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// Beispielcode, um Temperatur/Luftfeuchtigkeit
// eines DHT22 auf einem Sparkfun SerialLCD auszugeben
 
#include "DHT.h"
#include <SoftwareSerial.h>
 
#define DHTPIN 2     // Pin für den DHT22
SoftwareSerial mySerial(4,3); // SoftwareSerial für das LCD
 
#define DHTTYPE DHT22   // DHT 22  (AM2302)
DHT dht(DHTPIN, DHTTYPE);
 
float maxtemp = 0.0;
float mintemp = 100.0;
 
 
void setup() {
  mySerial.begin(9600); // starte LCD Verbindung
  Serial.begin(9600); // starte zus. serielle Verbindung
  delay(500); // wait for display to boot up
 
  mySerial.write(254); // setze Cursor in die erste Zeile
  mySerial.write(128);
 
  mySerial.write("                "); // clear LCD
  mySerial.write("                ");
  delay(500);
  mySerial.write("  DHT22 Sensor");
 
  dht.begin();
}
 
char tempstring[10], humstring[10];
 
void loop() {
  float h = dht.readHumidity();
  float t = dht.readTemperature();
  delay(5000); // lese alle 5 Sekunden ein
 
  // check if returns are valid, if they are NaN (not a number) then something went wrong!
  if (isnan(t) || isnan(h)) {
    mySerial.write(254); // move cursor to beginning of first line
    mySerial.write(128);
    mySerial.println("DHT22 nicht gefunden");
  } else {
    mySerial.write(254); // move cursor to beginning of first line
    mySerial.write(128);
    mySerial.write("                "); // clear display
    mySerial.write("                ");
    mySerial.write(254); // move cursor to beginning of first line
    mySerial.write(128); 
    mySerial.print(t);
    mySerial.print(" *C ");      
    mySerial.print(h);
    mySerial.print("%");
    mySerial.write(254); // move cursor to beginning of 2nd line
    mySerial.write(192);
    if (t<mintemp){mintemp = t;};
    if (t>maxtemp){maxtemp = t;};
    mySerial.print(mintemp);
    mySerial.print(" ");
    mySerial.print(maxtemp);
    Serial.println(t);
 
  }
}