#include <DHT.hh>

Inheritance diagram for DHT22:

Collaboration diagram for DHT22:

Public Types
enum	InterruptMode { ON_LOW_LEVEL_MODE = 0, ON_CHANGE_MODE = _BV(ISC00), ON_FALLING_MODE = _BV(ISC01), ON_RISING_MODE = (_BV(ISC01) \| _BV(ISC00)) }

enum	Mode { OUTPUT_MODE = 0, INPUT_MODE = 1 }

enum	Direction { MSB_FIRST = 0, LSB_FIRST = 1 }

Public Member Functions
	DHT22 (Board::ExternalInterruptPin pin=Board::EXT0)

int16_t	humidity () const

int16_t	temperature () const

bool	sample_request ()

bool	sample_await ()

bool	sample ()

bool	sample (int16_t &humidity, int16_t &temperature)

OutputPin &	operator<< (int value)

virtual void	enable ()

virtual void	disable ()

virtual void	clear ()

void	clear () const

void	mode (Mode mode)

Mode	mode () const

void	_set () const

void	_set (int value) const

void	set () const

void	set (int value) const

void	high () const

void	on () const

void	_clear () const

void	low () const

void	off () const

void	_toggle () const

void	toggle () const

void	_write (int value) const

void	write (int value) const

void	write (uint8_t value, OutputPin &clk, Direction order=MSB_FIRST) const

void	write (uint16_t value, uint8_t bits, uint16_t us) const

void	pulse (uint16_t us) const

uint8_t	pin () const

bool	is_set () const

bool	is_high () const

bool	is_on () const

bool	is_clear () const

bool	is_low () const

bool	is_off () const

bool	read () const

uint8_t	read (OutputPin &clk, Direction order=MSB_FIRST) const

	operator bool () const

Pin &	operator>> (uint8_t &var)

Static Public Member Functions
static void	mode (Board::DigitalPin pin, Mode mode)

static Mode	mode (Board::DigitalPin pin)

static void	mode (Board::DigitalPin pin, uint8_t initial=0)

static void	toggle (Board::DigitalPin pin)

static void	_write (Board::DigitalPin pin, uint8_t value)

static void	write (Board::DigitalPin pin, int value)

static uint8_t	MASK (uint8_t pin)

static volatile uint8_t *	PIN (uint8_t pin)

static volatile uint8_t *	DDR (uint8_t pin)

static volatile uint8_t *	PORT (uint8_t pin)

static bool	read (Board::DigitalPin pin)

Static Public Attributes
static const int16_t	INIT_HUMIDITY_SAMPLE = 1000

static const int16_t	INIT_TEMPERATURE_SAMPLE = 850

Protected Types
enum	{ INIT, IDLE, REQUEST, RESPONSE, SAMPLING, COMPLETED }

Protected Member Functions
virtual void	adjust_data ()

virtual void	on_interrupt (uint16_t arg=0)

virtual void	on_sample_completed (bool valid)

bool	is_valid ()

volatile uint8_t *	PIN () const

volatile uint8_t *	DDR () const

volatile uint8_t *	PORT () const

volatile uint8_t *	PCIMR () const

Protected Attributes
volatile uint8_t	m_state

uint16_t	m_start

uint8_t	m_value

uint8_t	m_bits

uint8_t	m_ix

data_t	m_data

int16_t	m_humidity

int16_t	m_temperature

volatile uint8_t *const	m_sfr

const uint8_t	m_mask

const uint8_t	m_pin

Static Protected Attributes
static const uint16_t	MIN_PERIOD = 2048

static const uint16_t	LOW_THRESHOLD = 50

static const uint16_t	BIT_THRESHOLD = 100

static const uint16_t	HIGH_THRESHOLD = 200

static const uint8_t	DATA_MAX = 5

static const uint8_t	DATA_LAST = DATA_MAX - 1

Detailed Description

DHT22 Humidity & Temperature Sensor device driver. Note that the values read from the device are scaled by a factor of 10, i.e. one decimal accurracy.

Circuit

                          DHT22
                      +------------+
(VCC)---------------1-|VCC  ====== |
(D2/EXT0)-----------2-|DATA ====== |
                    3-|     ====== |
(GND)---------------4-|GND  ====== |
                      +------------+

Connect DHT22 to pin, VCC and ground. A pullup resistor from the pin to VCC should be used. Most DHT22 modules have a built-in pullup resistor.

