1# Sensor<a name="EN-US_TOPIC_0000001148682248"></a> 2 3- [Introduction](#section11660541593) 4- [Directory Structure](#section44981327519) 5- [Constraints](#section98068674513) 6- [Usage](#section1581412211528) 7 - [Available APIs](#section15684191115524) 8 - [How to Use](#section1543714111810) 9 10- [Repositories Involved](#section96071132185310) 11 12## Introduction<a name="section11660541593"></a> 13 14A sensor is a device to detect events or changes in an environment and send messages about the events or changes to another device \(for example, a CPU\). Generally, a sensor is composed of sensitive components and conversion components. Sensors are the cornerstone of the IoT. A unified sensor management framework is required to achieve data sensing at a low latency and low power consumption, thereby keeping up with requirements of "1+8+N" products or business in the Seamless AI Life Strategy. Based on the usage, sensors are divided into the following categories: 15 16- Motion: acceleration sensors, gyroscope sensors, gravity sensors, linear acceleration sensors, etc. 17- Orientation: rotation vector sensors, orientation sensors, etc. 18- Environment: magnetic field sensors, barometric pressure sensors, humidity sensors, etc. 19- Light: ambient light sensors, proximity sensors, color temperature sensors, etc. 20- Body: heart rate sensors, heartbeat sensors, etc. 21- Other: Hall effect sensors, grip detection sensors, etc. 22 23The following figure shows the sensor architecture. 24 25**Figure 1** Sensor architecture<a name="fig18632347122018"></a> 26 27 28 29 30## Directory Structure<a name="section44981327519"></a> 31 32The sample code for importing the sensor module is as follows: 33 34``` 35/base/sensors/sensor 36├── frameworks # Framework code 37│ └── native # Sensor client code 38├── interfaces # External APIs 39│ ├── native # Native Implementation for sensors 40│ └── plugin # JS APIs 41├── sa_profile # Configuration file of system ability names and dynamic libraries 42├── services # Code of services 43│ └── sensor # Sensor service for reporting data about sensors, such as the acceleration and gyroscope sensors 44└── utils # Common code, including permissions and communication capabilities 45``` 46 47## Constraints<a name="section98068674513"></a> 48 49- To use sensor functions, ensure that the device where your application runs has the required sensor components. 50 51- To obtain data of some sensors, you need to request the required permissions. 52 53 **Table 1** Permissions required by sensors 54 55 <a name="table1379101653916"></a> 56 <table><thead align="left"><tr id="row137911161397"><th class="cellrowborder" valign="top" width="23.46765323467653%" id="mcps1.2.5.1.1"><p id="p15138132134118"><a name="p15138132134118"></a><a name="p15138132134118"></a>Sensor</p> 57 </th> 58 <th class="cellrowborder" valign="top" width="27.61723827617238%" id="mcps1.2.5.1.2"><p id="p2798169398"><a name="p2798169398"></a><a name="p2798169398"></a>Permission Name</p> 59 </th> 60 <th class="cellrowborder" valign="top" width="13.358664133586636%" id="mcps1.2.5.1.3"><p id="p14791716163914"><a name="p14791716163914"></a><a name="p14791716163914"></a>Sensitivity</p> 61 </th> 62 <th class="cellrowborder" valign="top" width="35.55644435556444%" id="mcps1.2.5.1.4"><p id="p379171633919"><a name="p379171633919"></a><a name="p379171633919"></a>Permission Description</p> 63 </th> 64 </tr> 65 </thead> 66 <tbody><tr id="row12791216173912"><td class="cellrowborder" valign="top" width="23.46765323467653%" headers="mcps1.2.5.1.1 "><p id="p41385264116"><a name="p41385264116"></a><a name="p41385264116"></a>Acceleration sensor, uncalibrated acceleration sensor, and linear acceleration sensor</p> 67 </td> 68 <td class="cellrowborder" valign="top" width="27.61723827617238%" headers="mcps1.2.5.1.2 "><p id="p177941653914"><a name="p177941653914"></a><a name="p177941653914"></a>ohos.permission.ACCELEROMETER</p> 69 </td> 70 <td class="cellrowborder" valign="top" width="13.358664133586636%" headers="mcps1.2.5.1.3 "><p id="p207991683914"><a name="p207991683914"></a><a name="p207991683914"></a>system_grant</p> 71 </td> 72 <td class="cellrowborder" valign="top" width="35.55644435556444%" headers="mcps1.2.5.1.4 "><p id="p118061614399"><a name="p118061614399"></a><a name="p118061614399"></a>Allows an application to subscribe to data of these acceleration-related sensors.