Merge remote-tracking branch 'upstream/master'

docs/README.md

@@ -335,13 +335,12 @@ or
  values: TempUnit_Celsius = return degrees Celsius, TempUnit_Fahrenheit = return degrees Fahrenheit
 ```
 
-#### int HeatIndex(float temperature, float humidity, TempUnit tempUnit = TempUnit_Celsius)
+#### float HeatIndex(float temperature, float humidity, TempUnit tempUnit = TempUnit_Celsius)
 
  Calculate the heat index based on the temperature and humidity with the specified units. 
- The heat index is only calculated if the temperature is above 26.7°C or 80°F and humidity above 40%.
- The precision is +/- 0.7°C / 1.3°F. 
+ The U.S. NWS algorithm is used.
 ```
- return: int heat index
+ return: float heat index in TempUnit
 
  * Temperature: float
  values: any float related to TempUnit

examples/Environment_Calculations/Environment_Calculations.ino

@@ -134,15 +134,9 @@ void printBME280Data
  client->print(String( presUnit == BME280::PresUnit_hPa ? "hPa" :"Pa")); // expected hPa and Pa only
 
  client->print("\t\tHeat Index: ");
- if (temp > (tempUnit == BME280::TempUnit_Celsius ? 26.7 : 80))
- {
- int heatIndex = EnvironmentCalculations::HeatIndex(temp, hum, envTempUnit);
- client->print(heatIndex);
- }
- else
- {
- client->print("Temperature out of range");
- }
+ float heatIndex = EnvironmentCalculations::HeatIndex(temp, hum, envTempUnit);
+ client->print(heatIndex);
+ client->print("°"+ String(envTempUnit == EnvironmentCalculations::TempUnit_Celsius ? "C" :"F"));
 
  client->print("\t\tAbsolute Humidity: ");
  client->println(absHum);

keywords.txt

@@ -1,12 +1,12 @@
 BME280I2C KEYWORD1
 BME280Spi KEYWORD1
-begin KEYWORD2
-temp KEYWORD2
-pres KEYWORD2
-hum KEYWORD2
-read KEYWORD2
-Altitude KEYWORD2
-EquivalentSeaLevelPressure KEYWORD2
-DewPoint KEYWORD2
-HeatIndex KEYWORD2
-AbsoluteHumidity KEYWORD2
+begin KEYWORD2
+temp KEYWORD2
+pres KEYWORD2
+hum KEYWORD2
+read KEYWORD2
+Altitude KEYWORD2
+EquivalentSeaLevelPressure KEYWORD2
+DewPoint KEYWORD2
+HeatIndex KEYWORD2
+AbsoluteHumidity KEYWORD2

src/BME280.cpp

@@ -53,6 +53,12 @@ bool BME280::Initialize()
  if(success)
  {
  success &= ReadTrim();
+
+ if(m_settings.filter != Filter_Off)
+ {
+ InitializeFilter();
+ }
+
  WriteSettings();
  }
 
@@ -61,6 +67,24 @@ bool BME280::Initialize()
  return m_initialized;
 }
 
+
+/****************************************************************/
+bool BME280::InitializeFilter()
+{
+ // Force an unfiltered measurement to populate the filter buffer.
+ // This fixes a bug that causes the first read to always be 28.82 °C 81732.34 hPa.
+ Filter filter = m_settings.filter;
+ m_settings.filter = Filter_Off;
+
+ WriteSettings();
+
+ float dummy;
+ read(dummy, dummy, dummy);
+
+ m_settings.filter = filter;
+}
+
+
 /****************************************************************/
 bool BME280::ReadChipID()
 {

src/BME280.h

@@ -209,10 +209,16 @@ class BME280
 /* CONSTRUCTOR INIT FUNCTIONS */
 /*****************************************************************/
 
- //////////////////////////////////////////////////////////////////
+ ///////////////////////////////////////////////////////////////
  /// Write configuration to BME280, return true if successful.
+ /// Must be called from any child classes.
  virtual bool Initialize();
 
+ ///////////////////////////////////////////////////////////////
+ /// Force a unfiltered measurement to populate the filter 
+ /// buffer.
+ bool InitializeFilter();
+
 
