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Sensor

Tizen provides functions for managing sensors and receiving sensor data.

The main features of the Sensor API include:

Note
All devices may not support all sensor types. For more information, see System Information.

Sensor Handle

A device can have various physical and virtual sensors. Tizen supports the following sensor types:

The Sensor API enables your application to receive data from the device's internal sensors. The application can receive the sensor data only when the data is modified.

Note

All sensors may not be available on all devices.

The Sensor API finds sensors, and monitors their availability. Key sensor features provided by the Sensor API include getting and setting the following:

  • Sensor name
  • Sensor vendor
  • Sensor type
  • Resolution
  • Sensing interval
  • Measurement range

Accelerometer

The accelerometer measures changes in the velocity of a device. It is a combination of gravity and linear acceleration components. The accelerometer measures the device's accelerometer vector in 3 axes relative to its body frame.

An acceleration shift of 1g always exists on the axis aligned to Earth's gravity. If the device is at rest, the sensor data reads 1g (the gravity offset) on one of the device axis and tells you which device axis is aligned to the direction of gravity. A falling device which has reached terminal velocity ideally shows the accelerometer value of 0 on all axis. The change in the effect of Earth's gravity is observed on the 3 device axes by rotating the device along any of the 3 axes.

The linear acceleration components which correspond to the measure of the linear motion subjected on the device can be obtained by removing the gravity components from the accelerometer data.

The accelerometer provides 3 components of acceleration (X, Y, and Z), as the following figure illustrates.

Figure: Accelerometer vector and axes

Accelerometer vector and axes

The accelerometer outputs 4 values: 3 Cartesian axis values and a timestamp. The accelerometer sensor measures and returns axes values in "m/s2" (meters per second squared). When a device is moved in the ±X, ±Y, or ±Z direction, the corresponding output increases (+) or decreases (-).

The following table lists the measurement data that the accelerometer provides.

Table: Measurement data detected by the accelerometer
Measurement Type Range Unit
Timestamp unsigned long long - Nanoseconds
values[0]: X float Min. value = -19.6

Max. value = 19.6

 m/s2
values[1]: Y float Min. value = -19.6

Max. value = 19.6

 m/s2
values[2]: Z float Min. value = -19.6

Max. value = 19.6

 m/s2

The following table provides information about the accelerometer output for a device at rest.

Table: Accelerometer output for a device at rest
Position 1 2 3 4 5 6
Diagram Accelerometer output Accelerometer output Accelerometer output Accelerometer output Accelerometer output Accelerometer output
values[0]: X 0g 1g 0g -1g 0g 0g
values[1]: Y 1g 0g -1g 0g 0g 0g
values[2]: Z 0g 0g 0g 0g 1g -1g
Axis up (down) Y X -Y -X Z -Z
X-polarity 0 + 0 - 0 0
Y-polarity + 0 - 0 0 0
Z-polarity 0 0 0 0 + -

Gravity Sensor

The gravity sensor is a virtual sensor derived from the 3-axis acceleration sensor. The 3-axis gravity components provide a measure of the effect of Earth's gravity observed on the device reference axes. The gravity components measured on a device vary based on the change in the device orientation, and hence they provide a measure of the rotation subjected to the device.

Figure: Gravity sensor vector and axes

Gravity sensor vector and axes

The gravity sensor outputs 4 values: 3 Cartesian axis values and a timestamp. The gravity sensor measures and returns axes values in "m/s2" (meters per second squared). When a device is rotated in the ±X, ±Y, or ±Z direction, the corresponding output increases (+) or decreases (-).

The following table lists the measurement data that the gravity sensor provides.

Table: Measurement data detected by the gravity sensor
Measurement Type Range Unit
Timestamp unsigned long long - Nanoseconds
values[0]: X float Min. value = -9.8

Max. value = 9.8

 m/s2
values[1]: Y float Min. value = -9.8

Max. value = 9.8

 m/s2
values[2]: Z float Min. value = -9.8

Max. value = 9.8

 m/s2

Linear Acceleration Sensor

The linear acceleration sensor is derived from the accelerometer by excluding the gravity value, and it measures the user-driven changes in the velocity. The linear acceleration sensor is used to detect the dynamic movement of the device and analyze the user's motion profile. The 3-axes linear acceleration components provide a measure of the combined linear motion subjected to the device in the euclidean space.

The linear acceleration sensor provides 3 components of acceleration (X, Y, and Z), as the following figure illustrates.

Figure: User-acceleration sensor vector and axes

User-acceleration sensor vector and axes

The linear acceleration sensor outputs 4 values: 3 Cartesian axis values and a timestamp. The linear acceleration sensor measures and returns axes values in "m/s2" (meters per second squared). When a device is accelerated in the ±X, ±Y, or ±Z direction, the corresponding output increases (+) or decreases (-). The acceleration output is shown in the same direction as the user-driven force.

