[Interest] QLowEnergyController always disconnected after service discovery finished

[Jérôme Godbout]

Hi,

You should find and resolve the first error, any error could lead to disconnection:
qt.bluetooth.bluez: Error1: "no attribute in given range found" last command: 10 handle: 1
m_controller discoveryFinished

Also make sure you finish the discovery before you start doing any other services/characteristics discovery with BlueZ.

Side note: In the case of the Bluez (especially the Android one), give it some delay between your request and avoid sending multiple request at the same time. After you connect put a sleep delay of a few hundred ms and always request a single services and characteristic at a time.

The stack is so buggy it’s the only way to make it work properly and reliably. Don’t base your “it work” with BlueZ on a single test run, the results change a lot with the device load and BLE usage by other application. iOS and OS X on the other hand seem t work just fine, they do not need the artificial delay, so it’s a delay festival with ifdef.

Jerome

From: Interest <interest-bounces+godboutj=amotus.ca at qt-project.org> On Behalf Of nus1998
Sent: October 30, 2018 4:42 AM
To: interest at qt-project.org
Subject: [Interest] QLowEnergyController always disconnected after service discovery finished

Hi,
When I use QLowEnergyController to scan the service, it's always disconnected about 15 seconds after services discovery is finished. the error is not certain, sometimes it's "Connection reset by peer", sometimes it's "Connection timeout".

The log is attached, can anyone have a look at it and give me some advice? thanks in advance.

qt.bluetooth.bluez: Bluez 5 detected.
qt.bluetooth.bluez: Creating QtBluezDiscoveryManager
m_discoveryAgent is active
qt.bluetooth.bluez: BluetoothManagement: Ignored event: 13
qt.bluetooth.bluez: Discovered:  "00:07:80:2E:9B:85" "BLE Module" Num UUIDs 0 total device 0 cached RSSI -94 Class 0
"00:07:80:2E:9B:85" "00:07:80:2E:9B:85" "BLE Module" QFlags(0x1)
qt.bluetooth.bluez: void QBluetoothDeviceDiscoveryAgentPrivate::stop()
found lead MkIII
qt.bluetooth.bluez: Enabling GATT request timeout behavior 20000
qt.bluetooth.bluez: addresstypeToUse: "Public"
qt.bluetooth.bluez: No settings found for peer device.
qt.bluetooth.bluez: BluetoothManagement: Ignored event: 13
qt.bluetooth.bluez: HCI event triggered, type: f
qt.bluetooth.bluez: HCI event triggered, type: 3e
qt.bluetooth.bluez: received connection complete event, handle: 1025
qt.bluetooth.bluez: BluetoothManagement: Ignored event: b
qt.bluetooth.bluez: Current l2cp sec level: 1
qt.bluetooth.bluez: Exchanging MTU
m_controller connected
qt.bluetooth.bluez: Sending read_by_group_type request, startHandle: 1 endHandle: ffff 2800
qt.bluetooth.bluez: Received size: 3 data: "031700"
qt.bluetooth.bluez: Server MTU: 23 resulting mtu: 23
qt.bluetooth.bluez: HCI event triggered, type: 13
qt.bluetooth.bluez: Received size: 8 data: "1106010005000018"
qt.bluetooth.bluez: Found uuid: "{00001800-0000-1000-8000-00805f9b34fb}" start handle: 1 end handle: 5
service discovered
qt.bluetooth.bluez: Sending read_by_group_type request, startHandle: 6 endHandle: ffff 2800
qt.bluetooth.bluez: HCI event triggered, type: 13
qt.bluetooth.bluez: HCI event triggered, type: 13
qt.bluetooth.bluez: Received size: 22 data: "111406001200e34bc643730f1e930e7fe83ae1b11fab"
qt.bluetooth.bluez: Found uuid: "{ab1fb1e1-3ae8-7f0e-931e-0f7343c64be3}" start handle: 6 end handle: 12
service discovered
qt.bluetooth.bluez: Sending read_by_group_type request, startHandle: 13 endHandle: ffff 2800
qt.bluetooth.bluez: Received size: 14 data: "1106130017000a1818001a000518"
qt.bluetooth.bluez: Found uuid: "{0000180a-0000-1000-8000-00805f9b34fb}" start handle: 13 end handle: 17
service discovered
qt.bluetooth.bluez: Found uuid: "{00001805-0000-1000-8000-00805f9b34fb}" start handle: 18 end handle: 1a
service discovered
qt.bluetooth.bluez: Sending read_by_group_type request, startHandle: 1b endHandle: ffff 2800
qt.bluetooth.bluez: HCI event triggered, type: 13
qt.bluetooth.bluez: Received size: 22 data: "11141b002d00e8b84b71b98489ab01fb06bec3bad7af"
qt.bluetooth.bluez: Found uuid: "{afd7bac3-be06-fb01-ab89-84b9714bb8e8}" start handle: 1b end handle: 2d
service discovered
qt.bluetooth.bluez: Sending read_by_group_type request, startHandle: 2e endHandle: ffff 2800
qt.bluetooth.bluez: HCI event triggered, type: 13
qt.bluetooth.bluez: HCI event triggered, type: 13
qt.bluetooth.bluez: Received size: 22 data: "11142e0044000adea862315e215dbab961a5b3dc493c"
qt.bluetooth.bluez: Found uuid: "{3c49dcb3-a561-b9ba-5d21-5e3162a8de0a}" start handle: 2e end handle: 44
service discovered
qt.bluetooth.bluez: Sending read_by_group_type request, startHandle: 45 endHandle: ffff 2800
qt.bluetooth.bluez: Received size: 22 data: "11144500fffffac79ce402ae50e53c3c6b32ffba88f7"
qt.bluetooth.bluez: Found uuid: "{f788baff-326b-3c3c-e550-ae02e49cc7fa}" start handle: 45 end handle: ffff
service discovered
qt.bluetooth.bluez: Sending read_by_group_type request, startHandle: 1 endHandle: ffff 2801
qt.bluetooth.bluez: HCI event triggered, type: 13
qt.bluetooth.bluez: Received size: 5 data: "011001000a"
qt.bluetooth.bluez: Error1: "no attribute in given range found" last command: 10 handle: 1
m_controller discoveryFinished
qt.bluetooth.bluez: HCI event triggered, type: 13
qt.bluetooth.bluez: HCI event triggered, type: 5
qt.bluetooth.bluez: void QBluetoothSocketPrivate::_q_readNotify() 19 error: -1 "Connection reset by peer"
m_controller disconnected
qt.bluetooth.bluez: BluetoothManagement: Ignored event: c

B.R.
Jie



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