 /*****************************************************************/
 /* ACCESSOR FUNCTIONS */

src/BME280I2C.cpp

@@ -73,7 +73,7 @@ bool BME280I2C::WriteRegister
  Wire.write(data);
  Wire.endTransmission();
 
- return true; // TODO: Chech return values from wire calls.
+ return true; // TODO: Check return values from wire calls.
 }
 
 

src/BME280SpiSw.h

@@ -81,7 +81,8 @@ class BME280SpiSw: public BME280{
 protected:
 
  ////////////////////////////////////////////////////////////////
- /// Method used at start up to initialize the class. Starts the I2C interface.
+ /// Method used at start up to initialize the class. Starts the
+ /// software SPI interface.
  virtual bool Initialize();
 
 private:

src/EnvironmentCalculations.cpp

@@ -22,13 +22,20 @@ Last Updated: Dec 23 2017.
 This header must be included in any derived code or copies of the code.
 
  */
-
 #include "EnvironmentCalculations.h"
 
 #include <Arduino.h>
 #include <math.h>
 
-
+#define hi_coeff1 -42.379
+#define hi_coeff2 2.04901523
+#define hi_coeff3 10.14333127
+#define hi_coeff4 -0.22475541
+#define hi_coeff5 -0.00683783
+#define hi_coeff6 -0.05481717
+#define hi_coeff7 0.00122874
+#define hi_coeff8 0.00085282
+#define hi_coeff9 -0.00000199
 /****************************************************************/
 float EnvironmentCalculations::Altitude
 (
@@ -44,7 +51,7 @@ float EnvironmentCalculations::Altitude
  if (!isnan(pressure) && !isnan(referencePressure) && !isnan(outdoorTemp))
  {
  if(tempUnit != TempUnit_Celsius)
- outdoorTemp = (outdoorTemp - 32.0) * (5.0 / 9.0); /*conversion to [�C]*/
+ outdoorTemp = (outdoorTemp - 32.0) * (5.0 / 9.0); /*conversion to [°C]*/
 
  altitude = pow(referencePressure / pressure, 0.190234) - 1;
  altitude *= ((outdoorTemp + 273.15) / 0.0065);
@@ -89,40 +96,69 @@ float EnvironmentCalculations::AbsoluteHumidity
 
 
 /****************************************************************/
-int EnvironmentCalculations::HeatIndex
+//FYI: https://ehp.niehs.nih.gov/1206273/ in detail this flow graph: https://ehp.niehs.nih.gov/wp-content/uploads/2013/10/ehp.1206273.g003.png
+float EnvironmentCalculations::HeatIndex
 (
  float temperature,
  float humidity,
  TempUnit tempUnit
 )
 {
- float heatindex = NAN;
- bool metric = true;
- float hi[2][9] = { {-8.784695,1.61139411,2.338549,-0.14611605,-1.2308094/100,-1.6424828/100,2.211732/1000,7.2546/10000,-3.582/1000000},
- {-42.379,2.04901523,10.1433127,-0.22475541,-6.83783/1000,-5.481717/100,1.22874/1000,8.5282/10000,-1.99/1000000} };
+ float heatIndex(NAN);
 