The following table lists the measurement data that the linear acceleration sensor provides.

Table: Measurement data detected by the linear acceleration sensor
Measurement Type Range Unit
Timestamp unsigned long long - Nanoseconds
values[0]: X float Min. value = -19.6

Max. value = 19.6

 m/s2
values[1]: Y float Min. value = -19.6

Max. value = 19.6

 m/s2
values[2]: Z float Min. value = -19.6

Max. value = 19.6

 m/s2

Magnetic Sensor

The magnetic sensor is a 3-axis electronic compass (sometimes referred to as a "magnetometer" or "geomagnetic sensor"). It can also be used in determining the azimuth component of the device orientation provided that the tilt of the device is already computed. The magnetic sensor measures the Earth's magnetic field strength and fluctuations, and splits the measurement into X, Y, and Z components.

The following factors can have an impact on the sensor readings:

  • The weather or the season of the year
  • Your location on the planet
  • Nearby, strong magnetic fields, such as magnets, electric coils, or objects which contain a ferrite element

The following table lists the measurement data that the magnetic sensor provides.

Table: Measurement data detected by the magnetic sensor
Measurement Type Unit
Timestamp unsigned long long Nanoseconds
values[0]: X float μT (micro Tesla)
values[1]: Y float μT (micro Tesla)
values[2]: Z float μT (micro Tesla)

The magnetic sensor uses the 3-axis Cartesian space coordinate system, as the following figure illustrates.

Figure: Magnetic field vector and axes

Magnetic field vector and axes

Uncalibrated Magnetic Sensor

The uncalibrated magnetic sensor is a 3-axis electronic compass (sometimes referred to as a "magnetometer" or "geomagnetic sensor"). It can also be used in determining the azimuth component of the device orientation provided that the tilt of the device is already computed. It measures the Earth's magnetic field strength and fluctuations, and splits the measurement into X, Y, and Z components. The uncalibrated magnetic sensor is similar in functionality to a magnetic sensor, but does not perform hard iron calibration. Factory calibration and temperature compensation are applied.

The following factors can have an impact on the sensor readings:

  • The weather or the season of the year
  • Your location on the planet
  • Nearby, strong magnetic fields, such as magnets, electric coils, or objects which contain a ferrite element

The following table lists the measurement data that the uncalibrated magnetic sensor provides.

Table: Measurement data detected by the uncalibrated magnetic sensor
Measurement Type Unit
Timestamp unsigned long long Nanoseconds
values[0]: X float μT (micro Tesla)
values[1]: Y float μT (micro Tesla)
values[2]: Z float μT (micro Tesla)
values[3]: X-axis bias float μT (micro Tesla)
values[4]: Y-axis bias float μT (micro Tesla)
values[5]: Z-axis bias float μT (micro Tesla)

Rotation Vector Sensor

The rotation vector sensor represents the orientation of the device as a combination of an angle and an axis, in which the device has rotated through a specific angle around an axis (x, y, or z). The rotation vector is the output of a software/hardware-based sensor fusion solution, which uses the accelerometer, gyroscope, and magnetic sensor as inputs to compute the orientation of the device.

The following table lists the measurement data that the rotation vector sensor provides.

Table: Measurement data detected by the rotation vector
Measurement Type Range Unit
Timestamp unsigned long long - Nanoseconds
Accuracy sensor_data_accuracy_e - int
values[0]: X float Min. value = -1

Max. value = 1

 -
values[1]: Y float Min. value = -1

Max. value = 1

 -
values[2]: Z float Min. value = -1

Max. value = 1

 -
values[3]: W float Min. value = -1

Max. value = 1

 -

Gyroscope Rotation Vector Sensor

The gyroscope rotation vector sensor is the output of a software/hardware-based sensor fusion solution which uses the accelerometer and gyroscope to compute the orientation of the device. In this sensor, the pitch and roll equivalent representations are free of drift while the azimuth equivalent component is allowed to drift due to the absence of the magnetic sensor. The gyroscope rotation vector sensor represents the orientation of the device as a combination of an angle and an axis in which the device has rotated through a specific angle around an axis (x, y, or z).

The following table lists the measurement data that the gyroscope rotation vector sensor provides.

