The board can ask the phone for its own sensors:

PhyphoxBleExperiment::Sensor acc(SENSOR_ACCELEROMETER);
acc.setRate(50);            // Hz; unset = as fast as the phone offers
acc.setAverage(false);
acc.mapChannel("x", 1);     // components: x, y, z, abs, t, accuracy
acc.mapChannel("y", 2);
acc.mapChannel("z", 3);
exp.addSensor(acc);

The values arrive in input channels 1…3 like user input (PhyphoxBLE::read(x, y, z) or onChange), continuously while the experiment runs. All components of one sensor arrive in one Bluetooth write, so the callbacks of its channels fire together.

Sensor types

Every sensor the phyphox file format knows, under the format's own name:

constant	reading	unit
`SENSOR_ACCELEROMETER`	acceleration including gravity	m/s²
`SENSOR_LINEAR_ACCELERATION`	acceleration without gravity	m/s²
`SENSOR_GRAVITY`	gravity in the device frame	m/s²
`SENSOR_GYROSCOPE`	angular velocity	rad/s
`SENSOR_MAGNETIC_FIELD`	magnetic field	µT
`SENSOR_PRESSURE`	air pressure	hPa
`SENSOR_LIGHT`	illuminance	lx
`SENSOR_PROXIMITY`	proximity (most phones: 0 or 5)	cm
`SENSOR_TEMPERATURE`	ambient temperature, where a phone has it	°C
`SENSOR_HUMIDITY`	relative humidity	%
`SENSOR_ATTITUDE`	orientation as a quaternion: `x`, `y`, `z` are its vector part, `abs` is `w`	—
`SENSOR_CUSTOM`	any sensor the phone exposes, selected with `setNameFilter` / `setTypeFilter` (Android)	sensor-specific

Not every phone has every sensor; the app tells the user which are missing.

Components

mapChannel(component, channel) takes x, y, z, abs (the magnitude, or w for the attitude), t (the phone's timestamp of the reading, in seconds) and accuracy (the sensor's own accuracy flag). The sensor's type is given to the constructor or setType(SENSOR_...).

Rate

setRate(hz) asks for a rate; setRateStrategy("auto" | "request" | "generate" | "limit") says how the phone reconciles it with what the sensor offers, and setStride(n) keeps only every n-th reading. setAverage(true) averages readings between deliveries instead of dropping them.

1.x names

Two constants from 1.x are aliases of the names above:

SENSOR_ACCELEROMETER_WITHOUT_G is the same sensor as SENSOR_LINEAR_ACCELERATION and emits the same name. It always worked and stays.
SENSOR_MAGNETOMETER is a deprecated alias of SENSOR_MAGNETIC_FIELD — in 1.x it emitted a name the format does not know, so it never worked. It now emits the correct name and will be removed in 2.1.