HTU21D Class Reference

API for the HTU21D Temperature & Humidity Sensor. More...

Detailed Description

• ID: htu21d
• Name: HTU21D Temperature & Humidity Sensor
• Category: temp
• Manufacturer: seeed adafruit sparkfun
• Link: http://www.meas-spec.com/downloads/HTU21D.pdf
• Connection: i2c

HTU21D by Measurement Specialties is a digital humidity sensor with temperature output. RH reports between 0 and 100%, and the temperature range is -40 to +125 degC. Note: getCompRH is the preferred function below (passing true to cause a measurement cycle). If actual values used for the compensated ready are necessary, use the getHumidity(false) and getTemperature(false) functions following the getCompRH call. Also note the sensor should not perform more than a couple of measurements per second to limit the heating of the sensor.

        float humidity = 0;
        float temperature = 0;
        float compRH = 0;

        upm_htu21d.HTU21D sensor = new upm_htu21d.HTU21D(0);
        sensor.testSensor();

        while (true) {
            compRH = sensor.getCompRH();
            humidity = sensor.getHumidity();
            temperature = sensor.getTemperature();

            System.out.println("Humidity: " + humidity + ", Temperature: " + temperature
                    + ", compensated RH: " + compRH);

            Thread.sleep(5000);
        }

Public Member Functions
synchronized void	delete ()
	HTU21D (int bus, int devAddr)
	HTU21D (int bus)
int	sampleData ()
float	getHumidity (int bSampleData)
float	getHumidity ()
float	getTemperature (int bSampleData)
float	getTemperature ()
float	getCompRH (int bSampleData)
float	getCompRH ()
int	setHeater (int bEnable)
int	setHeater ()
void	resetSensor ()
int	testSensor ()
int	i2cWriteReg (short reg, short value)
int	i2cReadReg_16 (int reg)
short	i2cReadReg_8 (int reg)

Constructor & Destructor Documentation

HTU21D	(	int	bus,
		int	devAddr
	)

Instantiates an HTU21D object

Parameters

bus	Number of the used bus
devAddr	Address of the used I2C device
mode	HTU21D oversampling

Member Function Documentation

float getCompRH

(

int

bSampleData

)

Using the current humidity and temperature, the function calculates the compensated RH using the equation from the datasheet.

float getHumidity

(

int

bSampleData

)

Gets the current measured humidity [RH]

float getTemperature

(

int

bSampleData

)

Gets the humidity cell temperature [degC]

int i2cReadReg_16

(

int

reg

)

Reads a two-byte register

Parameters

reg	Address of the register

short i2cReadReg_8

(

int

reg

)

Reads a one-byte register

Parameters

reg	Address of the register

int i2cWriteReg	(	short	reg,
		short	value
	)

Writes to a one-byte register

Parameters

reg	Address of the register
value	Byte to be written

int setHeater

(

int

bEnable

)

Sets the heater state. The heater is used to test the sensor functionality since the temperature should increase 0.5 to 1.5 degC, and the humidity should decrease. The testSensor() function below uses the heater.

Parameters

bEnable

Sets to non-zero to turn the heater on

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The documentation for this class was generated from the following file:

• /var/lib/jenkins/workspace/upm-doc-stable/build-33/src/htu21d/HTU21D.java