612 lines
16 KiB
C
612 lines
16 KiB
C
/****************************************************************************
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* drivers/sensors/dhtxx.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <errno.h>
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#include <debug.h>
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#include <nuttx/kmalloc.h>
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#include <nuttx/fs/fs.h>
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#include <nuttx/signal.h>
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#include <nuttx/time.h>
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#include <nuttx/clock.h>
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#include <nuttx/semaphore.h>
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#include <nuttx/sensors/dhtxx.h>
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#define DHTXX_START_SIGNAL_LOW_US 20000
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#define DHTXX_START_SIGNAL_HIGH_US 100
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#define DHTXX_RESPONSE_SIGNAL_US 85
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#define DHTXX_TRANSMISSION_START_US 55
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#define DHTXX_MIN_ZERO_DURATION 22
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#define DHTXX_MAX_ZERO_DURATION 30
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#define DHTXX_MIN_ONE_DURATION 40
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#define DHTXX_MAX_ONE_DURATION 75
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#define DHTXX_SAMPLING_PERIOD_S 2
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#define DHTXX_RESPONSE_BITS 40U
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#define DHT11_MIN_HUM 20.0F
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#define DHT11_MAX_HUM 90.0F
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#define DHT11_MIN_TEMP 0.0F
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#define DHT11_MAX_TEMP 50.0F
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#define DHT12_MIN_HUM 20.0F
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#define DHT12_MAX_HUM 95.0F
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#define DHT12_MIN_TEMP -20.0F
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#define DHT12_MAX_TEMP 60.0F
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#define DHT22_MIN_HUM 0.0F
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#define DHT22_MAX_HUM 100.0F
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#define DHT22_MIN_TEMP -40.0F
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#define DHT22_MAX_TEMP 80.0F
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/****************************************************************************
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* Private Type Definitions
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****************************************************************************/
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struct dhtxx_dev_s
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{
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FAR struct dhtxx_config_s *config;
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sem_t devsem;
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uint8_t raw_data[5];
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};
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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static void dht_standby_mode(FAR struct dhtxx_dev_s *priv);
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static void dht_send_start_signal(FAR struct dhtxx_dev_s *priv);
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static int dht_prepare_reading(FAR struct dhtxx_dev_s *priv);
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static int dht_read_raw_data(FAR struct dhtxx_dev_s *priv);
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static bool dht_verify_checksum(FAR struct dhtxx_dev_s *priv);
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static bool dht_check_data(FAR struct dhtxx_sensor_data_s *data,
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float min_hum, float max_hum,
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float min_temp, float max_temp);
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static int dht_parse_data(FAR struct dhtxx_dev_s *priv,
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FAR struct dhtxx_sensor_data_s *data);
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/* Character driver methods */
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static int dhtxx_open(FAR struct file *filep);
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static int dhtxx_close(FAR struct file *filep);
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static ssize_t dhtxx_read(FAR struct file *filep, FAR char *buffer,
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size_t buflen);
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static ssize_t dhtxx_write(FAR struct file *filep, FAR const char *buffer,
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size_t buflen);
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static int dhtxx_ioctl(FAR struct file *filep, int cmd,
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unsigned long arg);
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static const struct file_operations g_dhtxxfops =
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{
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dhtxx_open, /* open */
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dhtxx_close, /* close */
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dhtxx_read, /* read */
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dhtxx_write, /* write */
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NULL, /* seek */
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dhtxx_ioctl, /* ioctl */
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NULL /* poll */
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#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
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, NULL /* unlink */
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#endif
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};
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: dht_standby_mode
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*
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* Description:
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* Put the sensor in low power consumption (standby) mode.
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*
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****************************************************************************/
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static void dht_standby_mode(FAR struct dhtxx_dev_s *priv)
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{
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priv->config->config_data_pin(priv->config, false);
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priv->config->set_data_pin(priv->config, true);
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}
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/****************************************************************************
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* Name: dht_send_start_signal
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*
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* Description:
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* Send a start signal to the sensor.
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*
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****************************************************************************/
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static void dht_send_start_signal(FAR struct dhtxx_dev_s *priv)
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{
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int64_t start_time;
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int64_t current_time;
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priv->config->config_data_pin(priv->config, false);
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priv->config->set_data_pin(priv->config, false);
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start_time = priv->config->get_clock(priv->config);
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while (1)
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{
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current_time = priv->config->get_clock(priv->config);
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if (current_time - start_time >= DHTXX_START_SIGNAL_LOW_US)
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{
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break;
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}
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}
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priv->config->set_data_pin(priv->config, true);
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start_time = priv->config->get_clock(priv->config);
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while (1)
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{
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current_time = priv->config->get_clock(priv->config);
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if (current_time - start_time >= DHTXX_START_SIGNAL_HIGH_US)
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{
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break;
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}
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}
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}
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/****************************************************************************
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* Name: dht_prepare_reading
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*
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* Description:
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* Gets the sensor ready for transmitting data.
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*
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****************************************************************************/
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static int dht_prepare_reading(FAR struct dhtxx_dev_s *priv)
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{
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int64_t start_time;
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int64_t current_time;
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/* Prepare for reading data. */
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priv->config->config_data_pin(priv->config, true);
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/* The DHT will clear the data pin for about 80uS. */
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start_time = priv->config->get_clock(priv->config);
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while (!priv->config->read_data_pin(priv->config))
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{
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current_time = priv->config->get_clock(priv->config);
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if (current_time - start_time > DHTXX_RESPONSE_SIGNAL_US)
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{
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return -1;
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}
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}
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/* The DHT will set the data pin for about 80uS. */
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while (priv->config->read_data_pin(priv->config))
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{
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current_time = priv->config->get_clock(priv->config);
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if (current_time - start_time > DHTXX_RESPONSE_SIGNAL_US)
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{
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return -1;
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}
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}
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return 0;
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}
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/****************************************************************************
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* Name: dht_read_raw_data
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*
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* Description:
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* Reads raw data from the sensor.
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*
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****************************************************************************/
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static int dht_read_raw_data(FAR struct dhtxx_dev_s *priv)
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{
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int64_t start_time;
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int64_t end_time;
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int64_t current_time;
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uint8_t i;
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uint8_t j;
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j = 0u;
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for (i = 0u; i < DHTXX_RESPONSE_BITS; i++)
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{
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/* Start of transmission begins with a ~50uS low. */
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start_time = priv->config->get_clock(priv->config);
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while (!priv->config->read_data_pin(priv->config))
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{
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current_time = priv->config->get_clock(priv->config);
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if (current_time - start_time > DHTXX_TRANSMISSION_START_US)
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{
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return -1;
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}
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}
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/* Get start time. */
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start_time = priv->config->get_clock(priv->config);
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while (priv->config->read_data_pin(priv->config))
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{
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current_time = priv->config->get_clock(priv->config);
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if (current_time - start_time > DHTXX_MAX_ONE_DURATION)
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{
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return -1;
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}
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}
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end_time = priv->config->get_clock(priv->config);
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if (end_time - start_time >= DHTXX_MIN_ONE_DURATION)
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{
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priv->raw_data[j] = (priv->raw_data[j] << 1U) | 1U;
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}
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else
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{
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priv->raw_data[j] = priv->raw_data[j] << 1U;
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}
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if (i % 8U == 7U)
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{
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j++;
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}
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}
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return 0;
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}
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/****************************************************************************
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* Name: dht_verify_checksum
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*
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* Description:
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* Verify the sent checksum with the calculated checksum.
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*
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****************************************************************************/
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static bool dht_verify_checksum(FAR struct dhtxx_dev_s *priv)
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{
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uint8_t sum;
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sum = (priv->raw_data[0] + priv->raw_data[1] +
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priv->raw_data[2] + priv->raw_data[3]) & 0xffu;
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return (sum == priv->raw_data[4]);
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}
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/****************************************************************************
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* Name: dht_check_data
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*
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* Description:
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* Check for data integrity in regards with the sensors range.
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*
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****************************************************************************/
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static bool dht_check_data(FAR struct dhtxx_sensor_data_s *data,
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float min_hum, float max_hum,
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float min_temp, float max_temp)
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{
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if (data->hum < min_hum || data->hum > max_hum)
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{
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return false;
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}
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if (data->temp < min_temp || data->temp > max_temp)
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{
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return false;
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}
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return true;
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}
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/****************************************************************************
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* Name: dht_check_data
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*
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* Description:
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* Get the humidity and temperature's values from raw data.
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*
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****************************************************************************/
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static int dht_parse_data(FAR struct dhtxx_dev_s *priv,
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FAR struct dhtxx_sensor_data_s *data)
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{
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int ret = OK;
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switch (priv->config->type)
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{
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case DHTXX_DHT11:
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data->hum = priv->raw_data[0];
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data->temp = priv->raw_data[2];
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/* if data is not within sensor's measurement range,
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* an error must have occurred.
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*/
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if (!dht_check_data(data, DHT11_MIN_HUM, DHT11_MAX_HUM,
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DHT11_MIN_TEMP, DHT11_MAX_TEMP))
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{
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ret = -1;
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}
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break;
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case DHTXX_DHT12:
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data->hum = priv->raw_data[0] + priv->raw_data[1] * 0.1F;
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data->temp = priv->raw_data[2] + (priv->raw_data[3] & 0x7fu) * 0.1F;
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if (priv->raw_data[3] & 0x80u)
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{
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data->temp *= -1;
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}
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if (!dht_check_data(data, DHT12_MIN_HUM, DHT12_MAX_HUM,
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DHT12_MIN_TEMP, DHT12_MAX_TEMP))
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{
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ret = -1;
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}
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break;
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case DHTXX_DHT21:
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case DHTXX_DHT22:
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case DHTXX_DHT33:
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case DHTXX_DHT44:
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data->hum = (priv->raw_data[0] << 8u | priv->raw_data[1]) * 0.1F;
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data->temp = (((priv->raw_data[2] & 0x7fu) << 8u) |
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priv->raw_data[3]) * 0.1F;
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if (priv->raw_data[2] & 0x80u)
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{
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data->temp *= -1;
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}
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if (!dht_check_data(data, DHT22_MIN_HUM, DHT22_MAX_HUM,
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DHT22_MIN_TEMP, DHT22_MAX_TEMP))
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{
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ret = -1;
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}
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break;
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}
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return ret;
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}
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/****************************************************************************
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* Name: dhtxx_open
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*
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* Description:
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* This function is called whenever the Dhtxx device is opened.
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*
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****************************************************************************/
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static int dhtxx_open(FAR struct file *filep)
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{
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FAR struct inode *inode = filep->f_inode;
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FAR struct dhtxx_dev_s *priv = inode->i_private;
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int ret;
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/* Acquire the semaphore, wait the sampling time before sending anything to
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* pass unstable state.
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*/
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ret = nxsem_wait_uninterruptible(&priv->devsem);
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if (ret < 0)
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{
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return ret;
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}
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dht_standby_mode(priv);
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nxsig_sleep(DHTXX_SAMPLING_PERIOD_S);
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/* Sensor ready. */
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nxsem_post(&priv->devsem);
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return OK;
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}
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/****************************************************************************
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* Name: dhtxx_close
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*
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* Description:
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* This routine is called when the Dhtxx device is closed.
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*
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****************************************************************************/
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static int dhtxx_close(FAR struct file *filep)
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{
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return OK;
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}
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/****************************************************************************
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* Name: dhtxx_read
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****************************************************************************/
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static ssize_t dhtxx_read(FAR struct file *filep, FAR char *buffer,
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size_t buflen)
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{
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int ret = OK;
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FAR struct inode *inode = filep->f_inode;
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FAR struct dhtxx_dev_s *priv = inode->i_private;
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FAR struct dhtxx_sensor_data_s *data =
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(FAR struct dhtxx_sensor_data_s *)buffer;
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if (!buffer)
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{
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snerr("ERROR: Buffer is null.\n");
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return -1;
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}
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if (buflen < sizeof(FAR struct dhtxx_sensor_data_s))
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{
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snerr("ERROR: Not enough memory to read data sample.\n");
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return -ENOSYS;
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}
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memset(priv->raw_data, 0u, sizeof(priv->raw_data));
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ret = nxsem_wait_uninterruptible(&priv->devsem);
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if (ret < 0)
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{
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return (ssize_t)ret;
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}
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dht_send_start_signal(priv);
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if (dht_prepare_reading(priv) != 0)
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{
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data->status = DHTXX_TIMEOUT;
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ret = -1;
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goto out;
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}
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if (dht_read_raw_data(priv) != 0)
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{
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data->status = DHTXX_TIMEOUT;
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ret = -1;
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goto out;
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}
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if (!dht_verify_checksum(priv))
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{
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data->status = DHTXX_CHECKSUM_ERROR;
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ret = -1;
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goto out;
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}
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if (dht_parse_data(priv, data) != 0)
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{
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data->status = DHTXX_READ_ERROR;
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ret = -1;
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}
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else
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{
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data->status = DHTXX_SUCCESS;
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}
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out:
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/* Done reading, set the sensor back to low mode. */
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dht_standby_mode(priv);
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/* Don't release the semaphore just yet. The sensor needs time between
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* consecutive readings.
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*/
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nxsig_sleep(DHTXX_SAMPLING_PERIOD_S);
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/* Sensor ready for new reading */
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nxsem_post(&priv->devsem);
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return ret;
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}
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/****************************************************************************
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* Name: dhtxx_write
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****************************************************************************/
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static ssize_t dhtxx_write(FAR struct file *filep, FAR const char *buffer,
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size_t buflen)
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{
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return -ENOSYS;
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}
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/****************************************************************************
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* Name: dhtxx_ioctl
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****************************************************************************/
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static int dhtxx_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
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{
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int ret = OK;
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switch (cmd)
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{
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/* Command was not recognized */
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default:
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snerr("ERROR: Unrecognized cmd: %d\n", cmd);
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ret = -ENOTTY;
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break;
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}
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return ret;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: dhtxx_register
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*
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* Description:
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* Register the Dhtxx character device as 'devpath'
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*
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* Input Parameters:
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* devpath - The full path to the driver to register. E.g., "/dev/dht0"
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*
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* Returned Value:
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* Zero (OK) on success; a negated errno value on failure.
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*
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****************************************************************************/
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int dhtxx_register(FAR const char *devpath,
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FAR struct dhtxx_config_s *config)
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{
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FAR struct dhtxx_dev_s *priv;
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int ret;
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/* Initialize the Dhtxx device structure */
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priv = (FAR struct dhtxx_dev_s *)kmm_malloc(sizeof(struct dhtxx_dev_s));
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if (priv == NULL)
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{
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snerr("ERROR: Failed to allocate instance\n");
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return -ENOMEM;
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}
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|
|
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priv->config = config;
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|
|
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/* Register the character driver */
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|
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ret = register_driver(devpath, &g_dhtxxfops, 0666, priv);
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if (ret < 0)
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|
{
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|
kmm_free(priv);
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|
snerr("ERROR: Failed to register driver: %d\n", ret);
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}
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|
|
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return ret;
|
|
}
|