References

http://www.humiditycn.com/pic/20135318405067570.pdf

Definition at line 286 of file DHT.hh.

Member Enumeration Documentation

anonymous enum

protectedinherited

Enumerator
INIT	Initial state.
IDLE	Periodic wait.
REQUEST	Issued a request.
RESPONSE	Waiting for response.
SAMPLING	Collecting samples.
COMPLETED	Data transfer completed.

Definition at line 152 of file DHT.hh.

enum Pin::Direction

inherited

Serialization directions; most or least significant bit first.

Enumerator
MSB_FIRST
LSB_FIRST

Definition at line 84 of file Pin.hh.

enum ExternalInterrupt::InterruptMode

inherited

Enumerator
ON_LOW_LEVEL_MODE
ON_CHANGE_MODE
ON_FALLING_MODE
ON_RISING_MODE

Definition at line 35 of file ExternalInterrupt.hh.

enum IOPin::Mode

inherited

Enumerator
OUTPUT_MODE
INPUT_MODE

Definition at line 31 of file IOPin.hh.

Constructor & Destructor Documentation

DHT22::DHT22 ( Board::ExternalInterruptPin pin = Board::EXT0 )

inline

Construct connection to a DHT22 device on given in/output-pin.

Parameters

[in] pin data (Default EXT0).

Definition at line 292 of file DHT.hh.

Member Function Documentation

void OutputPin::_clear ( ) const

inlineinherited

Clear the output pin. Unprotected version.

Definition at line 114 of file OutputPin.hh.

void OutputPin::_set ( ) const

inlineinherited

Set the output pin. Unprotected version.

Definition at line 75 of file OutputPin.hh.

void OutputPin::_set ( int value ) const

inlineinherited

Set the output pin with the given value. Zero(0) to clear and non-zero to set. Unprotected version.

Parameters

[in] value to set.

Definition at line 184 of file OutputPin.hh.

void OutputPin::_toggle ( ) const

inlineinherited

Toggle the output pin. Unprotected version.

Definition at line 153 of file OutputPin.hh.

void OutputPin::_write ( int value ) const

inlineinherited

Set the output pin with the given value. Zero(0) to clear and non-zero to set. Unprotected version.

Parameters

[in] value to set.

Definition at line 219 of file OutputPin.hh.

static void OutputPin::_write	(	Board::DigitalPin	pin,
		uint8_t	value
	)

inlinestaticinherited

Set the given output pin with the given value. Zero(0) to clear and non-zero to set. Unprotected version when pin and value are constants.

Parameters

[in]	pin	number (must be constant).
[in]	value	to write (must be constant).

Definition at line 345 of file OutputPin.hh.

void DHT22::adjust_data ( )

protectedvirtual

Adjust data from the DHT22 device. Byte order and representation of negative temperature values.

Implements DHT.

Definition at line 133 of file DHT.cpp.

void ExternalInterrupt::clear ( )

virtualinherited

Clear external interrupt flag.

Note: atomic

Reimplemented from Interrupt::Handler.

Definition at line 205 of file ExternalInterrupt.cpp.

void OutputPin::clear ( ) const

inlineinherited

Clear the output pin.

Note: atomic

Definition at line 124 of file OutputPin.hh.

static volatile uint8_t* Pin::DDR ( uint8_t pin )

inlinestaticinherited

Return pointer to Data Direction Register.

Parameters

[in] pin number.

Returns: DDR register pointer.

Definition at line 64 of file Pin.hh.

volatile uint8_t* Pin::DDR ( ) const

inlineprotectedinherited

Return pointer to Data Direction Register.

Returns: DDR register pointer.

Definition at line 245 of file Pin.hh.

void ExternalInterrupt::disable ( )

virtualinherited

Disable external interrupt handler.

Note: atomic

Reimplemented from Interrupt::Handler.

Definition at line 199 of file ExternalInterrupt.cpp.

void ExternalInterrupt::enable ( )

virtualinherited

Enable external interrupt handler.

Note: atomic

Reimplemented from Interrupt::Handler.

Definition at line 190 of file ExternalInterrupt.cpp.

void OutputPin::high ( ) const

inlineinherited

Set the output pin.

Note: atomic

Definition at line 95 of file OutputPin.hh.

int16_t DHT::humidity ( ) const

inlineinherited

Return humidity from latest read.

