Adafruit_BME280.h

/*!
 * @file Adafruit_BME280.h
 *
 * Designed specifically to work with the Adafruit BME280 Breakout
 * ----> http://www.adafruit.com/products/2650
 *
 * These sensors use I2C or SPI to communicate, 2 or 4 pins are required
 * to interface.
 *
 * Adafruit invests time and resources providing this open source code,
 * please support Adafruit and open-source hardware by purchasing
 * products from Adafruit!
 *
 * Written by Kevin "KTOWN" Townsend for Adafruit Industries.
 *
 * BSD license, all text here must be included in any redistribution.
 * See the LICENSE file for details.
 *
 */

#ifndef __BME280_H__
#define __BME280_H__

#include "Arduino.h"

#include <Adafruit_Sensor.h>
#include <SPI.h>
#include <Wire.h>

/*!
 *  @brief  default I2C address
 */
#define BME280_ADDRESS (0x77)           // Primary I2C Address
                                        /*!
                                         *  @brief  alternate I2C address
                                         */
#define BME280_ADDRESS_ALTERNATE (0x76) // Alternate Address

/*!
 *  @brief Register addresses
 */
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_STATUS = 0XF3,
  BME280_REGISTER_CONTROL = 0xF4,
  BME280_REGISTER_CONFIG = 0xF5,
  BME280_REGISTER_PRESSUREDATA = 0xF7,
  BME280_REGISTER_TEMPDATA = 0xFA,
  BME280_REGISTER_HUMIDDATA = 0xFD
};

/**************************************************************************/
/*!
    @brief  calibration data
*/
/**************************************************************************/
typedef struct {
  uint16_t dig_T1; ///< temperature compensation value
  int16_t dig_T2;  ///< temperature compensation value
  int16_t dig_T3;  ///< temperature compensation value

  uint16_t dig_P1; ///< pressure compensation value
  int16_t dig_P2;  ///< pressure compensation value
  int16_t dig_P3;  ///< pressure compensation value
  int16_t dig_P4;  ///< pressure compensation value
  int16_t dig_P5;  ///< pressure compensation value
  int16_t dig_P6;  ///< pressure compensation value
  int16_t dig_P7;  ///< pressure compensation value
  int16_t dig_P8;  ///< pressure compensation value
  int16_t dig_P9;  ///< pressure compensation value

  uint8_t dig_H1; ///< humidity compensation value
  int16_t dig_H2; ///< humidity compensation value
  uint8_t dig_H3; ///< humidity compensation value
  int16_t dig_H4; ///< humidity compensation value
  int16_t dig_H5; ///< humidity compensation value
  int8_t dig_H6;  ///< humidity compensation value
} bme280_calib_data;
/*=========================================================================*/

class Adafruit_BME280;

/** Adafruit Unified Sensor interface for temperature component of BME280 */
class Adafruit_BME280_Temp : public Adafruit_Sensor {
public:
  /** @brief Create an Adafruit_Sensor compatible object for the temp sensor
      @param parent A pointer to the BME280 class */
  Adafruit_BME280_Temp(Adafruit_BME280 *parent) { _theBME280 = parent; }
  bool getEvent(sensors_event_t *);
  void getSensor(sensor_t *);

private:
  int _sensorID = 280;
  Adafruit_BME280 *_theBME280 = NULL;
};

/** Adafruit Unified Sensor interface for pressure component of BME280 */
class Adafruit_BME280_Pressure : public Adafruit_Sensor {
public:
  /** @brief Create an Adafruit_Sensor compatible object for the pressure sensor
      @param parent A pointer to the BME280 class */
  Adafruit_BME280_Pressure(Adafruit_BME280 *parent) { _theBME280 = parent; }
  bool getEvent(sensors_event_t *);
  void getSensor(sensor_t *);

private:
  int _sensorID = 280;
  Adafruit_BME280 *_theBME280 = NULL;
};