- //taken from https://de.wikipedia.org/wiki/Hitzeindex#Berechnung
- if (tempUnit != TempUnit_Celsius)
+ if ( isnan(temperature) || isnan(humidity) ) 
  {
- metric = false;
+ return heatIndex;
  }
- if (!isnan(humidity) && !isnan(temperature) && humidity>40 && (metric ? temperature>26.7 : temperature>80)) {
- heatindex = hi[metric ? 0: 1][0];
- heatindex =+ hi[metric ? 0: 1][1] * temperature;
- heatindex =+ hi[metric ? 0: 1][2] * humidity;
- heatindex =+ hi[metric ? 0: 1][3] * temperature * humidity;
- heatindex =+ hi[metric ? 0: 1][4] * temperature * temperature;
- heatindex =+ hi[metric ? 0: 1][5] * humidity * humidity;
- heatindex =+ hi[metric ? 0: 1][6] * temperature * temperature * humidity;
- heatindex =+ hi[metric ? 0: 1][7] * temperature * humidity * humidity;
- heatindex =+ hi[metric ? 0: 1][8] * temperature * temperature * humidity * humidity;
- return int(heatindex);
+
+ if (tempUnit == TempUnit_Celsius) 
+ {
+ temperature = (temperature * (9.0 / 5.0) + 32.0); /*conversion to [°F]*/
  }
- else {
- return NAN;
+ // Using both Rothfusz and Steadman's equations
+ // https://www.wpc.ncep.noaa.gov/html/heatindex_equation.shtml
+ if (temperature <= 40) 
+ {
+ heatIndex = temperature; //first red block
+ }
+ else
+ {
+ heatIndex = 0.5 * (temperature + 61.0 + ((temperature - 68.0) * 1.2) + (humidity * 0.094)); //calculate A -- from the official site, not the flow graph
+
+ if (heatIndex >= 79) 
+ {
+ /*
+ * calculate B 
+ * the following calculation is optimized. Simply spoken, reduzed cpu-operations to minimize used ram and runtime. 
+ * Check the correctness with the following link:
+ * https://www.wolframalpha.com/input/?source=nav&i=b%3D+x1+%2B+x2*T+%2B+x3*H+%2B+x4*T*H+%2B+x5*T*T+%2B+x6*H*H+%2B+x7*T*T*H+%2B+x8*T*H*H+%2B+x9*T*T*H*H
+ */
+ heatIndex = hi_coeff1
+ + (hi_coeff2 + hi_coeff4 * humidity + temperature * (hi_coeff5 + hi_coeff7 * humidity)) * temperature
+ + (hi_coeff3 + humidity * (hi_coeff6 + temperature * (hi_coeff8 + hi_coeff9 * temperature))) * humidity;
+ //third red block
+ if ((humidity < 13) && (temperature >= 80.0) && (temperature <= 112.0))
+ {
+ heatIndex -= ((13.0 - humidity) * 0.25) * sqrt((17.0 - abs(temperature - 95.0)) * 0.05882);
+ } //fourth red block
+ else if ((humidity > 85.0) && (temperature >= 80.0) && (temperature <= 87.0))
+ {
+ heatIndex += (0.02 * (humidity - 85.0) * (87.0 - temperature));
+ }
+ }
+ }
+
+ if (tempUnit == TempUnit_Celsius) 
+ {
+ return (heatIndex - 32.0) * (5.0 / 9.0); /*conversion back to [°C]*/
+ }
+ else 
+ {
+ return heatIndex; //fifth red block
  }
 }
 
+
 /****************************************************************/
 float EnvironmentCalculations::EquivalentSeaLevelPressure
 (
@@ -137,7 +173,7 @@ float EnvironmentCalculations::EquivalentSeaLevelPressure
  if(!isnan(altitude) && !isnan(temp) && !isnan(pres))
  {
  if(tempUnit != TempUnit_Celsius)
- temp = (temp - 32.0) * (5.0 / 9.0); /*conversion to [�C]*/
+ temp = (temp - 32.0) * (5.0 / 9.0); /*conversion to [°C]*/
 
  if(altUnit != AltitudeUnit_Meters)
  altitude *= 0.3048; /*conversion to meters*/

src/EnvironmentCalculations.h

@@ -70,12 +70,13 @@ namespace EnvironmentCalculations
  /////////////////////////////////////////////////////////////////
  /// Calculate the heatindex based on the humidity and temperature
  /// in tempUnit.
- /// the heatindex does work for values above 26.7°C/80°F and 40% humidity.
+ /// The formula based on the Heat Index Equation of the US National Weather Service
+ /// https://www.wpc.ncep.noaa.gov/html/heatindex_equation.shtml
  /// @param temperature in tempUnit
  /// @param humidity in percentage
  /// @param temptUnit in °C or °F. default=TempUnit_Celsius
- /// @return Calculated heatindex as integer in TempUnit
- int HeatIndex(
+ /// @return Calculated heatindex as float in TempUnit
+ float HeatIndex(
  float temperature, 
  float humidity, 
  TempUnit tempUnit = TempUnit_Celsius);