SendTempHumiPressViaESPtoThingSpeak

//DHT22 connection
// Connect pin 1 (on the left) of the sensor to +5V
// Connect pin 2 of the sensor to whatever your DHTPIN is
// Connect pin 4 (on the right) of the sensor to GROUND
// Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor

#include "DHT.h"
#define DHTPIN 13     //digital pin
#include <Adafruit_Sensor.h>
#include <Adafruit_BMP085_U.h>
Adafruit_BMP085_Unified bmp = Adafruit_BMP085_Unified(10085);
#include <Wire.h>
/*#include <LCD.h>
#include <LiquidCrystal_I2C.h>
#define I2C_ADDR    0x27  // Define I2C Address where the PCF8574A is
#define BACKLIGHT_PIN     3
#define En_pin  2
#define Rw_pin  1
#define Rs_pin  0
#define D4_pin  4
#define D5_pin  5
#define D6_pin  6
#define D7_pin  7*/
#define DHTTYPE DHT22   // DHT 22  (AM2302)
//LiquidCrystal_I2C	lcd(I2C_ADDR,En_pin,Rw_pin,Rs_pin,D4_pin,D5_pin,D6_pin,D7_pin);
DHT dht(DHTPIN, DHTTYPE);

#include <SoftwareSerial.h> //Software Serial is needed to interface with ESP8266 because the hardware serial 
//is being used for monitoring Serial line with computer during trouble shooting.
SoftwareSerial ESP8266(10,11);//RX,TX



#define IP "184.106.153.149" // thingspeak.com IP address; see their website for more detail
String GET = "GET /update?api_key=PBYP9SAE447AVT24&field"; // you channel will have unique code
String field1="1=";
String field2="2=";
String field3="3=";
String field4="4=";

float h_=0.0,hi_=0.0,f_=0.0,p_=0.0;

void setup() {
  // put your setup code here, to run once:
  /*lcd.begin (16,2);
  lcd.setBacklightPin(BACKLIGHT_PIN,POSITIVE);
  lcd.setBacklight(HIGH);
  lcd.home ();*/              
  Serial.begin(9600); // this is to start serial monitoring with your Arduino IDE Serial monitor.
  ESP8266.begin(9600); // this is to start serial communication with the ESP via Software Serial.
  ESP8266.println("AT+RST"); // this resets the ESP8266.
  Serial.println("AT+RST"); // this is just echoing the command to your serial monitor so you can
  // follow what is going on - this is not really needed.
  // through out the code below I echo almost everything to the Serial monitor which you
  // you don't have to do and can eliminate from the code.
 
  delay(2000);
  dht.begin();
  if(!bmp.begin())
  {
    /* There was a problem detecting the BMP085 ... check your connections */
    Serial.print("Ooops, no BMP085 detected ... Check your wiring or I2C ADDR!");
    while(1);
  }
  ESP8266.println("AT");
  Serial.println("AT");
  
  delay(5000);
  if(ESP8266.find("OK")){
      Serial.println("OK");  
  
      Serial.println("Connected");
  }    
}

void loop() {
  delay(2000);
  sensors_event_t event;
  bmp.getEvent(&event);
  char buffer[16];
  Serial.println("in the main loop");
  // 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);
  // Compute heat index
  // Must send in temp in Fahrenheit!
  float hi = dht.computeHeatIndex(f, h);
  /*lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("H:");lcd.print(h,2);
  lcd.print(" F:");lcd.print(f,2);
  lcd.setCursor(0,1);
  lcd.print("HI:");lcd.print(hi,2);*/
  float temperature;
  bmp.getTemperature(&temperature);
  float seaLevelPressure = 1000.3; // adjusted for Minnesota 1mb = 1hPa
  //lcd.print("mb:");lcd.print(event.pressure,2);
  
  Serial.print("Humidity: "); 
  Serial.print(h);
  Serial.print(" %\t");
  Serial.print("Temperature: "); 
  //Serial.print(t);
  //Serial.print(" *C ");
  Serial.print(f);
  Serial.println(" *F\t");
  Serial.print("Heat index: ");
  Serial.print(hi);
  Serial.println(" *F");
  Serial.print("Altitude in meter: ");
  Serial.println(bmp.pressureToAltitude(seaLevelPressure,event.pressure,temperature));
  Serial.print("Pressure in mb or hPA: ");
  Serial.println(event.pressure);
  String tempF=dtostrf(f,4,1,buffer);
  Serial.println(tempF);
  if(abs(f-f_)>=0.2) { 
    update(tempF,field1,"f_");
    f_=f;
  }
  //delay(120000);
  String humidity=dtostrf(h,4,1,buffer);
  Serial.println(humidity);
  if (abs(h-h_)>=0.5) {
    update(humidity,field2,"h_");
    h_=h;
  }
  //delay(120000);
  String heatindex=dtostrf(hi,4,1,buffer);
  Serial.println(heatindex);
  if (abs(hi-hi_)>=0.1) {
     update(heatindex,field3,"hi_");
     hi_=hi;
  }   
    
  String pressurehPA=dtostrf(event.pressure,4,1,buffer);
  Serial.println(pressurehPA);
  if (abs(event.pressure-p_)>1.0) {
    update(pressurehPA,field4,"p_");
    p_=event.pressure;
  }
  delay(1000);
  Serial.println("loop-de-loop");  
}

void update(String value, String field, String previous_value_var){

  Serial.println("in the update loop"); 
  ESP8266.println("AT+RST"); // it seems that mine works better if I reset it everytime before I do CIPSTART
  Serial.println("AT+RST");
  delay(5000);
  String cmd = "AT+CIPSTART=\"TCP\",\""; //standard code. see https://github.com/espressif/esp8266_at/wiki //
  cmd += IP; // += is concatenating the previous cmd string with the content of IP
  cmd += "\",80"; // same thing here it just keep adding stuff to the cmd string content

  ESP8266.println(cmd);//type in the string in cmd into the ESP8266
  Serial.println(cmd);
  delay(5000);
  
  if(ESP8266.find("Error")){
    Serial.println("AT+CIPSTART Error");
    return;
  }
  cmd = GET;
  cmd += field;
  cmd += value;
  cmd += "\r\n\r\n"; // it seems that this part is important, to input enough \r\n, mine does not work if I only have one pair.
  ESP8266.print("AT+CIPSEND="); 
  ESP8266.println(cmd.length());
  Serial.print("AT+CIPSEND=");
  Serial.println(cmd.length());
  delay(17000);
  if(ESP8266.find(">")){ // if ESP8266 return the > prompt back from the CIPSEND command, you are set, if not something is wrong
    ESP8266.print(cmd); //type in the GET command string and done
    Serial.print(">");
    Serial.println(cmd);
    previous_value_var=value;    
  }
  else
  {
   //Serial.println("AT+CIPCLOSE"); //this command somehow does not work and always return errors so I just comment it out
   Serial.println("AT+CIPSEND error");
  }

}