DHT Class
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 = 6);
Parameters
pin: selected GPIO pin on Ameba board
type: The DHT sensor type (DHT11, DHT22, or DHT21)
count: The count is now ignored as the DHT reading algorithm adjusts itself based on the speed of the processor. Default value: 6
Returns
NA
Example Code
Example:DHTTester
(https://github.com/ambiot/amb1_arduino/blob/dev/Arduino_package/hardware/libraries/GPIO/examples/DHTtester/DHTtester.ino)
Notes and Warnings
“DHT.h” must be included to use the class function.
DHT::begin
Description
Initialize the DHT sensor.
Syntax
void begin(void);
Parameters
NA
Returns
NA
Example Code
Example: DHTTester
(https://github.com/ambiot/amb1_arduino/blob/dev/Arduino_package/hardware/libraries/GPIO/examples/DHTtester/DHTtester.ino)
Notes and Warnings
“DHT.h” must be included to use the class function.
DHT::readTemperature
Description
Read temperature (Fahrenheit or Celsius) from the DHT sensor.
Syntax
float readTemperature(bool S = false, bool force = false);
Parameters
s: Temperature scale, True is Fahrenheit and False is Celsius
force: Enable or disable force mode. Default value: False
Returns
This function returns the current temperature as a float value in selected scale.
Example Code
Example: DHTTester
(https://github.com/ambiot/amb1_arduino/blob/dev/Arduino_package/hardware/libraries/GPIO/examples/DHTtester/DHTtester.ino)
Notes and Warnings
“DHT.h” must be included to use the class function.
DHT::convertCtoF
Description
Convert a 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: DHTTester
(https://github.com/ambiot/amb1_arduino/blob/dev/Arduino_package/hardware/libraries/GPIO/examples/DHTtester/DHTtester.ino)
Notes and Warnings
“DHT.h” must be included to use the class function.
DHT::convertFtoC
Description
Convert a 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: DHTTester
(https://github.com/ambiot/amb1_arduino/blob/dev/Arduino_package/hardware/libraries/GPIO/examples/DHTtester/DHTtester.ino)
Notes and Warnings
“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 = false);
Parameters
force: force read mode. Default value: False
Returns
This function returns current humidity value represented in float as percentage.
Example Code
Example: DHTTester
(https://github.com/ambiot/amb1_arduino/blob/dev/Arduino_package/hardware/libraries/GPIO/examples/DHTtester/DHTtester.ino)
Notes and Warnings
“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.
DHT::computeHeatIndex
Description
Compute the HeatIndex from the readings (Using both Rothfusz and Steadman’s equations). More details refer to http://www.wpc.ncep.noaa.gov/html/heatindex_equation.shtml .
Syntax
float computeHeatIndex(bool isFahrenheit = true);
float computeHeatIndex(float temperature, float percentHumidity, bool isFahrenheit = true);
Parameters
temperature: The temperature value
percentHumidity: humidity value in percentage
isFahrenheit: True, temperature value in Fahrenheit; False, temperature value in Celsius. Default value: True
Returns
This function returns the heat index in Fahrenheit or Celsius as a float value.
Example Code
Example: DHTTester
(https://github.com/ambiot/amb1_arduino/blob/dev/Arduino_package/hardware/libraries/GPIO/examples/DHTtester/DHTtester.ino)
Notes and Warnings
“DHT.h” must be included to use the class function.
DHT::read
Description
Check if the sensor is readable.
Syntax
boolean read (bool force = false);
Parameters
force: True if using force mode. False if not using force mode. Default value: False.
Returns
This function returns the last correct measurement of the sensor.
Example Code
Example: DHTTester
(https://github.com/ambiot/amb1_arduino/blob/dev/Arduino_package/hardware/libraries/GPIO/examples/DHTtester/DHTtester.ino)
Notes and Warnings
“DHT.h” must be included to use the class function.
