Crate sensors 

Available on crate feature sensors only.

Provides a sensor abstraction layer.

Definitions

In the context of this abstraction:

• A sensor device is a device measuring one or multiple physical quantities and reporting them as one or more digital values—we call these values samples.
• Sensor devices measuring the same physical quantity are said to be part of the same sensor category. A sensor device may be part of multiple sensor categories.
• A measurement is the physical operation of measuring one or several physical quantities.
• A reading is the digital result returned by a sensor device after carrying out a measurement. Samples of different physical quantities can therefore be part of the same reading.
• A sensor driver refers to a sensor device as exposed by the sensor abstraction layer.
• A sensor driver instance is an instance of a sensor driver.

Goals

This abstraction has two main goals:

• Providing a unified way of accessing the readings from all registered sensor driver instances in a homogeneous way.
• Making it easy and as transparent as possible to substitute a specific sensor device by a similar one from the same category.

Accessing sensor driver instances

Registered sensor driver instances can be accessed using REGISTRY::sensors(). Sensor drivers implement the Sensor trait, which allows to trigger measurements and obtain the resulting readings.

Obtaining a sensor reading

After triggering a measurement with Sensor::trigger_measurement(), a reading can be obtained using Sensor::wait_for_reading(). It is additionally necessary to use Sensor::reading_channels() to make sense of the obtained reading:

• Sensor::wait_for_reading() returns a Samples, a data “tuple” containing values returned by the sensor driver.
• Sensor::reading_channels() returns a ReadingChannels which indicates which physical quantity each Sample from that tuple corresponds to, using a Label. For instance, this allows to disambiguate the values provided by a temperature & humidity sensor.

To avoid handling floats, Samples returned by Sensor::wait_for_reading() are integers, and a fixed scaling value is provided in ReadingChannel, for each Sample returned. See Sample for more details.

For implementors

Sensor drivers must implement the Sensor trait.

Modules

registry

Provides a sensor driver instance registry, allowing to register sensor driver instances and access them in a centralized location.

sensor

Provides a Sensor trait abstracting over implementation details of a sensor driver.

signal

This module contains a custom Signal struct meant to be used in the [ariel-os-sensors][ariel-os-sensors] ecosystem.

Enums

Category

Categories a sensor driver can be part of.

Label

Label of a Sample part of a Samples tuple.

MeasurementUnit

Represents a unit of measurement.

Statics

REGISTRY

The global registry instance.

Traits

Reading

Implemented on Samples, returned by Sensor::wait_for_reading().

Sensor

This trait must be implemented by sensor drivers.