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/*
* Copyright 2015 Ludwig Knüpfer, Christian Mehlis
*
* 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 driver_dht DHT Family of Humidity and Temperature Sensors
* @ingroup drivers
* @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>
*/
#ifndef DHT_H
#define DHT_H
#include <stdint.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 gpio; /**< GPIO pin of the device's data pin */
dht_type_t type; /**< type of the DHT device */
} dht_t;
/**
* @brief initialize a new DHT device
*
* @param[in] dev device descriptor of a DHT device
* @param[in] type type of the DHT device
* @param[in] gpio GPIO pin the device's data pin is connected to
*
* @return 0 on success
* @return -1 on error
*/
int dht_init(dht_t *dev, dht_type_t type, gpio_t gpio);
/**
* @brief read sensor data from device
*
* @param[in] dev device descriptor of a DHT device
* @param[out] relhum pointer to relative humidity in g/m^3
* @param[out] temp pointer to temperature in degrees Celsius
*
* @return 0 on success
* @return -1 on error
*/
int dht_read(dht_t *dev, float *relhum, float *temp);
/**
* @brief read sensor data from device
*
* @note When reading fails and the function indicates an error,
* data will contain garbage.
*
* @param[in] dev device descriptor of a DHT device
* @param[in] data pointer to DHT data object
*
* @return 0 on success
* @return -1 on checksum error
*/
int dht_read_raw(dht_t *dev, dht_data_t *data);
/**
* @brief parse raw sensor data into relative humidity and Celsius
*
* @param[in] dev device descriptor of a DHT device
* @param[in] data sensor data
* @param[out] relhum pointer to relative humidity in g/m^3
* @param[out] temp pointer to temperature in degrees Celsius
*/
void dht_parse(dht_t *dev, dht_data_t *data, float *relhum, float *temp);
#ifdef __cplusplus
}
#endif
#endif /* DHT_H */
/** @} */