source: de.wigbels.avr/sketchbook/hothotheat/hothotheat.pde

/*
 * HotHotHeat
 *
 * Compile with the Arduino IDE (http://arduino.cc); is deployed against a 
 * Atmel Butterfly - so you also need the Butteruino project
 * (http://code.google.com/p/butteruino/)
 *
 * ...will
 * 1) Read the Butterfly temperature sensor and output
 * the result permanently to UART.
 *
 * 2) Read a reed sensor and output
 * the result permanently to UART
 *
 * Contact: Norbert Wigbels
 * (http://foobla.wigbels.de/uber-foobla/)
 *
 * Format: <# of Sensor> <data>
 * Example: 1  23.4    --    Temperature
 *          2  HIGH    --    Reed count
 *          3  14      --    Total of Reed counts since start of programm
 */
 
#include <butterfly_temp.h>
#include <pins_butterfly.h>

#include <LCD_Driver.h>
#include <timer2_RTC.h>


int inputReed = PBPIN4;
int outputLED = PBPIN7;

int value = 0;
int debounce = 0;
int slewRate = LOW;
int everySecond = 0;

unsigned long gasReeds = 0;
int  temp = 0;


void setup() {
  // Identify butterfly running program...
  LCD.prints_f( PSTR( "HOTHOTHEAT" ) );
  delay( 1400 );

  TempSense.overSample = true;
  pinMode( inputReed, INPUT );
  pinMode( outputLED, OUTPUT );
  
  digitalWrite( outputLED, HIGH );
  temp = TempSense.getTemp( CELSIUS );
  
  Serial.begin( 9600 );
}


void logOutput()
{
  LCD.print( gasReeds );
  LCD.print( " G " );
  LCD.print( temp );
  LCD.println( " C" );

  // Temperature
  Serial.print( "1" );
  Serial.print( "\t" );
  Serial.println( temp );

  // Reed HIGH or Low  
  Serial.print( "2" );
  Serial.print( "\t" );
  if( slewRate==1 ) {
      Serial.println( "HIGH" );
  } else {
      Serial.println( "LOW" );
  }
 
  // Total of Gas Reeds
  Serial.print( "3" );
  Serial.print( "\t" );
  Serial.println( gasReeds );
}


int getSamples() {
  // Sensor 1 - Temperature
  temp = TempSense.getTemp( CELSIUS );
  
  // switchtime of reed is 18 ms including debouncing...
  value = digitalRead( inputReed );
  delay( 20 );
  debounce = digitalRead( inputReed );

  // Sensor 2 - Reedcontact
  // ...we are just interested in falling levels
  // __|----|count_here__|----|_count_here__
  if ( value==debounce ) {    
    if ( value==HIGH ) {
      slewRate=HIGH;
      return HIGH;
    }
    else {
      if( slewRate==HIGH ) {
        slewRate=LOW;
        gasReeds++;
      }
      return LOW;
    }
  }
}


void loop() {  
  // LED marks Butterfly working; dark to mark a reed contact
  if( getSamples()==HIGH ) {
    digitalWrite( outputLED, LOW );
  } else {
    digitalWrite( outputLED, HIGH );
  }
   
  if ( everySecond > 20 ) {
    everySecond = 0;
    logOutput();
  } else {
    everySecond++;
  } 
   
  delay( 30 );
}