For any Linux BlueZ/BT experts here:
I'm looking for a way to "ping" known BT devices (known BDADDR) and if they are in range I'd like to know the approximate signal strength.
I know that I could first run l2ping, then establish a connection to the device and finally check the rssi or link quality if the connection worked without pairing first.
However what I'm looking for is a way of getting the signal strength without connecting to the device first. Perfect would be a signal strength measurement from the l2ping reply packet, but I don't know if that info is available at all and passed along the stack.
You can obtain RSSI during inquiry scan, without connecting to devices. Here's an example using pybluez. You could also do the same thing directly from C using Bluez on linux.