678 lines
18 KiB
C
678 lines
18 KiB
C
/****************************************************************************
|
||
* drivers/sensors/sht21.c
|
||
*
|
||
* Licensed to the Apache Software Foundation (ASF) under one or more
|
||
* contributor license agreements. See the NOTICE file distributed with
|
||
* this work for additional information regarding copyright ownership. The
|
||
* ASF licenses this file to you under the Apache License, Version 2.0 (the
|
||
* "License"); you may not use this file except in compliance with the
|
||
* License. You may obtain a copy of the License at
|
||
*
|
||
* http://www.apache.org/licenses/LICENSE-2.0
|
||
*
|
||
* Unless required by applicable law or agreed to in writing, software
|
||
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
|
||
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
|
||
* License for the specific language governing permissions and limitations
|
||
* under the License.
|
||
*
|
||
****************************************************************************/
|
||
|
||
/****************************************************************************
|
||
* Included Files
|
||
****************************************************************************/
|
||
|
||
#include <nuttx/config.h>
|
||
|
||
#include <stdio.h>
|
||
#include <assert.h>
|
||
#include <errno.h>
|
||
#include <debug.h>
|
||
#include <time.h>
|
||
|
||
#include <nuttx/kmalloc.h>
|
||
#include <nuttx/fs/fs.h>
|
||
#include <nuttx/i2c/i2c_master.h>
|
||
#include <nuttx/sensors/sht21.h>
|
||
#include <nuttx/random.h>
|
||
|
||
#if defined(CONFIG_I2C) && defined(CONFIG_SENSORS_SHT21)
|
||
|
||
/****************************************************************************
|
||
* Pre-processor Definitions
|
||
****************************************************************************/
|
||
|
||
#ifdef CONFIG_SHT21_DEBUG
|
||
# define sht21_dbg(x, ...) _info(x, ##__VA_ARGS__)
|
||
#else
|
||
# define sht21_dbg(x, ...) sninfo(x, ##__VA_ARGS__)
|
||
#endif
|
||
|
||
#ifndef CONFIG_SHT21_I2C_FREQUENCY
|
||
# define CONFIG_SHT21_I2C_FREQUENCY 400000
|
||
#endif
|
||
|
||
/* I2C command bytes */
|
||
|
||
#define SHT21_TRIG_T_MEAS_HM 0xe3
|
||
#define SHT21_TRIG_RH_MEAS_HM 0xe5
|
||
#define SHT21_WRITE_USERREG 0xe6
|
||
#define SHT21_READ_USERREG 0xe7
|
||
#define SHT21_SOFT_RESET 0xfe
|
||
|
||
/****************************************************************************
|
||
* Private
|
||
****************************************************************************/
|
||
|
||
struct sht21_dev_s
|
||
{
|
||
FAR struct i2c_master_s *i2c; /* I2C interface */
|
||
uint8_t addr; /* I2C address */
|
||
bool valid; /* If cached readings are valid */
|
||
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
|
||
bool unlinked; /* True, driver has been unlinked */
|
||
#endif
|
||
struct timespec last_update; /* Last time when sensor was read */
|
||
int temperature; /* Cached temperature */
|
||
int humidity; /* Cached humidity */
|
||
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
|
||
int16_t crefs; /* Number of open references */
|
||
#endif
|
||
sem_t devsem;
|
||
};
|
||
|
||
/****************************************************************************
|
||
* Private Function Prototypes
|
||
****************************************************************************/
|
||
|
||
/* I2C Helpers */
|
||
|
||
static int sht21_access(FAR struct sht21_dev_s *priv,
|
||
uint8_t reg_addr, bool read,
|
||
FAR uint8_t *reg_value, uint8_t len);
|
||
#ifdef CONFIG_SHT21_DEBUG
|
||
