Class DHT

DHT Class

Description

A class to use DHT temperature and humidity sensors.

Syntax

class DHT

Members

Public Constructors
DHT::DHT	Constructs a DHT object
Public Methods
DHT::begin	Initialize the DHT sensor
DHT::readTemperature	Read temperature (Fahrenheit or Celsius) from the DHT sensor
DHT::convertCtoF	Convert a value from Celsius to Fahrenheit
DHT::convertFtoC	Convert a value from Fahrenheit to Celsius
DHT::readHumidity	Read humidity value from the DHT sensor as percentage.
DHT::computeHeatIndex	Compute the HeatIndex from the readings (Using both Rothfusz and Steadman’s equations)
DHT::read	Check if the sensor is readable

DHT::DHT

Description

Constructs a DHT object.

Syntax

DHT(uint8_t pin, uint8_t type, uint8_t count);

Parameters

pin: selected GPIO pin. Default value is 8.

type: The DHT sensor type.

DHT11, DHT22, or DHT21. Default is DHT11.

count: The count is ignored as the DHT reading algorithm adjusts itself based on the speed of the processor. Default value is 6 (Refer to function declaration in DHT.h)

Returns

NA

Example Code

Example: DHT_Tester

Note

“DHT.h” must be included to use the class function.

DHT::begin

Description

Initialize the DHT sensor by setting up the sensor GPIO pin and set pull timings.

Syntax

void begin(uint8_t usec);

Parameters

usec: Optionally pass pull-up time (in microseconds) before DHT reading starts. Default value is 55 (Refer to function declaration in DHT.h)

Returns

NA

Example Code

Example: DHT_Tester

Note

“DHT.h” must be included to use the class function.

DHT::readTemperature

Description

Read temperature (Fahrenheit or Celsius) from the DHT sensor in selected scale.

Syntax

float readTemperature(bool S, bool force);

Parameters

S: Scale for temperature. Default value is False (Refer to function declaration in DHT.h)

True (Fahrenheit)
False (Celsius).

force: Enable or disable force mode. Default value is False (Refer to function declaration in DHT.h)

True (Force mode)
False (Disable force mode)

Returns

This function returns the current temperature as a float value in selected scale.

Example Code

Example: DHT_Tester

Note

“DHT.h” must be included to use the class function.

DHT::convertCtoF

Description

Convert a temperature value from Celsius to Fahrenheit.

Syntax

float convertCtoF(float c);

Parameters

c: Temperature in Celsius.

Returns

This function returns the temperature in Fahrenheit as a float number.

Example Code

Example: DHT_Tester

Note

“DHT.h” must be included to use the class function.

DHT::convertFtoC

Description

Convert a temperature value from Fahrenheit to Celsius.

Syntax

float convertFtoC(float f);

Parameters

f: Temperature in Fahrenheit.

Returns

This function returns the temperature in Celsius as a float number.

Example Code

Example: DHT_Tester

Note

“DHT.h” must be included to use the class function.

DHT::readHumidity

Description

Read humidity value from the DHT sensor as percentage.

Syntax

float readHumidity(bool force);

Parameters

force: Enable or disable force mode. Default value is False (Refer to function declaration in DHT.h)

True (Force mode)
False (Disable force mode)

Returns

This function returns current humidity value represented in float as percentage.

Example Code

Example: DHT_Tester

Note

“DHT.h” must be included to use the class function. Reading temperature or humidity takes about 250 milliseconds. Sensor readings may also be up to 2 seconds.

float computeHeatIndex(bool isFahrenheit);
float computeHeatIndex(float temperature, float percentHumidity, bool isFahrenheit = true);

Parameters

temperature: The temperature value in selscted scale percentHumidity: humidity value in percentage.

isFahrenheit: choose temperature vale in Farenheit or Celsius. Default value is True.

True (in Fahrenheit)
False (Celsius)

Returns

This function returns the heat index in Fahrenheit or Celsius as a float value.

Example Code

Example: DHT_Tester

Note

“DHT.h” must be included to use the class function.

bool read (bool force);

Parameters

force: Enable or disable force mode. Default value is False (Refer to function declaration in DHT.h)

True (Force mode)
False (Disable force mode)

Returns

This function returns whether the sensor is readable in every 2 seconds.

Example Code

Example: DHT_Tester

Note

“DHT.h” must be included to use the class function.