> ## 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.notifyBLECharacteristicValueChange

> Enable notifications for a BLE device characteristic.

Use this API to enable notifications for changes to a BLE device characteristic. The target characteristic must support `notify` or `indicate`. This must be called before `my.onBLECharacteristicValueChange` will receive updates pushed by the device, and is more efficient than repeatedly calling `my.readBLECharacteristicValue`.

## Parameters

| Property         | Type     | Required | Description                                                                                             |
| ---------------- | -------- | -------- | ------------------------------------------------------------------------------------------------------- |
| deviceId         | String   | Yes      | Device identifier                                                                                       |
| serviceId        | String   | Yes      | Service UUID                                                                                            |
| characteristicId | String   | Yes      | Characteristic UUID                                                                                     |
| descriptorId     | String   | No       | Descriptor UUID for notification (Android-specific; defaults to `00002902-0000-1000-8000-00805F9b34fb`) |
| state            | Boolean  | No       | Enables or disables `notify`/`indicate`                                                                 |
| success          | Function | No       | Callback on success                                                                                     |
| fail             | Function | No       | Callback on failure                                                                                     |
| complete         | Function | No       | Callback that always executes                                                                           |

## Code Example

```javascript theme={null}
my.notifyBLECharacteristicValueChange({
  deviceId: 'XX:XX:XX:XX:XX:XX',
  serviceId: '0000FFF0-0000-1000-8000-00805F9B34FB',
  characteristicId: '0000FFF1-0000-1000-8000-00805F9B34FB',
  state: true,
  success: (res) => {
    console.log('Notifications enabled:', res);
  }
});
```

<Info>
  Subscribing to notifications is recommended over polling with `my.readBLECharacteristicValue`. IDE simulation is not supported for this API — test on a real device.
</Info>

## Related APIs

<CardGroup cols={2}>
  <Card title="my.onBLECharacteristicValueChange" icon="bell" href="/jsapi/device/bluetooth/my.onBLECharacteristicValueChange">
    Listen for value changes
  </Card>

  <Card title="my.writeBLECharacteristicValue" icon="arrow-up" href="/jsapi/device/bluetooth/my.writeBLECharacteristicValue">
    Write a characteristic value
  </Card>
</CardGroup>