ukBaz
commented
2 months ago OK, there is a lot to unpack here...
At the core of the issue is that BlueZ doesn't want to flood the D-Bus with every single advertisement from every device. And in most situations this the correct thing to do. So BlueZ and the Linux kernel deliberately filter repeated advertisements from the same device.
BlueZ has SetDiscoveryFilter({'DuplicateData': True}) which is meant to show every advertisement from a device during Device Discovery if it contains ManufacturerData and/or ServiceData (i.e. it is likely to be a beacon) irrespective of whether the device have been discovered previously or not.
On Bluezero this is accessed with show_duplicates
https://github.com/ukBaz/python-bluezero/blob/e1202855bf25ee145d5bd6941afddcda88998808/bluezero/adapter.py#L230-L237
However, there was/is also filtering done by the Linux kernel which meant that advertisements would still be missed. As a workaround to this I implemented clean_beacons which deletes a "beacon" after it has been discovered and processed. This tricked BlueZ and the Linux kernel in to believing it was always discovering a new beacon and no filtering took place.
This means that you should never need to call clean_beacon as on_device_found is already taking care of it. So my speculation is that the race condition is being caused by you calling clean_beacon.
If you are only seeing one advertisement from your iBeacon, have you set logging to debug to see if the device is being "cleaned" after it has been processed?
I thinking something like:
import logging
from bluezero import observer
def print_ibeacon_range(data):
print(f'iBeacon data: {data.major}-{data.minor} @ {data.rssi} [{data.tx_pwer}]')
def main():
observer.start_beacon_scan(on_ibeacon=print_ibeacon_range)
if __name__ == '__main__':
observer.logger.setLevel(logging.DEBUG)
main()Implementing a range calculation is bit like saying there should only be one programming language. Which ever one I choose, it would be the wrong one for people depending on what they were trying to do. As a result Bluezero has not implemented a range calculation.
I'm not sure where you are on this, but if you need an introduction then take a look at: http://www.davidgyoungtech.com/2020/05/15/how-far-can-you-go
furgerf
Hi, I'd like to detect ibeacons with a raspi and ideally range with them. For testing, I'm using two identical beacons, but I'm encountering some issues. Maybe you can help me understand what I'm doing wrong 🙂
Maybe first off - ranging doesn't seem to be implemented here, is there some limitation or is it just a matter of time/priority?
Regardless, I thought I'd start with just reading out some rssi values, to at least get a broad feeling for beacon proximity: using
Scanner.start_beacon_scan(on_ibeacon=...)normally works, but I only get an initial callback invocation, presumably because it's only called on new devices. By the looks of it, that's whatScanner.clean_beaconsis intended for, so I'm calling that every 10s, expecting to get a new rssi every 10s. (The beacons are configured to advertise every 1s.)Now, my main issue is that I'm not consistently seeing the beacons. It seems they start disappearing (not re-appearing after cleaning) after running for a while. I verified that the same device still receives advertisements from the beacons (visible in
bluetoothctl devices) and I also see them on my smartphone with nRF connect. I'm not quite sure when/why the beacons disappear, but I'm seeing two errors in the logs.The first seems to be a race condition in the observer (an advertisement is received while determining devices to remove) - if you want I can submit a patch with some locking:
I "feel like" I've been getting that one more frequently a few days ago (but not so much anymore), so I had also experimented with
Scanner.stop_scanandadapter.quit.The other error still pops up frequently, though not regularly - sometimes it appears several times a few seconds apart, sometimes not for a while. Not sure if it's related to beacons not showing up, since it doesn't necessarily seem to correlate.
Thanks in advance!