Sensors Overview
Introduction
The pan-sensor service subsystem provides a lightweight sensor service framework. You can call APIs offered by this framework to query the sensor list, enable or disable a sensor, and subscribe to or unsubscribe from sensor data. The following figure shows the architecture of the lightweight sensor framework.
Figure 1 Sensor service framework
- Sensor API: provides APIs for performing basic operations on sensors, including querying the sensor list, subscribing to or unsubscribing from sensor data, and executing control commands. This module makes application development simpler.
- Sensor Framework: manages sensor data subscription, creates and destroys data channels, and implements communication with the Sensor Service module.
- Sensor Service: interacts with the HDF module to receive, parse, and distribute data, manages sensors on hardware and sensor data reporting, and controls sensor permissions.
Available APIs
Table 1 APIs of the sensor framework
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Function
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Description
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Parameter
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int32_t GetAllSensors(SensorInfo **sensorInfo, int32_t *count)
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Obtains information about all sensors in the system.
Return value: Returns 0 if the information is obtained; returns a non-zero value otherwise.
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sensorInfo (not NULL): information about all sensors in the system
count (not NULL): total number of sensors in the system
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int32_t SubscribeSensor(int32_t sensorTypeId, SensorUser *user)
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Subscribes to sensor data. The system will report the obtained sensor data to the subscriber.
Return value: Returns 0 if the subscription is successful; returns a non-zero value otherwise.
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sensorTypeId: ID of a sensor type
user (not NULL): sensor subscriber that requests sensor data. A subscriber can obtain data from only one sensor.
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int32_t UnsubscribeSensor(int32_t sensorTypeId, SensorUser *user)
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Unsubscribes from sensor data. The system will no longer report sensor data to the subscriber.
Return value: Returns 0 if the unsubscription is successful; returns a non-zero value otherwise.
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sensorTypeId: ID of a sensor type
user (not NULL): sensor subscriber that requests sensor data. A subscriber can obtain data from only one sensor.
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int32_t SetBatch(int32_t sensorTypeId, SensorUser *user, int64_t samplingInterval, int64_t reportInterval)
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Sets the data sampling interval and data reporting interval for the specified sensor.
Return value: Returns 0 if the setting is successful; returns a non-zero value otherwise.
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sensorTypeId: ID of a sensor type
user (not NULL): sensor subscriber that requests sensor data. A subscriber can obtain data from only one sensor.
samplingInterval: sensor data sampling interval, in nanoseconds
reportInterval: sensor data reporting interval, in nanoseconds
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int32_t ActivateSensor(int32_t sensorTypeId, SensorUser *user)
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Enables the specified sensor that has been subscribed to.
Return value: Returns 0 if the sensor is successfully enabled; returns a non-zero value otherwise.
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sensorTypeId: ID of a sensor type
user (not NULL): sensor subscriber that requests sensor data. A subscriber can obtain data from only one sensor.
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int32_t DeactivateSensor(int32_t sensorTypeId, SensorUser *user)
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Disables an enabled sensor.
Return value: Returns 0 if the sensor is successfully disabled; returns a non-zero value otherwise.
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sensorTypeId: ID of a sensor type
user (not NULL): sensor subscriber that requests sensor data. A subscriber can obtain data from only one sensor.
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int32_t SetMode(int32_t sensorTypeId, SensorUser *user, int32_t mode)
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Sets the data reporting mode for the specified sensor.
Return value: Returns 0 if the sensor data reporting mode is successfully set; returns a non-zero value otherwise.
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sensorTypeId: ID of a sensor type
user (not NULL): sensor subscriber that requests sensor data. A subscriber can obtain data from only one sensor.
mode: data reporting mode of the sensor
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