# node-eddystone-beacon-scanner

Scan for [Eddystone beacons](https://github.com/google/eddystone) using Node.js

Uses [noble](https://github.com/sandeepmistry/noble) for BLE peripheral scanning, then attempts to parse discovered peripherals using the [Eddystone Protocol Specification](https://github.com/google/eddystone/blob/master/protocol-specification.md).

## Setup

```sh
npm install eddystone-beacon-scanner
```

## Examples

See [examples](examples) folder.


## Usage

```javascript
var EddystoneBeaconScanner = require('eddystone-beacon-scanner');
```

### Register event handlers

#### Found

Triggered when a beacon is first found.


```javascript
EddystoneBeaconScanner.on('found', function(beacon) {
  // ...
});
```

#### Updated

Triggered when a beacon advertisement detected.

```javascript
EddystoneBeaconScanner.on('updated', function(beacon) {
  // ...
});
```

#### Lost

Triggered when a beacon has not been detected for 5 seconds.

```javascript
EddystoneBeaconScanner.on('lost', function(beacon) {
  // ...
});
```

The ```beacon``` object will have the following properties depending on the frame type:
##### URL

 * ```type``` - Eddystone type
 * ```txPower``` - Measured received power at 0 m in dBm
 * ```url``` - (expanded) URL the beacon is broadcasting
 * ```tlm``` - TLM data, only present when interleaved broadcasts are used by the beacon
 * ```rssi``` - RSSI of discovered beacon
 * ```distance``` - Approximate distance from beacon

##### UID
 * ```type``` - Eddystone type
 * ```txPower``` - Measured received power at 0 m in dBm
 * ```namespace``` - 10-byte ID Namespace
 * ```instance``` - 6-byte ID Instance
 * ```tlm``` - TLM data, only present when interleaved broadcasts are used by the beacon
 * ```rssi``` - RSSI of discovered beacon
 * ```distance``` - Approximate distance from beacon

##### TLM
 * ```tlm```
   * ```version``` - TLM version
   * ```vbatt``` - Battery voltage
   * ```temp``` - Temperature
   * ```advCnt``` - Advertising PDU count
   * ```secCnt``` - Time since power-on or reboot
 * ```rssi``` - RSSI of discovered beacon
 * ```distance``` - Approximate distance from beacon

### Start scanning

Start scanning for Eddystone beacons, you can specify whether to allow duplicates (default is false).

You can also specify the grace period (time to wait before declaring the beacon as lost). Default is 5000 ms.

```javascript
EddystoneBeaconScanner.startScanning(allowDuplicates, gracePeriod);
```

__Note:__ the ```lost``` event will only be triggered when ```allowDuplicates``` is set to true.

### Stop scanning

Stop scanning for Eddystone beacons.

```javascript
EddystoneBeaconScanner.stopScanning();
```