mirror of
https://github.com/RIOT-OS/RIOT.git
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a582da1f31
- many backports from @maribu's IRQ based implementation (#18591) - use of ztimer and errno.h - separation of dht_read() steps into functions for better readability - reintroduction of DHT11/DHT22 differentiation - sensor presence checking in dht_init() - default input mode changed to open drain - AVR support without platform-specific handling by avoiding ztimer_spin() and using the overflow of an 8-bit variable as a pre-timeout to minimize time-consuming ztimer_now() calls - add a new DHT11_2022 type for 0.01 °C resolution devices - data caching removed
137 lines
4.3 KiB
C
137 lines
4.3 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 <errno.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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* @deprecated The functions use errno codes instead now
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*/
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enum {
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DHT_OK = 0, /**< all good */
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DHT_NOCSUM = -EIO, /**< checksum error */
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DHT_TIMEOUT = -ETIMEDOUT, /**< 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 humidity in deci-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 Device type of the DHT device
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*/
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typedef enum {
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DHT11, /**< Older DHT11 variants with either 1 °C or
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* 0.1 °C resolution */
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DHT11_2022, /**< New DHT11 variant with 0.01 °C resolution */
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DHT22, /**< DHT22 device identifier */
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DHT21 = DHT22, /**< DHT21 device identifier */
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AM2301 = DHT22, /**< AM2301 device identifier */
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} dht_type_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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dht_type_t type; /**< type of the DHT device */
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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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} 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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* @retval 0 Success
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* @retval -EXDEV A low level on the input after the sensor's startup
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* time indicates that either no sensor or pull-up
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* resistor is connected, or the sensor is physically
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* poorly connected or powered.
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* @retval -ENODEV The sensor did not respond to the transmission of a
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* start signal. Likely there were a pull-up resistor but
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* no sensor connected on the data line.
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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 0 Success
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* @retval -ENODEV The sensor did not respond to the transmission of a
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* start signal. Likely the RESPAWN_TIMEOUT is
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* insufficient.
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* @retval -EIO The received and the expected checksum didn't match.
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* @retval -ENOSYS Unable to parse the received data. Likely the data
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* format is not implemented.
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* @retval -ERANGE Temperature low byte >= 10. Likely misconfigured
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* device type (DHT11_2022).
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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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