Breathalyzer

/*
  Analog input, analog output, serial output

 Reads an analog input pin, maps the result to a range from 0 to 255
 and uses the result to set the pulsewidth modulation (PWM) of an output pin.
 Also prints the results to the serial monitor.

 The circuit:
 * potentiometer connected to analog pin 0.
   Center pin of the potentiometer goes to the analog pin.
   side pins of the potentiometer go to +5V and ground
 * LED connected from digital pin 9 to ground

 created 29 Dec. 2008
 modified 9 Apr 2012
 by Tom Igoe

 This example code is in the public domain.

 */

#include <Wire.h>  // Comes with Arduino IDE
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);  // Set the LCD I2C address

// These constants won't change.  They're used to give names
// to the pins used:
const int analogInPin = A0;  // Analog input pin that the potentiometer is attached to
const int analogOutPin = 9; // Analog output pin that the LED is attached to

int s = 0;        // value read from the pot
int outputValue = 0;        // value output to the PWM (analog out)

void setup() {
  // initialize serial communications at 9600 bps:
  Serial.begin(9600);
  pinMode(8,OUTPUT);
  pinMode(9,OUTPUT);
  pinMode(10,OUTPUT);
  pinMode(11,OUTPUT);
  digitalWrite(8,LOW);
  digitalWrite(9,LOW);
  digitalWrite(10,LOW);
  digitalWrite(11,LOW);

  lcd.begin(16,2);   // initialize the lcd for 16 chars 2 lines, turn on backlight
  lcd.backlight(); // finish with backlight on

  lcd.clear();
  lcd.setCursor(0,0); //Start at character 0 on line 0
  lcd.print("XXXXXXXX");
  lcd.setCursor(0,1);
  lcd.print("Alchohol level");
}

void loop() {
  // read the analog in value:
  s = analogRead(analogInPin);
  // map it to the range of the analog out:
  //outputValue = map(sensorValue, 0, 1023, 0, 255);
  // change the analog out value:
  analogWrite(analogOutPin, outputValue);

if(s<400) {
 digitalWrite(9,LOW);
 digitalWrite(10,HIGH);
 digitalWrite(11,LOW);
  lcd.clear();
  lcd.setCursor(0,0); //Start at character 0 on line 0
  lcd.print("Low");
  lcd.setCursor(0,1);
  lcd.print("Alchohol level");
}
else if ((s>=400)&&(s<600)){
 digitalWrite(9,HIGH);
 digitalWrite(10,LOW);
 digitalWrite(11,LOW);
  lcd.clear();
  lcd.setCursor(0,0); //Start at character 0 on line 0
  lcd.print("Medium");
  lcd.setCursor(0,1);
  lcd.print("Alchohol level");
}
else if (s>=600){
 digitalWrite(9,LOW);
 digitalWrite(10,LOW);
 digitalWrite(11,HIGH);
  lcd.clear();
  lcd.setCursor(0,0); //Start at character 0 on line 0
  lcd.print("High");
  lcd.setCursor(0,1);
  lcd.print("Alchohol level");

}

  // print the results to the serial monitor:
  Serial.print("sensor = " );
  Serial.print(s);
  Serial.print("\t output = ");
  Serial.println(outputValue);

  // wait 2 milliseconds before the next loop
  // for the analog-to-digital converter to settle
  // after the last reading:
  delay(2);
}