Device Driver for Sensirion SHT30/SHT31/SHT35 Humidity and Temperature Sensors. More...

Detailed Description

Device Driver for Sensirion SHT30/SHT31/SHT35 Humidity and Temperature Sensors.

Author: Gunar Schorcht gunar.nosp@m.@sch.nosp@m.orcht.nosp@m..net

Definition in file sht3x.h.

#include <stdint.h>
#include <stdbool.h>
#include "periph/i2c.h"

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Go to the source code of this file.

Data Structures
struct	sht3x_params_t
	SHT3x device initialization parameters. More...

struct	sht3x_dev_t
	SHT3x sensor device data structure. More...

#define	SHT3X_I2C_ADDR_1 (0x44)
	possible I2C slave addresses

#define	SHT3X_I2C_ADDR_2 (0x45)
	ADDR pin connected to VDD.

enum	sht3x_error_codes { SHT3X_OK , SHT3X_ERROR_I2C , SHT3X_ERROR_CRC , SHT3X_ERROR_STATUS , SHT3X_ERROR_MEASURE_CMD_INV }
	Driver error codes (returned as negative values) More...

enum	sht3x_mode_t { SHT3X_SINGLE_SHOT = 0 , SHT3X_PERIODIC_0_5_MPS , SHT3X_PERIODIC_1_MPS , SHT3X_PERIODIC_2_MPS , SHT3X_PERIODIC_4_MPS , SHT3X_PERIODIC_10_MPS }
	SHT3x measurement modes. More...

enum	sht3x_repeat_t { SHT3X_HIGH = 0 , SHT3X_MEDIUM , SHT3X_LOW }
	SHT3x repeatability levels. More...

int	sht3x_init (sht3x_dev_t dev, const sht3x_params_t params)
	Initialize the SHT3x sensor device.

int	sht3x_read (sht3x_dev_t dev, int16_t temp, int16_t *hum)
	Read SHT3x measurement results (temperature and humidity)

Macro Definition Documentation

◆ SHT3X_I2C_ADDR_1

#define SHT3X_I2C_ADDR_1 (0x44)

possible I2C slave addresses

ADDR pin connected to GND/VSS

Definition at line 30 of file sht3x.h.

◆ SHT3X_I2C_ADDR_2

#define SHT3X_I2C_ADDR_2 (0x45)

ADDR pin connected to VDD.

Definition at line 31 of file sht3x.h.

Enumeration Type Documentation

◆ sht3x_error_codes

enum sht3x_error_codes

Driver error codes (returned as negative values)

Enumerator
SHT3X_OK	no error
SHT3X_ERROR_I2C	I2C communication failure.
SHT3X_ERROR_CRC	CRC check failed.
SHT3X_ERROR_STATUS	sensor has wrong status
SHT3X_ERROR_MEASURE_CMD_INV	measurement command not executed

Definition at line 36 of file sht3x.h.

◆ sht3x_mode_t

enum sht3x_mode_t

SHT3x measurement modes.

Enumerator
SHT3X_SINGLE_SHOT	single shot measurement
SHT3X_PERIODIC_0_5_MPS	periodic with 0.5 measurements per second (mps)
SHT3X_PERIODIC_1_MPS	periodic with 1 measurements per second (mps)
SHT3X_PERIODIC_2_MPS	periodic with 2 measurements per second (mps)
SHT3X_PERIODIC_4_MPS	periodic with 4 measurements per second (mps)
SHT3X_PERIODIC_10_MPS	periodic with 10 measurements per second (mps)

Definition at line 47 of file sht3x.h.

◆ sht3x_repeat_t

enum sht3x_repeat_t

SHT3x repeatability levels.

The stated repeatability is 3 times the standard deviation of multiple consecutive measurements at the stated repeatability and at constant ambient conditions. It is a measure for the noise on the physical sensor output. Different measurement modes allow for high/medium/low repeatability. [Datasheet SHT3x-DIS]

The configured repeatability level determines the time required for a measurement:

Reapeatability	T typ.	RH typ.	Maximum Measurement Duration
high	0.04	0.08	15.5 ms
medium	0.08	0.15	6.5 ms
low	0.15	0.21	4.5 ms

Enumerator
SHT3X_HIGH	high repeatability
SHT3X_MEDIUM	medium repeatability
SHT3X_LOW	low repeatability

Definition at line 74 of file sht3x.h.

Function Documentation

◆ sht3x_init()

int sht3x_init	(	sht3x_dev_t *	dev,
		const sht3x_params_t *	params
	)

Initialize the SHT3x sensor device.

This function initializes the sensor device.

If the sensor device is configured in any periodic measurement mode, it immediately starts the periodic measurement with configured measurement period and configured repeatability.

In single-shot mode, the sensor device goes into the sleep mode to save power. The single measurement is started when sht3x_read is called.

Parameters

[in]	dev	Device descriptor of SHT3x device to be initialized
[in]	params	SHT3x initialization parameters

Returns: 0 on success or negative error code, see sht3x_error_codes

◆ sht3x_read()

int sht3x_read	(	sht3x_dev_t *	dev,
		int16_t *	temp,
		int16_t *	hum
	)

Read SHT3x measurement results (temperature and humidity)

The function returns the results of one measurement once they are available.

If the single-shot measurement mode is configured, the function

starts the measurement according to the configured repeatability
waits for the sensor to complete the measurement depending on the configured repeatability, and
returns the measurement results.

Note: Since in single-shot measurement mode the measurement is only started when this function is called, it delays the calling task up to 16 ms, depending on the configured repeatability, in order to wait for the results of the measurement.

In the periodic measurement modes, the function returns the results of the last periodic measurement, if already available.

Note: The sht3x_read function should be called less frequently than the periodic measurements are performed. Otherwise, the function implicitly delays the calling task until the results of the next measurement cycle become available to avoid data underrun and sensor blocking.

For either temp or hum also NULL can be passed, if only one value is of interest.