# Sensors overview

Note

The Qualcomm® sensing hub (QSH) is available only on [QCS5430](https://www.qualcomm.com/products/internet-of-things/industrial/industrial-automation/qcs5430) and [QCS6490](https://www.qualcomm.com/products/internet-of-things/industrial/building-enterprise/qcs6490).

The Qualcomm® system-on-chip (SoC) includes an application processor
that runs the Linux operating system, a low-power application digital signal processor (aDSP), and
other processors. The low-power processor runs the real-time operating
system (RTOS) for handling the QSH use cases.
The aDSP supports the following for QSH operations:

- GPIOs configurable as serial bus: serial peripheral interface (SPI),
inter-integrated circuit (I^2^C), improved I^2^C (I^3^C), and universal asynchronous receiver/transmitter (UART).
- Serial buses in low-power mode.
- Dedicated local memory, also known as the island in QSH.

## QSH sensors

QSH provides a framework to use data from a wide range of sensors. The sensor data is useful in fields such as IoT, gaming, health, and
fitness.

A device can have more than one sensor of a given type. For example, a flip-phone has an accelerometer placed on each of the two planes. The published attributes or capabilities distinguish each accelerometer sensor. You can access the availability, attributes, and capabilities of a sensor on the platform using the QSH client APIs. Use the same QSH client APIs to get the sensor data from the QSH framework.

The QSH framework APIs include QSH client APIs and sensor APIs, to perform the following sensor-related tasks:

- Identify the sensors available on a development kit.
- Determine sensor capabilities using attributes, such as supported
sample rate, maximum range, manufacturer, power requirement, and
resolution.
- Collect and provide data according to the configuration, thereby enabling
sensors with a specified sample rate.

The QSH framework provides access to both hardware-based and software-based sensors.

### Hardware-based sensors

Hardware-based sensors are physical sensors that gather data by directly measuring specific environmental properties, such as acceleration, magnetic field, pressure, humidity, light, and angular velocity.

The following table lists the hardware-based sensors that the QSH framework supports:

> 
> 
> Table : Hardware-based sensors
> 
> 
> | Sensor name | Sensor type | Description | Proto API |
> | --- | --- | --- | --- |
> | Accelerometer | `accel` | Measures the acceleration applied to a device on all the 3 physical axes (x, y, and z) in meter/second square (m/s2) | `sns_accel.proto` |
> | Gyroscope | `gyro` | Measures the rate of rotation of a device around each of the 3 physical axes (x, y, and z) in radians/second (rad/s) | `sns_gyro.proto` |
> | Sensor temperature | `sensor_temperature` | Measures the temperature of the sensor in degrees Celsius (°C) | `sns_sensor_temperature.proto` |
> | Magnetometer | `mag` | Measures the ambient magnetic field for all the 3 physical axes (x, y, and z) in microtesla (μT) | `sns_mag.proto` |
> | Proximity | `proximity` | Measures the proximity of an object and provides *near/far* events | `sns_proximity.proto` |
> | Ambient light | `ambient_light` | Measures the ambient light level illumination in lux (lx) | `sns_ambient_light.proto` |
> | Pressure | `pressure` | Measures the ambient air pressure in hectoPascal (hPa) | `sns_pressure.proto` |
> | Humidity | `humidity` | Measures the relative ambient humidity in percentage (%) | `sns_humidity.proto` |
> | Ambient temperature | `ambient_temperature` | Provides the ambient room temperature in degrees Celsius (°C) | `sns_ambient_temperature.proto` |
> | Hall | `hall` | Measures the magnetic field and provides a magnet *near/far* indication | `sns_hall.proto` |
> | Capacitive proximity | `sar` | Detects human object proximity using change in capacitance and reports *near/ far* events | `sns_sar.proto` |

### Software-based sensors

Software-based sensors, also known as virtual sensors, are algorithms that gather data from one or more physical sensors and generate the intended output. The common examples are gravity, step counter, and game rotation vector.

The following table lists the software-based sensors that the QSH framework supports:

> 
> 
> Table : Software-based sensors
> 
> 
> | Sensor name | Sensor type | Proto API | Description |
> | --- | --- | --- | --- |
> | Absolute motion detector | `amd` | `sns_amd.proto` | <ul class="simple"><br><li><p>Reports a stationary state event when the device is at absolute<br>rest. For example, the device is placed on a stationary object, such as desk or table.</p></li><br><li><p>Reports a moving state event when the device transitions from absolute rest to moving state.<br>For example, the device is being lifted from a desk or table.</p></li><br><li><p>Uses the accelerometer motion detect interrupt to reduce<br>the power.</p></li><br></ul> |
> | Relative motion detector | `rmd` | `sns_rmd.proto` | Reports a stationary state when the device is not moving significantly with respect to gravity. |
> | Significant motion detector | `sig_motion` | `sns_sig_motion.proto` | <ul class="simple"><br><li><p>Triggers when detecting a significant motion - a motion<br>that might lead to a change in the user location. For<br>example, walking, biking, or sitting in a moving car,<br>coach, or train.</p></li><br><li><p>The following examples do not trigger a significant<br>motion:</p><ul><br><li><p>The device is in a pocket and the person is not<br>moving.</p></li><br><li><p>The device is on a table and the table shakes a bit.</p></li><br></ul><br></li><br><li><p>Reporting mode: Single response, after the notification<br>sensor automatically disables itself.</p></li><br></ul> |
> | Pedometer | `pedometer` | `sns_pedometer.proto` | Reports the number of step counts to the client. |
> | Step detector | `step_detect` | `sns_step_detect.proto` | Detects steps and generates an event on each step. |
> | Tilt detector | `tilt` | `sns_tilt.proto` | Generates an event each time there is a tilt. The direction of the 2-second window, with average gravity changing by at least 35 degrees since the activation or the last event generated by the sensor, defines a tilt event. |
> | Tilt to wake | `tilt_to_wake` | `sns_tilt_to_wake.proto` | Detects the substantial device rotation gesture event when the picked device is in a specific range of the pitch and roll angles. |
> | Gyroscope calibration | `gyro_cal` | `sns_gyro_cal.proto` | <ul class="simple"><br><li><p>A low-power dynamic calibration algorithm for gyroscopes.</p></li><br><li><p>Validated across multiple gyroscope parts from different<br>vendors.</p></li><br></ul> |
> | Magnetometer calibration | `mag_cal` | `sns_mag_cal.proto` | <ul class="simple"><br><li><p>A low-power dynamic calibration algorithm for the magnetometer sensor.</p></li><br><li><p>Validated across multiple magnetometer parts from<br>different vendors.</p></li><br></ul> |
> | Game rotation vector | `game_rv` | `sns_game_rv.proto` | <ul class="simple"><br><li><p>Reports the orientation of the device that is relative to<br>an unspecified coordinate frame.</p></li><br><li><p>Obtains the orientation through integration of<br>accelerometer and gyroscope readings. Therefore, the<br>Y-axis does not point north; instead, it points to an arbitrary<br>reference.</p></li><br></ul> |
> | Gravity/linear acceleration | `gravity` | `sns_gravity.proto` | <ul class="simple"><br><li><p>Provides a three-dimensional vector indicating the<br>direction and magnitude of gravity.</p></li><br><li><p>Determines the relative orientation of the device in space.</p></li><br></ul> |
> | Persistent stationary detector | `persist_stationary_detect` | `sns_persist_stationary_detect.proto` | Reports an event when the device is stationary for at least 5 seconds. |
> | Persistent motion detector | `persist_motion_detect` | `sns_persist_motion_detect.proto` | Reports an event when the device is in motion for at least 5 seconds. |
> | Device orientation | `device_orient` | `sns_device_orient.proto` | Reports whether the device is in portrait mode or landscape mode. |
> | Geo-mag rotation vector (RV) | `geomag_rv` | `sns_geomag_rv.proto` | Reports the orientation of the device relative to the East-North-Up coordinates frame; obtained through the integration of accelerometer and magnetometer readings. |
> | Rotation vector | `rotv` | `sns_rotv.proto` | <ul class="simple"><br><li><p>Reports the orientation of the device relative to the East-North-Up coordinates frame.</p></li><br><li><p>Obtains orientation through the integration of accelerometer, gyroscope, and magnetometer readings.</p></li><br></ul> |
> | Device position classifier | `device_position_classi fier` | `sns_dpc.proto` | Provides the device position information. |
> | Activity recognition algorithm | `activity_recognition` | `sns_activity_recognition.proto` | Determines relative stationary, such as walk, run, bike, car, nonmotorized vehicle, and motorized vehicle states and classifications. |
> | Distance bound | `distance_bound` | `sns_distance_bound.proto` | <ul class="simple"><br><li><p>Tracks the distance in meters, and reports to the client when the requested distance is covered.</p></li><br><li><p>The client can query the accumulated distance anytime before the final distance is reached.</p></li><br></ul> |

- [Features](https://docs.qualcomm.com/doc/80-70018-7/topic/supported_features.html)
Describes the Qualcomm® sensing hub (QSH) features and their impact on the IoT use cases.
- [QSH architecture](https://docs.qualcomm.com/doc/80-70018-7/topic/architecture.html)
Describes the QSH unified event-driven framework.
- [QSH APIs](https://docs.qualcomm.com/doc/80-70018-7/topic/qsh_api_reference.html)
Describes the QSH interfaces and important QSH functions, classes, methods, and data structures.
- [Software](https://docs.qualcomm.com/doc/80-70018-7/topic/software.html)
Describes the application processor and low-power processor directory structure.
- [Platform](https://docs.qualcomm.com/doc/80-70018-7/topic/platform.html)
Describes the sensors supported on Qualcomm® RB3 Gen 2 Development Kit.

Last Published: Apr 08, 2025

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