Returns: humidity.

Definition at line 61 of file DHT.hh.

bool Pin::is_clear ( ) const

inlineinherited

Return true(1) if the pin is clear otherwise false(0).

Returns: boolean.

Definition at line 142 of file Pin.hh.

bool Pin::is_high ( ) const

inlineinherited

Return true(1) if the pin is set otherwise false(0).

Returns: boolean.

Definition at line 122 of file Pin.hh.

bool Pin::is_low ( ) const

inlineinherited

Return true(1) if the pin is clear otherwise false(0).

Returns: boolean.

Definition at line 152 of file Pin.hh.

bool Pin::is_off ( ) const

inlineinherited

Return true(1) if the pin is clear otherwise false(0).

Returns: boolean.

Definition at line 162 of file Pin.hh.

bool Pin::is_on ( ) const

inlineinherited

Return true(1) if the pin is set otherwise false(0).

Returns: boolean.

Definition at line 132 of file Pin.hh.

bool Pin::is_set ( ) const

inlineinherited

Return true(1) if the pin is set otherwise false(0).

Returns: boolean.

Definition at line 112 of file Pin.hh.

bool DHT::is_valid ( )

protectedinherited

Validate received data block. Return true if valid data with correct check sum otherwise false.

Returns: bool.

Definition at line 116 of file DHT.cpp.

void OutputPin::low ( ) const

inlineinherited

Clear the output pin.

Note: atomic

Definition at line 134 of file OutputPin.hh.

static uint8_t Pin::MASK ( uint8_t pin )

inlinestaticinherited

Return bit mask for given Arduino pin number.

Parameters

[in] pin number.

Returns: pin bit mask.

Definition at line 42 of file Pin.hh.

void IOPin::mode ( Mode mode )

inlineinherited

Change IO-pin to given mode.

Parameters

[in] mode new operation mode.

Note: atomic

Definition at line 56 of file IOPin.hh.

static void OutputPin::mode	(	Board::DigitalPin	pin,
		uint8_t	initial = `0`
	)

inlinestaticinherited

Set output pin to mode.

Parameters

[in]	pin	number.
[in]	initial	value.

Note: atomic

Definition at line 56 of file OutputPin.hh.

Mode IOPin::mode ( ) const

inlineinherited

Get current IO-pin mode.

Returns: mode.

Definition at line 71 of file IOPin.hh.

static void IOPin::mode	(	Board::DigitalPin	pin,
		Mode	mode
	)

inlinestaticinherited

Change IO-pin to given mode.

Parameters

[in]	pin	number.
[in]	mode	new operation mode.

Note: atomic

Definition at line 83 of file IOPin.hh.

static Mode IOPin::mode ( Board::DigitalPin pin )

inlinestaticinherited

Get IO-pin mode.

Parameters

[in] pin number.

Returns: mode.

Definition at line 101 of file IOPin.hh.

void OutputPin::off ( ) const

inlineinherited

Clear the output pin.

Note: atomic

Definition at line 144 of file OutputPin.hh.

void OutputPin::on ( ) const

inlineinherited

Set the output pin.

Note: atomic

Definition at line 105 of file OutputPin.hh.

void DHT::on_interrupt ( uint16_t arg = 0 )

protectedvirtualinherited

The device driver interrupt level state machine.

Parameters

[in] arg argument from interrupt service routine.

Reimplemented from ExternalInterrupt.

Definition at line 35 of file DHT.cpp.

virtual void DHT::on_sample_completed ( bool valid )

inlineprotectedvirtualinherited

Callback when data sample is completed. Called from interrupt service routine. Typically used to push an event for further processing. Default implementation is an empty function.

Parameters

[in] valid data received and adjusted.

Definition at line 131 of file DHT.hh.

Pin::operator bool ( ) const

inlineinherited

Read input pin and assign variable.

Parameters

[out] var to assign.

Returns: pin.

Definition at line 204 of file Pin.hh.

OutputPin& OutputPin::operator<< ( int value )

inlineinherited

Set the output pin with the given value. Zero(0) to clear and non-zero to set. Output operator syntax.

Parameters

[in] value to write.

Returns: output pin.

Definition at line 364 of file OutputPin.hh.

Pin& Pin::operator>> ( uint8_t & var )

inlineinherited

Read input pin and assign variable.

