discovering own GATT services(UUID128) fails #1204

StefJar · 2023-01-18T15:12:58Z

StefJar
Jan 18, 2023

bleak version: 19.5.0
Python version: 3.10
Operating System: Ubuntu 22.10
BlueZ version (bluetoothctl -v) in case of Linux: 5.65

Description

I like to connect to a peripheral that offers a special GATT service.

import asyncio
import bleak

_MY_SERVICE = "49535343-fe7d-4ae5-8fa9-9fafd205e000"

bleak.uuids.register_uuids({_MY_SERVICE: "my_io",})

def connect(addr) -> bool:
    c = bleak.BleakClient(addr)
    r = asyncio.run(c.connect())
    sL = c.services
    for s in sL:
        print(s)

Output

...
2023-01-18 15:06:46.559 DEBUG client - connect: Connecting to BlueZ path /org/bluez/hci0/dev_EA_55_E3_4F_55_55
...
2023-01-18 15:06:48.327 DEBUG manager - _parse_msg: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031/char0040', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': <dbus_fast.signature.Variant ('s', 00002a2a-0000-1000-8000-00805f9b34fb)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031)>, 'Value': <dbus_fast.signature.Variant ('ay', bytearray(b''))>, 'Flags': <dbus_fast.signature.Variant ('as', ['read'])>, 'MTU': <dbus_fast.signature.Variant ('q', 96)>}, 'org.freedesktop.DBus.Properties': {}}]
2023-01-18 15:06:48.327 DEBUG manager - _parse_msg: received D-Bus signal: org.freedesktop.DBus.Properties.PropertiesChanged (/org/bluez/hci0/dev_EA_55_E3_4F_55_55): ['org.bluez.Device1', {'UUIDs': <dbus_fast.signature.Variant ('as', ['00001800-0000-1000-8000-00805f9b34fb', '00001801-0000-1000-8000-00805f9b34fb', '0000180a-0000-1000-8000-00805f9b34fb', '49535343-fe7d-4ae5-8fa9-9fafd205e000'])>, 'ServicesResolved': <dbus_fast.signature.Variant ('b', True)>}, []]
00001801-0000-1000-8000-00805f9b34fb (Handle: 33): Generic Attribute Profile
0000180a-0000-1000-8000-00805f9b34fb (Handle: 49): Device Information

What I Did

I have a device with an own primary GATT service. I can connect and use it via NRFconnect perfectly.
Before I used the bluepy. Now I like to try bleak. So I try to rebuild a simple connection write/notify example.

Is this a bug or did I understood the bleak concept wrongly?

dlech · 2023-01-18T16:38:44Z

dlech
Jan 18, 2023
Collaborator

BlueZ caches the services, so if you don't provide a Services Changed or GATT Database attribute, it won't always pick up new services. See https://bleak.readthedocs.io/en/latest/troubleshooting.html#id4 for how to clear the cache.

11 replies

StefJar Jan 19, 2023
Author

after checking today again, my code fails. So prob because of the caching(/var/... dir is only in RAM and gets deleted when restarting).

I am seeing in my logs that the "D-Bus signal: org.freedesktop.DBus.Properties.PropertiesChanged" message is handled. Turning on my debugger reveals that the BleakClient backend gets the service (

)
but it does not update the service/characteristic list

Feels for me that
2023-01-19 11:03:05.525 DEBUG manager - _parse_msg: received D-Bus signal: org.freedesktop.DBus.Properties.PropertiesChanged (/org/bluez/hci0/dev_EA_55_E3_4F_55_55): ['org.bluez.Device1', {'UUIDs': <dbus_fast.signature.Variant ('as', ['00001800-0000-1000-8000-00805f9b34fb', '00001801-0000-1000-8000-00805f9b34fb', '0000180a-0000-1000-8000-00805f9b34fb', '49535343-fe7d-4ae5-8fa9-9fafd205e000'])>, 'ServicesResolved': <dbus_fast.signature.Variant ('b', True)>}, []]
does not triggers a service update

StefJar Jan 19, 2023
Author

also checked on the system level
seems like bluetoothctl does not recover uuid128 services
https://stackoverflow.com/questions/75172756/how-to-enable-a-uuid128-service-and-its-characteristcs-at-bluez-bluetoothctl
guess since my service is not "explored" by the bluetooth service the dbus objects are not created. Therefore we don't see the service in python.

Any ideas how to solve that?

fyi
with bluepy I can recover/explore own uuid128 services/characteristics. So there must be a way

dlech Jan 19, 2023
Collaborator

Can you share the full log output? And also inspect the _properties attribute of the global manager (in manager.py) when you are debugging.

StefJar Jan 19, 2023
Author

here comes the log

023-01-19 23:23:27.783 DEBUG selector_events - __init__: Using selector: EpollSelector
2023-01-19 23:23:27.784 DEBUG client - connect: Connecting to device @ EA:55:E3:4F:55:55
2023-01-19 23:23:27.790 DEBUG manager - async_init: initial properties: {'/org/bluez': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.AgentManager1': {}, 'org.bluez.ProfileManager1': {}}, '/org/bluez/hci0': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.Adapter1': {'Address': '3C:E9:F7:B5:EA:45', 'AddressType': 'public', 'Name': 'stefan-XPS-9320', 'Alias': 'stefan-XPS-9320', 'Class': 7078156, 'Powered': True, 'Discoverable': False, 'DiscoverableTimeout': 180, 'Pairable': False, 'PairableTimeout': 0, 'Discovering': False, 'UUIDs': ['0000110e-0000-1000-8000-00805f9b34fb', '0000111f-0000-1000-8000-00805f9b34fb', '00001200-0000-1000-8000-00805f9b34fb', '0000110b-0000-1000-8000-00805f9b34fb', '00001108-0000-1000-8000-00805f9b34fb', '0000110c-0000-1000-8000-00805f9b34fb', '00001800-0000-1000-8000-00805f9b34fb', '0000110a-0000-1000-8000-00805f9b34fb', '00001801-0000-1000-8000-00805f9b34fb', '0000180a-0000-1000-8000-00805f9b34fb'], 'Modalias': 'usb:v1D6Bp0246d0541', 'Roles': ['central', 'peripheral']}, 'org.freedesktop.DBus.Properties': {}, 'org.bluez.BatteryProviderManager1': {}, 'org.bluez.GattManager1': {}, 'org.bluez.AdvertisementMonitorManager1': {'SupportedMonitorTypes': ['or_patterns'], 'SupportedFeatures': ['controller-patterns']}, 'org.bluez.Media1': {}, 'org.bluez.NetworkServer1': {}, 'org.bluez.LEAdvertisingManager1': {'ActiveInstances': 0, 'SupportedInstances': 12, 'SupportedIncludes': ['tx-power', 'appearance', 'local-name'], 'SupportedSecondaryChannels': ['1M', '2M', 'Coded'], 'SupportedFeatures': ['CanSetTxPower', 'HardwareOffload'], 'SupportedCapabilities': {'MinTxPower': -34, 'MaxTxPower': 7, 'MaxAdvLen': 31, 'MaxScnRspLen': 31}}}, '/org/bluez/hci0/dev_D0_03_4B_10_9D_EB': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.Device1': {'Address': 'D0:03:4B:10:9D:EB', 'AddressType': 'public', 'Alias': 'D0-03-4B-10-9D-EB', 'Paired': False, 'Bonded': False, 'Trusted': False, 'Blocked': False, 'LegacyPairing': False, 'Connected': False, 'UUIDs': [], 'Adapter': '/org/bluez/hci0', 'ManufacturerData': {76: bytearray(b'\x10\x05\x01\x10\xc7\r\xfe')}, 'ServicesResolved': False, 'AdvertisingFlags': bytearray(b'\x1a')}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_59_24_32_24_1F_FA': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.Device1': {'Address': '59:24:32:24:1F:FA', 'AddressType': 'random', 'Alias': '59-24-32-24-1F-FA', 'Paired': False, 'Bonded': False, 'Trusted': False, 'Blocked': False, 'LegacyPairing': False, 'Connected': False, 'UUIDs': [], 'Adapter': '/org/bluez/hci0', 'ManufacturerData': {76: bytearray(b'\x10\x07\x04\x1f\xccc\x84-(')}, 'ServicesResolved': False, 'AdvertisingFlags': bytearray(b'\x1a')}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_33_F4_D6_CC_9A_CC': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.Device1': {'Address': '33:F4:D6:CC:9A:CC', 'AddressType': 'random', 'Alias': '33-F4-D6-CC-9A-CC', 'Paired': False, 'Bonded': False, 'Trusted': False, 'Blocked': False, 'LegacyPairing': False, 'Connected': False, 'UUIDs': [], 'Adapter': '/org/bluez/hci0', 'ManufacturerData': {76: bytearray(b'\t\x06\x03\x07\xc0\xa8\x01A')}, 'ServicesResolved': False, 'AdvertisingFlags': bytearray(b'\x1a')}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_EA_55_E3_4F_55_55': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.Device1': {'Address': 'EA:55:E3:4F:55:55', 'AddressType': 'random', 'Name': 'LE_MW2-0006', 'Alias': 'LE_MW2-0006', 'Paired': False, 'Bonded': False, 'Trusted': False, 'Blocked': False, 'LegacyPairing': False, 'Connected': False, 'UUIDs': [], 'Adapter': '/org/bluez/hci0', 'ServicesResolved': False, 'AdvertisingFlags': bytearray(b'\x1a')}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_72_89_E7_C5_21_30': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.Device1': {'Address': '72:89:E7:C5:21:30', 'AddressType': 'random', 'Alias': '72-89-E7-C5-21-30', 'Paired': False, 'Bonded': False, 'Trusted': False, 'Blocked': False, 'LegacyPairing': False, 'Connected': False, 'UUIDs': [], 'Adapter': '/org/bluez/hci0', 'ManufacturerData': {76: bytearray(b'\x10\x06)\x1e\xfd1m\xed')}, 'ServicesResolved': False, 'AdvertisingFlags': bytearray(b'\x1a')}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_00_A0_50_2E_62_99': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.Device1': {'Address': '00:A0:50:2E:62:99', 'AddressType': 'public', 'Name': 'HwZ_fb063d4917002b0a19', 'Alias': 'HwZ_fb063d4917002b0a19', 'Paired': False, 'Bonded': False, 'Trusted': False, 'Blocked': False, 'LegacyPairing': False, 'Connected': False, 'UUIDs': [], 'Adapter': '/org/bluez/hci0', 'ServicesResolved': False, 'AdvertisingFlags': bytearray(b'\x06')}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_5F_D0_FB_5A_FF_B7': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.Device1': {'Address': '5F:D0:FB:5A:FF:B7', 'AddressType': 'random', 'Alias': '5F-D0-FB-5A-FF-B7', 'Paired': False, 'Bonded': False, 'Trusted': False, 'Blocked': False, 'LegacyPairing': False, 'Connected': False, 'UUIDs': [], 'Adapter': '/org/bluez/hci0', 'ManufacturerData': {76: bytearray(b'\x10\x05\r\x18\xbe\xf4\xf7')}, 'ServicesResolved': False, 'AdvertisingFlags': bytearray(b'\x06')}, 'org.freedesktop.DBus.Properties': {}}}
2023-01-19 23:23:27.791 DEBUG client - connect: Connecting to BlueZ path /org/bluez/hci0/dev_EA_55_E3_4F_55_55
2023-01-19 23:23:28.202 DEBUG manager - _parse_msg: received D-Bus signal: org.freedesktop.DBus.Properties.PropertiesChanged (/org/bluez/hci0/dev_EA_55_E3_4F_55_55): ['org.bluez.Device1', {'Connected': <dbus_fast.signature.Variant ('b', True)>}, []]
2023-01-19 23:23:29.419 DEBUG manager - _parse_msg: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0021', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattService1': {'UUID': <dbus_fast.signature.Variant ('s', 00001801-0000-1000-8000-00805f9b34fb)>, 'Device': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_EA_55_E3_4F_55_55)>, 'Primary': <dbus_fast.signature.Variant ('b', True)>, 'Includes': <dbus_fast.signature.Variant ('ao', [])>}, 'org.freedesktop.DBus.Properties': {}}]
2023-01-19 23:23:29.420 DEBUG manager - _parse_msg: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0021/char0022', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': <dbus_fast.signature.Variant ('s', 00002a05-0000-1000-8000-00805f9b34fb)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0021)>, 'Value': <dbus_fast.signature.Variant ('ay', bytearray(b''))>, 'Notifying': <dbus_fast.signature.Variant ('b', False)>, 'Flags': <dbus_fast.signature.Variant ('as', ['read', 'write-without-response', 'indicate'])>, 'WriteAcquired': <dbus_fast.signature.Variant ('b', False)>, 'MTU': <dbus_fast.signature.Variant ('q', 96)>}, 'org.freedesktop.DBus.Properties': {}}]
2023-01-19 23:23:29.420 DEBUG manager - _parse_msg: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattService1': {'UUID': <dbus_fast.signature.Variant ('s', 0000180a-0000-1000-8000-00805f9b34fb)>, 'Device': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_EA_55_E3_4F_55_55)>, 'Primary': <dbus_fast.signature.Variant ('b', True)>, 'Includes': <dbus_fast.signature.Variant ('ao', [])>}, 'org.freedesktop.DBus.Properties': {}}]
2023-01-19 23:23:29.420 DEBUG manager - _parse_msg: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031/char0032', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': <dbus_fast.signature.Variant ('s', 00002a29-0000-1000-8000-00805f9b34fb)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031)>, 'Value': <dbus_fast.signature.Variant ('ay', bytearray(b''))>, 'Flags': <dbus_fast.signature.Variant ('as', ['read'])>, 'MTU': <dbus_fast.signature.Variant ('q', 96)>}, 'org.freedesktop.DBus.Properties': {}}]
2023-01-19 23:23:29.421 DEBUG manager - _parse_msg: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031/char0034', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': <dbus_fast.signature.Variant ('s', 00002a24-0000-1000-8000-00805f9b34fb)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031)>, 'Value': <dbus_fast.signature.Variant ('ay', bytearray(b''))>, 'Flags': <dbus_fast.signature.Variant ('as', ['read'])>, 'MTU': <dbus_fast.signature.Variant ('q', 96)>}, 'org.freedesktop.DBus.Properties': {}}]
2023-01-19 23:23:29.421 DEBUG manager - _parse_msg: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031/char0036', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': <dbus_fast.signature.Variant ('s', 00002a25-0000-1000-8000-00805f9b34fb)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031)>, 'Value': <dbus_fast.signature.Variant ('ay', bytearray(b''))>, 'Flags': <dbus_fast.signature.Variant ('as', ['read'])>, 'MTU': <dbus_fast.signature.Variant ('q', 96)>}, 'org.freedesktop.DBus.Properties': {}}]
2023-01-19 23:23:29.421 DEBUG manager - _parse_msg: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031/char0038', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': <dbus_fast.signature.Variant ('s', 00002a27-0000-1000-8000-00805f9b34fb)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031)>, 'Value': <dbus_fast.signature.Variant ('ay', bytearray(b''))>, 'Flags': <dbus_fast.signature.Variant ('as', ['read'])>, 'MTU': <dbus_fast.signature.Variant ('q', 96)>}, 'org.freedesktop.DBus.Properties': {}}]
2023-01-19 23:23:29.422 DEBUG manager - _parse_msg: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031/char003a', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': <dbus_fast.signature.Variant ('s', 00002a26-0000-1000-8000-00805f9b34fb)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031)>, 'Value': <dbus_fast.signature.Variant ('ay', bytearray(b''))>, 'Flags': <dbus_fast.signature.Variant ('as', ['read'])>, 'MTU': <dbus_fast.signature.Variant ('q', 96)>}, 'org.freedesktop.DBus.Properties': {}}]
2023-01-19 23:23:29.422 DEBUG manager - _parse_msg: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031/char003c', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': <dbus_fast.signature.Variant ('s', 00002a28-0000-1000-8000-00805f9b34fb)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031)>, 'Value': <dbus_fast.signature.Variant ('ay', bytearray(b''))>, 'Flags': <dbus_fast.signature.Variant ('as', ['read'])>, 'MTU': <dbus_fast.signature.Variant ('q', 96)>}, 'org.freedesktop.DBus.Properties': {}}]
2023-01-19 23:23:29.422 DEBUG manager - _parse_msg: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031/char003e', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': <dbus_fast.signature.Variant ('s', 00002a23-0000-1000-8000-00805f9b34fb)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031)>, 'Value': <dbus_fast.signature.Variant ('ay', bytearray(b''))>, 'Flags': <dbus_fast.signature.Variant ('as', ['read'])>, 'MTU': <dbus_fast.signature.Variant ('q', 96)>}, 'org.freedesktop.DBus.Properties': {}}]
2023-01-19 23:23:29.422 DEBUG manager - _parse_msg: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031/char0040', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': <dbus_fast.signature.Variant ('s', 00002a2a-0000-1000-8000-00805f9b34fb)>, 'Service': <dbus_fast.signature.Variant ('o', /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031)>, 'Value': <dbus_fast.signature.Variant ('ay', bytearray(b''))>, 'Flags': <dbus_fast.signature.Variant ('as', ['read'])>, 'MTU': <dbus_fast.signature.Variant ('q', 96)>}, 'org.freedesktop.DBus.Properties': {}}]
2023-01-19 23:23:29.423 DEBUG manager - _parse_msg: received D-Bus signal: org.freedesktop.DBus.Properties.PropertiesChanged (/org/bluez/hci0/dev_EA_55_E3_4F_55_55): ['org.bluez.Device1', {'UUIDs': <dbus_fast.signature.Variant ('as', ['00001800-0000-1000-8000-00805f9b34fb', '00001801-0000-1000-8000-00805f9b34fb', '0000180a-0000-1000-8000-00805f9b34fb', '49535343-fe7d-4ae5-8fa9-9fafd205e000'])>, 'ServicesResolved': <dbus_fast.signature.Variant ('b', True)>}, []]
0000180a-0000-1000-8000-00805f9b34fb (Handle: 49): Device Information
00001801-0000-1000-8000-00805f9b34fb (Handle: 33): Generic Attribute Profile

I also like to share the bluetoothctrl log.

[bluetooth]# connect EA:55:E3:4F:55:55
Attempting to connect to EA:55:E3:4F:55:55
[CHG] Device EA:55:E3:4F:55:55 Connected: yes
Connection successful
[NEW] Primary Service (Handle 0x0000)
    /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0021
    00001801-0000-1000-8000-00805f9b34fb
    Generic Attribute Profile
[NEW] Characteristic (Handle 0x0000)
    /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0021/char0022
    00002a05-0000-1000-8000-00805f9b34fb
    Service Changed
[NEW] Primary Service (Handle 0x0000)
    /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031
    0000180a-0000-1000-8000-00805f9b34fb
    Device Information
[NEW] Characteristic (Handle 0x0000)
    /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031/char0032
    00002a29-0000-1000-8000-00805f9b34fb
    Manufacturer Name String
[NEW] Characteristic (Handle 0x0000)
    /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031/char0034
    00002a24-0000-1000-8000-00805f9b34fb
    Model Number String
[NEW] Characteristic (Handle 0x0000)
    /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031/char0036
    00002a25-0000-1000-8000-00805f9b34fb
    Serial Number String
[NEW] Characteristic (Handle 0x0000)
    /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031/char0038
    00002a27-0000-1000-8000-00805f9b34fb
    Hardware Revision String
[NEW] Characteristic (Handle 0x0000)
    /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031/char003a
    00002a26-0000-1000-8000-00805f9b34fb
    Firmware Revision String
[NEW] Characteristic (Handle 0x0000)
    /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031/char003c
    00002a28-0000-1000-8000-00805f9b34fb
    Software Revision String
[NEW] Characteristic (Handle 0x0000)
    /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031/char003e
    00002a23-0000-1000-8000-00805f9b34fb
    System ID
[NEW] Characteristic (Handle 0x0000)
    /org/bluez/hci0/dev_EA_55_E3_4F_55_55/service0031/char0040
    00002a2a-0000-1000-8000-00805f9b34fb
    IEEE 11073-20601 Regulatory Cert. Data List
[CHG] Device EA:55:E3:4F:55:55 UUIDs: 00001800-0000-1000-8000-00805f9b34fb
[CHG] Device EA:55:E3:4F:55:55 UUIDs: 00001801-0000-1000-8000-00805f9b34fb
[CHG] Device EA:55:E3:4F:55:55 UUIDs: 0000180a-0000-1000-8000-00805f9b34fb
[CHG] Device EA:55:E3:4F:55:55 UUIDs: 49535343-fe7d-4ae5-8fa9-9fafd205e000
[CHG] Device EA:55:E3:4F:55:55 ServicesResolved: yes

You can see that the python module perfectly reflects what I am manually doing. So all good from your module side.

Since my GATT service & characteristic are no standard - no ones knows how to resolve them. Alter reading around, I think that I found what is missing. Its a dbus object called "org.bluez.GattProfile1" (https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/doc/gatt-api.txt).

Till now I have no idea how to create and publish some kind of profile that let the bluez and its deamon resolve my service.

my service looks like

_SERVICE_UUID = "49535343-fe7d-4ae5-8fa9-9fafd205e000"
_SERVICE_NAME = "my_io"
_CHARACTERISTIC_RX_UUID = "49535343-1e4d-4bd9-ba61-23c647249616"
_CHARACTERISTIC_TX_UUID = "49535343-8841-43f4-a8d4-ecbe34729bb3"
_CHARACTERISTIC_TRANS_CTRL_UUID = "49535343-aca3-481c-91ec-d85e28a60318"

_CHARCATERISTICS = {
    # uuid, (<name> , operations (r -read, n - notify, w - write))
    _CHARACTERISTIC_RX_UUID : ("rx", "n"),
    _CHARACTERISTIC_TX_UUID : ("tx", "w"),
    _CHARACTERISTIC_TRANS_CTRL_UUID : ("trans_ctrl" , "wn"),
}

def updateUUIDs():
    bleak.uuids.register_uuids({
        _SERVICE_UUID: _SERVICE_NAME,
        _CHARACTERISTIC_RX_UUID : "io_rx",
        _CHARACTERISTIC_TX_UUID : "io_tx",
        _CHARACTERISTIC_TRANS_CTRL_UUID : "io_cntl",
        })

Guess we might an extension to the bleak.uuids.register_uuids function so it does the registration work in Linux.

StefJar Jan 20, 2023
Author

when looking into the bluepy it seems that they are doing a manual recovery - via find(https://github.com/IanHarvey/bluepy/blob/master/bluepy/bluepy-helper.c#L630). Maybe that is missing

dlech · 2023-01-20T01:38:48Z

dlech
Jan 20, 2023
Collaborator

def connect(addr) -> bool:
c = bleak.BleakClient(addr)
r = asyncio.run(c.connect())
sL = c.services
for s in sL:
print(s)

I just realized this program is wrong. There should only be one top-level run loop and everything run inside of it. Trying to use anything outside of the loop is not going to work right.

Try running the service explorer example. You may need to use this version since IIRC the develop branch has changes that require new features that haven't been released yet.

14 replies

dlech Jan 26, 2023
Collaborator

This says it is for automatic connecting. In Bleak we use manual connecting. Going back to this comment, I think BlueZ is picking up the custom service UUID from the advertising data but it is not seeing the custom service when enumerating the device after connection. BlueZ uses different BLE commands to enumerate devices compared to Windows and Android. So, I have a strong suspicion that the firmware on the device is not fully compatible with BlueZ. Logging packets with Wireshark will probably shed some light on this.

StefJar Jan 27, 2023
Author

good point
as far as I know and can see at the bluetooth SIG page - the bm64 is a fully certified BT classic & le device. So I am sure the device side is good.
After reading around for the last days I am sure that I understand how bluez is working. To my understanding bluez has a subset of GATT services implemented. These services are recovered automatic. Since one of the main features of bt le is the ability for users to create their own services(vendor spezific) bluez can't know them all. Therefore they created an interface where you can add you vendor specific services. Guess its like:
org.bluez.GattProfile1.uuid = org.bluez.GattProfile1.uuid.append(myUUID)
sadly bluetoothctl is not exposing that to user space. So everyone who likes to use own services needs to add this to his code

Thats my understanding. Please correct me :)

Currently I would like to have a function at the bluezdbus backend that I can call, that is registering my service uuid. After I- guess bluez is recovering the characteristics + service into dbus nodes

dlech Jan 27, 2023
Collaborator

Capturing packets with wireshark is the only way to see what is really going on.

StefJar Feb 1, 2023
Author

I done some testing. So it unlikely that there is a wrong gatt database @ peripheral.
Also run the code on Windows and it works nicely.
Fun fact the bluepy python module perfectly manages the service & characteristics recovery.
I am also in the bluez slack and trying to figure out how I can register a vector specific service via bluetoothctl. (https://bluezorg.slack.com/archives/C01820ZPLMV/p1675245833559629)

When looking abit deeper into pyblue, I am seeing that they found a way to discover services
https://github.com/IanHarvey/bluepy/blob/master/bluepy/bluepy-helper.c#L652
the c function is called out of the python module
So I am sure that this is the feature that is missing here in bleak

Any thoughts on that?

dlech Feb 1, 2023
Collaborator

capture Bluetooth packets and compare them - it is the best way to see the difference

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discovering own GATT services(UUID128) fails #1204

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discovering own GATT services(UUID128) fails #1204

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