth module using Arduino YUN.
This is quite different from Arduino UNO!!
We connect bluetooth module's Rx to Arduino YUN's Tx(D1) and vice versa.
Define "serial" for serial monitor on IDE, and define "Serial1" for HC-05.
WE MUST USING THE SAME SPEED ON "Serial" and "Serial1"!!
So, for the AT setup, we use both 38400 baud as our communication speed.
Note. Set the serial monitor as "NL & CR", baud rate "38400".
======================================================================================*/
 
#include <SoftwareSerial.h>
 
void setup()
{
  Serial1.begin(38400);    //This is for bluetooth.
  Serial.begin(38400);     //This is for serial monitor.
  Serial.println("Enter commands:");
}
 
void loop()
{
  if (Serial1.available())  //If bluetooth has something to tell arduino...
  {
    char data = Serial1.read();
    Serial.print(data);
  }
  if (Serial.available())   //If arduino has something to tell bluetooth...
    Serial1.write(Serial.read());
}