Adafruit_Si7021.h

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#ifndef __Si7021_H__
#define __Si7021_H__

#include "Arduino.h"
#include <Adafruit_I2CDevice.h>

#define SI7021_DEFAULT_ADDRESS 0x40

#define SI7021_MEASRH_HOLD_CMD                                                 \
  0xE5 
#define SI7021_MEASRH_NOHOLD_CMD                                               \
  0xF5 
#define SI7021_MEASTEMP_HOLD_CMD                                               \
  0xE3 
#define SI7021_MEASTEMP_NOHOLD_CMD                                             \
  0xF3 
#define SI7021_READPREVTEMP_CMD                                                \
  0xE0 
#define SI7021_RESET_CMD 0xFE           
#define SI7021_WRITERHT_REG_CMD 0xE6    
#define SI7021_READRHT_REG_CMD 0xE7     
#define SI7021_WRITEHEATER_REG_CMD 0x51 
#define SI7021_READHEATER_REG_CMD 0x11  
#define SI7021_REG_HTRE_BIT 0x02        
#define SI7021_ID1_CMD 0xFA0F           
#define SI7021_ID2_CMD 0xFCC9           
#define SI7021_FIRMVERS_CMD 0x84B8      
#define SI7021_REV_1 0xff 
#define SI7021_REV_2 0x20 
enum si_sensorType {
  SI_Engineering_Samples,
  SI_7013,
  SI_7020,
  SI_7021,
  SI_UNKNOWN,
};

enum si_heatLevel {
  SI_HEATLEVEL_LOWEST = 0x00,
  SI_HEATLEVEL_LOW = 0x01,
  SI_HEATLEVEL_MEDIUM = 0x02,
  SI_HEATLEVEL_HIGH = 0x04,
  SI_HEATLEVEL_HIGHER = 0x08,
  SI_HEATLEVEL_HIGHEST = 0x0F,
};

class Adafruit_Si7021 {
public:
  Adafruit_Si7021(TwoWire *theWire = &Wire);
  bool begin();

  float readTemperature();
  void reset();
  void readSerialNumber();
  float readHumidity();

  void heater(bool h);
  bool isHeaterEnabled();

  void setHeatLevel(uint8_t level);

  uint8_t getRevision() { return _revision; };
  si_sensorType getModel();

  uint32_t sernum_a; 
  uint32_t sernum_b; 
private:
  void _readRevision();
  si_sensorType _model;
  uint8_t _revision;
  uint8_t _readRegister8(uint8_t reg);
  void _writeRegister8(uint8_t reg, uint8_t value);

  Adafruit_I2CDevice *i2c_dev = NULL;          
  const static int _TRANSACTION_TIMEOUT = 100; // Wire NAK/Busy timeout in ms
};

#endif // __Si7021_H__