/** Adafruit Unified Sensor interface for humidity component of BME280 */
class Adafruit_BME280_Humidity : public Adafruit_Sensor {
public:
  /** @brief Create an Adafruit_Sensor compatible object for the humidity sensor
      @param parent A pointer to the BME280 class */
  Adafruit_BME280_Humidity(Adafruit_BME280 *parent) { _theBME280 = parent; }
  bool getEvent(sensors_event_t *);
  void getSensor(sensor_t *);

private:
  int _sensorID = 280;
  Adafruit_BME280 *_theBME280 = NULL;
};

/**************************************************************************/
/*!
    @brief  Class that stores state and functions for interacting with BME280 IC
*/
/**************************************************************************/
class Adafruit_BME280 {
public:
  /**************************************************************************/
  /*!
      @brief  sampling rates
  */
  /**************************************************************************/
  enum sensor_sampling {
    SAMPLING_NONE = 0b000,
    SAMPLING_X1 = 0b001,
    SAMPLING_X2 = 0b010,
    SAMPLING_X4 = 0b011,
    SAMPLING_X8 = 0b100,
    SAMPLING_X16 = 0b101
  };

  /**************************************************************************/
  /*!
      @brief  power modes
  */
  /**************************************************************************/
  enum sensor_mode {
    MODE_SLEEP = 0b00,
    MODE_FORCED = 0b01,
    MODE_NORMAL = 0b11
  };

  /**************************************************************************/
  /*!
      @brief  filter values
  */
  /**************************************************************************/
  enum sensor_filter {
    FILTER_OFF = 0b000,
    FILTER_X2 = 0b001,
    FILTER_X4 = 0b010,
    FILTER_X8 = 0b011,
    FILTER_X16 = 0b100
  };

  /**************************************************************************/
  /*!
      @brief  standby duration in ms
  */
  /**************************************************************************/
  enum standby_duration {
    STANDBY_MS_0_5 = 0b000,
    STANDBY_MS_10 = 0b110,
    STANDBY_MS_20 = 0b111,
    STANDBY_MS_62_5 = 0b001,
    STANDBY_MS_125 = 0b010,
    STANDBY_MS_250 = 0b011,
    STANDBY_MS_500 = 0b100,
    STANDBY_MS_1000 = 0b101
  };

  // constructors
  Adafruit_BME280();
  Adafruit_BME280(int8_t cspin, SPIClass *theSPI = &SPI);
  Adafruit_BME280(int8_t cspin, int8_t mosipin, int8_t misopin, int8_t sckpin);
  ~Adafruit_BME280(void);
  bool begin(uint8_t addr = BME280_ADDRESS, TwoWire *theWire = &Wire);
  bool init();

  void setSampling(sensor_mode mode = MODE_NORMAL,
                   sensor_sampling tempSampling = SAMPLING_X16,
                   sensor_sampling pressSampling = SAMPLING_X16,
                   sensor_sampling humSampling = SAMPLING_X16,
                   sensor_filter filter = FILTER_OFF,
                   standby_duration duration = STANDBY_MS_0_5);

  void takeForcedMeasurement();
  float readTemperature(void);
  float readPressure(void);
  float readHumidity(void);

  float readAltitude(float seaLevel);
  float seaLevelForAltitude(float altitude, float pressure);
  uint32_t sensorID(void);

  float getTemperatureCompensation(void);
  void setTemperatureCompensation(float);

  Adafruit_Sensor *getTemperatureSensor(void);
  Adafruit_Sensor *getPressureSensor(void);
  Adafruit_Sensor *getHumiditySensor(void);

protected:
  TwoWire *_wire; //!< pointer to a TwoWire object
  SPIClass *_spi; //!< pointer to SPI object

  Adafruit_BME280_Temp *temp_sensor = NULL;
  //!< Adafruit_Sensor compat temperature sensor component