static int sht21_read8(FAR struct sht21_dev_s *priv, uint8_t regaddr,
|
||
FAR uint8_t *regvalue);
|
||
#endif
|
||
static int sht21_read16(FAR struct sht21_dev_s *priv, uint8_t regaddr,
|
||
FAR uint16_t *regvalue);
|
||
|
||
/* Character driver methods */
|
||
|
||
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
|
||
static int sht21_open(FAR struct file *filep);
|
||
static int sht21_close(FAR struct file *filep);
|
||
#endif
|
||
static ssize_t sht21_read(FAR struct file *filep, FAR char *buffer,
|
||
size_t buflen);
|
||
static ssize_t sht21_write(FAR struct file *filep, FAR const char *buffer,
|
||
size_t buflen);
|
||
static int sht21_ioctl(FAR struct file *filep, int cmd,
|
||
unsigned long arg);
|
||
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
|
||
static int sht21_unlink(FAR struct inode *inode);
|
||
#endif
|
||
|
||
/****************************************************************************
|
||
* Private Data
|
||
****************************************************************************/
|
||
|
||
static const struct file_operations g_sht21fops =
|
||
{
|
||
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
|
||
sht21_open, /* open */
|
||
sht21_close, /* close */
|
||
#else
|
||
NULL, /* open */
|
||
NULL, /* close */
|
||
#endif
|
||
sht21_read, /* read */
|
||
sht21_write, /* write */
|
||
NULL, /* seek */
|
||
sht21_ioctl, /* ioctl */
|
||
NULL /* poll */
|
||
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
|
||
, sht21_unlink /* unlink */
|
||
#endif
|
||
};
|
||
|
||
/****************************************************************************
|
||
* Private Functions
|
||
****************************************************************************/
|
||
|
||
/****************************************************************************
|
||
* Name: sht21_access
|
||
*
|
||
* Description:
|
||
* I2C access helper.
|
||
*
|
||
****************************************************************************/
|
||
|
||
static int sht21_access(FAR struct sht21_dev_s *priv,
|
||
uint8_t reg_addr, bool read,
|
||
FAR uint8_t *reg_value, uint8_t len)
|
||
{
|
||
struct i2c_msg_s msg[2];
|
||
int ret;
|
||
|
||
msg[0].frequency = CONFIG_SHT21_I2C_FREQUENCY;
|
||
msg[0].addr = priv->addr;
|
||
msg[0].flags = 0;
|
||
msg[0].buffer = ®_addr;
|
||
msg[0].length = 1;
|
||
|
||
msg[1].frequency = CONFIG_SHT21_I2C_FREQUENCY;
|
||
msg[1].addr = priv->addr;
|
||
msg[1].flags = read ? I2C_M_READ : I2C_M_NOSTART;
|
||
msg[1].buffer = reg_value;
|
||
msg[1].length = len;
|
||
|
||
ret = I2C_TRANSFER(priv->i2c, msg, (len > 0) ? 2 : 1);
|
||
|
||
sht21_dbg("reg_addr: 0x%02X len: %d reg_value: 0x%02x ret: %d\n",
|
||
reg_addr, len, reg_value ? *reg_value : 0, ret);
|
||
return (ret >= 0) ? OK : ret;
|
||
}
|
||
|
||
/****************************************************************************
|
||
* Name: sht21_read8
|
||
*
|
||
* Description:
|
||
* Read 8-bit value from the I2C device.
|
||
*
|
||
****************************************************************************/
|
||
|
||
#ifdef CONFIG_SHT21_DEBUG
|
||
static int sht21_read8(FAR struct sht21_dev_s *priv, uint8_t regaddr,
|
||
FAR uint8_t *regvalue)
|
||
{
|
||
uint8_t buf[1];
|
||
int ret;
|
||
|
||
ret = sht21_access(priv, regaddr, true, buf, 1);
|
||
if (ret == 0)
|
||
{
|
||
*regvalue = buf[0];
|
||
}
|
||
|
||
return ret;
|
||
}
|
||
#endif
|
||
|
||
/****************************************************************************
|
||
* Name: sht21_read16
|
||
*
|
||
* Description:
|
||
* Read 16-bit value from the I2C device (MSB first).
