nrfcxx::sensor::ccs811::threshold_s Struct Reference

Thresholds for detecting significant changes in readings. More...

#include <nrfcxx/sensor/ccs811.hpp>

Public Member Functions
int	env_data_changed (uint32_t ed1, uint32_t ed2) const
	Compare two encoded environmental values for closeness. More...
int	observation_beacon_changed (const observation_beacon_type &ob1, const observation_beacon_type &ob2) const
	Assess whether two observations differ significantly. More...

Data Fields
uint16_t	eCO2_ppm = 20
	Threshold for changes in observations_type::eCO2.
uint16_t	eTVOC_ppb = 5
	Threshold for changes in observations_type::eTVOC.
uint8_t	temperature_Cel = 1
	Threshold for changes to the temperature value in env_data().
uint8_t	humidity_pph = 2
	Threshold for changes to the relative humidity value in env_data().

Detailed Description

Thresholds for detecting significant changes in readings.

Note

Thresholds are inclusive of the alerting value. In other words, if a field is zero then readings with the same value are considered to have met the threshold for change. This allows trivial configuration to disable transmission limits for mains-powered devices in sparse environments.

Member Function Documentation

env_data_changed()

int nrfcxx::sensor::ccs811::threshold_s::env_data_changed	(	uint32_t	ed1,
		uint32_t	ed2
	)		const

Compare two encoded environmental values for closeness.

The HTS221 sensor on the Thingy:52 has abysmal repeatability and frequently bounces back and forth across half-unit boundaries, resulting in unnecessary updates to the environment setting and possibly contributing to variation in eCO2 estimates.

Determine whether the difference between two values is large enough to warrant doing an update, using the threshold limits specified in temperature_Cel and humidity_pph.

Returns

nonzero if the two encoded environment values differ in at least the threshold value for at least one encoded measurement.

observation_beacon_changed()

int nrfcxx::sensor::ccs811::threshold_s::observation_beacon_changed	(	const observation_beacon_type &	ob1,
		const observation_beacon_type &	ob2
	)		const

Assess whether two observations differ significantly.

A change is diagnosed if:

• the internal observation_beacon_type::status values differ;
• the observation_beacon_type::baseline values differ;
• #eCO2 differs by at least threshold_s::eCO2_ppm;
• #eTVOC differs by at least threshold_s::eTVOC_ppb;
• env_data differs at all. (It is assumed that the sensor value would not have been updated if it weren't considered significant.)

Parameters

from	a previous instance against which differences are calculated.
thr	the thresholds for detecting differences.

Returns

zero` iff all measurements are equally present/valid in each instance and the differences are less than the measurement threshold. If a significant change is detected it is indicated by non-zero return value.

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

• nrfcxx/sensor/ccs811.hpp