//--------------------------------------
//file  :gas.ino
//author:Victor Chen
//web   :www.vic8051.com
//參考資料:Arduino實作入門與應用 ----台灣/松崗
//--------------------------------------
#include <LiquidCrystal.h>
int bz=8;                                                     
int ad=A0;                                                    
int adc,gv;                                                   
//--------------------------------------                      
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);                        
void setup() {                                                
  lcd.begin(16, 2);                                           
  lcd.print("adc test.... ");                                 
  Serial.begin(9600);                                         
  pinMode(bz, OUTPUT);                                        
  digitalWrite(bz, LOW);                                      
}                                                             
                                                              
void be()                                                     
{                                                             
int i;                                                        
 for(i=0; i<100; i++)                                         
  {                                                           
   digitalWrite(bz, HIGH); delay(1);                          
   digitalWrite(bz, LOW);  delay(1);                          
  } 
}  
//-----------------------------------                         
void loop()                                                   
{                                                             
int i; 
 be();
 lcd.setCursor(0, 0); lcd.print("GAS heating...."); 
 for(i=0; i<3; i++)  delay(1000);
 be();
 while(1)                                                     
  {                                                           
   adc=analogRead(ad);                                        
   lcd.setCursor(0, 1);lcd.print("     ");                    
   lcd.setCursor(0, 1);lcd.print(adc);                        
   Serial.print(adc); Serial.print(' ');                      
   if(adc<500) break;                                         
   delay(500);                                                
  }                                                           
//-------------------------------------
 be();// stand by to check gas                                                             
 lcd.setCursor(0, 0);lcd.print("GAS check      ");            
 gv=200;                                                      
 lcd.setCursor(10, 0);lcd.print(gv);                          
 while(1)                                                     
  {                                                           
   adc=analogRead(ad);                                        
   lcd.setCursor(0, 1);lcd.print("     ");                    
   lcd.setCursor(0, 1);lcd.print(adc);                        
   Serial.print(adc); Serial.print(' ');                      
   if(adc>gv) 
    { be(); //ry                                     
      lcd.setCursor(8, 1);lcd.print("GAS!!!");
    }    
   else {lcd.setCursor(8, 1);lcd.print("      ");}
   delay(500);                                                
  }                                                           
}