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* Changing Pressure reading to pressure_raw #33

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* Changing Pressure reading to pressure_raw #33

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17 changes: 14 additions & 3 deletions Firmware/Weather_Shield_with_GPS_V12/Weather_Shield_with_GPS_V12.ino
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Original file line number Diff line number Diff line change
Expand Up @@ -405,6 +405,17 @@ int get_wind_direction()
return (-1); // error, disconnected?
}

/* Normalize Pressure to Sea Level based on GPS altitude
* See https://www.sensorsone.com/altitude-pressure-units-conversion/ for a chart
* used to derive the eqns below. or https://www.engineeringtoolbox.com/air-altitude-pressure-d_462.html
* linear approximation and interpolation used as it's close enough for sea level to 10,000ft (3048m)
*/
float BarometricNormalization(float ALT, float Pressure) {
//Imperial Pressure units in inHG
return Pressure + (0.00094797505*ALT+0.1407194); //inHG
//Metric Pressure units in kPa
//return Pressure + (0.10543757571*ALT+0.4668666); //kPa
}

//Prints the various variables directly to the port
//I don't like the way this function is written but Arduino doesn't support floats under sprintf
Expand Down Expand Up @@ -437,8 +448,10 @@ void printWeather()
Serial.print(rainin, 2);
Serial.print(",dailyrainin=");
Serial.print(dailyrainin, 2);
Serial.print(",pressure=");
Serial.print(",pressure_raw=");
Serial.print(pressure, 2);
Serial.print(",pressure_normalized=");
Serial.print(BarometricNormalization(gps.altitude.feet(),pressure), 2); //can set static Altitude if you wanted instead of basing it on GPS as That will hunt around
Serial.print(",batt_lvl=");
Serial.print(batt_lvl, 2);
Serial.print(",light_lvl=");
Expand Down Expand Up @@ -466,5 +479,3 @@ void printWeather()
Serial.println("#");

}