Abstraction around BME280 temperature/humidity/pressure sensor. More...

#include <nrfcxx/sensor/bme280.hpp>

Inheritance diagram for nrfcxx::sensor::bme280:

Data Structures
struct	observations_type
	Structure used to return sampled values. More...

Public Member Functions
	bme280 (notifier_type notify, nrfcxx::periph::SPI &spi, int csn_psel)
	Construct an instance that controls through the SPI interface. More...

	bme280 (notifier_type notify, nrfcxx::periph::TWI &twi, bool addr_sec=false)
	Construct an instance that controls through the I2C interface. More...

int	initialize ()
	Initialize the BME280. More...

int	sample ()
	Request a new sample from the device. More...

int	fetch (observations_type &obs)
	Retrieve the results from the most recent observation. More...

const observations_type &	observations () const
	Retrieve the most recent observations calculated through the LPM infrastructure.

Public Member Functions inherited from nrfcxx::lpm::lpsm_capable
virtual int	lpsm_start ()
	Validate and prepare to initiate an LPM collection. More...

virtual int	lpsm_sample ()
	Ask the LPM infrastructure to initiate a new sample. More...

lpm::state_machine::process_flags_type	lpsm_process ()
	Make progress on an LPM collection. More...

int	lpsm_stop ()

int	lpsm_reset ()

int	lpsm_process_rc () const
	Get the internal result code from the last invocation of lpsm_process_(). More...

const lpm::state_machine &	machine () const
	Gain read-only access to the LPM machine state.

Static Public Attributes
static constexpr unsigned int	SAMPLE_DELAY_utt = clock::uptime::from_ms(10)
	Lower bound for wait after sample() before get_sensor_data(). More...

static constexpr uint16_t	INVALID_TEMPHUMID = 30000
	Value used for invalid temperature and humidity observations.

static constexpr unsigned int	INVALID_PRESSURE = 0x00C00000
	Value used for invalid pressure observations. More...

Additional Inherited Members
Protected Types inherited from nrfcxx::lpm::lpsm_capable
using	state_type = state_machine::state_type

using	process_flags_type = state_machine::process_flags_type

Protected Member Functions inherited from nrfcxx::lpm::lpsm_capable
	lpsm_capable (notifier_type notify)
	Create a state machine that records state and supports delayed transitions. More...

virtual int	lpsm_process_ (int &delay, process_flags_type &pf)
	Override to implement machine-specific operations of lpsm_process(). More...

virtual void	lpsm_reset_ ()
	Override to reset state that is held outside the machine.

Protected Attributes inherited from nrfcxx::lpm::lpsm_capable
state_machine	machine_

Detailed Description

Abstraction around BME280 temperature/humidity/pressure sensor.

Interface to the Bosch Sensortec BME280 sensor, wrapping the vendor-supplied library.

This uses forced (one-shot) sampling only, hard-coded with the parameters recommended for weather monitoring.

Note: Due to limitations in the vendor-provided API only one SPI-based and one TWI-based instance may be present in a single application.

lpm::lpsm_capable::lpsm_process() for this sensor returns the following flags in addition to the diagnostic flags:

lpm::state_machine::PF_OBSERVATION

Constructor & Destructor Documentation

◆ bme280() [1/2]

nrfcxx::sensor::bme280::bme280	(	notifier_type	notify,
		nrfcxx::periph::SPI &	spi,
		int	csn_psel
	)

Construct an instance that controls through the SPI interface.

Parameters

notify	the notifier to inform the application of LPM processing needs.
spi	reference to the SPI peripheral to use.
csn_psel	GPIO pin selector (index) identifying the GPIo connected to the BME280 CSn signal.

◆ bme280() [2/2]

nrfcxx::sensor::bme280::bme280	(	notifier_type	notify,
		nrfcxx::periph::TWI &	twi,
		bool	addr_sec = `false`
	)

Construct an instance that controls through the I2C interface.

Parameters

notify	the notifier to inform the application of LPM processing needs.
twi	reference to the TWI peripheral to use.
addr_sec	`false` to use the primary I2C address, `true` to use the secondary I2C address.

Member Function Documentation

◆ fetch()

int nrfcxx::sensor::bme280::fetch ( observations_type & obs )

Retrieve the results from the most recent observation.

Note: The SPI/TWI peripheral must be enabled before this method is invoked.

Returns: zero on success, or a non-zero error code.

◆ initialize()

int nrfcxx::sensor::bme280::initialize ( )

Initialize the BME280.

Issue this only once for each instance. This confirms communication with the device and configures the sample options.

Note: The SPI/TWI peripheral must be enabled before this method is invoked.

Warning: If the BME280 is non-responsive this may delay internally for up to 15 ms waiting to successfully connect to the device. This is due to busy-wait calls inside the vendor-supplied library.

Returns: zero on success, or a non-zero error code.

◆ sample()

int nrfcxx::sensor::bme280::sample ( )

inline

Request a new sample from the device.

Note: Wait for SAMPLE_DELAY_utt ticks before attempting to invoke fetch().; The SPI/TWI peripheral must be enabled before this method is invoked.

Returns: zero on success, or a non-zero error code.

Field Documentation

◆ INVALID_PRESSURE

constexpr unsigned int nrfcxx::sensor::bme280::INVALID_PRESSURE = 0x00C00000

staticconstexpr

Value used for invalid pressure observations.

This is sized to fit in a 24-bit unsigned integer, with a maximum representable value of 1258.2911 hPa.

◆ SAMPLE_DELAY_utt

constexpr unsigned int nrfcxx::sensor::bme280::SAMPLE_DELAY_utt = clock::uptime::from_ms(10)

staticconstexpr

Lower bound for wait after sample() before get_sensor_data().

This value is designed for the weather monitoring configuration hard-coded into the implementation. Nominal maximum 9.3 ms.

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

nrfcxx/sensor/bme280.hpp

Data Structures

Public Member Functions

Static Public Attributes

Additional Inherited Members