723 lines
20 KiB
C
723 lines
20 KiB
C
/****************************************************************************
|
||
* drivers/sensors/sht21.c
|
||
* Driver for the Sensirion SHT20 and SHT21 temperature and humidity sensors
|
||
*
|
||
* Copyright (C) 2018 Haltian Ltd. All rights reserved.
|
||
* Author: Juha Niskanen <juha.niskanen@haltian.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.
|
||
*
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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 <stdio.h>
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#include <errno.h>
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#include <debug.h>
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#include <time.h>
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||
#include <nuttx/kmalloc.h>
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#include <nuttx/fs/fs.h>
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#include <nuttx/i2c/i2c_master.h>
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#include <nuttx/sensors/sht21.h>
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#include <nuttx/random.h>
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#if defined(CONFIG_I2C) && defined(CONFIG_SENSORS_SHT21)
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/****************************************************************************
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||
* Pre-processor Definitions
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****************************************************************************/
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#ifdef CONFIG_SHT21_DEBUG
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# define sht21_dbg(x, ...) _info(x, ##__VA_ARGS__)
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#else
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# define sht21_dbg(x, ...) sninfo(x, ##__VA_ARGS__)
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#endif
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#ifndef CONFIG_SHT21_I2C_FREQUENCY
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# define CONFIG_SHT21_I2C_FREQUENCY 400000
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#endif
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/* I2C command bytes */
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#define SHT21_TRIG_T_MEAS_HM 0xe3
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#define SHT21_TRIG_RH_MEAS_HM 0xe5
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#define SHT21_WRITE_USERREG 0xe6
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#define SHT21_READ_USERREG 0xe7
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#define SHT21_SOFT_RESET 0xfe
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/****************************************************************************
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* Private
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****************************************************************************/
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struct sht21_dev_s
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{
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FAR struct i2c_master_s *i2c; /* I2C interface */
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uint8_t addr; /* I2C address */
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bool valid; /* If cached readings are valid */
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#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
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bool unlinked; /* True, driver has been unlinked */
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#endif
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struct timespec last_update; /* Last time when sensor was read */
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int temperature; /* Cached temperature */
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int humidity; /* Cached humidity */
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#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
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int16_t crefs; /* Number of open references */
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#endif
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sem_t devsem;
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};
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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/* I2C Helpers */
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static int sht21_access(FAR struct sht21_dev_s *priv,
|
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uint8_t reg_addr, bool read,
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FAR uint8_t *reg_value, uint8_t len);
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#ifdef CONFIG_SHT21_DEBUG
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static int sht21_read8(FAR struct sht21_dev_s *priv, uint8_t regaddr,
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FAR uint8_t *regvalue);
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#endif
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static int sht21_read16(FAR struct sht21_dev_s *priv, uint8_t regaddr,
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FAR uint16_t *regvalue);
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|
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/* Character driver methods */
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#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
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static int sht21_open(FAR struct file *filep);
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static int sht21_close(FAR struct file *filep);
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#endif
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static ssize_t sht21_read(FAR struct file *filep, FAR char *buffer,
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size_t buflen);
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static ssize_t sht21_write(FAR struct file *filep, FAR const char *buffer,
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size_t buflen);
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static int sht21_ioctl(FAR struct file *filep, int cmd,
|
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unsigned long arg);
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#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
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static int sht21_unlink(FAR struct inode *inode);
|
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#endif
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/****************************************************************************
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||
* Private Data
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||
****************************************************************************/
|
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static const struct file_operations g_sht21fops =
|
||
{
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#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
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sht21_open, /* open */
|
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sht21_close, /* close */
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#else
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NULL, /* open */
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NULL, /* close */
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#endif
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sht21_read, /* read */
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sht21_write, /* write */
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NULL, /* seek */
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sht21_ioctl /* ioctl */
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#ifndef CONFIG_DISABLE_POLL
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, NULL /* poll */
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#endif
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#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
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, sht21_unlink /* 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: sht21_access
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*
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* Description:
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* I2C access helper.
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*
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****************************************************************************/
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static int sht21_access(FAR struct sht21_dev_s *priv,
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uint8_t reg_addr, bool read,
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FAR uint8_t *reg_value, uint8_t len)
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{
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struct i2c_msg_s msg[2];
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int ret;
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msg[0].frequency = CONFIG_SHT21_I2C_FREQUENCY;
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msg[0].addr = priv->addr;
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msg[0].flags = 0;
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msg[0].buffer = ®_addr;
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msg[0].length = 1;
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msg[1].frequency = CONFIG_SHT21_I2C_FREQUENCY;
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msg[1].addr = priv->addr;
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msg[1].flags = read ? I2C_M_READ : I2C_M_NOSTART;
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msg[1].buffer = reg_value;
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msg[1].length = len;
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ret = I2C_TRANSFER(priv->i2c, msg, (len > 0) ? 2 : 1);
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sht21_dbg("reg_addr: 0x%02X len: %d reg_value: 0x%02x ret: %d\n",
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reg_addr, len, reg_value ? *reg_value : 0, ret);
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return (ret >= 0) ? OK : ret;
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}
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/****************************************************************************
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* Name: sht21_read8
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*
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* Description:
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* Read 8-bit value from the I2C device.