Parameters

[out] var to assign.

Returns: pin.

Definition at line 215 of file Pin.hh.

volatile uint8_t* Pin::PCIMR ( ) const

inlineprotectedinherited

Return pin change interrupt mask register.

Returns: pin change mask register pointer.

Definition at line 263 of file Pin.hh.

static volatile uint8_t* Pin::PIN ( uint8_t pin )

inlinestaticinherited

Return pointer to PIN register.

Parameters

[in] pin number.

Returns: PIN register pointer.

Definition at line 53 of file Pin.hh.

uint8_t Pin::pin ( ) const

inlineinherited

Return Arduino pin number of abstract pin.

Returns: pin number.

Definition at line 103 of file Pin.hh.

volatile uint8_t* Pin::PIN ( ) const

inlineprotectedinherited

Return pointer to PIN register.

Returns: PIN register pointer.

Definition at line 236 of file Pin.hh.

static volatile uint8_t* Pin::PORT ( uint8_t pin )

inlinestaticinherited

Return pointer to data PORT register.

Parameters

[in] pin number.

Returns: PORT register pointer.

Definition at line 75 of file Pin.hh.

volatile uint8_t* Pin::PORT ( ) const

inlineprotectedinherited

Return pointer to data PORT register.

Returns: PORT register pointer.

Definition at line 254 of file Pin.hh.

void OutputPin::pulse ( uint16_t us ) const

inlineinherited

Toggle the output pin to form a pulse with given width in micro-seconds.

Parameters

[in] us pulse width in micro seconds

Note: atomic; pulse width is limited to 1000 us

Definition at line 378 of file OutputPin.hh.

bool Pin::read ( ) const

inlineinherited

Return true(1) if the pin is set otherwise false(0).

Returns: boolean.

Definition at line 172 of file Pin.hh.

uint8_t Pin::read	(	OutputPin &	clk,
		Direction	order = `MSB_FIRST`
	)		const

inherited

Shift in a byte from the input pin using the given clock output pin. Shift in according to given direction.

Parameters

[in]	clk	output pin.
[in]	order	bit first.

Returns: value.

Definition at line 25 of file Pin.cpp.

static bool Pin::read ( Board::DigitalPin pin )

inlinestaticinherited

Use pin number directly to read value. Does not require an instance. Return true(1) if the pin is set otherwise false(0).

Parameters

[in] pin number.

Returns: boolean.

Definition at line 193 of file Pin.hh.

bool DHT::sample ( )

inlineinherited

Read temperature and humidity from the device. Return true(1) and values if successful otherwise false(0).

Returns: bool.

Definition at line 94 of file DHT.hh.

bool DHT::sample	(	int16_t &	humidity,
		int16_t &	temperature
	)

inlineinherited

Read temperature and humidity from the device. Return true(1) and values if successful otherwise false(0).

Parameters

[out]	humidity	reading.
[out]	temperature	reading.

Returns: bool.

Definition at line 107 of file DHT.hh.

bool DHT::sample_await ( )

inherited

Wait for a sample request to complete. Return true(1) and values if successful otherwise false(0).

Returns: bool.

Definition at line 102 of file DHT.cpp.

bool DHT::sample_request ( )

inherited

Initiate a sample request from the device. Return true(1) and values if successful otherwise false(0).

Returns: bool.

Definition at line 83 of file DHT.cpp.

void OutputPin::set ( ) const

inlineinherited

Set the output pin.

Note: atomic

Definition at line 85 of file OutputPin.hh.

void OutputPin::set ( int value ) const

inlineinherited

Set the output pin with the given value. Zero(0) to clear and non-zero to set.

Parameters

[in] value to set.

Note: atomic

Definition at line 201 of file OutputPin.hh.

int16_t DHT::temperature ( ) const

inlineinherited

Return temperature from latest read.

Returns: temperature.

Definition at line 70 of file DHT.hh.

void OutputPin::toggle ( ) const

inlineinherited

Toggle the output pin.

Note: atomic

Definition at line 163 of file OutputPin.hh.

static void OutputPin::toggle ( Board::DigitalPin pin )

inlinestaticinherited

Toggle the output pin. Atomic per definition

Parameters

[in] pin number.

Definition at line 173 of file OutputPin.hh.

void OutputPin::write ( int value ) const

inlineinherited

Set the output pin with the given value. Zero(0) to clear and non-zero to set.

