SHT2x Humidity and Temperature sensor

Device driver interface for the SHT2x sensor. More...

Detailed Description

Device driver interface for the SHT2x sensor.

Files
file	sht2x.h
	Device driver implementation for the SHT2x humidity and temperature humidity sensor.
file	sht2x_params.h
	Default configuration for SHT2x humidity and temperature sensor.

Data Structures
struct	sht2x_params_t
	Device initialization parameters. More...
struct	sht2x_t
	Device descriptor for the SHT2X sensor. More...

Enumerations
enum	{   SHT2X_OK = 0 , SHT2X_ERR_I2C = -1 , SHT2X_ERR_NODEV = -2 , SHT2X_ERR_NOCAL = -3 ,   SHT2X_ERR_I2C_READ = -4 , SHT2X_ERR_TIMEDOUT = -5 , SHT2X_ERR_CRC = -6 , SHT2X_ERR_USERREG = -7 ,   SHT2X_ERR_RES = -8 , SHT2X_ERR_OTHER = -999 }
	Status and error return codes. More...
enum	sht2x_res_t { SHT2X_RES_12_14BIT = 0x00 , SHT2X_RES_8_12BIT = 0x01 , SHT2X_RES_10_13BIT = 0x80 , SHT2X_RES_11_11BIT = 0x81 }
	Available resolutions. More...
enum	sht2x_measure_mode_t { SHT2X_MEASURE_MODE_HOLD = 0 , SHT2X_MEASURE_MODE_NO_HOLD = 1 }
	Available Measuring modes. More...

Functions
int	sht2x_init (sht2x_t *dev, const sht2x_params_t *params)
	Initialize the given SHT2X device. More...
int	sht2x_reset (sht2x_t *dev)
	Reset the SHT2X device. More...
int16_t	sht2x_read_temperature (const sht2x_t *dev)
	Read temperature value from the given SHT2X device, returned in centi °C. More...
uint16_t	sht2x_read_humidity (const sht2x_t *dev)
	Read humidity value from the given SHT2X device, returned in centi RH. More...
int	sht2x_read_ident (const sht2x_t *dev, uint8_t *buffer, size_t buflen)
	Read identification code from the given SHT2X device. More...
int	sht2x_read_userreg (const sht2x_t *dev, uint8_t *userreg)
	Read User Register from the given SHT2X device. More...
int	sht2x_write_userreg (const sht2x_t *dev, uint8_t userreg)
	Write User Register to the given SHT2X device. More...
#define	SHT2X_USER_RESOLUTION_MASK   0x81
	User register masks. More...
#define	SHT2X_USER_EOB_MASK   0x40
#define	SHT2X_USER_HEATER_MASK   0x04
#define	SHT2X_USER_RESERVED_MASK   0x38
#define	SHT2X_USER_OTP_MASK   0x02

Macro Definition Documentation

SHT2X_USER_RESOLUTION_MASK

#define SHT2X_USER_RESOLUTION_MASK   0x81

User register masks.

Notice that the values of sht2x_res_t must only have the bits in SHT2X_USER_RESOLUTION_MASK.

Definition at line 78 of file sht2x.h.

Enumeration Type Documentation

anonymous enum

anonymous enum

Status and error return codes.

Enumerator
SHT2X_OK	everything was fine
SHT2X_ERR_I2C	error initializing the I2C bus
SHT2X_ERR_NODEV	did not detect SHT2x
SHT2X_ERR_NOCAL	could not read calibration data
SHT2X_ERR_I2C_READ	I2C read error.
SHT2X_ERR_TIMEDOUT	timed out
SHT2X_ERR_CRC	CRC error.
SHT2X_ERR_USERREG	cannot write User Reg
SHT2X_ERR_RES	invalid resolution
SHT2X_ERR_OTHER	fatal error

Definition at line 39 of file sht2x.h.

sht2x_measure_mode_t

enum sht2x_measure_mode_t

Available Measuring modes.

