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RIOT/drivers/include/dht.h 2.95 KB
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  /*
   * Copyright 2015 Ludwig Knüpfer,
   *           2015 Christian Mehlis
   *           2016 Freie Universität Berlin
   *
   * This file is subject to the terms and conditions of the GNU Lesser
   * General Public License v2.1. See the file LICENSE in the top level
   * directory for more details.
   */
  
  /**
   * @defgroup    drivers_dht DHT Family of Humidity and Temperature Sensors
   * @ingroup     drivers_sensors
   * @brief       Device driver for the DHT Family of humidity
   *              and temperature sensors
   *
   * @{
   *
   * @file
   * @brief       Device driver interface for the DHT family of humidity
   *              and temperature sensors
   *
   * @author      Ludwig Knüpfer <ludwig.knuepfer@fu-berlin.de
   * @author      Christian Mehlis <mehlis@inf.fu-berlin.de>
   * @author      Hauke Petersen <hauke.petersen@fu-berlin.de>
   */
  
  #ifndef DHT_H
  #define DHT_H
  
  #include <stdint.h>
  
  #include "saul.h"
  #include "periph/gpio.h"
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /**
   * @brief data type for storing DHT sensor readings
   */
  typedef struct {
      uint16_t humidity;      /**< relative deca-humidity */
      uint16_t temperature;   /**< temperature in deca-Celsius */
  } dht_data_t;
  
  /**
   * @brief device type of the DHT device
   */
  typedef enum {
      DHT11,                  /**< DHT11 device identifier */
      DHT22,                  /**< DHT22 device identifier */
      DHT21 = DHT22           /**< DHT21 device identifier */
  } dht_type_t;
  
  /**
   * @brief device descriptor for DHT sensor devices
   */
  typedef struct {
      gpio_t pin;             /**< GPIO pin of the device's data pin */
      dht_type_t type;        /**< type of the DHT device */
      gpio_mode_t in_mode;    /**< input pin configuration, with or without pull
                               *   resistor */
  } dht_t;
  
  /**
   * @brief configuration parameters for DHT devices
   */
  typedef dht_t dht_params_t;
  
  /**
   * @brief export SAUL endpoints
   * @{
   */
  extern const saul_driver_t dht_temp_saul_driver;
  extern const saul_driver_t dht_hum_saul_driver;
  /** @} */
  
  /**
   * @brief auto-initialize all configured DHT devices
   */
  void dht_auto_init(void);
  
  /**
   * @brief initialize a new DHT device
   *
   * @param[out] dev      device descriptor of a DHT device
   * @param[in]  params   configuration parameters
   *
   * @return              0 on success
   * @return              -1 on error
   */
  int dht_init(dht_t *dev, const dht_params_t *params);
  
  /**
   * @brief   get a new temperature and humidity value from the device
   *
   * @note    if reading fails or checksum is invalid, no new values will be
   *          written into the result values
   *
   * @param[in]  dev      device descriptor of a DHT device
   * @param[out] temp     temperature value [in °C * 10^-1]
   * @param[out] hum      relative humidity value [in percent * 10^-1]
   *
   * @return              0 on success
   * @return              -1 on checksum error
   * @return              -2 on parsing error
   */
  int dht_read(dht_t *dev, int16_t *temp, int16_t *hum);
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif /* DHT_H */
  /** @} */