Buffer overflow windspeed fixed

firmware/weather_station.ino

@@ -27,6 +27,11 @@
  *    You should have received a copy of the GNU General Public License
  *    along with weather_station. If not, see <https://www.gnu.org/licenses/>.
  *
+ * 2023-01-21: - Buffer overflow when calculating average wind speed in AverageOfArray()
+ *               Fix: use 32 bit register for average_value.
+ *             - Changed some variables to the propper standard (uint8_t, uint16_t, etc.)
+ *             - SparkFun wind interrupt now calculates over 3 seconds in stead of 1 second (KNMI standard)
+ *
  **********************************************************************************/
 #include <ModbusSerial.h>
 #include "SparkFun_Weather_Meter_Kit_Arduino_Library.h"
@@ -114,28 +119,28 @@ ModbusSerial mb (MySerial, SlaveId, TxenPin);
 
 unsigned long ts;
 unsigned long HourTimer;
-int WindGustData1[30];
-unsigned char WindGustData1Counter=0;
-int WindGustData2[10];
-unsigned char WindGustData2Counter=0;
-int WindAverageData1[30];
-unsigned char WindAverageData1Counter=0;
-int WindAverageData2[10];
-unsigned char WindAverageData2Counter=0;
-int RainPerHour[24];
-unsigned char RainPerHourCounter=0;
+uint16_t WindGustData1[30];
+uint8_t WindGustData1Counter=0;
+uint16_t WindGustData2[10];
+uint8_t WindGustData2Counter=0;
+uint16_t WindAverageData1[30];
+uint8_t WindAverageData1Counter=0;
+uint16_t WindAverageData2[10];
+uint8_t WindAverageData2Counter=0;
+uint16_t RainPerHour[24];
+uint8_t RainPerHourCounter=0;
 
 struct MeasuredData {
-  int WindDirection;
-  int WindSpeed;
-  int WindGust;
-  int Rain;
-  int RainLast24;
-  int SensorRainSinceMidnight;
-  int Pressure;
-  int Luminosity;
-  int StatusBits = 0;
-  unsigned int RainfallCounter = 0;
+  uint16_t WindDirection;
+  uint16_t WindSpeed;
+  uint16_t WindGust;
+  uint16_t Rain;
+  uint16_t RainLast24;
+  uint16_t SensorRainSinceMidnight;
+  uint16_t Pressure;
+  uint16_t Luminosity;
+  uint16_t StatusBits = 0;
+  uint16_t RainfallCounter = 0;
 
   float Temperature;
   float Humidity;
@@ -287,7 +292,7 @@ void ReadBMP280 (void)
 
 }
 
-int MaxOfArray (int array[], unsigned int length)
+int MaxOfArray (int array[], uint16_t length)
 {
   int maximum_value = 0;
   
@@ -299,11 +304,11 @@ int MaxOfArray (int array[], unsigned int length)
   return maximum_value;
 }
 
-int AverageOfArray (int array[], unsigned int length)
+uint16_t AverageOfArray (uint16_t array[], uint16_t length)
 {
-  int tmp_value = 0;
-  unsigned char tmp_length = length;
-  int average_value = 0;
+  uint32_t tmp_value = 0;
+  uint8_t tmp_length = length;
+  uint16_t average_value = 0;
  
   while (length--)
   {
@@ -329,7 +334,7 @@ void ReadSparkfunWeatherStation (void)
   MeasuredData.Rain = tmpRegister;
 
   // FIFO for calculating wind gust of last 10 minutes
-  // to preserve valuable RAM we caanot store all measurements of the last 10 minutes.
+  // to preserve valuable RAM we cannot store all measurements of the last 10 minutes.
   // So we use a hack: store the last 30 values in a FIFO and every minute we store the maximum value from this FIFO in another FIFO.
   // This second FIFO is 10 deep: it stores the maximum values of the last 10 minutes.
   // The maximum value from this FIFO is the maximum wind gust of the last 10 minutes.
@@ -446,7 +451,7 @@ void setup() {
   mb.Ireg (SensorRainSinceMidnightIreg, 0);
   mb.Ireg (SensorSnowFallIreg, 0);
  
-  Serial.println(F("Weather station v0.2.1"));
+  Serial.println(F("Weather station v0.2.2"));
   Serial.println(F("(C)2024 M.T. Konstapel"));
   Serial.println(F("This project is free and open source"));
   Serial.println(F("More details: https://meezenest.nl/mees/"));
@@ -553,7 +558,9 @@ void setup() {
   // is implemented in the library that averages the wind speed over a certain
   // time period, which defaults to 1 second. Longer intervals result in more
   // accurate measurements, but cause delay in the measurement
-  calibrationParams.windSpeedMeasurementPeriodMillis = 1000;
+  // Dutch metrology institute (KNMI) defines that the windspeed and gust should
+  // be calculated from 3 seconds measurements.
+  calibrationParams.windSpeedMeasurementPeriodMillis = 3000;
 
   // Now we can set all the calibration parameters at once
   weatherMeterKit.setCalibrationParams(calibrationParams);