/****************************************************************************
* include/nuttx/sensors/dhtxx.c
*
* Copyright (C) 2018 Abdelatif GUETTOUCHE. All rights reserved.
* Author: Abdelatif GUETTOUCHE <abdelatif.guettouche@gmail.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include <nuttx/fs/fs.h>
#include <nuttx/signal.h>
#include <nuttx/semaphore.h>
#include <nuttx/time.h>
#include <nuttx/clock.h>
#include <nuttx/sensors/dhtxx.h>
/*****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define DHTXX_START_SIGNAL_LOW_US 20000
#define DHTXX_START_SIGNAL_HIGH_US 100
#define DHTXX_RESPONSE_SIGNAL_US 85
#define DHTXX_TRANSMISSION_START_US 55
#define DHTXX_MIN_ZERO_DURATION 22
#define DHTXX_MAX_ZERO_DURATION 30
#define DHTXX_MIN_ONE_DURATION 40
#define DHTXX_MAX_ONE_DURATION 75
#define DHTXX_SAMPLING_PERIOD_S 2
#define DHTXX_RESPONSE_BITS 40U
#define DHT11_MIN_HUM 20.0F
#define DHT11_MAX_HUM 90.0F
#define DHT11_MIN_TEMP 0.0F
#define DHT11_MAX_TEMP 50.0F
#define DHT12_MIN_HUM 20.0F
#define DHT12_MAX_HUM 95.0F
#define DHT12_MIN_TEMP -20.0F
#define DHT12_MAX_TEMP 60.0F
#define DHT22_MIN_HUM 0.0F
#define DHT22_MAX_HUM 100.0F
#define DHT22_MIN_TEMP -40.0F
#define DHT22_MAX_TEMP 80.0F
/****************************************************************************
* Private Type Definitions
****************************************************************************/
struct dhtxx_dev_s
{
FAR struct dhtxx_config_s *config;
sem_t devsem;
uint8_t raw_data[5];
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static void dht_standby_mode(FAR struct dhtxx_dev_s *priv);
static void dht_send_start_signal(FAR struct dhtxx_dev_s *priv);
static int dht_prepare_reading(FAR struct dhtxx_dev_s *priv);
static int dht_read_raw_data(FAR struct dhtxx_dev_s *priv);
static bool dht_verify_checksum(FAR struct dhtxx_dev_s *priv);
static bool dht_check_data(FAR struct dhtxx_sensor_data_s *data,
float min_hum, float max_hum,
float min_temp, float max_temp);
static int dht_parse_data(FAR struct dhtxx_dev_s *priv,
FAR struct dhtxx_sensor_data_s *data);
/* Character driver methods */
static int dhtxx_open(FAR struct file *filep);
static int dhtxx_close(FAR struct file *filep);
static ssize_t dhtxx_read(FAR struct file *filep, FAR char *buffer,
size_t buflen);
static ssize_t dhtxx_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen);
static int dhtxx_ioctl(FAR struct file *filep, int cmd,
unsigned long arg);
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations g_dhtxxfops =
{
dhtxx_open, /* open */
dhtxx_close, /* close */
dhtxx_read, /* read */
dhtxx_write, /* write */
NULL, /* seek */
dhtxx_ioctl /* ioctl */
#ifndef CONFIG_DISABLE_POLL
, NULL /* poll */
#endif
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
, NULL /* unlink */
#endif
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: dht_standby_mode
*
* Description:
* Put the sensor in low power consumption (standby) mode.
*
****************************************************************************/
static void dht_standby_mode(FAR struct dhtxx_dev_s *priv)
{
priv->config->config_data_pin(priv->config, false);
priv->config->set_data_pin(priv->config, true);
}
/****************************************************************************
* Name: dht_send_start_signal
*
* Description:
* Send a start signal to the sensor.
*
****************************************************************************/
static void dht_send_start_signal(FAR struct dhtxx_dev_s *priv)
{
int64_t start_time;
int64_t current_time;
priv->config->config_data_pin(priv->config, false);
priv->config->set_data_pin(priv->config, false);
start_time = priv->config->get_clock(priv->config);
while (1)
{
current_time = priv->config->get_clock(priv->config);
if (current_time - start_time >= DHTXX_START_SIGNAL_LOW_US)
{
break;
}
}
priv->config->set_data_pin(priv->config, true);
start_time = priv->config->get_clock(priv->config);
while (1)
{
current_time = priv->config->get_clock(priv->config);
if (current_time - start_time >= DHTXX_START_SIGNAL_HIGH_US)
{
break;
}
}
}
/****************************************************************************
* Name: dht_prepare_reading
*
* Description:
* Gets the sensor ready for transmitting data.
