Posted on Leave a comment

Arduino LCD thermometer code

<pre lang="”LANGUAGE”">double Fahrenheit(double celsius) 

{

 return 1.8 * celsius + 32;

} //摄氏温度度转化为华氏温度
 

double Kelvin(double celsius)

{

 return celsius + 273.15;

} //摄氏温度转化为开氏温度
 

// 露点(点在此温度时,空气饱和并产生露珠)

// 参考: [url=http://wahiduddin.net/calc/density_algorithms.htm]http://wahiduddin.net/calc/density_algorithms.htm[/url] 

double dewPoint(double celsius, double humidity)

{

 double A0= 373.15/(273.15 + celsius);

 double SUM = -7.90298 * (A0-1);

 SUM += 5.02808 * log10(A0);

 SUM += -1.3816e-7 * (pow(10, (11.344*(1-1/A0)))-1) ;

 SUM += 8.1328e-3 * (pow(10,(-3.49149*(A0-1)))-1) ;

 SUM += log10(1013.246);

 double VP = pow(10, SUM-3) * humidity;

 double T = log(VP/0.61078); // temp var

 return (241.88 * T) / (17.558-T);

}
 

// 快速计算露点,速度是5倍dewPoint()

// 参考: [url=http://en.wikipedia.org/wiki/Dew_point]http://en.wikipedia.org/wiki/Dew_point[/url]

double dewPointFast(double celsius, double humidity)

{

 double a = 17.271;

 double b = 237.7;

 double temp = (a * celsius) / (b + celsius) + log(humidity/100);

 double Td = (b * temp) / (a - temp);

 return Td;

}
 

#include &lt;dht11.h&gt;

#include &lt;Wire.h&gt;

#include &lt;LiquidCrystal_I2C.h&gt;
 

LiquidCrystal_I2C lcd(0x27,16,2); // set the LCD address to 0x27 for a 16 chars and 2 line display
 

dht11 DHT11;
 

#define DHT11PIN 2
 

void setup()

{

 lcd.init(); // initialize the lcd 

 lcd.backlight();

 lcd.print("Waiting...");

 Serial.begin(9600); 

}

void loop()

{

 int chk = DHT11.read(DHT11PIN);
 

 switch (chk)

 {

 case DHTLIB_OK: 

 lcd.setCursor(0, 0);

 lcd.print("Temp:");

 lcd.print((float)DHT11.temperature,2);

 lcd.write(0xDF);

 lcd.print("C");
 

 lcd.setCursor(0, 1);

 lcd.print("Humidity:");

 lcd.print((float)DHT11.humidity,2);

 lcd.print("%");
 

 break;

 case DHTLIB_ERROR_CHECKSUM: 

 lcd.clear();

 lcd.print("Checksum error"); 

 delay(1000); 

 lcd.clear();

 break;

 case DHTLIB_ERROR_TIMEOUT: 

 lcd.clear();

 lcd.print("Time out error"); 

 delay(1000); 

 lcd.clear();

 break;

 default: 

 lcd.clear();

 lcd.print("Unknown error"); 

 delay(1000); 

 lcd.clear();

 break;

 }

 delay(1000);

}</pre>
Leave a Reply

Your email address will not be published. Required fields are marked *