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110 lines
2.9 KiB
C
110 lines
2.9 KiB
C
/*
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* Copyright 2015 Ludwig Knüpfer,
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* 2015 Christian Mehlis
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* 2016-2017 Freie Universität Berlin
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @defgroup drivers_dht DHT Family of Humidity and Temperature Sensors
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* @ingroup drivers_sensors
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* @ingroup drivers_saul
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* @brief Device driver for the DHT Family of humidity
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* and temperature sensors
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*
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* This driver provides @ref drivers_saul capabilities.
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*
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* @{
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*
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* @file
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* @brief Device driver interface for the DHT family of humidity
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* and temperature sensors
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*
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* @author Ludwig Knüpfer <ludwig.knuepfer@fu-berlin.de
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* @author Christian Mehlis <mehlis@inf.fu-berlin.de>
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* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
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*/
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#ifndef DHT_H
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#define DHT_H
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#include <stdint.h>
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#include "periph/gpio.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* @brief Possible return codes
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*/
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enum {
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DHT_OK = 0, /**< all good */
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DHT_NOCSUM = -1, /**< checksum error */
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DHT_TIMEOUT = -2, /**< communication timed out */
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};
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/**
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* @brief Data type for storing DHT sensor readings
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*/
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typedef struct {
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uint16_t humidity; /**< relative percent */
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uint16_t temperature; /**< temperature in deci-Celsius */
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} dht_data_t;
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/**
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* @brief Configuration parameters for DHT devices
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*/
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typedef struct {
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gpio_t pin; /**< GPIO pin of the device's data pin */
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gpio_mode_t in_mode; /**< input pin configuration, with or without pull
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* resistor */
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} dht_params_t;
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/**
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* @brief Device descriptor for DHT sensor devices
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*/
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typedef struct {
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dht_params_t params; /**< Device parameters */
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dht_data_t last_val; /**< Values of the last measurement */
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uint32_t last_read_us; /**< Time of the last measurement */
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} dht_t;
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/**
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* @brief Initialize a new DHT device
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*
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* @param[out] dev device descriptor of a DHT device
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* @param[in] params configuration parameters
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*
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* @return 0 on success
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* @return -1 on error
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*/
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int dht_init(dht_t *dev, const dht_params_t *params);
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/**
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* @brief get a new temperature and humidity value from the device
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*
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* @note if reading fails or checksum is invalid, no new values will be
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* written into the result values
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*
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* @param[in] dev device descriptor of a DHT device
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* @param[out] temp temperature value [in °C * 10^-1]
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* @param[out] hum relative humidity value [in percent * 10^-1]
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*
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* @retval DHT_OK Success
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* @retval DHT_NOCSUM Checksum error
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* @retval DHT_TIMEOUT Reading data timed out (check wires!)
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*/
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int dht_read(dht_t *dev, int16_t *temp, int16_t *hum);
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#ifdef __cplusplus
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}
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#endif
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#endif /* DHT_H */
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/** @} */
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