> ## Documentation Index
> Fetch the complete documentation index at: https://docs.rebellapp.com/llms.txt
> Use this file to discover all available pages before exploring further.

# my.startAccelerometer

> Start listening for accelerometer data.

Use this API to start the accelerometer sensor. After calling this, you can use `my.onAccelerometerChange` to receive accelerometer data.

## Parameters

| Property | Type     | Required | Description                                                                              |
| -------- | -------- | -------- | ---------------------------------------------------------------------------------------- |
| interval | String   | No       | Data reporting interval: `game` (20ms), `ui` (60ms), `normal` (200ms). Default: `normal` |
| success  | Function | No       | Callback on success                                                                      |
| fail     | Function | No       | Callback on failure                                                                      |
| complete | Function | No       | Callback that always executes                                                            |

## Code Example

### Basic Usage

```javascript theme={null}
my.startAccelerometer({
  success() {
    console.log('Accelerometer started');
  }
});
```

### High Frequency for Games

```javascript theme={null}
my.startAccelerometer({
  interval: 'game', // 20ms updates
  success() {
    my.onAccelerometerChange((res) => {
      this.updatePlayerPosition(res.x, res.y);
    });
  }
});
```

### Motion Tracking App

```javascript theme={null}
Page({
  data: {
    isTracking: false
  },

  startTracking() {
    my.startAccelerometer({
      interval: 'ui',
      success: () => {
        this.setData({ isTracking: true });
        my.onAccelerometerChange(this.recordMotion);
      },
      fail(err) {
        my.showToast({
          content: 'Failed to start accelerometer',
          type: 'fail'
        });
      }
    });
  },

  stopTracking() {
    my.offAccelerometerChange(this.recordMotion);
    this.setData({ isTracking: false });
  },

  recordMotion(res) {
    // Store motion data
    this.motionData.push({
      x: res.x,
      y: res.y,
      z: res.z,
      timestamp: Date.now()
    });
  }
});
```

## Interval Options

| Value    | Update Frequency      | Use Case                           |
| -------- | --------------------- | ---------------------------------- |
| `game`   | \~50 times/sec (20ms) | Games requiring real-time response |
| `ui`     | \~16 times/sec (60ms) | UI animations and interactions     |
| `normal` | \~5 times/sec (200ms) | General motion detection           |

<Warning>
  Higher frequency intervals consume more battery. Use `normal` or `ui` unless you specifically need `game` frequency for real-time applications.
</Warning>

## Related APIs

<CardGroup cols={2}>
  <Card title="my.onAccelerometerChange" icon="gauge" href="/jsapi/device/accelerometer/my.onAccelerometerChange">
    Listen for accelerometer data
  </Card>

  <Card title="my.offAccelerometerChange" icon="xmark" href="/jsapi/device/accelerometer/my.offAccelerometerChange">
    Stop listening
  </Card>
</CardGroup>