I have some BLE beacon modules (Radioland Beacon) using the Nordic nrf51822 and I want to make an indoor positioning system with them.

There is a problem with my beacons that they are not always discoverable (when scanning with an Android app) and I can't get the beacon RSSI which is needed in my app.

I have searched the web for this problem and I found that every beacon has a 5-bit flag indicating the behavior of the beacon (you can check these flags with scan section of Beacon Simulator Android app).

I think the problem is the that "LE Limited Discoverable" mode is set instead of "LE General Discoverable", so the beacon went out from scanning app after some minutes. So my questions are as follows:

  1. Is the problem caused by "LE Limited Discoverable" flag?
  2. If yes, How can I change it?
  • \$\begingroup\$ I use the LE Limited Discoverable flag and have no problems with RSSI. Have you tested a different phone brand? \$\endgroup\$ – Turbo J Aug 1 '17 at 10:20
  • \$\begingroup\$ Those flags are purely indicative. It is even not mandatory to broadcast them (they consume some bytes in the very limited 31 byte space allowed to broadcast some messages). So unless your scanning program react to those flags, there should be no incidence at all. \$\endgroup\$ – Vincent Hiribarren Aug 1 '17 at 11:17

so the beacon went out from scanning app after some minute

Nope. This only happens if the beacon stops advertising altogether - which they tend to do in order to save power.

This is also why you usually want to program those NRF5x chips yourself - so you can customize timouts and other important stuff.


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