Enumerator
SHT2X_MEASURE_MODE_HOLD	trigger measurement, hold master
SHT2X_MEASURE_MODE_NO_HOLD	trigger measurement, no hold master (i.e. poll)

Definition at line 67 of file sht2x.h.

sht2x_res_t

enum sht2x_res_t

Available resolutions.

The values represent bits 7 and 0 in the User Register

Enumerator
SHT2X_RES_12_14BIT	RH=12bit, T=14bit.
SHT2X_RES_8_12BIT	RH= 8bit, T=12bit.
SHT2X_RES_10_13BIT	RH=10bit, T=13bit.
SHT2X_RES_11_11BIT	RH=11bit, T=11bit.

Definition at line 57 of file sht2x.h.

Function Documentation

sht2x_init()

int sht2x_init	(	sht2x_t *	dev,
		const sht2x_params_t *	params
	)

Initialize the given SHT2X device.

Parameters

[out]	dev	Initialized device descriptor of SHT2X device
[in]	params	The parameters for the SHT2x device

Returns

SHT2X_OK on success

SHT2X_ERR_I2C if given I2C is not enabled in board config

SHT2X_ERR_RES invalid resolution

SHT2X_ERR_USERREG error writing User Register

errors returned by sht2x_write_userreg or sht2x_read_userreg

sht2x_read_humidity()

uint16_t sht2x_read_humidity

(

const sht2x_t *

dev

)

Read humidity value from the given SHT2X device, returned in centi RH.

Notice that this function will sleep (max 29 ms) when the measure_mode is set to SHT2X_MEASURE_MODE_NO_HOLD.

Parameters

[in]

dev

Device descriptor of SHT2X device to read from

Returns

Humidity in centi RH (i.e. the percentage times 100). In case of an error it returns 0 (i.e. an unrealistic value).

sht2x_read_ident()

int sht2x_read_ident	(	const sht2x_t *	dev,
		uint8_t *	buffer,
		size_t	buflen
	)

Read identification code from the given SHT2X device.

Parameters

[in]	dev	Device descriptor of SHT2X device to read from
[out]	buffer	Buffer to write the identification code to
[in]	buflen	The size of buffer

Returns

>= 0 on success, number of bytes read

SHT2X_ERR_CRC in case of a CRC mismatch

<0 errors returned by i2c_read_regs

sht2x_read_temperature()

int16_t sht2x_read_temperature

(

const sht2x_t *

dev

)

Read temperature value from the given SHT2X device, returned in centi °C.

Notice that this function will sleep (max 85 ms) when the measure_mode is set to SHT2X_MEASURE_MODE_NO_HOLD.

Parameters

[in]

dev

Device descriptor of SHT2X device to read from

Returns

The temperature in centi Celsius. In case of an error it returns INT16_MIN.

sht2x_read_userreg()

int sht2x_read_userreg	(	const sht2x_t *	dev,
		uint8_t *	userreg
	)

Read User Register from the given SHT2X device.

Parameters

[in]	dev	Device descriptor of SHT2X device to read from
[out]	userreg	The value of User Register

Returns

SHT2X_OK on success

SHT2X_ERR_I2C if given I2C is not enabled in board config

SHT2X_ERR_OTHER if NULL pointer was given for buffer

sht2x_reset()

int sht2x_reset

(

sht2x_t *

dev

)

Reset the SHT2X device.

Parameters

[in]

dev

Device descriptor of SHT2X device to read from

Returns

SHT2X_OK on success

SHT2X_ERR_I2C if given I2C is not enabled in board config

sht2x_write_userreg()

int sht2x_write_userreg	(	const sht2x_t *	dev,
		uint8_t	userreg
	)

Write User Register to the given SHT2X device.

Parameters

[in]	dev	Device descriptor of SHT2X device to read from
[in]	userreg	The value of User Register

Returns

SHT2X_OK on success

SHT2X_ERR_I2C if given I2C is not enabled in board config