  Adafruit_BME280_Pressure *pressure_sensor = NULL;
  //!< Adafruit_Sensor compat pressure sensor component

  Adafruit_BME280_Humidity *humidity_sensor = NULL;
  //!< Adafruit_Sensor compat humidity sensor component

  void readCoefficients(void);
  bool isReadingCalibration(void);
  uint8_t spixfer(uint8_t x);

  void write8(byte reg, byte value);
  uint8_t read8(byte reg);
  uint16_t read16(byte reg);
  uint32_t read24(byte reg);
  int16_t readS16(byte reg);
  uint16_t read16_LE(byte reg); // little endian
  int16_t readS16_LE(byte reg); // little endian

  uint8_t _i2caddr;  //!< I2C addr for the TwoWire interface
  int32_t _sensorID; //!< ID of the BME Sensor
  int32_t t_fine; //!< temperature with high resolution, stored as an attribute
                  //!< as this is used for temperature compensation reading
                  //!< humidity and pressure

  int8_t _cs;   //!< for the SPI interface
  int8_t _mosi; //!< for the SPI interface
  int8_t _miso; //!< for the SPI interface
  int8_t _sck;  //!< for the SPI interface

  int32_t t_fine_adjust = 0; //!< add to compensate temp readings and in turn
                             //!< to pressure and humidity readings

  bme280_calib_data _bme280_calib; //!< here calibration data is stored

  /**************************************************************************/
  /*!
      @brief  config register
  */
  /**************************************************************************/
  struct config {
    // inactive duration (standby time) in normal mode
    // 000 = 0.5 ms
    // 001 = 62.5 ms
    // 010 = 125 ms
    // 011 = 250 ms
    // 100 = 500 ms
    // 101 = 1000 ms
    // 110 = 10 ms
    // 111 = 20 ms
    unsigned int t_sb : 3; ///< inactive duration (standby time) in normal mode

    // filter settings
    // 000 = filter off
    // 001 = 2x filter
    // 010 = 4x filter
    // 011 = 8x filter
    // 100 and above = 16x filter
    unsigned int filter : 3; ///< filter settings

    // unused - don't set
    unsigned int none : 1;     ///< unused - don't set
    unsigned int spi3w_en : 1; ///< unused - don't set

    /// @return combined config register
    unsigned int get() { return (t_sb << 5) | (filter << 2) | spi3w_en; }
  };
  config _configReg; //!< config register object

  /**************************************************************************/
  /*!
      @brief  ctrl_meas register
  */
  /**************************************************************************/
  struct ctrl_meas {
    // temperature oversampling
    // 000 = skipped
    // 001 = x1
    // 010 = x2
    // 011 = x4
    // 100 = x8
    // 101 and above = x16
    unsigned int osrs_t : 3; ///< temperature oversampling

    // pressure oversampling
    // 000 = skipped
    // 001 = x1
    // 010 = x2
    // 011 = x4
    // 100 = x8
    // 101 and above = x16
    unsigned int osrs_p : 3; ///< pressure oversampling

    // device mode
    // 00       = sleep
    // 01 or 10 = forced
    // 11       = normal
    unsigned int mode : 2; ///< device mode

    /// @return combined ctrl register
    unsigned int get() { return (osrs_t << 5) | (osrs_p << 2) | mode; }
  };
  ctrl_meas _measReg; //!< measurement register object

  /**************************************************************************/
  /*!
      @brief  ctrl_hum register
  */
  /**************************************************************************/
  struct ctrl_hum {
    /// unused - don't set
    unsigned int none : 5;

    // pressure oversampling
    // 000 = skipped
    // 001 = x1
    // 010 = x2
    // 011 = x4
    // 100 = x8
    // 101 and above = x16
    unsigned int osrs_h : 3; ///< pressure oversampling

    /// @return combined ctrl hum register
    unsigned int get() { return (osrs_h); }
  };
  ctrl_hum _humReg; //!< hum register object
};

#endif