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/*
Arduino --> ThingSpeak Channel via Ethernet

This sketch updates a channel feed with sensor inputs 
via the ThingSpeak API (https://thingspeak.com/docs)
using HTTP POST. 

The Arduino uses DHCP and DNS for a simpler network setup.
The sketch also includes a Watchdog / Reset function to make sure the
Arduino stays connected and/or regains connectivity after a network outage.
Use the Serial Monitor on the Arduino IDE to see verbose network feedback
and ThingSpeak connectivity status.

Sensors:
* DHT22
* Simple Solar Cell
* NOx Sensor MQ135 
* Micro Particle Sensor Sharp GP2Y1010AU0F 

Based on a sketches written by: 
* Hans Scharler (http://www.iamshadowlord.com)
* Arduino Team
* Deng Peng for Micro Particle Sensor 
* Ethernet by Adrian McEwen
* Compiled by Thomas Thurner
*/

// Definition für Ethernet Shield -----------------
#include <SPI.h>
#include <Ethernet.h>

// Definition für DHT -----------------
#define DHTPIN 2 // what pin we're connected to
#define DHTTYPE DHT22 // DHT 22 (AM2302)
#include "DHT.h"

// Setup DHT ----------------------------------
DHT dht(DHTPIN, DHTTYPE);

// Definition DUST ----------------------------------
int dustPin=2;
int dustVal=0;
 
int ledPower=3;
int delayTime=280;
int delayTime2=40;
float offTime=9680;



// Setup SolarCell ----------------------------------
const int analogInPin = A1;  // Analog input pin that the potentiometer is attached to
int sensorValue = 0;        // value read from the pot

// Setup MQ135 ----------------------------------
const int MQ135PIN = A0;  // Analog input pin that the potentiometer is attached to
int gas = 0; 

// Local Network Settings  ----------------------------------
byte mac[] = { 0xD4, 0x28, 0xB2, 0xFF, 0xA0, 0xA1 }; // Must be unique on local network

// ThingSpeak Settings  ----------------------------------
char thingSpeakAddress[] = "api.thingspeak.com";
String writeAPIKey = "XWLYV67U7D22XCLU";
const int updateThingSpeakInterval = 16 * 1000; // Time interval in milliseconds to update ThingSpeak (number of seconds * 1000 = interval)
// Variable Setup
long lastConnectionTime = 0;
boolean lastConnected = false;
int failedCounter = 0;
// Initialize Arduino Ethernet Client
EthernetClient client;
void setup()
{
// Start Serial for debugging on the Serial Monitor
Serial.begin(9600);

// Setup DUST ----------------------------------
pinMode(ledPower,OUTPUT);
pinMode(4, OUTPUT);


// Start Ethernet on Arduino
startEthernet();
}

// LOOP   ----------------------------------

void loop()
{
// Read DHT ----------------------------------
  String temperatur = String(dht.readTemperature(), DEC);
  String humidity = String(dht.readHumidity(), DEC);
  
// Read SolarCell ----------------------------------
  String light = String(analogRead(analogInPin), DEC);
  
// MQ135 ----------------------------------
  String gas = String(analogRead(MQ135PIN), DEC);
  
// DUST ----------------------------------
digitalWrite(ledPower,LOW); // power on the LED
delayMicroseconds(delayTime);
String dustVal = String(analogRead(dustPin), DEC); // read the dust value via pin 5 on the sensor
delayMicroseconds(delayTime2);
digitalWrite(ledPower,HIGH); // turn the LED off
delayMicroseconds(offTime);

// Print Update Response to Serial Monitor  ----------------------------------
if (client.available())
{
char c = client.read();
Serial.print(c);
}
// Disconnect from ThingSpeak  ----------------------------------
if (!client.connected() && lastConnected)
{
Serial.println("...disconnected");
Serial.println();
client.stop();
}
// Update ThingSpeak  ----------------------------------
if(!client.connected() && (millis() - lastConnectionTime > updateThingSpeakInterval))
{
updateThingSpeak("field1="+temperatur+"&field2="+humidity+"&field3="+light+"&field4="+gas+"&field5="+dustVal);
}
// Check if Arduino Ethernet needs to be restarted  ----------------------------------
if (failedCounter > 3 ) {startEthernet();}
lastConnected = client.connected();
}
void updateThingSpeak(String tsData)
{
if (client.connect(thingSpeakAddress, 80))
{
client.print("POST /update HTTP/1.1\n");
client.print("Host: api.thingspeak.com\n");
client.print("Connection: close\n");
client.print("X-THINGSPEAKAPIKEY: "+writeAPIKey+"\n");
client.print("Content-Type: application/x-www-form-urlencoded\n");
client.print("Content-Length: ");
client.print(tsData.length());
client.print("\n\n");
client.print(tsData);
lastConnectionTime = millis();
if (client.connected())
{
Serial.println("Connecting to ThingSpeak...");
Serial.println();
failedCounter = 0;
}
else
{
failedCounter++;
Serial.println("Connection to ThingSpeak failed ("+String(failedCounter, DEC)+")");
Serial.println();
}
}
else
{
failedCounter++;
Serial.println("Connection to ThingSpeak Failed ("+String(failedCounter, DEC)+")");
Serial.println();
lastConnectionTime = millis();
}
}
void startEthernet()
{
client.stop();
Serial.println("Connecting Arduino to network...");
Serial.println();
delay(1000);
// Connect to network amd obtain an IP address using DHCP
if (Ethernet.begin(mac) == 0)
{
Serial.println("DHCP Failed, reset Arduino to try again");
Serial.println();
}
else
{
Serial.println("Arduino connected to network using DHCP");
Serial.println();
}
delay(1000);
}