HDC2021 Class Reference

A class for the Texas Instruments HDC2021 digital temperature and humidity sensor. More...

#include <HDC2021.h>

Public Member Functions
void	begin ()
	Initialize the HDC2021 sensor (HDC2021_I2C_ADDRESS — 0x40).
	HDC2021 (uint8_t sdaPin, uint8_t sclPin, uint8_t interruptPin)
	Construct a new HDC2021 object with specified I2C pins and optional interrupt pin.
float	readHumidity ()
	Read the current relative humidity in percentage.
float	readTemperature ()
	Read the current temperature in degrees Celsius.
void	setHighHumidityThreshold (float humid)
	Set the high humidity threshold.
void	setHighTempThreshold (float temp)
	Set the high temperature threshold.
void	setLowHumidityThreshold (float humid)
	Set the low humidity threshold.
void	setLowTempThreshold (float temp)
	Set the low temperature threshold.
void	stop ()
	Stop the HDC2021 sensor.

Detailed Description

A class for the Texas Instruments HDC2021 digital temperature and humidity sensor.

The HDC2021 is a low-power, high-accuracy sensor connected via I2C at address HDC2021_I2C_ADDRESS (0x40). It measures both temperature and relative humidity with 14-bit resolution.

Default connections:

Signal	I2C Macro	GPIO	Description
SDA	DEFAULT_I2C_SDA_PIN	12	I2C data
SCL	DEFAULT_I2C_SCL_PIN	13	I2C clock
Address	HDC2021_I2C_ADDRESS	0x40	Sensor I2C address
Interrupt	HDC2021_INTERRUPT	21	Optional alert pin

Default thresholds configured by init_hdc2021_():

• Temperature low: -30 °C
  
• Temperature high: +50 °C
  
• Humidity low: 0 %
  
• Humidity high: 100 %
  

These thresholds are part of the sensor’s alert system.

Precondition

The I2C interface must be initialized (use TKJHAT::begin() or HDC2021::begin()).

See also

Datasheet: https://www.ti.com/lit/ds/symlink/hdc2021.pdf

Usage Guide: https://www.ti.com/lit/ug/snau250/snau250.pdf {@

Constructor & Destructor Documentation

HDC2021()

HDC2021::HDC2021	(	uint8_t	sdaPin,
		uint8_t	sclPin,
		uint8_t	interruptPin )

Construct a new HDC2021 object with specified I2C pins and optional interrupt pin.

Parameters

sdaPin	GPIO pin number for I2C SDA (default: DEFAULT_I2C_SDA_PIN)
sclPin	GPIO pin number for I2C SCL (default: DEFAULT_I2C_SCL_PIN)
interruptPin	GPIO pin number for optional alert interrupt (default: HDC2021_INTERRUPT)

Member Function Documentation

begin()

void HDC2021::begin

(

)

Initialize the HDC2021 sensor (HDC2021_I2C_ADDRESS — 0x40).

Performs a soft reset and configures the sensor for continuous measurement mode with default thresholds and 1 Hz sampling rate:

• Resolution: 14 bits (temperature and humidity)
• Thresholds: -30 °C / +50 °C and 0 % / 100 %

readHumidity()

float HDC2021::readHumidity

(

)

Read the current relative humidity in percentage.

Returns

Relative humidity in percentage

readTemperature()

float HDC2021::readTemperature

(

)

Read the current temperature in degrees Celsius.

Returns

Temperature in degrees Celsius

setHighHumidityThreshold()

void HDC2021::setHighHumidityThreshold

(

float

humid

)

Set the high humidity threshold.

Parameters

humid

Humidity threshold in percentage

setHighTempThreshold()

void HDC2021::setHighTempThreshold

(

float

temp

)

Set the high temperature threshold.

Parameters

temp	Temperature threshold in degrees Celsius

setLowHumidityThreshold()

void HDC2021::setLowHumidityThreshold

(

float

humid

)

Set the low humidity threshold.

Parameters

humid

Humidity threshold in percentage

setLowTempThreshold()

void HDC2021::setLowTempThreshold

(

float

temp

)

Set the low temperature threshold.

Parameters

temp	Temperature threshold in degrees Celsius

stop()

void HDC2021::stop

(

)

Stop the HDC2021 sensor.

Puts the sensor into a low-power state and stops measurements.

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

• src/HDC2021.h