Table: Measurement data detected by the gyroscope rotation vector sensor
Measurement Type Range Unit
Timestamp unsigned long long - Nanoseconds
Accuracy sensor_data_accuracy_e - int
values[0]: X float Min. value = -1

Max. value = 1

 -
values[1]: Y float Min. value = -1

Max. value = 1

 -
values[2]: Z float Min. value = -1

Max. value = 1

 -
values[3]: W float Min. value = -1

Max. value = 1

 -

Geomagnetic Rotation Vector Sensor

The geomagnetic rotation vector sensor is the output of a software/hardware-based sensor fusion solution which uses the accelerometer and magnetic sensors to compute the orientation of the device. In this sensor, the computed orientation is free of any drift, but it is inaccurate compared to a sensor fusion solution using the gyroscope sensor. The geomagnetic rotation vector sensor represents the orientation of the device as a combination of an angle and an axis in which the device has rotated through a specific angle around an axis (x, y, or z).

The following table lists the measurement data that the geomagnetic rotation vector sensor provides.

Table: Measurement data detected by the geomagnetic rotation vector sensor
Measurement Type Range Unit
Timestamp unsigned long long - Nanoseconds
Accuracy sensor_data_accuracy_e - int
values[0]: X float Min. value = -1

Max. value = 1

 -
values[1]: Y float Min. value = -1

Max. value = 1

 -
values[2]: Z float Min. value = -1

Max. value = 1

 -
values[3]: W float Min. value = -1

Max. value = 1

 -

Orientation Sensor

The orientation sensor combines the 3-axis accelerometer, 3-axis magnetic sensor, and 3-axis gyroscope to determine the orientation (rotation angles) of the device. The orientation is the output of a software/hardware-based sensor fusion solution which uses the accelerometer, magnetic sensor, and gyroscope. The orientation sensor output is an alternative representation to the rotation vector sensor output used to determine the rotation of the device, and it is calculated in terms of Euler angles:

  • Azimuth
  • Pitch
  • Roll

The following table lists the measurement data that the orientation sensor provides.

Table: Measurement data detected by the orientation sensor
Measurement Type Range Unit
Timestamp unsigned long long - Nanoseconds
values[0]: Azimuth float Min. value = 0

Max. value = 360

 Degrees (°)
values[1]: Pitch float Min. value = -180

Max. value = 180

 Degrees (°)
values[2]: Roll float Min. value = -90

Max. value = 90

 Degrees (°)

The angular positions are measured using a fixed frame reference (XE, YE, ZE).

Figure: Angular positions and the fixed frame reference

Angular positions and the fixed frame reference

Gyroscope

The gyroscope detects angular velocity or angular rates of a device. The 3D gyroscope data is considered to be very sensitive in detecting incremental rotation angles. The rotation angles obtained by integrating the angular rates over longer duration is inaccurate due to the build-up of drift.

Figure: Gyroscope vector and axes

Gyroscope vector and axes

The following table lists the measurement data that the gyroscope provides.

Table: Measurement data detected by the gyroscope
Measurement Type Range Unit
Timestamp unsigned long long - Nanoseconds
values[0]: X float Min. value = -573.0

Max. value = 573.0

 Degrees/s (°/s)
values[1]: Y float Min. value = -573.0

Max. value = 573.0

 Degrees/s (°/s)
values[2]: Z float Min. value = -573.0

Max. value = 573.0

 Degrees/s (°/s)

Uncalibrated Gyroscope

The uncalibrated gyroscope detects angular velocity or angular rates of a device. The 3D uncalibrated gyroscope sensor is considered to be very sensitive in detecting incremental rotation angles. The rotation angles obtained by integrating the angular rates over longer duration is inaccurate due to the build-up of drift. The uncalibrated gyroscope data also consists of drift compensation values for each axis, which can be used to subtract the drift from the detected angular rates. The values of drift for the 3 axes are obtained from the output of a software/hardware-based sensor fusion solution.

The following table lists the measurement data that the uncalibrated gyroscope provides.

Table: Measurement data detected by the uncalibrated gyroscope
Measurement Type Range Unit
Timestamp unsigned long long - Nanoseconds
values[0]: X float Min. value = -573.0

Max. value = 573.0

 Degrees/s (°/s)
values[1]: Y float Min. value = -573.0

Max. value = 573.0

 Degrees/s (°/s)
values[2]: Z float Min. value = -573.0

Max. value = 573.0

 Degrees/s (°/s)
values[3]: Drift around the X axis float Min. value = -573.0

Max. value = 573.0

 Degrees/s (°/s)
values[4]: Drift around the Y axis float Min. value = -573.0

Max. value = 573.0

 Degrees/s (°/s)
values[5]: Drift around the Z axis float Min. value = -573.0

Max. value = 573.0

 Degrees/s (°/s)

Light Sensor

The light sensor detects the brightness of ambient light. It can be used to measure the brightness level.

