BLE service discovery behaviours are different on two central devices via "nRF Connect APP"

RE: BLE service discovery behaviours are different on two central devices via "nRF Connect APP"

Simonr — Mon, 17 Feb 2025 11:59:22 GMT

With the nRF Connect for Desktop BLE app, you will get prompted when you open the app and choose the DK you want to use to connect to program the board with the correct firmware. It is a connectivity sample that we don't have available as it is based on some rather old connectivity firmware at this point.

Best regards,

Simon

RE: BLE service discovery behaviours are different on two central devices via "nRF Connect APP"

Yanpengwu — Mon, 17 Feb 2025 08:37:10 GMT

Hi Simonr,

I have a nRF5340 DK, what sample or image should I download to it if I want to use the app "Bluetooth low energy"?
From nRF Sniffer for Bluetooth LE， it seems the firmware is only for nRF52* DK.
Thank you very much.

Best regards,
Yanpeng Wu

RE: BLE service discovery behaviours are different on two central devices via "nRF Connect APP"

Simonr — Fri, 14 Feb 2025 11:59:47 GMT

Glad to hear you got around your issue. I see, that makes sense! Some phones handle bonding/discovery differently int heir BT stacks, so some different behavior must be expected.

We don't have any specific suggested Windows based program for BLE directly, but we do have the nRF Connect for Desktop BLE app with the source code available here: https://github.com/NordicSemiconductor/pc-nrfconnect-ble It requires that an nRF52/53 series DK or Dongle is connected to the computer though.

Best regards,

Simon

RE: BLE service discovery behaviours are different on two central devices via "nRF Connect APP"

Yanpengwu — Fri, 14 Feb 2025 09:54:24 GMT

Hi Simonr,

It's a nRF5340 custom board and the problem is fixed now. The BLE on our custom board is used for the system provision, which allows boned central to configure it only.

what I changed to fix this problem is:
1. Disable the settings for BLE and force the central device to bond for every connection request.

        CONFIG_BT_SETTINGS=n

2. Set the Security with Mode 1 Level 4, and ensure the central device bond with Passkey Confirmation(Numeric Comparison):

        CONFIG_BT_SMP=y
        CONFIG_BT_BONDABLE=y
        CONFIG_BT_PRIVACY=y
        CONFIG_BT_SMP_SC_ONLY=y
        CONFIG_BT_SMP_APP_PAIRING_ACCEPT=y
        CONFIG_BT_SMP_ENFORCE_MITM=y

And in the on_connected_cb, set bt_conn_set_security(conn, BT_SECURITY_L4 | BT_SECURITY_FORCE_PAIR).

After these changes, Both phones bonded with the target and discovered the services successfully. A little difference is one phone discovers the services automatically after a secure connection, and the other phone needs to discover manually (click Discover Services in the nrf connect for mobile APP ). Both read/write via BLE are successful.

Now I use the APP "nrf connect for mobile" to configure my device, I need to develop a Windows-based dialog program for this purpose. Could you help give some suggestions for this? (1) Need I use a Nordic dongle on my laptop? I found my laptop can scan and find the target, but can not connect it stable (short connected then disconnected for an unknow reason). (2) For the Windows dialog program, are there any open sources or tools I can base on to develop it quickly? Thank you very much.

Best regards,
Yanpeng Wu

RE: BLE service discovery behaviours are different on two central devices via "nRF Connect APP"

Simonr — Wed, 05 Feb 2025 10:21:34 GMT

Can you share some details on what phones you're using here, both the one that's working and the one with issues doing service discovery on? And what service exactly is it you're trying to discover? Also, what kind of IoT device is it, is this an nRF5340 custom board or DK? In the IoT device log there seems to be some packets dropped and no mention of service discovery, so maybe these are lost somehow.

One thing you could try is to get a sniffer trace so we can see what is going on over the air since the logs don't really point to anything specific being wrong here. You can either use a dedicated Bluetooth sniffer like the Ellisys Snfifers or an nRF52 series DK with the nRF Sniffer firmware and Wireshark to sniff the connection. Check out the nRF Sniffer user guide here: https://docs.nordicsemi.com/bundle/nrfutil_ble_sniffer_pdf/resource/nRF_Sniffer_BLE_UG_v4.0.0.pdf

Best regards,

Simon

RE: BLE service discovery behaviours are different on two central devices via "nRF Connect APP"

Yanpengwu — Tue, 04 Feb 2025 18:06:31 GMT

About two months ago, the BLE service can be found on phone_A, after one or two Bluetooth upgrades, the service discovery failed now.

Maybe this was caused Bluetooth version mismatch? Could you help give some hints? Thank you.

RE: BLE service discovery behaviours are different on two central devices via "nRF Connect APP"

Yanpengwu — Tue, 04 Feb 2025 10:41:14 GMT

I added the log on the peripheral side (my IoT device) here.devzone.nordicsemi.com/.../IoT_5F00_device_5F00_peripheral.txt