|
||
*
|
||
****************************************************************************/
|
||
|
||
static int sht21_read16(FAR struct sht21_dev_s *priv, uint8_t regaddr,
|
||
FAR uint16_t *regvalue)
|
||
{
|
||
uint8_t buf[2];
|
||
int ret;
|
||
|
||
ret = sht21_access(priv, regaddr, true, buf, 2);
|
||
if (ret == 0)
|
||
{
|
||
*regvalue = ((uint16_t)buf[0] << 8) | (uint16_t)buf[1];
|
||
}
|
||
|
||
return ret;
|
||
}
|
||
|
||
/****************************************************************************
|
||
* Name: sht21_softreset
|
||
*
|
||
* Description:
|
||
* Reset the SHT2x sensor. This takes less than 15 ms.
|
||
*
|
||
****************************************************************************/
|
||
|
||
static inline int sht21_softreset(FAR struct sht21_dev_s *priv)
|
||
{
|
||
return sht21_access(priv, SHT21_SOFT_RESET, false, NULL, 0);
|
||
}
|
||
|
||
/****************************************************************************
|
||
* Name: has_time_passed
|
||
*
|
||
* Description:
|
||
* Return true if curr >= start + secs_since_start
|
||
*
|
||
****************************************************************************/
|
||
|
||
static bool has_time_passed(struct timespec curr,
|
||
struct timespec start,
|
||
unsigned int secs_since_start)
|
||
{
|
||
if ((long)((start.tv_sec + secs_since_start) - curr.tv_sec) == 0)
|
||
{
|
||
return start.tv_nsec <= curr.tv_nsec;
|
||
}
|
||
|
||
return (long)((start.tv_sec + secs_since_start) - curr.tv_sec) <= 0;
|
||
}
|
||
|
||
/****************************************************************************
|
||
* Name: sht21_temp_to_mcelsius
|
||
*
|
||
* Description:
|
||
* Convert raw temperature value to milli celsius.
|
||
*
|
||
****************************************************************************/
|
||
|
||
static inline int sht21_temp_to_mcelsius(int raw)
|
||
{
|
||
/* Clear status bits. */
|
||
|
||
raw &= ~0x03;
|
||
|
||
/* Formula T = -46.85 + 175.72 * ST / 2^16 from datasheet 6.2,
|
||
* converted to integer fixed point (3 digits) representation.
|
||
*/
|
||
|
||
return (((175720 >> 3) * raw) >> 13) - 46850;
|
||
}
|
||
|
||
/****************************************************************************
|
||
* Name: sht21_rh_to_pcm
|
||
*
|
||
* Description:
|
||
* Convert raw humidity value to one-thousandths of a percent
|
||
* (per cent mille) relative humidity.
|
||
*
|
||
****************************************************************************/
|
||
|
||
static inline int sht21_rh_to_pcm(int raw)
|
||
{
|
||
/* Clear status bits. */
|
||
|
||
raw &= ~0x03;
|
||
|
||
/* Formula RH = -6.0 + 125.0 * SRH / 2^16 from datasheet 6.1,
|
||
* converted to integer fixed point (3 digits) representation.
|
||
*/
|
||
|
||
return (((125000 >> 3) * raw) >> 13) - 6000;
|
||
}
|
||
|
||
/****************************************************************************
|
||
* Name: sht21_read_values
|
||
*
|
||
* Description:
|
||
*
|
||
****************************************************************************/
|
||
|
||
static int sht21_read_values(FAR struct sht21_dev_s *priv, FAR int *temp,
|
||
FAR int *rh)
|
||
{
|
||
uint16_t temp16;
|
||
uint16_t rh16;
|
||
struct timespec ts;
|
||
int ret;
|
||
|
||
clock_gettime(CLOCK_REALTIME, &ts);
|
||
|
||
/* Datasheet section 2.3: "To keep self heating below 0.1°C, SHT2x
|
||
* should not be active for more than 10% of the time – e.g. maximum
|
||
* two measurements per second at 12bit accuracy shall be made."