</p> 73 </td> 74 </tr> 75 <tr id="row480116123911"><td class="cellrowborder" valign="top" width="23.46765323467653%" headers="mcps1.2.5.1.1 "><p id="p1213992174111"><a name="p1213992174111"></a><a name="p1213992174111"></a>Gyroscope sensor and uncalibrated gyroscope sensor</p> 76 </td> 77 <td class="cellrowborder" valign="top" width="27.61723827617238%" headers="mcps1.2.5.1.2 "><p id="p13807165395"><a name="p13807165395"></a><a name="p13807165395"></a>ohos.permission.GYROSCOPE</p> 78 </td> 79 <td class="cellrowborder" valign="top" width="13.358664133586636%" headers="mcps1.2.5.1.3 "><p id="p188031617391"><a name="p188031617391"></a><a name="p188031617391"></a>system_grant</p> 80 </td> 81 <td class="cellrowborder" valign="top" width="35.55644435556444%" headers="mcps1.2.5.1.4 "><p id="p4804168392"><a name="p4804168392"></a><a name="p4804168392"></a>Allows an application to subscribe to data of these gyroscope-related sensors.</p> 82 </td> 83 </tr> 84 <tr id="row68051693916"><td class="cellrowborder" valign="top" width="23.46765323467653%" headers="mcps1.2.5.1.1 "><p id="p191397210413"><a name="p191397210413"></a><a name="p191397210413"></a>Pedometer sensor</p> 85 </td> 86 <td class="cellrowborder" valign="top" width="27.61723827617238%" headers="mcps1.2.5.1.2 "><p id="p9802016183911"><a name="p9802016183911"></a><a name="p9802016183911"></a>ohos.permission.ACTIVITY_MOTION</p> 87 </td> 88 <td class="cellrowborder" valign="top" width="13.358664133586636%" headers="mcps1.2.5.1.3 "><p id="p11801216143916"><a name="p11801216143916"></a><a name="p11801216143916"></a>user_grant</p> 89 </td> 90 <td class="cellrowborder" valign="top" width="35.55644435556444%" headers="mcps1.2.5.1.4 "><p id="p48010163399"><a name="p48010163399"></a><a name="p48010163399"></a>Allows an application to subscribe to the motion status.</p> 91 </td> 92 </tr> 93 <tr id="row20323104234015"><td class="cellrowborder" valign="top" width="23.46765323467653%" headers="mcps1.2.5.1.1 "><p id="p3139172144118"><a name="p3139172144118"></a><a name="p3139172144118"></a>Heart rate sensor</p> 94 </td> 95 <td class="cellrowborder" valign="top" width="27.61723827617238%" headers="mcps1.2.5.1.2 "><p id="p7323942174013"><a name="p7323942174013"></a><a name="p7323942174013"></a>ohos.permission.READ_HEALTH_DATA</p> 96 </td> 97 <td class="cellrowborder" valign="top" width="13.358664133586636%" headers="mcps1.2.5.1.3 "><p id="p1232314214407"><a name="p1232314214407"></a><a name="p1232314214407"></a>user_grant</p> 98 </td> 99 <td class="cellrowborder" valign="top" width="35.55644435556444%" headers="mcps1.2.5.1.4 "><p id="p12323144254018"><a name="p12323144254018"></a><a name="p12323144254018"></a>Allows an application to read health data.</p> 100 </td> 101 </tr> 102 </tbody> 103 </table> 104 105 106## Usage<a name="section1581412211528"></a> 107 108This section uses the sensor JS APIs as an example to describe their functionalities and usage. 109 110### Available APIs<a name="section15684191115524"></a> 111 112The sensor JS APIs listen for sensor data changes. If an API is called multiple times, the last call takes effect. The following table describes these APIs. 113 114**Table 2** Sensor JS APIs 115 116<a name="table13821942165419"></a> 117<table><thead align="left"><tr id="row6821194225417"><th class="cellrowborder" valign="top" width="40.11%" id="mcps1.2.3.1.1"><p id="p3822542145420"><a name="p3822542145420"></a><a name="p3822542145420"></a>API</p> 118</th> 119<th class="cellrowborder" valign="top" width="59.89%" id="mcps1.2.3.1.2"><p id="p0822942175411"><a name="p0822942175411"></a><a name="p0822942175411"></a>Description</p> 120</th> 121</tr> 122</thead> 123<tbody><tr id="row1782284211544"><td class="cellrowborder" valign="top" width="40.11%" headers="mcps1.2.3.1.1 "><p id="p18666622171316"><a name="p18666622171316"></a><a name="p18666622171316"></a>on(type: SensorType, callback: Callback<Response>, options?: Options)</p> 124</td> 125<td class="cellrowborder" valign="top" width="59.89%" headers="mcps1.2.3.1.2 "><p id="p1476355071517"><a name="p1476355071517"></a><a name="p1476355071517"></a>Subscribes to a type of sensor that listens for changes of sensor data. <strong id="b14384115423516"><a name="b14384115423516"></a><a name="b14384115423516"></a>SensorType</strong> indicates the type of the sensor that can be subscribed to. <strong id="b6384145413356"><a name="b6384145413356"></a><a name="b6384145413356"></a>callback</strong> specifies whether the subscription is successful. <strong id="b562874515315"><a name="b562874515315"></a><a name="b562874515315"></a>options</strong> indicates the interval for reporting sensor data.</p> 126</td> 127</tr> 128<tr id="row1489993155613"><td class="cellrowborder" valign="top" width="40.11%" headers="mcps1.2.3.1.1 "><p id="p1490010315564"><a name="p1490010315564"></a><a name="p1490010315564"></a>once(type: SensorType, callback: Callback<Response>)</p> 129</td> 130<td class="cellrowborder" valign="top" width="59.89%" headers="mcps1.2.3.1.2 "><p id="p5900163115564"><a name="p5900163115564"></a><a name="p5900163115564"></a>Subscribes to a type of sensor that listens for the sensor data change once. <strong id="b16369115653114"><a name="b16369115653114"></a><a name="b16369115653114"></a>SensorType</strong> indicates the type of the sensor that can be subscribed to. <strong id="b2370135693114"><a name="b2370135693114"></a><a name="b2370135693114"></a>callback</strong> specifies whether the subscription is successful.</p> 131</td> 132</tr> 133<tr id="row1909165317562"><td class="cellrowborder" valign="top" width="40.11%" headers="mcps1.2.3.1.1 "><p id="p16909135319564"><a name="p16909135319564"></a><a name="p16909135319564"></a>off(type: SensorType, callback: Callback<Response>)</p> 134</td> 135<td class="cellrowborder" valign="top" width="59.89%" headers="mcps1.2.3.1.2 "><p id="p3909165315613"><a name="p3909165315613"></a><a name="p3909165315613"></a>Unsubscribes from a type of sensor that listens for data changes. <strong id="b63331753103316"><a name="b63331753103316"></a><a name="b63331753103316"></a>SensorType</strong> indicates the type of the sensor that can be unsubscribed from. <strong id="b153331453173315"><a name="b153331453173315"></a><a name="b153331453173315"></a>callback</strong> specifies whether the unsubscription is successful.</p> 136</td> 137</tr> 138</tbody> 139</table> 140 141 142 143### How to Use<a name="section1543714111810"></a> 144 1451. Import the sensor package. 1462. Subscribe to and listen for data changes of an acceleration sensor. 1473. Unsubscribe from data changes of the acceleration sensor. 1484. Subscribe to and listen for a data change of an acceleration sensor. 149 150Example: 151 152``` 153// Step 1 Import the sensor package. 154import sensor from '@ohos.sensor'; 155export default { 156 onCreate() { 157 // Step 2 Subscribe to and listen for data changes of a type of sensor. 158 sensor.on(sensor.SensorType.SENSOR_TYPE_ID_ACCELEROMETER, (data) => { 159 console.info("Acceleration data obtained. x: " + data.x + "; y: " + data.y + "; z: " + data.z); 160 }, {'interval':200000000}); 161 // Step 3 Unsubscribe from data changes of the sensor 10 seconds later. 162 sensor.off(sensor.SensorType.SENSOR_TYPE_ID_LINEAR_ACCELERATION); 163 // Step 4 Subscribe to and listen for a data change of a type of sensor. 164 sensor.once(sensor.SensorType.SENSOR_TYPE_ID_ACCELEROMETER, (data) => { 165 console.info("Acceleration data obtained. x: " + data.x + "; y: " + data.y + "; z: " + data.z); 166 }); 167 } 168 onDestroy() { 169 console.info('AceApplication onDestroy'); 170 } 171} 172``` 173 174## Repositories Involved<a name="section96071132185310"></a> 175 176Pan-sensor subsystem 177 178**sensors\_sensor** 179 180[sensors\_miscdevice](https://gitee.com/openharmony/sensors_miscdevice) 181 182
