Room Temperature Based Fan Speed Control

Code with LCD:



#include <LiquidCrystal.h>

LiquidCrystal lcd(7,6,5,4,3,2);

int tempPin = A1;   // the output pin of LM35

int fan = 11;       // the pin where fan is

int led = 8;        // led pin

int temp;

int tempMin = 30;   // the temperature to start the fan 0%

int tempMax = 60;   // the maximum temperature when fan is at 100%

int fanSpeed;

int fanLCD;



void setup() {

  pinMode(fan, OUTPUT);

  pinMode(led, OUTPUT);

  pinMode(tempPin, INPUT);

  lcd.begin(16,2); 

  Serial.begin(9600);

}



void loop()

{ 

   temp = readTemp();     // get the temperature

   Serial.print( temp );

   if(temp < tempMin)     // if temp is lower than minimum temp

   { 

       fanSpeed = 0;      // fan is not spinning

       analogWrite(fan, fanSpeed);

       fanLCD=0;

       digitalWrite(fan, LOW);     

   }

   if((temp >= tempMin) && (temp <= tempMax)) // if temperature is higher than minimum temp

   { 

       fanSpeed = temp;//map(temp, tempMin, tempMax, 0, 100); // the actual speed of fan//map(temp, tempMin, tempMax, 32, 255);

       fanSpeed=1.5*fanSpeed;

       fanLCD = map(temp, tempMin, tempMax, 0, 100);  // speed of fan to display on LCD100

       analogWrite(fan, fanSpeed);  // spin the fan at the fanSpeed speed

   }

 

   if(temp > tempMax) // if temp is higher than tempMax

     {       

     digitalWrite(led, HIGH);  // turn on led

     }

   else               // else turn of led

     {                   

     digitalWrite(led, LOW);

     }

 

   lcd.print("TEMP: ");

   lcd.print(temp);      // display the temperature

   lcd.print("C ");

   lcd.setCursor(0,1);   // move cursor to next line

   lcd.print("FANS: ");

   lcd.print(fanLCD);    // display the fan speed

   lcd.print("%");

   delay(200);

   lcd.clear(); 

}



int readTemp() {  // get the temperature and convert it to celsius

  temp = analogRead(tempPin);

  return temp * 0.48828125;

}