exx21

/*
exercise 2.1 - Climate Control Judge
Created 14/04/2010 ---  By John Boxall --- http://tronixstuff.com ---  CC by-sa v3.0 Share the love!
Measures temperature with Analog Devices TMP36 and compares against minimum temperature to use a heater or air conditioner
*/
int redLED = 13; // define which colour LED is in which digital output
int greenLED = 12;
int blueLED = 11;
float voltage = 0; // set up some variables for temperature work
float sensor = 0;
float celsius = 0;
float heaterOn = 15; // it's ok to turn on the heater if the temperature is below this value
float airconOn = 26; // it's ok to turn on the air conditioner if the temperature is above this value
void setup()
{
pinMode(redLED, OUTPUT);    // set the digital pins for LEDs to outputs
pinMode(greenLED, OUTPUT);  // not necessary for analogue input pin
pinMode(blueLED, OUTPUT);
}
void loop()
{
digitalWrite(redLED, LOW);    // switch off the LEDs
digitalWrite(greenLED, LOW);
digitalWrite(blueLED, LOW);
// read the temperature sensor and convert the result to degrees Celsius
sensor = analogRead(0);       // TMP36 sensor output pin is connected to Arduino analogue pin 0
voltage = (sensor*5000)/1024; // convert raw sensor value to millivolts
voltage = voltage-400;        // remove voltage offset
celsius = voltage/10;         // convert millivolts to Celsius
// now decide if it is too hot or cold.
if (celsius>=airconOn)
{
digitalWrite(blueLED, HIGH); // ok to turn on the air conditioner
} else if (celsius<=heaterOn)
{
digitalWrite(redLED, HIGH);
} else
{
digitalWrite(greenLED, HIGH); // everything normal
}
delay(1000); // necessary to hold reading, otherwise the sketch runs too quickly and doesn't give the LEDs enough time to
                 // power up before shutting them down again
}