|
||
* We limit to one measurement per second to keep arithmetic simple.
|
||
*/
|
||
|
||
if (!priv->valid || has_time_passed(ts, priv->last_update, 1))
|
||
{
|
||
/* Read the raw temperature data */
|
||
|
||
ret = sht21_read16(priv, SHT21_TRIG_T_MEAS_HM, &temp16);
|
||
if (ret < 0)
|
||
{
|
||
snerr("ERROR: sht21_read16 failed: %d\n", ret);
|
||
return ret;
|
||
}
|
||
|
||
/* Read the raw humidity data */
|
||
|
||
ret = sht21_read16(priv, SHT21_TRIG_RH_MEAS_HM, &rh16);
|
||
if (ret < 0)
|
||
{
|
||
snerr("ERROR: sht21_read16 failed: %d\n", ret);
|
||
return ret;
|
||
}
|
||
|
||
add_sensor_randomness(ts.tv_nsec ^ ((int)temp16 << 16 | rh16));
|
||
|
||
priv->temperature = sht21_temp_to_mcelsius(temp16);
|
||
priv->humidity = sht21_rh_to_pcm(rh16);
|
||
priv->last_update = ts;
|
||
priv->valid = true;
|
||
}
|
||
|
||
*temp = priv->temperature;
|
||
*rh = priv->humidity;
|
||
return OK;
|
||
}
|
||
|
||
/****************************************************************************
|
||
* Name: sht21_open
|
||
*
|
||
* Description:
|
||
* This function is called whenever the SHT2x device is opened.
|
||
*
|
||
****************************************************************************/
|
||
|
||
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
|
||
static int sht21_open(FAR struct file *filep)
|
||
{
|
||
FAR struct inode *inode = filep->f_inode;
|
||
FAR struct sht21_dev_s *priv = inode->i_private;
|
||
int ret;
|
||
|
||
/* Get exclusive access */
|
||
|
||
ret = nxsem_wait_uninterruptible(&priv->devsem);
|
||
if (ret < 0)
|
||
{
|
||
return ret;
|
||
}
|
||
|
||
/* Increment the count of open references on the driver */
|
||
|
||
priv->crefs++;
|
||
DEBUGASSERT(priv->crefs > 0);
|
||
|
||
nxsem_post(&priv->devsem);
|
||
return OK;
|
||
}
|
||
#endif
|
||
|
||
/****************************************************************************
|
||
* Name: sht21_close
|
||
*
|
||
* Description:
|
||
* This routine is called when the SHT2x device is closed.
|
||
*
|
||
****************************************************************************/
|
||
|
||
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
|
||
static int sht21_close(FAR struct file *filep)
|
||
{
|
||
FAR struct inode *inode = filep->f_inode;
|
||
FAR struct sht21_dev_s *priv = inode->i_private;
|
||
int ret;
|
||
|
||
/* Get exclusive access */
|
||
|
||
ret = nxsem_wait_uninterruptible(&priv->devsem);
|
||
if (ret < 0)
|
||
{
|
||
return ret;
|
||
}
|
||
|
||
/* Decrement the count of open references on the driver */
|
||
|
||
DEBUGASSERT(priv->crefs > 0);
|
||
priv->crefs--;
|
||
|
||
/* If the count has decremented to zero and the driver has been unlinked,
|
||
* then free memory now.
