Lopy Bluetooth connection is lost after few seconds

  • Hi guys, I'm here to report a strange behavior I'am getting with Lopy.

    I'm trying to establish a connection between Lopy (server/peripheral role) and a Raspberry Pi 3 B (client/central role).

    From the RPi3 side I'm trying to connect to the Lopy using a Python script I wrote using Bluepy. Unfortunately, after I establish a connection, it lasts for a few seconds. This is very random: sometimes the connection lasts for half a second, sometimes it lasts for a minute (in this case I am able to see the services in the Lopy). I get the same issue if, instead of using my python script, I use the well known gatttool: even here same behavior (connections drops after few seconds).

    Both my python script and gatttool work fine if I connect my RPi3 to a BLENano2.

    Strangely, if I use the android app nRF Connect and try to connect with Lopy everything works fine! In this case the connection lasts untill I manually disconnect and I'm free to see the GATT server.

    Here is the code in the Lopy, as you can see I didn't create a GATT server (there are only the default services Generic Attribute and Generic Access and it works with nRF Connect) in order to keep the code smooth, I assure you that I get the same issue with services and characteristics:

    from network import Bluetooth
    import pycom
    import os
    print (os.uname())
    myBle = Bluetooth()
    def connection_cb (bt_o):
        events = bt_o.events()
        if  events & Bluetooth.CLIENT_CONNECTED:
            pycom.rgbled(0x000555) #If connected the RGB led has this color. I can see the disconnection if the color changes.
            print("Client connected")
        elif events & Bluetooth.CLIENT_DISCONNECTED:
            print("Client disconnected")
    myBle.callback(trigger=Bluetooth.CLIENT_CONNECTED | Bluetooth.CLIENT_DISCONNECTED, handler=connection_cb)

    Output of os.uname() is:
    (sysname='LoPy', nodename='LoPy', release='1.18.1', version='v1.8.6-849-f517b1d on 2018-08-28', machine='LoPy with ESP32', lorawan='1.0.2')

    I've seen other topics similar to this (link text) where people suggest to downgrade the firmware, however I'am not able to find the old firmware in this page link text.

    Let me know if you need to know more. Thank you guys for your help!

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