#define BME280_ADR 0x76

enum
    {
      BME280_REGISTER_DIG_T1              = 0x88,
      BME280_REGISTER_DIG_T2              = 0x8A,
      BME280_REGISTER_DIG_T3              = 0x8C,

      BME280_REGISTER_DIG_P1              = 0x8E,
      BME280_REGISTER_DIG_P2              = 0x90,
      BME280_REGISTER_DIG_P3              = 0x92,
      BME280_REGISTER_DIG_P4              = 0x94,
      BME280_REGISTER_DIG_P5              = 0x96,
      BME280_REGISTER_DIG_P6              = 0x98,
      BME280_REGISTER_DIG_P7              = 0x9A,
      BME280_REGISTER_DIG_P8              = 0x9C,
      BME280_REGISTER_DIG_P9              = 0x9E,

      BME280_REGISTER_DIG_H1              = 0xA1,
      BME280_REGISTER_DIG_H2              = 0xE1,
      BME280_REGISTER_DIG_H3              = 0xE3,
      BME280_REGISTER_DIG_H4              = 0xE4,
      BME280_REGISTER_DIG_H5              = 0xE5,
      BME280_REGISTER_DIG_H6              = 0xE7,

      BME280_REGISTER_CHIPID             = 0xD0,
      BME280_REGISTER_VERSION            = 0xD1,
      BME280_REGISTER_SOFTRESET          = 0xE0,

      BME280_REGISTER_CAL26              = 0xE1,  // R calibration stored in 0xE1-0xF0

      BME280_REGISTER_CONTROLHUMID       = 0xF2,
      BME280_REGISTER_CONTROL            = 0xF4,
      BME280_REGISTER_CONFIG             = 0xF5,
      BME280_REGISTER_PRESSUREDATA       = 0xF7,
      BME280_REGISTER_TEMPDATA           = 0xFA,
      BME280_REGISTER_HUMIDDATA          = 0xFD,
    }; 

// CALIBRATION DATA
    
    typedef struct
    {
      uint16_t dig_T1;
      int16_t  dig_T2;
      int16_t  dig_T3;

      uint16_t dig_P1;
      int16_t  dig_P2;
      int16_t  dig_P3;
      int16_t  dig_P4;
      int16_t  dig_P5;
      int16_t  dig_P6;
      int16_t  dig_P7;
      int16_t  dig_P8;
      int16_t  dig_P9;

      uint8_t  dig_H1;
      int16_t  dig_H2;
      uint8_t  dig_H3;
      int16_t  dig_H4;
      int16_t  dig_H5;
      int8_t   dig_H6;
    } bme280_calib_data; 


void bme280_readCoefficients(void);
float bme280_readTemperature(void);
float bme280_readPressure(void); 
float bme280_readHumidity(void);