|
||
*/
|
||
|
||
if (priv->crefs <= 0 && priv->unlinked)
|
||
{
|
||
nxsem_destroy(&priv->devsem);
|
||
kmm_free(priv);
|
||
return OK;
|
||
}
|
||
|
||
nxsem_post(&priv->devsem);
|
||
return OK;
|
||
}
|
||
#endif
|
||
|
||
/****************************************************************************
|
||
* Name: sht21_read
|
||
****************************************************************************/
|
||
|
||
static ssize_t sht21_read(FAR struct file *filep, FAR char *buffer,
|
||
size_t buflen)
|
||
{
|
||
FAR struct inode *inode = filep->f_inode;
|
||
FAR struct sht21_dev_s *priv = inode->i_private;
|
||
ssize_t length = 0;
|
||
int temp;
|
||
int rh;
|
||
int ret;
|
||
|
||
/* Get exclusive access */
|
||
|
||
ret = nxsem_wait_uninterruptible(&priv->devsem);
|
||
if (ret < 0)
|
||
{
|
||
return (ssize_t)ret;
|
||
}
|
||
|
||
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
|
||
if (priv->unlinked)
|
||
{
|
||
/* Do not allow operations on unlinked sensors. This allows
|
||
* sensor use on hot swappable I2C bus.
|
||
*/
|
||
|
||
nxsem_post(&priv->devsem);
|
||
return -ENODEV;
|
||
}
|
||
#endif
|
||
|
||
ret = sht21_read_values(priv, &temp, &rh);
|
||
if (ret < 0)
|
||
{
|
||
sht21_dbg("cannot read data: %d\n", ret);
|
||
}
|
||
else
|
||
{
|
||
/* This interface is mainly intended for easy debugging in nsh. */
|
||
|
||
length = snprintf(buffer, buflen, "%d %d\n", temp, rh);
|
||
if (length > buflen)
|
||
{
|
||
length = buflen;
|
||
}
|
||
}
|
||
|
||
nxsem_post(&priv->devsem);
|
||
return length;
|
||
}
|
||
|
||
/****************************************************************************
|
||
* Name: sht21_write
|
||
****************************************************************************/
|
||
|
||
static ssize_t sht21_write(FAR struct file *filep, FAR const char *buffer,
|
||
size_t buflen)
|
||
{
|
||
return -ENOSYS;
|
||
}
|
||
|
||
/****************************************************************************
|
||
* Name: sht21_ioctl
|
||
****************************************************************************/
|
||
|
||
static int sht21_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
|
||
{
|
||
FAR struct inode *inode = filep->f_inode;
|
||
FAR struct sht21_dev_s *priv = inode->i_private;
|
||
int ret;
|
||
|
||
/* Get exclusive access */
|
||
|
||
ret = nxsem_wait_uninterruptible(&priv->devsem);
|
||
if (ret < 0)
|
||
{
|
||
return ret;
|
||
}
|
||
|
||
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
|
||
if (priv->unlinked)
|
||
{
|
||
/* Do not allow operations on unlinked sensors. This allows
|
||
* sensor use on hot swappable I2C bus.
|
||
*/
|
||
|
||
nxsem_post(&priv->devsem);
|
||
return -ENODEV;
|
||
}
|
||
#endif
|
||
|
||
switch (cmd)
|
||
{
|
||
/* Soft reset the SHT2x, Arg: None */
|
||
|
||
case SNIOC_RESET:
|
||
{
|
||
ret = sht21_softreset(priv);
|
||
sht21_dbg("softreset ret: %d\n", ret);
|
||
}
|
||
break;
|
||
|
||
case SNIOC_READ_RAW_DATA:
|
||
case SNIOC_READ_CONVERT_DATA:
|
||
{
|
||
int temp;
|
||
int rh;
|
||
|
||
ret = sht21_read_values(priv, &temp, &rh);
|
||
if (ret < 0)
|
||
{
|
||
sht21_dbg("cannot read data: %d\n", ret);
|
||
}
|
||
else
|
||
{
|
||
FAR struct sht21_conv_data_s *data =
|
||
(FAR struct sht21_conv_data_s *)arg;
|
||
|
||
data->temperature = temp;
|
||
