precon_reader.ino

int humd_pin = A0;
int temp_pin = A1;

int temp_val = 0;
int humd_val = 0;

float temp = 0;  // Temperature in F
float temp_c = 0; // Temperature in C
float humd = 0;

float dp = 0; // Dew Point in F
float dp_c = 0; // Dew Point in C

void setup() {
  //Initialize serial and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }
}

float cnvt_temp() {
  temp = temp_val / 1023.0; // Scale to 0-1
  temp_c = (temp * 130) - 30; // Convert to C
  temp = (temp * 234) - 22; // Convert to F
}

float cnvt_humd() {
  humd = humd_val / 1023.0; // Scale 0-1
  humd = humd * 100; // Convert to Relative Humidity
}

float dew_pt() {
  // Calculation from here: https://en.wikipedia.org/wiki/Dew_point
  float b = 17.67;
  float c = 243.5; // C
  float gamma = log(humd / 100.0) + b*temp_c / (c + temp_c);
  dp_c = c*gamma / (b - gamma);
  dp = (dp_c * 1.8) + 32;
}

void loop() {

  temp_val = analogRead(temp_pin);
  humd_val = analogRead(humd_pin);

  cnvt_temp();
  cnvt_humd();
  dew_pt();

  Serial.print("Temp: ");
  Serial.print(temp);
  Serial.print(" Humd: ");
  Serial.print(humd);
  Serial.print(" Dew Pt: ");
  Serial.println(dp);
  delay(1000);
}