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*
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****************************************************************************/
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#ifdef CONFIG_SHT21_DEBUG
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static int sht21_read8(FAR struct sht21_dev_s *priv, uint8_t regaddr,
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FAR uint8_t *regvalue)
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{
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uint8_t buf[1];
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int ret;
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ret = sht21_access(priv, regaddr, true, buf, 1);
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if (ret == 0)
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{
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*regvalue = buf[0];
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}
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return ret;
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}
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#endif
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/****************************************************************************
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* Name: sht21_read16
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*
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* Description:
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* Read 16-bit value from the I2C device (MSB first).
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*
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****************************************************************************/
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static int sht21_read16(FAR struct sht21_dev_s *priv, uint8_t regaddr,
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FAR uint16_t *regvalue)
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{
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uint8_t buf[2];
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int ret;
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ret = sht21_access(priv, regaddr, true, buf, 2);
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if (ret == 0)
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{
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*regvalue = ((uint16_t)buf[0] << 8) | (uint16_t)buf[1];
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}
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return ret;
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}
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/****************************************************************************
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* Name: sht21_softreset
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*
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* Description:
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* Reset the SHT2x sensor. This takes less than 15 ms.
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*
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****************************************************************************/
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static inline int sht21_softreset(FAR struct sht21_dev_s *priv)
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{
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return sht21_access(priv, SHT21_SOFT_RESET, false, NULL, 0);
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}
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/****************************************************************************
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* Name: has_time_passed
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*
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* Description:
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* Return true if curr >= start + secs_since_start
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*
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****************************************************************************/
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static bool has_time_passed(struct timespec curr,
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struct timespec start,
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unsigned int secs_since_start)
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{
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if ((long)((start.tv_sec + secs_since_start) - curr.tv_sec) == 0)
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{
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return start.tv_nsec <= curr.tv_nsec;
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}
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return (long)((start.tv_sec + secs_since_start) - curr.tv_sec) <= 0;
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}
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/****************************************************************************
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* Name: sht21_temp_to_mcelsius
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*
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* Description:
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* Convert raw temperature value to milli celsius.
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*
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****************************************************************************/
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static inline int sht21_temp_to_mcelsius(int raw)
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{
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/* Clear status bits. */
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raw &= ~0x03;
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/* Formula T = -46.85 + 175.72 * ST / 2^16 from datasheet 6.2,
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* converted to integer fixed point (3 digits) representation.
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*/
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return (((175720 >> 3) * raw) >> 13) - 46850;
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}
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/****************************************************************************
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* Name: sht21_rh_to_pcm
|
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*
|
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* Description:
|
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* Convert raw humidity value to one-thousandths of a percent
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* (per cent mille) relative humidity.
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*
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****************************************************************************/
|
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static inline int sht21_rh_to_pcm(int raw)
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{
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/* Clear status bits. */
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raw &= ~0x03;
|
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|
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/* Formula RH = -6.0 + 125.0 * SRH / 2^16 from datasheet 6.1,
|
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* converted to integer fixed point (3 digits) representation.
|
||
*/
|
||
|
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return (((125000 >> 3) * raw) >> 13) - 6000;
|
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}
|
||
|
||
/****************************************************************************
|
||
* Name: sht21_read_values
|
||
*
|
||
* Description:
|
||
*
|
||
****************************************************************************/
|
||
|
||
static int sht21_read_values(FAR struct sht21_dev_s *priv, FAR int *temp,
|
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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 */
|
||
|
||
do
|
||
{
|
||
ret = nxsem_wait(&priv->devsem);
|
||
|
||
/* The only case that an error should occur here is if the wait was
|
||
* awakened by a signal.
|
||
*/
|
||
|
||
DEBUGASSERT(ret == OK || ret == -EINTR);
|
||
}
|
||
while (ret == -EINTR);
|
||
|
||
/* 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 */
|
||
|
||
do
|
||
{
|
||
ret = nxsem_wait(&priv->devsem);
|
||
|
||
/* The only case that an error should occur here is if the wait was
|
||
* awakened by a signal.
|
||
*/
|
||
|
||
DEBUGASSERT(ret == OK || ret == -EINTR);
|
||
}
|
||
while (ret == -EINTR);
|
||
|
||
/* 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 */
|
||
|
||
do
|
||
{
|
||
ret = nxsem_wait(&priv->devsem);
|
||
|
||
/* The only case that an error should occur here is if the wait was
|
||
* awakened by a signal.
|
||
*/
|
||
|
||
DEBUGASSERT(ret == OK || ret == -EINTR);
|
||
}
|
||
while (ret == -EINTR);
|
||
|
||
#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 */
|
||
|
||
do
|
||
{
|
||
ret = nxsem_wait(&priv->devsem);
|
||
|
||
/* The only case that an error should occur here is if the wait was
|
||
* awakened by a signal.
|
||
*/
|
||
|
||
DEBUGASSERT(ret == OK || ret == -EINTR);
|
||
}
|
||
while (ret == -EINTR);
|
||
|
||
#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 */
|
||
|
||
do
|
||
{
|
||
ret = nxsem_wait(&priv->devsem);
|
||
|
||
/* The only case that an error should occur here is if the wait was
|
||
* awakened by a signal.
|
||
*/
|
||
|
||
DEBUGASSERT(ret == OK || ret == -EINTR);
|
||
}
|
||
while (ret == -EINTR);
|
||
|
||
/* 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 ret;
|
||
}
|
||
#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 */
|