*
****************************************************************************/
static int dht_prepare_reading(FAR struct dhtxx_dev_s *priv)
{
int64_t start_time;
int64_t current_time;
/* Prepare for reading data. */
priv->config->config_data_pin(priv->config, true);
/* The DHT will clear the data pin for about 80uS. */
start_time = priv->config->get_clock(priv->config);
while (!priv->config->read_data_pin(priv->config))
{
current_time = priv->config->get_clock(priv->config);
if (current_time - start_time > DHTXX_RESPONSE_SIGNAL_US)
{
return -1;
}
}
/* The DHT will set the data pin for about 80uS. */
while (priv->config->read_data_pin(priv->config))
{
current_time = priv->config->get_clock(priv->config);
if (current_time - start_time > DHTXX_RESPONSE_SIGNAL_US)
{
return -1;
}
}
return 0;
}
/****************************************************************************
* Name: dht_read_raw_data
*
* Description:
* Reads raw data from the sensor.
*
****************************************************************************/
static int dht_read_raw_data(FAR struct dhtxx_dev_s *priv)
{
int64_t start_time;
int64_t end_time;
int64_t current_time;
uint8_t j, i;
j = 0U;
for (i = 0U; i < DHTXX_RESPONSE_BITS; i++)
{
/* Start of transmission begins with a ~50uS low. */
start_time = priv->config->get_clock(priv->config);
while (!priv->config->read_data_pin(priv->config))
{
current_time = priv->config->get_clock(priv->config);
if (current_time - start_time > DHTXX_TRANSMISSION_START_US)
{
return -1;
}
}
/* Get start time. */
start_time = priv->config->get_clock(priv->config);
while (priv->config->read_data_pin(priv->config))
{
current_time = priv->config->get_clock(priv->config);
if (current_time - start_time > DHTXX_MAX_ONE_DURATION)
{
return -1;
}
}
end_time = priv->config->get_clock(priv->config);
if (end_time - start_time >= DHTXX_MIN_ONE_DURATION)
{
priv->raw_data[j] = (priv->raw_data[j] << 1U) | 1U;
}
else
{
priv->raw_data[j] = priv->raw_data[j] << 1U;
}
if (i % 8U == 7U)
{
j++;
}
}
return 0;
}
/****************************************************************************
* Name: dht_verify_checksum
*
* Description:
* Verify the sent checksum with the calculated checksum.
*
****************************************************************************/
static bool dht_verify_checksum(FAR struct dhtxx_dev_s *priv)
{
uint8_t sum;
sum = (priv->raw_data[0] + priv->raw_data[1] +
priv->raw_data[2] + priv->raw_data[3]) & 0xFFU;
return (sum == priv->raw_data[4]);
}
/****************************************************************************
* Name: dht_check_data
*
* Description:
* Check for data integrity in regards with the sensors range.
*
****************************************************************************/
static bool dht_check_data(FAR struct dhtxx_sensor_data_s *data,
float min_hum, float max_hum,
float min_temp, float max_temp)
{
if (data->hum < min_hum || data->hum > max_hum)
{
return false;
}
if (data->temp < min_temp || data->temp > max_temp)
{
return false;
}
return true;
}
/****************************************************************************
* Name: dht_check_data
*
* Description:
* Get the humidity and temperature's values from raw data.
*
****************************************************************************/
static int dht_parse_data(FAR struct dhtxx_dev_s *priv,
FAR struct dhtxx_sensor_data_s *data)
{
int ret = OK;
switch (priv->config->type)
{
case DHTXX_DHT11:
data->hum = priv->raw_data[0];
data->temp = priv->raw_data[2];
/* if data is not within sensor's measurement range,
* an error must have accured.
*/
if (!dht_check_data(data, DHT11_MIN_HUM, DHT11_MAX_HUM,
DHT11_MIN_TEMP, DHT11_MAX_TEMP))
{
ret = -1;
}
break;
case DHTXX_DHT12:
data->hum = priv->raw_data[0] + priv->raw_data[1] * 0.1F;
data->temp = priv->raw_data[2] + (priv->raw_data[3] & 0x7FU) * 0.1F;
if (priv->raw_data[3] & 0x80U)
{
data->temp *= -1;
}
if (!dht_check_data(data, DHT12_MIN_HUM, DHT12_MAX_HUM,
DHT12_MIN_TEMP, DHT12_MAX_TEMP))
{
ret = -1;
}
break;
case DHTXX_DHT21:
case DHTXX_DHT22:
case DHTXX_DHT33:
case DHTXX_DHT44:
data->hum = (priv->raw_data[0] << 8U | priv->raw_data[1]) * 0.1F;
data->temp = (((priv->raw_data[2] & 0x7FU) << 8U) |
priv->raw_data[3]) * 0.1F;
if (priv->raw_data[2] & 0x80U)
{
data->temp *= -1;
}
if (!dht_check_data(data, DHT22_MIN_HUM, DHT22_MAX_HUM,
DHT22_MIN_TEMP, DHT22_MAX_TEMP))
{
ret = -1;
}
break;
}
return ret;
}
/****************************************************************************
* Name: dhtxx_open
*
* Description:
* This function is called whenever the Dhtxx device is opened.
