/*
Voltaat learn (http://learn.voltaat.com)
Link for full tutorial:

Tutorial: Measure the CO2 concentration using the Arduino!
Adafruit_ILI9341 Library:
Adafruit_GFX Library:
Wire Library:


The purpose of this sketch is to display the concentration of CO2 gas in ppm obtained from the MQ-135 gas sensor on the TFT Display.

Connections from the Arduino to the breadboard:

•Arduino GND pin → Breadboard ground line
•Arduino 5V pin → Breadboard 5V line

Connections from the MQ-135 gas sensor:

•MQ-135 gas sensor VCC pin → Breadboard 5V line
•MQ-135 gas sensor GND pin → Breadboard ground line
•MQ-135 gas sensor A0 pin → Arduino pin A0

Connections from the passive buzzer :

•passive buzzer GND pin → Breadboard ground line
•passive buzzer VCC pin (+ pin) → Arduino pin 3

Connections from the TFT Display to the breadboard:

•TFT Display VCC pin → Breadboard 5V line
•TFT Display GND pin → Breadboard ground line
•TFT Display LED pin → Breadboard 5V line

Connections from the TFT Display to arduino :

•TFT Display CS pin → Arduino pin 10
•TFT Display RST pin → Arduino pin 8
•TFT Display DC pin → Arduino pin 9
•TFT Display MOSI pin → Arduino pin 11
•TFT Display SCK pin → Arduino pin 13
•TFT Display MISO pin → Arduino pin 12

*/

#include "Adafruit_GFX.h"    
#include "Adafruit_ILI9341.h"
#include "Wire.h"
#include  "SPI.h"

//Define TFT Display pin numbers
#define TFT_DC 9              
#define TFT_CS 10            
#define TFT_RST 8            
#define TFT_MISO 12          
#define TFT_MOSI 11          
#define TFT_CLK 13          

Adafruit_ILI9341 tft = Adafruit_ILI9341(TFT_CS, TFT_DC, TFT_MOSI, TFT_CLK, TFT_RST, TFT_MISO);

#define anInput     A0  //analog feed from MQ135
#define co2Zero     265  //Adjust this value in the calibration process
#define passive_buzzer    3  //define passive buzzer pin
char co2ppmChar[10];  
void setup(){
 
Serial.begin(9600);
tft.begin();                      
tft.setRotation(0);            
tft.fillScreen(ILI9341_BLACK);
pinMode(anInput,INPUT); //MQ135 analog feed set for input
pinMode(passive_buzzer,OUTPUT); //define passive buzzer pin as an output pin

Wire.begin();
printText("CO2 Level", ILI9341_GREEN,20,130,3);

}

void loop()
{
int co2now[10];                               //int array for co2 readings
int co2raw = 0;                               //int for raw value of co2
int co2comp = 0;                              //int for compensated co2
float co2ppm = 0;                             //float for calculated ppm
int zzz = 0;                                  //int for averaging
int grafX = 0;                                //int for x value of graph

for (int x = 0;x<10;x++){                    //samplpe co2 10x over 2 seconds
   co2now[x]=analogRead(A0);
   delay(200);
 }

for (int x = 0;x<10;x++){                     //add samples together
   zzz=zzz + co2now[x];
   
 }
 co2raw = zzz/10;                            //divide samples by 10
 co2comp = co2raw - co2Zero;                 //get compensated value
 co2ppm = map(co2comp,0,1023,400,5000);      //map value for atmospheric levels


String co2ppmString = String(co2ppm,1); //Convert float to string

co2ppmString.toCharArray(co2ppmChar,10);

tft.fillRect(50,175,150,40,ILI9341_BLACK); //Draw a Rectangle

printText(co2ppmChar, ILI9341_WHITE,30,180,4); //printing the co2 gas concentration on the TFT Display

printText("ppm", ILI9341_WHITE,160,180,4);

grafX = map(co2ppm,0,1000,0,127);           //map value to screen width

tft.fillRect(0, 235, grafX, 30, ILI9341_WHITE);  //print graph 400min 1000max

if(co2ppm>999){                             //if co2 ppm > 1000
   digitalWrite(passive_buzzer,HIGH);                   //turn on the buzzer
}
else{                                       //if not
   digitalWrite(passive_buzzer,LOW);                    //turn off the buzzer
}

delay(500);

}

//The function of writing words on the TFT Display
void printText(char *text, uint16_t color, int x, int y,int textSize)
{
 tft.setCursor(x, y);
 tft.setTextColor(color);
 tft.setTextSize(textSize);
 tft.setTextWrap(true);
 tft.print(text);
}