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Author Topic: Help with DHT11  (Read 4442 times)
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- http://arduino.cc/playground/Main/DHTLib -

is 1.0 compatible but I have to update

- http://arduino.cc/playground/Main/DHT11Lib -

going to fix it now ...
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Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
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done.
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Rob Tillaart

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If you are looking for dew point and conversions, I use this code:
Code:
// dewPoint function NOAA
// reference: http://wahiduddin.net/calc/density_algorithms.htm
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);
}

// delta max = 0.6544 wrt dewPoint()
// 5x faster than dewPoint()
// reference: http://en.wikipedia.org/wiki/Dew_point
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;
}

//Celsius to Fahrenheit conversion
float Fahrenheit(float celsius)
{
  return 1.8 * celsius + 32;
}


duckie
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