sht21.hpp

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/* SPDX-License-Identifier: Apache-2.0 */
/* Copyright 2015-2019 Peter A. Bigot */
 
#ifndef NRFCXX_SENSOR_SHT21_HPP
#define NRFCXX_SENSOR_SHT21_HPP
#pragma once
 
#include <nrfcxx/clock.hpp>
#include <nrfcxx/lpm.hpp>
#include <nrfcxx/periph.hpp>
 
namespace nrfcxx {
namespace sensor {
 
class sht21 : public lpm::lpsm_capable
{
  using super = lpm::lpsm_capable;
public:
  using eic_type = uint8_t[8];
 
  constexpr static unsigned int RESET_DELAY_ms = 15;
 
  constexpr static unsigned int SAMPLE14_DELAY_ms = 85;
 
  constexpr static unsigned int SAMPLE12_DELAY_ms = 22;
 
  constexpr static uint8_t CONFIG_RES_H12T14 = 0x00;
 
  constexpr static uint8_t CONFIG_RES_H8T12 = 0x01;
 
  constexpr static uint8_t CONFIG_RES_H10T13 = 0x80;
 
  constexpr static uint8_t CONFIG_RES_H11T11 = 0x81;
 
  constexpr static uint8_t CONFIG_RES_Msk = 0x81;
 
  constexpr static uint8_t CONFIG_OTPRn = 0x02;
 
  constexpr static uint8_t CONFIG_HEATER = 0x04;
 
  constexpr static uint8_t CONFIG_EOB = 0x40;
 
  constexpr static int INVALID_OBSERVATION = -30000;
 
  struct observations_type
  {
    int16_t temperature_cK = INVALID_OBSERVATION;
 
    int16_t humidity_pptt = INVALID_OBSERVATION;
  };
 
  struct iface_config_type
  {
    periph::TWI& twi;
 
    uint8_t address;
 
    iface_config_type (const iface_config_type&) = delete;
    iface_config_type& operator= (const iface_config_type&) = delete;
    iface_config_type (iface_config_type&&) = delete;
    iface_config_type& operator= (iface_config_type&&) = delete;
  };
 
  const iface_config_type& iface_config () const
  {
    return iface_config_;
  }
 
  sht21 (notifier_type setter,
         iface_config_type& ifc);
 
  /* No copying or moving. */
  sht21 (const sht21&) = delete;
  sht21& operator= (const sht21&) = delete;
  sht21 (sht21&& ) = delete;
  sht21& operator= (sht21&) = delete;
 
  int reset ();
 
  int configure (int config);
 
  int read_eic (eic_type& eic);
 
  static bool eic_is_sht21 (const eic_type& eic)
  {
    return ((0x00 == eic[0]) && (0x80 == eic[1]));
  }
 
  static bool eic_is_htu21d (const eic_type& eic)
  {
    return (('H' == eic[0]) && ('T' == eic[1]));
  }
 
  int trigger_temperature ()
  {
    return trigger_(false);
  }
 
  int trigger_humidity ()
  {
    return trigger_(true);
  }
 
  constexpr static int NOT_READY = periph::TWI::error_encoded(periph::TWI::ERR_ANACK);
 
  int temperature_cK ()
  {
    return fetch_(false);
  }
 
  int humidity_pptt ()
  {
    return fetch_(true);
  }
 
  const observations_type& observations () const
  {
    return observations_;
  }
 
protected:
  int lpsm_process_ (int& delay,
                     process_flags_type& pf) override;
 
  int trigger_ (bool humidity);
 
  int fetch_ (bool humidity);
 
  iface_config_type& iface_config_;
  observations_type observations_;
};
 
} // ns sensor
} // ns nrfcxx
 
#endif /* NRFCXX_SENSOR_SHT21_HPP */