useSensors

Source: packages/sdk/src/hardware/useSensors.ts

Continuous multi-sensor telemetry from expo-sensors. Nothing is reported before the hardware has said it: pressure and light stay null until a first sample arrives, and isAvailable is false until subscriptions are attached. Per-sensor availability is reported separately, because a device can have an IMU and no barometer.

Altitude is derived from pressure with the international hypsometric formula, so it is relative and drifts with the weather. It is not a GNSS altitude and must not be presented as one.

Signature

function useSensors(updateIntervalMs?: number): SensorTelemetry & {
 hasMotionSample: boolean;
 barometerAvailable: boolean | null;
 lightAvailable: boolean | null;
 error: string | null;
 source: TelemetrySource;
};

Inputs

Parameter	Type	Default	Description
updateIntervalMs	number	100	Sampling period in milliseconds for the accelerometer, gyroscope, magnetometer and barometer. The light sensor is sampled at twice this interval because illuminance changes slowly. Changing it re-subscribes every sensor. Values below roughly 20 ms cost battery without adding usable resolution.

Outputs

Field	Type	Description
accelerometer	Vector3D — { x, y, z }	Proper acceleration including gravity, in g. Three decimals. {0,0,0} until the first sample.
gyroscope	Vector3D	Angular velocity in radians per second about each axis. Three decimals.
magnetometer	Vector3D	Geomagnetic field strength in microteslas (μT), one decimal. This is what a compass heading is computed from.
barometer	BarometerData — { pressure: number | null; relativeAltitude?: number | null }	Air pressure in hectopascals and the altitude derived from it in metres, relative to standard sea-level pressure (1013.25 hPa). Both null until a sample arrives or when the device has no barometer.
lightLux	number | undefined	Ambient illuminance in lux from the front photodiode, one decimal so a dark room reads 0.4 rather than 0. undefined until the first sample.
isAvailable	boolean	Whether the sensor subscriptions were attached successfully. false before setup completes and after a failure.
hasMotionSample	boolean	true once a real accelerometer sample has arrived. Until then the vectors are zeroed, so use this to distinguish “still” from “not started”.
barometerAvailable	boolean | null	Whether this device has a barometer. null until probed.
lightAvailable	boolean | null	Whether this device has an ambient light sensor. null until probed.
error	string | null	Why subscribing failed, if it did. null when healthy.
source	TelemetrySource	'hardware' once a motion sample has arrived, 'unavailable' before that.

Functions

useSensors() returns no callables. Change the sampling rate by passing a different updateIntervalMs; the hook re-subscribes when it changes.

Example

import { useSensors } from '@pixelkit-labs/sdk';

export function AltitudeHUD() {
 const { barometer, accelerometer, barometerAvailable } = useSensors(100);
 return (
 <View>
 <Text>Altitude: {barometerAvailable ? barometer.relativeAltitude ?? '—' : 'no barometer'} m</Text>
 <Text>Pressure: {barometer.pressure ?? '—'} hPa</Text>
 <Text>Accel Z: {accelerometer.z.toFixed(2)} g</Text>
 </View>
 );
}