data->humidity = rh;
|
||
}
|
||
}
|
||
break;
|
||
|
||
#ifdef CONFIG_SHT21_DEBUG
|
||
case SNIOC_DUMP_REGS:
|
||
{
|
||
uint8_t userreg = 0;
|
||
ret = sht21_read8(priv, SHT21_READ_USERREG, &userreg);
|
||
sht21_dbg("read8 ret = %d, userreg = %d\n", ret, userreg);
|
||
}
|
||
break;
|
||
#endif
|
||
|
||
default:
|
||
sht21_dbg("Unrecognized cmd: %d\n", cmd);
|
||
ret = -ENOTTY;
|
||
break;
|
||
}
|
||
|
||
nxsem_post(&priv->devsem);
|
||
return ret;
|
||
}
|
||
|
||
/****************************************************************************
|
||
* Name: sht21_unlink
|
||
****************************************************************************/
|
||
|
||
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
|
||
static int sht21_unlink(FAR struct inode *inode)
|
||
{
|
||
FAR struct sht21_dev_s *priv;
|
||
int ret;
|
||
|
||
DEBUGASSERT(inode != NULL && inode->i_private != NULL);
|
||
priv = (FAR struct sht21_dev_s *)inode->i_private;
|
||
|
||
/* Get exclusive access */
|
||
|
||
ret = nxsem_wait_uninterruptible(&priv->devsem);
|
||
if (ret < 0)
|
||
{
|
||
return ret;
|
||
}
|
||
|
||
/* Are there open references to the driver data structure? */
|
||
|
||
if (priv->crefs <= 0)
|
||
{
|
||
nxsem_destroy(&priv->devsem);
|
||
kmm_free(priv);
|
||
return OK;
|
||
}
|
||
|
||
/* No... just mark the driver as unlinked and free the resources when
|
||
* the last client closes their reference to the driver.
|
||
*/
|
||
|
||
priv->unlinked = true;
|
||
nxsem_post(&priv->devsem);
|
||
return OK;
|
||
}
|
||
#endif
|
||
|
||
/****************************************************************************
|
||
* Public Functions
|
||
****************************************************************************/
|
||
|
||
/****************************************************************************
|
||
* Name: sht21_register
|
||
*
|
||
* Description:
|
||
* Register the SHT2x character device as 'devpath'
|
||
*
|
||
* Input Parameters:
|
||
* devpath - The full path to the driver to register. E.g., "/dev/temp0"
|
||
* i2c - An instance of the I2C interface to use to communicate with
|
||
* the SHT2x
|
||
* addr - The I2C address of the SHT2x. The I2C address of both SHT20
|
||
* and SHT21 is always 0x40.
|
||
*
|
||
* Returned Value:
|
||
* Zero (OK) on success; a negated errno value on failure.
|
||
*
|
||
****************************************************************************/
|
||
|
||
int sht21_register(FAR const char *devpath, FAR struct i2c_master_s *i2c,
|
||
uint8_t addr)
|
||
{
|
||
FAR struct sht21_dev_s *priv;
|
||
int ret;
|
||
|
||
DEBUGASSERT(i2c != NULL);
|
||
DEBUGASSERT(addr == CONFIG_SHT21_ADDR);
|
||
|
||
/* Initialize the device structure */
|
||
|
||
priv = (FAR struct sht21_dev_s *)kmm_zalloc(sizeof(struct sht21_dev_s));
|
||
if (priv == NULL)
|
||
{
|
||
snerr("ERROR: Failed to allocate instance\n");
|
||
return -ENOMEM;
|
||
}
|
||
|
||
priv->i2c = i2c;
|
||
priv->addr = addr;
|
||
|
||
nxsem_init(&priv->devsem, 0, 1);
|
||
|
||
/* Register the character driver */
|
||
|
||
ret = register_driver(devpath, &g_sht21fops, 0666, priv);
|
||
if (ret < 0)
|
||
{
|
||
snerr("ERROR: Failed to register driver: %d\n", ret);
|
||
kmm_free(priv);
|
||
}
|
||
|
||
return ret;
|
||
}
|
||
#endif /* CONFIG_I2C && CONFIG_SENSORS_SHT21 */
|