Namespace: eddystone

Methods

Abstract types

EddystoneDevice

failCallback(errorString)

scanCallback(beacon)

Methods

public static

calculateAccuracy(txPower, rssi)

Calculate the accuracy (distance in meters) of the beacon.

The beacon distance calculation uses txPower at 1 meters, but the Eddystone protocol reports the value at 0 meters. 41dBm is the signal loss that occurs over 1 meter, this value is subtracted by default from the reported txPower. You can tune the calculation by adding or subtracting to param txPower.

Note that the returned distance value is not accurate, and that it fluctuates over time. Sampling/filtering over time is recommended to obtain a stable value.

Example

// Note that beacon.txPower and beacon.rssi many be undefined,
  // in which case calculateAccuracy returns null. This happens
  // before txPower and rssi have been reported by the beacon.
  var distance = evothings.eddystone.calculateAccuracy(
      beacon.txPower, beacon.rssi);

Parameters

Name	Type	Optional	Description
txPower			The txPower of the beacon.
rssi			The RSSI of the beacon, subtract or add to this value to tune the dBm strength. 41dBm is subtracted from this value in the distance algorithm used by calculateAccuracy.

Returns: Distance in meters, or null if unable to compute distance (occurs for example when txPower or rssi is undefined).

static

createLowPassFilter(cutOff)

Create a low-pass filter.

Example

// Create filter with cut off 0.8
  var lowpass = evothings.eddystone.createLowPassFilter(0.8)
  // Filter value (returns current filter value)
  distance = lowpass.filter(distance)
  // Get current value
  distance = lowpass.value()

Parameter

Name	Type	Optional	Description
cutOff			The filter cut off value.

Returns: Object with two functions: filter(value), value()

public static

startAdvertise(namespace, instance, advertiseCallback, failCallback)

Start Advertising Eddystone Beacon.

Namespace may only be 10 hex bytes

Instance may only be 6 hex bytes

Will keep advertising indefinitely until you call stopAdvertise().

Example

evothings.eddystone.startAdvertise("0123456789ABCDEF0123", "0123456789AB");

Parameters

Name	Type	Description
namespace	string	Hex namespace string (10 bytes, 20 chars)
instance	string	Hex instance string (6 bytes, 12 chars)
advertiseCallback	evothings.eddystone.advertiseCallback	Success function called when advertising started
failCallback	evothings.eddystone.failCallback	Error callback: fail(error).

public static

startScan(scanCallback, failCallback)

Starts scanning for Eddystone devices.

Found devices and errors will be reported to the supplied callbacks.

Will keep scanning indefinitely until you call stopScan().

To conserve energy, call stopScan() as soon as you've found the device you're looking for.

Calling startScan() while scanning is in progress will produce an error.

Example

evothings.eddystone.startScan(
    function(beacon)
    {
      console.log('Found beacon: ' + beacon.url);
    },
    function(error)
    {
      console.log('Scan error: ' + error);
    });

Parameters

Name	Type	Optional	Description
scanCallback	evothings.eddystone.scanCallback		Success function called when a beacon is found.
failCallback	evothings.eddystone.failCallback		Error callback: fail(error).

public static

stopAdvertise(onSuccess, failCallback)

Stop Advertising Eddystone Beacon.

Example

evothings.eddystone.stopAdvertise();

Parameters

Name	Type	Optional	Description
onSuccess	function()		Success function called when advertising stoppped
failCallback	evothings.eddystone.failCallback		Error callback: fail(error).

public static

stopScan()

Stop scanning for Eddystone devices.

Example

evothings.eddystone.stopScan();

Abstract types

static

EddystoneDevice Object

Object representing a BLE device. Inherits from evothings.easyble.EasyBLEDevice. Which properties are available depends on which packets types broadcasted by the beacon. Properties may be undefined. Typically properties are populated as scanning processes.

Properties

Name	Type	Description
url	string	An Internet URL.
txPower	number	A signed integer, the signal strength in decibels, factory-measured at a range of 0 meters.
nid	Uint8Array	10-byte namespace ID.
bid	Uint8Array	6-byte beacon ID.
voltage	number	Device's battery voltage, in millivolts, or 0 (zero) if device is not battery-powered.
temperature	number	Device's ambient temperature in 256:ths of degrees Celcius, or 0x8000 if device has no thermometer.
adv_cnt	number	Count of advertisement frames sent since device's startup.
dsec_cnt	number	Time since device's startup, in deci-seconds (10 units equals 1 second).

static

failCallback(errorString)

This function is called when an operation fails.

Parameter

Name	Type	Optional	Description
errorString	string		A human-readable string that describes the error that occurred.

static

scanCallback(beacon)

This function is a parameter to startScan() and is called when a beacons is discovered/updated.

Parameter

Name	Type	Optional	Description
beacon	evothings.eddystone.EddystoneDevice		Beacon found during scanning.