bme280 msgpack program

bme280-arduino-msgpack.ino

// libraries
// https://github.com/bakercp/CRC32
// https://github.com/DFRobot/DFRobot_BME280
// https://github.com/HEADS-project/arduino_msgpack

#include <CRC32.h>

#include <DFRobot_BME280.h>
#include <msgpck.h>



#define SEA_LEVEL_PRESSURE  1013.25f
#define BME_CS 10

DFRobot_BME280 bme; //I2C

float temp, pa, hum, alt, es, ea, vpd, ah_kgm3, ah_gm3;


void setup() {
    Serial.begin(115200);
    
    // I2c default address is 0x76, if the need to change please modify bme.begin(Addr)
    if (!bme.begin(0x77)) {
        Serial.println("No sensor device found, check line or address!");
        while (1);
    }
}

void loop() { 
  temp = bme.temperatureValue();
  hum = bme.humidityValue();
  pa = bme.pressureValue();
  alt = bme.altitudeValue(SEA_LEVEL_PRESSURE);
 
  
  // saturated vapor pressure
  es = 0.6108 * exp(17.27 * temp / (temp + 237.3));

  // actual vapor pressure
  ea = hum / 100.0 * es;

  // this equation returns a negative value (in kPa), which while technically correct,
  // is invalid in this case because we are talking about a deficit.
  vpd = (ea - es) * -1;

  // mixing ratio
  //w = 621.97 * ea / ((pressure64/10) - ea);
  // saturated mixing ratio
  //ws = 621.97 * es / ((pressure64/10) - es);
  
  // absolute humidity (in kg/m³)
  ah_kgm3 = es / (461.5 * (temp + 273.15));
  // report it as g/m³
  ah_gm3 = ah_kgm3*1000;
  CRC32 crc;
  
  float values[] = { temp, hum, pa, alt, es, ea, vpd, ah_gm3 };
  for ( byte i = 0; i  < 8; i++){
    crc.update(values[i]);
  }
  
  msgpck_write_map_header(&Serial, 9);
  msgpck_write_string(&Serial, "temp_c");
  msgpck_write_float(&Serial, temp);
  msgpck_write_string(&Serial, "hum_rh");
  msgpck_write_float(&Serial, hum);
  msgpck_write_string(&Serial, "pa_p");
  msgpck_write_float(&Serial, pa);
  msgpck_write_string(&Serial, "alt_m");
  msgpck_write_float(&Serial, alt);
 
  msgpck_write_string(&Serial, "es_kPa");
  msgpck_write_float(&Serial, es);
  msgpck_write_string(&Serial, "ea_kPa");
  msgpck_write_float(&Serial, ea);
  msgpck_write_string(&Serial, "vpd_kPa");
  msgpck_write_float(&Serial, vpd);
  msgpck_write_string(&Serial, "ah_gm3");
  msgpck_write_float(&Serial, ah_gm3);
  
  msgpck_write_string(&Serial, "crc16");
  msgpck_write_integer(&Serial, crc.finalize());
  Serial.write('\n');

  
//  
//  Serial.print("Temp: ");
//  Serial.print(temp);
//  Serial.println("°C");
//  
//  Serial.print("Pa: ");
//  Serial.print(pa);
//  Serial.println("Pa");
//  
//  Serial.print("Hum: ");
//  Serial.print(hum);
//  Serial.println("%");
//  
//  Serial.print("Alt: ");
//  Serial.print(alt);
//  Serial.println("m");

//  Serial.print("SVP: \t");
//  Serial.print(es);
//  Serial.println("kPa");
//    
//  Serial.print("AVP: \t");
//  Serial.print(ea);
//  Serial.println("kPa");
//  
//  Serial.print("VPD: \t");
//  Serial.print(vpd);
//  Serial.println("kPa");
//  
//  Serial.print("AH: \t");
//  Serial.print(ah_gm3);
//  Serial.println("g/m³");
  
  
  delay(1000);
}