Parameters

[in] value to write.

Note: atomic

Definition at line 236 of file OutputPin.hh.

void OutputPin::write	(	uint8_t	value,
		OutputPin &	clk,
		Direction	order = `MSB_FIRST`
	)		const

inherited

Shift out given byte to the output pin using the given clock output pin. Shift out according to given direction. Data (bits) are transfered on clock transition. Interrupts are allowed during the shift out.

Parameters

[in]	value	to write.
[in]	clk	output pin.
[in]	order	bit first.

Definition at line 24 of file OutputPin.cpp.

void OutputPin::write	(	uint16_t	value,
		uint8_t	bits,
		uint16_t	us
	)		const

inherited

Shift out given value and number of bits to the output pin using the given pulse length in micro-seconds. Shift out from LSB(0) to MSB(bits-1). This operation is synchronized and will turn off interrupt handling during the transmission period.

Parameters

[in]	value	to write.
[in]	bits	to write.
[in]	us	micro-second bit period.

Note: atomic; us should not exceed 1000

Definition at line 46 of file OutputPin.cpp.

static void OutputPin::write	(	Board::DigitalPin	pin,
		int	value
	)

inlinestaticinherited

Set the given output pin with the given value. Zero(0) to clear and non-zero to set.

Parameters

[in]	pin	number.
[in]	value	to write.

Note: atomic

Definition at line 306 of file OutputPin.hh.

Member Data Documentation

const uint16_t DHT::BIT_THRESHOLD = 100

staticprotectedinherited

Definition at line 166 of file DHT.hh.

const uint8_t DHT::DATA_LAST = DATA_MAX - 1

staticprotectedinherited

Last data element index

Definition at line 173 of file DHT.hh.

const uint8_t DHT::DATA_MAX = 5

staticprotectedinherited

Size of data buffer

Definition at line 170 of file DHT.hh.

const uint16_t DHT::HIGH_THRESHOLD = 200

staticprotectedinherited

Definition at line 167 of file DHT.hh.

const int16_t DHT::INIT_HUMIDITY_SAMPLE = 1000

staticinherited

Initial humidity; 100.0 % RH.

Definition at line 37 of file DHT.hh.

const int16_t DHT::INIT_TEMPERATURE_SAMPLE = 850

staticinherited

Initial temperature; 85 C.

Definition at line 40 of file DHT.hh.

const uint16_t DHT::LOW_THRESHOLD = 50

staticprotectedinherited

Sample thresholds.

Definition at line 165 of file DHT.hh.

uint8_t DHT::m_bits

protectedinherited

Current number of bits read.

Definition at line 198 of file DHT.hh.

data_t DHT::m_data

protectedinherited

Current data being transfered.

Definition at line 204 of file DHT.hh.

int16_t DHT::m_humidity

protectedinherited

Definition at line 207 of file DHT.hh.

uint8_t DHT::m_ix

protectedinherited

Current data byte index stream.

Definition at line 201 of file DHT.hh.

const uint8_t Pin::m_mask

protectedinherited

Pin mask in port.

Definition at line 227 of file Pin.hh.

const uint8_t Pin::m_pin

protectedinherited

Pin identity.

Definition at line 230 of file Pin.hh.

volatile uint8_t* const Pin::m_sfr

protectedinherited

Special function register pointer.

Definition at line 224 of file Pin.hh.

uint16_t DHT::m_start

protectedinherited

Micro-seconds since latest rising of data signal; pulse start.

Definition at line 192 of file DHT.hh.

volatile uint8_t DHT::m_state

protectedinherited

State of device driver.

Definition at line 189 of file DHT.hh.

int16_t DHT::m_temperature

protectedinherited

Definition at line 210 of file DHT.hh.

uint8_t DHT::m_value

protectedinherited

Current byte being read from device.

Definition at line 195 of file DHT.hh.

const uint16_t DHT::MIN_PERIOD = 2048

staticprotectedinherited

Minimum periodic wait (approx. 2 seconds).

Definition at line 162 of file DHT.hh.

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

libraries/DHT/DHT.hh
libraries/DHT/DHT.cpp

Public Types

Public Member Functions

Static Public Member Functions

Static Public Attributes

Protected Types

Protected Member Functions

Protected Attributes

Static Protected Attributes

Detailed Description

Circuit

References

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation