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LAUNCHXL-CC26X2R1: slow connection procedure

kazola
Guru 18595 points
Part Number: LAUNCHXL-CC26X2R1

Tool/software:

Dear all,

My BLE connection to a CC2642-based board is very slow on LINUX.

Please check the highlighted part of the following screenshot.



My laptop is the INTEL interface attempting the BLE connection.

The python code to test such BLE connection is simple and it comes next, I don't think this is the culprit.

I also attach you a wireshark capture files in 2 formats.

https://limewire.com/d/QFBjK#y6J9tH5dTP


As you can see, the delay between line 6495 and line 9558 is gigantic.

In my firmware, based on your SimpleBLEPeripheral example, SDK v7.40, the connection is done more or less OK, but then, there is such a pause where I think service discovery is taking place and it takes forever

ADV interval is 1 second. I don't think this is the culprit either, because the thing is also slow when using 300 ms ADV interval.

I was able to enable logging on the Bluetooth python library and the results are also interesting. Sorry, this is from another run of the same code.


2025-07-21 11:02:21,650 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.Properties.PropertiesChanged (/org/bluez/hci0): ['org.bluez.Adapter1', {'Discovering': <dbus_fast.signature.Variant ('b', False)>}, []]
2025-07-21 11:02:21,651 bleak.backends.bluezdbus.client MainThread DEBUG: Connecting to BlueZ path /org/bluez/hci0/dev_F0_5E_CD_25_95_E0
2025-07-21 11:02:25,612 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.Properties.PropertiesChanged (/org/bluez/hci0/dev_F0_5E_CD_25_95_E0): ['org.bluez.Device1', {'Connected': <dbus_fast.signature.Variant ('b', True)>}, []]
2025-07-21 11:02:31,038 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service000c', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattService1': {'Handle': <dbus_fast.signature.Variant ('q', 12)>, 'UUID': <dbus_fast.signature.Variant ('s', 00001801-0000-1000-8000-00805f9b34fb)>, 'Device': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0)>, 'Primary': <dbus_fast.signature.Variant ('b', True)>, 'Includes': <dbus_fast.signature.Variant ('ao', [])>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,039 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service000c/char000d', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'Handle': <dbus_fast.signature.Variant ('q', 13)>, 'UUID': <dbus_fast.signature.Variant ('s', 00002a05-0000-1000-8000-00805f9b34fb)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service000c)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>, 'Notifying': <dbus_fast.signature.Variant ('b', False)>, 'Flags': <dbus_fast.signature.Variant ('as', ['indicate'])>, 'MTU': <dbus_fast.signature.Variant ('q', 247)>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,041 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service000c/char000d/desc000f', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattDescriptor1': {'Handle': <dbus_fast.signature.Variant ('q', 39891)>, 'UUID': <dbus_fast.signature.Variant ('s', 00002902-0000-1000-8000-00805f9b34fb)>, 'Characteristic': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service000c/char000d)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,041 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0010', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattService1': {'Handle': <dbus_fast.signature.Variant ('q', 16)>, 'UUID': <dbus_fast.signature.Variant ('s', 0000180a-0000-1000-8000-00805f9b34fb)>, 'Device': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0)>, 'Primary': <dbus_fast.signature.Variant ('b', True)>, 'Includes': <dbus_fast.signature.Variant ('ao', [])>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,042 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0010/char0011', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'Handle': <dbus_fast.signature.Variant ('q', 17)>, 'UUID': <dbus_fast.signature.Variant ('s', 00002a23-0000-1000-8000-00805f9b34fb)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0010)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>, 'Flags': <dbus_fast.signature.Variant ('as', ['read'])>, 'MTU': <dbus_fast.signature.Variant ('q', 247)>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,043 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0010/char0013', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'Handle': <dbus_fast.signature.Variant ('q', 19)>, 'UUID': <dbus_fast.signature.Variant ('s', 00002a24-0000-1000-8000-00805f9b34fb)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0010)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>, 'Flags': <dbus_fast.signature.Variant ('as', ['read'])>, 'MTU': <dbus_fast.signature.Variant ('q', 247)>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,044 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0010/char0015', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'Handle': <dbus_fast.signature.Variant ('q', 21)>, 'UUID': <dbus_fast.signature.Variant ('s', 00002a25-0000-1000-8000-00805f9b34fb)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0010)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>, 'Flags': <dbus_fast.signature.Variant ('as', ['read'])>, 'MTU': <dbus_fast.signature.Variant ('q', 247)>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,045 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0010/char0017', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'Handle': <dbus_fast.signature.Variant ('q', 23)>, 'UUID': <dbus_fast.signature.Variant ('s', 00002a26-0000-1000-8000-00805f9b34fb)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0010)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>, 'Flags': <dbus_fast.signature.Variant ('as', ['read'])>, 'MTU': <dbus_fast.signature.Variant ('q', 247)>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,045 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0010/char0019', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'Handle': <dbus_fast.signature.Variant ('q', 25)>, 'UUID': <dbus_fast.signature.Variant ('s', 00002a27-0000-1000-8000-00805f9b34fb)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0010)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>, 'Flags': <dbus_fast.signature.Variant ('as', ['read'])>, 'MTU': <dbus_fast.signature.Variant ('q', 247)>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,046 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0010/char001b', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'Handle': <dbus_fast.signature.Variant ('q', 27)>, 'UUID': <dbus_fast.signature.Variant ('s', 00002a28-0000-1000-8000-00805f9b34fb)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0010)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>, 'Flags': <dbus_fast.signature.Variant ('as', ['read'])>, 'MTU': <dbus_fast.signature.Variant ('q', 247)>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,047 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0010/char001d', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'Handle': <dbus_fast.signature.Variant ('q', 29)>, 'UUID': <dbus_fast.signature.Variant ('s', 00002a29-0000-1000-8000-00805f9b34fb)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0010)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>, 'Flags': <dbus_fast.signature.Variant ('as', ['read'])>, 'MTU': <dbus_fast.signature.Variant ('q', 247)>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,047 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0010/char001f', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'Handle': <dbus_fast.signature.Variant ('q', 31)>, 'UUID': <dbus_fast.signature.Variant ('s', 00002a2a-0000-1000-8000-00805f9b34fb)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0010)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>, 'Flags': <dbus_fast.signature.Variant ('as', ['read'])>, 'MTU': <dbus_fast.signature.Variant ('q', 247)>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,048 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0010/char0021', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'Handle': <dbus_fast.signature.Variant ('q', 33)>, 'UUID': <dbus_fast.signature.Variant ('s', 00002a50-0000-1000-8000-00805f9b34fb)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0010)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>, 'Flags': <dbus_fast.signature.Variant ('as', ['read'])>, 'MTU': <dbus_fast.signature.Variant ('q', 247)>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,048 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0023', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattService1': {'Handle': <dbus_fast.signature.Variant ('q', 35)>, 'UUID': <dbus_fast.signature.Variant ('s', f0001130-0451-4000-b000-000000000000)>, 'Device': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0)>, 'Primary': <dbus_fast.signature.Variant ('b', True)>, 'Includes': <dbus_fast.signature.Variant ('ao', [])>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,049 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0023/char0024', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'Handle': <dbus_fast.signature.Variant ('q', 36)>, 'UUID': <dbus_fast.signature.Variant ('s', f0001131-0451-4000-b000-000000000000)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0023)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>, 'Flags': <dbus_fast.signature.Variant ('as', ['read', 'write'])>, 'MTU': <dbus_fast.signature.Variant ('q', 247)>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,049 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0023/char0026', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'Handle': <dbus_fast.signature.Variant ('q', 38)>, 'UUID': <dbus_fast.signature.Variant ('s', f0001132-0451-4000-b000-000000000000)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0023)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>, 'Notifying': <dbus_fast.signature.Variant ('b', False)>, 'Flags': <dbus_fast.signature.Variant ('as', ['write-without-response', 'notify'])>, 'WriteAcquired': <dbus_fast.signature.Variant ('b', False)>, 'NotifyAcquired': <dbus_fast.signature.Variant ('b', False)>, 'MTU': <dbus_fast.signature.Variant ('q', 247)>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,050 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0023/char0026/desc0028', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattDescriptor1': {'Handle': <dbus_fast.signature.Variant ('q', 39887)>, 'UUID': <dbus_fast.signature.Variant ('s', 00002902-0000-1000-8000-00805f9b34fb)>, 'Characteristic': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0023/char0026)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,050 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0029', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattService1': {'Handle': <dbus_fast.signature.Variant ('q', 41)>, 'UUID': <dbus_fast.signature.Variant ('s', f000ffc0-0451-4000-b000-000000000000)>, 'Device': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0)>, 'Primary': <dbus_fast.signature.Variant ('b', True)>, 'Includes': <dbus_fast.signature.Variant ('ao', [])>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,051 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0029/char002a', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'Handle': <dbus_fast.signature.Variant ('q', 42)>, 'UUID': <dbus_fast.signature.Variant ('s', f000ffc1-0451-4000-b000-000000000000)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0029)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>, 'Notifying': <dbus_fast.signature.Variant ('b', False)>, 'Flags': <dbus_fast.signature.Variant ('as', ['write-without-response', 'write', 'notify'])>, 'WriteAcquired': <dbus_fast.signature.Variant ('b', False)>, 'NotifyAcquired': <dbus_fast.signature.Variant ('b', False)>, 'MTU': <dbus_fast.signature.Variant ('q', 247)>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,051 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0029/char002a/desc002c', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattDescriptor1': {'Handle': <dbus_fast.signature.Variant ('q', 39893)>, 'UUID': <dbus_fast.signature.Variant ('s', 00002902-0000-1000-8000-00805f9b34fb)>, 'Characteristic': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0029/char002a)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,052 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0029/char002a/desc002d', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattDescriptor1': {'Handle': <dbus_fast.signature.Variant ('q', 39884)>, 'UUID': <dbus_fast.signature.Variant ('s', 00002901-0000-1000-8000-00805f9b34fb)>, 'Characteristic': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0029/char002a)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,052 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0029/char002e', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'Handle': <dbus_fast.signature.Variant ('q', 46)>, 'UUID': <dbus_fast.signature.Variant ('s', f000ffc2-0451-4000-b000-000000000000)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0029)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>, 'Notifying': <dbus_fast.signature.Variant ('b', False)>, 'Flags': <dbus_fast.signature.Variant ('as', ['write-without-response', 'write', 'notify'])>, 'WriteAcquired': <dbus_fast.signature.Variant ('b', False)>, 'NotifyAcquired': <dbus_fast.signature.Variant ('b', False)>, 'MTU': <dbus_fast.signature.Variant ('q', 247)>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,053 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0029/char002e/desc0030', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattDescriptor1': {'Handle': <dbus_fast.signature.Variant ('q', 39904)>, 'UUID': <dbus_fast.signature.Variant ('s', 00002902-0000-1000-8000-00805f9b34fb)>, 'Characteristic': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0029/char002e)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,053 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0029/char002e/desc0031', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattDescriptor1': {'Handle': <dbus_fast.signature.Variant ('q', 39892)>, 'UUID': <dbus_fast.signature.Variant ('s', 00002901-0000-1000-8000-00805f9b34fb)>, 'Characteristic': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0029/char002e)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,054 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0029/char0032', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'Handle': <dbus_fast.signature.Variant ('q', 50)>, 'UUID': <dbus_fast.signature.Variant ('s', f000ffc5-0451-4000-b000-000000000000)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0029)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>, 'Notifying': <dbus_fast.signature.Variant ('b', False)>, 'Flags': <dbus_fast.signature.Variant ('as', ['write-without-response', 'notify'])>, 'WriteAcquired': <dbus_fast.signature.Variant ('b', False)>, 'NotifyAcquired': <dbus_fast.signature.Variant ('b', False)>, 'MTU': <dbus_fast.signature.Variant ('q', 247)>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,054 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0029/char0032/desc0034', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattDescriptor1': {'Handle': <dbus_fast.signature.Variant ('q', 39886)>, 'UUID': <dbus_fast.signature.Variant ('s', 00002902-0000-1000-8000-00805f9b34fb)>, 'Characteristic': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0029/char0032)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,055 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0029/char0032/desc0035', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattDescriptor1': {'Handle': <dbus_fast.signature.Variant ('q', 39888)>, 'UUID': <dbus_fast.signature.Variant ('s', 00002901-0000-1000-8000-00805f9b34fb)>, 'Characteristic': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_F0_5E_CD_25_95_E0/service0029/char0032)>, 'Value': <dbus_fast.signature.Variant ('ay', b'')>}, 'org.freedesktop.DBus.Properties': {}}]
2025-07-21 11:02:31,055 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.Properties.PropertiesChanged (/org/bluez/hci0/dev_F0_5E_CD_25_95_E0): ['org.bluez.Device1', {'UUIDs': <dbus_fast.signature.Variant ('as', ['00001800-0000-1000-8000-00805f9b34fb', '00001801-0000-1000-8000-00805f9b34fb', '0000180a-0000-1000-8000-00805f9b34fb', 'f0001130-0451-4000-b000-000000000000', 'f000ffc0-0451-4000-b000-000000000000'])>, 'ServicesResolved': <dbus_fast.signature.Variant ('b', True)>}, []]

Connected: True
took 9.98526873899391 seconds

2025-07-21 11:02:31,056 bleak.backends.bluezdbus.client MainThread DEBUG: Disconnecting ({/org/bluez/hci0/dev_F0_5E_CD_25_95_E0})
2025-07-21 11:02:32,948 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.Properties.PropertiesChanged (/org/bluez/hci0/dev_F0_5E_CD_25_95_E0): ['org.bluez.Device1', {'Modalias': <dbus_fast.signature.Variant ('s', bluetooth:v000Dp0000d0110)>}, []]
2025-07-21 11:02:33,533 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.Properties.PropertiesChanged (/org/bluez/hci0/dev_F0_5E_CD_25_95_E0): ['org.bluez.Device1', {'ServicesResolved': <dbus_fast.signature.Variant ('b', False)>}, []]
2025-07-21 11:02:33,534 bleak.backends.bluezdbus.manager MainThread DEBUG: received D-Bus signal: org.freedesktop.DBus.Properties.PropertiesChanged (/org/bluez/hci0/dev_F0_5E_CD_25_95_E0): ['org.bluez.Device1', {'Connected': <dbus_fast.signature.Variant ('b', False)>}, []]
2025-07-21 11:02:33,534 bleak.backends.bluezdbus.client MainThread DEBUG: Device disconnected (/org/bluez/hci0/dev_F0_5E_CD_25_95_E0)
2025-07-21 11:02:33,535 bleak.backends.bluezdbus.client MainThread DEBUG: _cleanup_all(/org/bluez/hci0/dev_F0_5E_CD_25_95_E0)


You can clearly see it goes from 11:02:21 to 11:02:31 to set up the connection.

I used the simplelink connect app which seems to connect FASTER. This is the service table on the device. It does not seem excessive.

I have read this slow service discovery might happen if some characteristics / services are wrongly indicated but I dont think this is the case. 2 of this services are from TI. My "unknown service" is 2 chars long.

Also, this all thread seems to be suffering from exactly the same issue, although an answer was never provided.

https://e2e.ti.com/support/wireless-connectivity/bluetooth-group/bluetooth/f/bluetooth-forum/921209/cc2642r-read-write-gatt-characteristics-without-service-discovery-optimize-connection-times?tisearch=e2e-sitesearch&keymatch=cc2642%25252525252525252520service%25252525252525252520discovery%25252525252525252520slow#

We need to solve this for our next line of products.

I tried disabling bonding and extended advertising, it is slow anyway.

Thanks for your help in advance.

  • +1
    TI__Expert 5000 points

    Hi !

    It looks like your BLEAK python library is indeed performing a complete GATT lookup upon connection before entering your python callback with the prints.
    This will significantly reduce the performance, as it needs to perform service discovery, then attribute discovery, and then attribute description discovery. You can see that BLEAK is doing this because the logs receive in a very short amount of time all of the services, attributes and attribute description.

    The reason why BLEAK is doing this is because the API does not provide any function to discover those services and characteristics. Services are a field of the BleakClient class, which can be read at any time. Therefore I don't think it's possible to change this behavior.

    The only central-side solution I would see if you insist on using BLEAK is to use the services parameter of the BleakClient class. This would allow you to specify which services to look for. This may speed up the connection according to the docs.

    Another solution is to lower the connection interval and to set a higher MTU on your CC26X2R1.

    Kind regards,
    Maxence