bme280.hpp

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/* SPDX-License-Identifier: Apache-2.0 */
/* Copyright 2017-2019 Peter A. Bigot */
 
#ifndef NRFCXX_SENSOR_BME280_HPP
#define NRFCXX_SENSOR_BME280_HPP
#pragma once
 
#include <climits>
 
#include "bme280.h"
 
#include <nrfcxx/lpm.hpp>
#include <nrfcxx/periph.hpp>
 
namespace nrfcxx {
namespace sensor {
 
class bme280 : public lpm::lpsm_capable
{
  using super = lpm::lpsm_capable;
public:
  static constexpr unsigned int SAMPLE_DELAY_utt = clock::uptime::from_ms(10);
 
  static constexpr uint16_t INVALID_TEMPHUMID = 30000;
 
  static constexpr unsigned int INVALID_PRESSURE = 0x00C00000;
 
  struct observations_type {
    int16_t temperature_cCel{INVALID_TEMPHUMID};
 
    uint16_t humidity_pptt{INVALID_TEMPHUMID};
 
    unsigned int pressure_cPa{INVALID_PRESSURE};
  };
 
  bme280 (notifier_type notify,
          nrfcxx::periph::SPI& spi,
          int csn_psel);
 
  bme280 (notifier_type notify,
          nrfcxx::periph::TWI& twi,
          bool addr_sec = false);
 
  int initialize ();
 
  int sample ()
  {
    return ::bme280_set_sensor_mode(BME280_FORCED_MODE, &dev);
  }
 
  int fetch (observations_type& obs);
 
  const observations_type& observations () const
  {
    return observations_;
  }
 
private:
  /* Initialization shared between SPI and TWI interfaces. */
  void init_dev_ (bool spi, bool addr_sec = false);
 
  /* Pointer to the SPI peripheral, if a SPI instance exists. */
  static periph::SPI* spip_;
 
  /* Pointer to the TWI peripheral, if an I2C interface exists. */
  static periph::TWI* twip_;
 
  /* Pin selector for SPI CSn signal. */
  static uint8_t csn_psel_;
 
  /* Driver functions are static so they can peek at #spip_, #twip_,
   * and #csn_psel_ to do what they need to do. */
  static int8_t spi_read (uint8_t dev_id,
                          uint8_t reg_addr,
                          uint8_t* data,
                          uint16_t len);
 
  static int8_t spi_write (uint8_t dev_id,
                           uint8_t reg_addr,
                           uint8_t* data,
                           uint16_t len);
 
  static int8_t twi_read (uint8_t dev_id,
                          uint8_t reg_addr,
                          uint8_t* data,
                          uint16_t len);
 
  static int8_t twi_write (uint8_t dev_id,
                           uint8_t reg_addr,
                           uint8_t* data,
                           uint16_t len);
 
  /* Instance-specific device configuration. */
  struct bme280_dev dev;
 
  int lpsm_process_ (int& delay,
                     process_flags_type& pf) override;
 
  /* Last observations captured by LPM. */
  observations_type observations_;
};
 
} // ns sensor
} // ns nrfcxx
 
#endif /* NRFCXX_SENSOR_BME280_HPP */