// Sonic Anemometer

#include <math.h> 
  
const int Wcalm = 529;      //West sensor reading in still air
const int Ecalm = 535;      //East sensor reading in still air
const int Wnorth = 530;     //West sensor reading in north wind
const int Enorth = 537;     //East sensor reading in north wind
const int Weast =525;       //West sensor reading in east wind
const int Eeast = 540;      //East sensor reading in east wind
const float windspeed = 15.3;   //Wind speed during calibration

const int west = A1;        //West sensor analog pin
const int east = A2;        //East sensor analog pin
 
void setup()
{
   Serial.begin(9600);
    pinMode(west, INPUT);
    pinMode(east, INPUT);
    delay(100);
    }
void loop()
{
int Vwest = analogRead(west);        // Measure west sensor voltage
Vwest = analogRead(west);        // Repeat for settling time
int Veast = analogRead(east);        //Measure east sensor voltage
Veast = analogRead(east);
 Serial.println(" ");
 Serial.print("West sensor reading ");
 Serial.println(Vwest);
 Serial.print("East sensor reading ");
 Serial.println(Veast);

double northwind = (Vwest+Veast-Ecalm-Wcalm)/(Wnorth+Enorth-Ecalm-Wcalm)*windspeed; 
double eastwind = (Vwest-Wcalm-(Veast-Ecalm))/(Weast-Wcalm-(Eeast-Ecalm))*windspeed;
 
int wind =round(sqrt(northwind*northwind+eastwind*eastwind)); //Calculate wind speed
int heading=270-round(atan2((double)-northwind,(double)-eastwind)*57.3);//*(northwind<0);
if (heading>359)heading=heading-360; //Calculate wind direction
Serial.print("Wind speed ");
Serial.print(wind);
Serial.println(" m/s");
Serial.print("Wind direction " );
Serial.print(heading);
Serial.println(" degrees");
  delay(3000);
}