HS4xxx Sensor API

HS4xxx Temperature/Humidity Sensor API. More...

Files
file	hs4xxx.h
	HS4xxx sensor declarations.

Functions
int	HS4xxx_Init (HSxxxx_t *sensor, Interface_t *hal)
	Initialize the sensor object. More...
int	HS4xxx_ReadID (HSxxxx_t *sensor, uint32_t *id)
	Read the unique sensor ID of the HS4xxx. More...
int	HS4xxx_Measure (HSxxxx_t *sensor, HSxxxx_Results_t *results)
	Perform a temperature/humidity measurement cycle. More...
int	HS4xxx_MeasureHold (HSxxxx_t *sensor, HSxxxx_Results_t *results)
	Perform a temperature/humidity measurement cycle using hold mode. More...
int	HS4xxx_MeasureStart (HSxxxx_t *sensor)
	Start a temperature/humidity measurement cycle in non-hold mode. More...
int	HS4xxx_MeasureRead (HSxxxx_t *sensor, HSxxxx_Results_t *results)
	Read temperature/humidity results in non-hold mode. More...

Enumerations
enum	HS4xxx_ErrorCodes_t { hteHS4xxxCRCError = 1 }
	Error code definitions specific for the HS4xxx API. More...

Detailed Description

HS4xxx Temperature/Humidity Sensor API.

HS4xxx is a series of highly accurate, fully calibrated automotive-grade relative humidity and temperature sensors. HS4xxx sensors provide a CRC checksum for communication integrity checking and have different modes of operation.

The HS4xxx API provides convenient access to the sensor's temperature & humidity measurement capabilities.

Enumeration Type Documentation

HS4xxx_ErrorCodes_t

enum HS4xxx_ErrorCodes_t

Error code definitions specific for the HS4xxx API.

Enumerator
hteHS4xxxCRCError	Result CRC error

Function Documentation

HS4xxx_Init()

int HS4xxx_Init	(	HSxxxx_t *	sensor,
		Interface_t *	hal
	)

Initialize the sensor object.

This function tries accessing the HS4xxx I2C address using hal as hardware interface. On success, the sensor object is initialized and can be used afterwards. Otherwise, an error code is returned and the sensor object is not usable.

Note

The HS4xxx API requires that the HAL interface object has the Interface_t::i2cRead and Interface_t::i2cWrite members defined. In addition, HS4xxx_Measure() requires the Interface_t::msSleep member.

Parameters

sensor	Pointer to sensor object to be initialized
hal	Pointer to HAL object providing physical communication

Returns

int Error code

Return values

0	On success
other	On error

HS4xxx_Measure()

int HS4xxx_Measure	(	HSxxxx_t *	sensor,
		HSxxxx_Results_t *	results
	)

Perform a temperature/humidity measurement cycle.

This function starts a measurement cycle in non-hold mode, waits for the result to be available and reads it. If the checksum computation is correct the result is stored in the results data structure. Otherwise the contents of results is left unmodified and an error code is returned.

Note

Although the HS4xxx is able to perform the requested measurement with a single I2C transaction (refer to HS4xxx_MeasureHold), this function uses the HS4xxx_MeasureStart() and HS4xxx_MeasureRead() functions together with the Interface_t::msSleep function. This is to allow operation on a wider variety of I2C interfaces. HS4xxx_MeasureHold() requires a minimum of 200kHz I2C clock frequency which is not supported by all interfaces.

Parameters

sensor	Pointer to an initialized sensor object
results	Pointer to a data structure, to store results in

Returns

int Error code

Return values

0	On success
other	On error

HS4xxx_MeasureHold()

int HS4xxx_MeasureHold	(	HSxxxx_t *	sensor,
		HSxxxx_Results_t *	results
	)

Perform a temperature/humidity measurement cycle using hold mode.

This function performs temperature/humidity measurements in hold mode and reads the results form the sensor. If the checksum computation is correct the result is stored in the results data structure. Otherwise the contents of results is left unmodified and an error code is returned.

Note

For hold measurements, the I2C clock frequency must be at least 200kHz. Otherwise the result readout is unreliable.

Parameters

sensor	Pointer to an initialized sensor object
results	Pointer to a data structure, to store results in

Returns

int Error code

Return values

0	On success
other	On error

HS4xxx_MeasureRead()

int HS4xxx_MeasureRead	(	HSxxxx_t *	sensor,
		HSxxxx_Results_t *	results
	)

Read temperature/humidity results in non-hold mode.

This function reads the temperature/humidity results from a measurement that has been started through HS4xxx_MeasureStart() previously. If the checksum computation is correct the result is stored in the results data structure. Otherwise the contents of results is left unmodified and an error code is returned.

Parameters

sensor	Pointer to an initialized sensor object
results	Pointer to a data structure, to store results in

Returns

int Error code

Return values

0	On success
other	On error

HS4xxx_MeasureStart()

int HS4xxx_MeasureStart

(

HSxxxx_t *

sensor

)

Start a temperature/humidity measurement cycle in non-hold mode.

Parameters

sensor

Pointer to an initialized sensor object

Returns

int Error code

Return values

0	On success
other	On error

HS4xxx_ReadID()

int HS4xxx_ReadID	(	HSxxxx_t *	sensor,
		uint32_t *	id
	)

Read the unique sensor ID of the HS4xxx.

Parameters

sensor	Pointer to an initialized sensor object
id	Pointer buffer to store the ID

Returns

int Error code

Return values

0	On success
other	On error