idfxx::dht::sensor Class Reference

DHT11/DHT22 sensor on a single GPIO data line. More...

Classes
struct	config
	Configuration for a DHT sensor. More...

Public Member Functions
	sensor (config config)
	Constructs a sensor driver.
	~sensor ()
	sensor (const sensor &)=delete
sensor &	operator= (const sensor &)=delete
	sensor (sensor &&other) noexcept
sensor &	operator= (sensor &&other) noexcept
idfxx::gpio	pin () const noexcept
	Returns the configured data-line GPIO.
enum model	model () const noexcept
	Returns the configured sensor model.
std::chrono::milliseconds	min_read_interval () const noexcept
	Returns the minimum interval between reads for the model.
reading	read ()
	Performs one measurement.
result< reading >	try_read ()
	Performs one measurement.

Static Public Member Functions
static result< sensor >	make (config config)
	Creates a sensor driver.

Detailed Description

DHT11/DHT22 sensor on a single GPIO data line.

Move-only. The destructor releases the RMT receive channel.

idfxx::dht::sensor sensor({.pin = idfxx::gpio_1, .model = idfxx::dht::model::dht22});
auto r = sensor.read();
// r.temperature, r.humidity_pct

Definition at line 74 of file dht.hpp.

Constructor & Destructor Documentation

sensor() [1/3]

idfxx::dht::sensor::sensor ( config  config )

explicit

Constructs a sensor driver.

Claims an RMT receive channel for the data line and configures the pin as an open-drain input/output.

Parameters

config

Sensor configuration.

Note

Only available when CONFIG_COMPILER_CXX_EXCEPTIONS is enabled in menuconfig.

Exceptions

std::system_error

on failure (e.g. no free RMT channel).

~sensor()

idfxx::dht::sensor::~sensor

(

)

sensor() [2/3]

idfxx::dht::sensor::sensor ( const sensor &  )

delete

sensor() [3/3]

idfxx::dht::sensor::sensor ( sensor &&  other )

noexcept

Member Function Documentation

make()

static result< sensor > idfxx::dht::sensor::make ( config  config )

static

Creates a sensor driver.

Claims an RMT receive channel for the data line and configures the pin as an open-drain input/output.

Parameters

config

Sensor configuration.

Returns

The driver, or an error.

Return values

idfxx::errc::invalid_arg

If the pin is not connected.

min_read_interval()

std::chrono::milliseconds idfxx::dht::sensor::min_read_interval ( ) const

noexcept

Returns the minimum interval between reads for the model.

1 s for the DHT11, 2 s for the DHT22. try_read fails with idfxx::errc::invalid_state when called again sooner.

Returns

The model's minimum sampling period.

model()

enum model idfxx::dht::sensor::model ( ) const

noexcept

Returns the configured sensor model.

operator=() [1/2]

sensor & idfxx::dht::sensor::operator= ( const sensor &  )

delete

operator=() [2/2]

sensor & idfxx::dht::sensor::operator= ( sensor &&  other )

noexcept

pin()

idfxx::gpio idfxx::dht::sensor::pin ( ) const

noexcept

Returns the configured data-line GPIO.

read()

reading idfxx::dht::sensor::read ( )

inline

Performs one measurement.

Issues the start pulse, captures the sensor's 40-bit reply, verifies its checksum, and converts it. Blocks for the start pulse plus the reply: roughly 25 ms for the DHT11 (its ~20 ms start pulse dominates) and under 10 ms for the DHT22.

Returns

The measurement.

Note

Only available when CONFIG_COMPILER_CXX_EXCEPTIONS is enabled in menuconfig.

Exceptions

std::system_error

on failure; see try_read for the error conditions.

Definition at line 151 of file dht.hpp.

References try_read(), and idfxx::unwrap().

try_read()

result< reading > idfxx::dht::sensor::try_read

(

)

Performs one measurement.

Issues the start pulse, captures the sensor's 40-bit reply, verifies its checksum, and converts it. Blocks for the start pulse plus the reply: roughly 25 ms for the DHT11 (its ~20 ms start pulse dominates) and under 10 ms for the DHT22.

Returns

The measurement, or an error.

Return values

idfxx::errc::invalid_state	Called again within min_read_interval of the previous read (the sensor needs the gap to refresh its measurement).
idfxx::errc::timeout	The sensor did not answer the start pulse: no response preamble was captured. Typically no sensor on the line, or a wiring, power, or pull-up fault.
idfxx::errc::invalid_response	A reply began but the 40-bit frame was incomplete or malformed — line noise, a marginal pull-up, or the wrong model selected.
idfxx::errc::invalid_crc	The reply failed its checksum.

Referenced by read().

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

• idfxx_dht/include/idfxx/dht.hpp