*
****************************************************************************/
static int dhtxx_open(FAR struct file *filep)
{
int ret;
FAR struct inode *inode = filep->f_inode;
FAR struct dhtxx_dev_s *priv = inode->i_private;
/* Acquire the semaphore, wait the sampling time before sending anything to
* pass unstable state.
*/
do
{
ret = nxsem_wait(&priv->devsem);
}
while (ret == -EINTR);
dht_standby_mode(priv);
nxsig_sleep(DHTXX_SAMPLING_PERIOD_S);
/* Sensor ready. */
nxsem_post(&priv->devsem);
return OK;
}
/****************************************************************************
* Name: dhtxx_close
*
* Description:
* This routine is called when the Dhtxx device is closed.
*
****************************************************************************/
static int dhtxx_close(FAR struct file *filep)
{
return OK;
}
/****************************************************************************
* Name: dhtxx_read
****************************************************************************/
static ssize_t dhtxx_read(FAR struct file *filep, FAR char *buffer,
size_t buflen)
{
int ret;
FAR struct inode *inode = filep->f_inode;
FAR struct dhtxx_dev_s *priv = inode->i_private;
FAR struct dhtxx_sensor_data_s *data =
(FAR struct dhtxx_sensor_data_s *)buffer;
if (!buffer)
{
snerr("ERROR: Buffer is null.\n");
return -1;
}
if (buflen < sizeof(FAR struct dhtxx_sensor_data_s))
{
snerr("ERROR: Not enough memory for reading out a sensor data sample.\n");
return -ENOSYS;
}
memset(priv->raw_data, 0U, sizeof(priv->raw_data));
do
{
ret = nxsem_wait(&priv->devsem);
}
while (ret == -EINTR);
dht_send_start_signal(priv);
if (dht_prepare_reading(priv) != 0)
{
data->status = DHTXX_TIMEOUT;
ret = -1;
goto out;
}
if (dht_read_raw_data(priv) != 0)
{
data->status = DHTXX_TIMEOUT;
ret = -1;
goto out;
}
if (!dht_verify_checksum(priv))
{
data->status = DHTXX_CHECKSUM_ERROR;
ret = -1;
goto out;
}
if (dht_parse_data(priv, data) != 0)
{
data->status = DHTXX_READ_ERROR;
ret = -1;
}
else
{
data->status = DHTXX_SUCCESS;
}
out:
/* Done reading, set the sensor back to low mode. */
dht_standby_mode(priv);
/* Don't release the semaphore just yet. The sensor needs time between
* consecutive readings.
*/
nxsig_sleep(DHTXX_SAMPLING_PERIOD_S);
/* Sensor ready for new reading */
nxsem_post(&priv->devsem);
return ret;
}
/****************************************************************************
* Name: dhtxx_write
****************************************************************************/
static ssize_t dhtxx_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen)
{
return -ENOSYS;
}
/****************************************************************************
* Name: dhtxx_ioctl
****************************************************************************/
static int dhtxx_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
int ret = OK;
switch (cmd)
{
/* Command was not recognized */
default:
snerr("ERROR: Unrecognized cmd: %d\n", cmd);
ret = -ENOTTY;
break;
}
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: dhtxx_register
*
* Description:
* Register the Dhtxx character device as 'devpath'
*
* Input Parameters:
* devpath - The full path to the driver to register. E.g., "/dev/dht0"
*
* Returned Value:
* Zero (OK) on success; a negated errno value on failure.
*
****************************************************************************/
int dhtxx_register(FAR const char *devpath, FAR struct dhtxx_config_s *config)
{
FAR struct dhtxx_dev_s *priv;
int ret;
/* Initialize the Dhtxx device structure */
priv = (FAR struct dhtxx_dev_s *)kmm_malloc(sizeof(struct dhtxx_dev_s));
if (priv == NULL)
{
snerr("ERROR: Failed to allocate instance\n");
return -ENOMEM;
}
priv->config = config;
/* Register the character driver */
ret = register_driver(devpath, &g_dhtxxfops, 0666, priv);
if (ret < 0)
{
kmm_free(priv);
snerr("ERROR: Failed to register driver: %d\n", ret);
}
return ret;
}