IoT -based water quality sensor

1//include libraries
2#include <SoftwareSerial.h>
3#include <LiquidCrystal.h>
4
5//for  bluetooth - create an object called BTserial, with RX pin at 3 and TX pin at 2
6SoftwareSerial  BTserial(3,2); // RX | TX
7
8//decraration of all our variables
9
10float  reads;
11int pin = A0;
12
13float vOut = 0 ;//voltage drop across 2 points
14float  vIn = 5;
15float R1 = 1000;
16float R2 = 0;
17float buffer = 0;
18float TDS;
19
20float  R = 0;//resistance between the 2 wires
21float r = 0;//resistivity 
22float L  = 0.06;//distance between the wires in m
23double A = 0.000154;//area of cross  section of wire in m^2
24
25float C = 0;//conductivity in S/m
26float Cm = 0;//conductivity  in mS/cm
27
28int rPin = 9;
29int bPin = 5;
30int gPin = 6;
31int rVal = 255;
32int  bVal = 255;
33int gVal = 255;
34
35//we will use this formula to get the resistivity  after using ohm's law -> R = r L/A => r = R A/L
36
37//creating lcd object from  Liquid Crystal library
38LiquidCrystal lcd(7,8,10,11,12,13);
39
40void setup()  {
41  //initialise BT serial and   serial monitor
42  Serial.begin(9600);
43  BTserial.begin(9600);
44
45  //initialise lcd
46  lcd.begin(16, 2);
47
48  //set rgb led pins (all to be pwm pins on Arduino) as output
49  pinMode(rPin,OUTPUT);
50  pinMode(bPin,OUTPUT);
51  pinMode(gPin,OUTPUT);
52  pinMode(pin,INPUT);
53  //Print stagnant message to LCD
54  lcd.print("Conductivity: ");
55}
56
57void  loop() {
58    reads = analogRead(A0);
59  
60  vOut = reads*5/1023;
61  Serial.println(reads);
62//  Serial.println(vOut);
63  buffer = (vIn/vOut)-1;
64  R2 = R1*buffer;
65  Serial.println(R2);
66  delay(500);
67    //convert voltage to resistance
68    //Apply formula mentioned  above
69      r = R2*A/L;//R=rL/A
70    //convert resistivity to condictivity
71    C = 1/r;
72    Cm = C*10;
73    //convert conductivity in mS/cm to TDS
74    TDS = Cm *700;
75    //Set cursor of LCD to next row
76    lcd.setCursor(0,1);
77    lcd.println(C);
78
79    //display corresponding colours on rgb led according  to the analog read
80     if( reads < 600 )
81  {
82      if (reads <= 300){
83        setColor( 255, 0, 255 ) ;
84      }
85      if (reads > 200){
86        setColor(  200, 0, 255 ) ;
87      }
88  }
89  else{
90    if( reads <= 900 )
91    {
92      setColor( 0, 0, 255 ) ;
93    }
94    if( reads > 700 )
95  {
96    setColor(  0, 255, 255 ) ;
97  }
98    }
99
100//send data to Ardutooth app on mobile phone  through bluetooth
101BTserial.print(C);
102BTserial.print(",");
103BTserial.print(TDS);
104BTserial.print(";");
105delay(500);
106}
107
108
109void  setColor(int red, int green, int blue)
110{
111  analogWrite( rPin, 255 - red )  ;
112  analogWrite( gPin, 255 - green ) ;
113  analogWrite( bPin, 255 - blue ) ;  
114}