As an example use case, the light sensor can be used to control the brightness of the screen. In a dark environment, the light sensor detects the brightness of the environment and can be used to increase the device screen backlight brightness level. In a brighter environment, the backlight brightness level is lowered to save battery power.

The following table lists the measurement data that the light sensor provides.

Table: Measurement data detected by the light sensor
Measurement Type Range Unit
Timestamp unsigned long long - Nanoseconds
values[0]: Level float Min. value = 0

Max. value = 45875

 Lux

Proximity Sensor

The proximity sensor detects the presence of nearby objects in close proximity to the sensor. It can be used to measure the distance between nearby objects and the device.

As an example use case, the proximity sensor can be used to lock or unlock the device screen. When the device user holds the device to their ear, the proximity sensor detects the user as an object, and automatically locks the device screen. When the user moves the device away from their ear to input data, the proximity sensor determines that there are no nearby objects, and unlocks the screen.

The following table lists the measurement data that the proximity sensor provides.

Table: Measurement data detected by the proximity sensor
Measurement Type Range Unit
Timestamp unsigned long long - Nanoseconds
values[0]: proximity float - -

Pressure Sensor

The pressure sensor measures the atmospheric pressure in the device's surrounding environment.

The following table lists the measurement data that the pressure sensor provides.

Table: Measurement data detected by the pressure sensor
Measurement Type Range Unit
Timestamp unsigned long long - Nanoseconds
values[0]: pressure float Min. value = 260

Max. value = 1260

 hPa

Ultraviolet Sensor

The ultraviolet (UV) sensor measures the ultraviolet index. The sensor detects and provides a measure of the UV rays being exposed to the device.

The following table lists the measurement data that the ultraviolet sensor provides.

Table: Measurement data detected by the ultraviolet sensor
Measurement Type Range Unit
Timestamp unsigned long long - Nanoseconds
values[0]: uv index float Min. value = 0

Max. value = 15

 uv index

Temperature Sensor

The temperature sensor measures the ambient room temperature in the device's surrounding environment.

The following table lists the measurement data that the temperature sensor provides.

Table: Measurement data detected by the temperature sensor
Measurement Type Range Unit
Timestamp unsigned long long - Nanoseconds
values[0]: temperature float Min. value = -30

Max. value = 100

 ℃

Humidity Sensor

The humidity sensor measures the relative ambient air humidity in percentage.

The following table lists the measurement data that the humidity sensor provides.

Table: Measurement data detected by the humidity sensor
Measurement Type Range Unit
Timestamp unsigned long long - Nanoseconds
values[0]: humidity float 100 %

Heart Rate Monitor Sensor

The Heart Rate Monitor (HRM) sensor measures a person's heart rate in real time.

The following table lists the measurement data that the HRM sensor provides.

Table: Measurement data detected by the HRM sensor
Measurement Type Range Unit
Timestamp unsigned long long - Nanoseconds
values[0]: Beats per minute int Min. value = 0

Max. value = 240

 -

Heart Rate Monitor LED Green Sensor

The Heart Rate Monitor (HRM) LED green sensor measures the amount of green light that is reflected back from a person's blood vessel.

The following table lists the measurement data that the HRM LED green sensor provides.

Table: Measurement data detected by the HRM LED green sensor
Measurement Type Range Unit
Timestamp unsigned long long - Nanoseconds
values[0]: HRM green light value int Min. value = 0

Max. value = 1081216

 -

Heart Rate Monitor LED IR Sensor

The Heart Rate Monitor (HRM) LED infrared (IR) sensor measures the amount of infrared light that is reflected back from a person's blood vessel.

The following table lists the measurement data that the HRM LED IR sensor provides.

Table: Measurement data detected by the HRM LED IR sensor
Measurement Type Range Unit
Timestamp unsigned long long - Nanoseconds
values[0]: HRM IR light value int Min. value = 0

Max. value = 1081216

 -

Heart Rate Monitor LED Red Sensor

The Heart Rate Monitor (HRM) LED red sensor measures the amount of red light that is reflected back from a person's blood vessel.

The following table lists the measurement data that the HRM LED red sensor provides.

Table: Measurement data detected by the HRM LED red sensor
Measurement Type Range Unit
Timestamp unsigned long long - Nanoseconds
values[0]: HRM red light value int Min. value = 0

Max. value = 1081216

 -

Sensor Listener

The Sensor API detects sensors and monitors their availability. The key sensor listening features provided by the Sensor API include:

  • Adding and removing sensor listeners
  • Checking available sensors
  • Getting sensor data

When running an application on the Emulator, you can use the Event Injector view to provide sensor data for the application.

Sensor listeners can be added or removed at any time. Listeners receive registered sensor events and deliver the event data to applications at predefined intervals. The applications can add multiple sensor listeners for the same sensor type.

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