Linux-enabled BLE HID peripheral

RE: Linux-enabled BLE HID peripheral

DX_HK — Wed, 18 Feb 2026 03:28:48 GMT

After further testing, I found that setting CONFIG_BT_CTLR_PHY_2M=n enabled connection.
According to a comment from zmk user, setting CONFIG_BT_CTLR_PHY_2M=n in Windows 11 also seems to resolve connection issues.

RE: Linux-enabled BLE HID peripheral

DX_HK — Tue, 02 Dec 2025 03:37:02 GMT

I did a bit of research and found information that Linux forces pairing on the HoG.
I'm not sure, but the validity of requiring security for HIDs is clear, so this is likely the cause.

I could probably rewrite the sample code for MITM-less pairing, but I'd rather focus on my product.

My one request would be if Nordic provided more practical sample code (that runs on Windows, Mac, Linux, Android, and iOS).

Thank you for your support !!

RE: Linux-enabled BLE HID peripheral

Edvin — Mon, 01 Dec 2025 14:18:30 GMT

I understand. Can you please try to capture a sniffer trace of the connection? It will make it a bit clearer exactly what the operating system is expecting to use with the HID Mouse.

Best regards,

Edvin

RE: Linux-enabled BLE HID peripheral

DX_HK — Mon, 01 Dec 2025 02:48:54 GMT

As a result, I still couldn't connect to the Linux machine.

Regular advertising started
[00:00:04.936,492] <wrn> bt_smp: The in-progress pairing has been deleted!
Disconnected from 14:5A:FC:4B:71:00 (public), reason 0x08

The MITM popup is no longer displayed, but I still get immediately disconnected.
There seems to be another problem...

In conclusion, the title of this post indicates that there is a problem with the sample code, but I am still interested in the cause of this problem.
It is probably the same cause as the mouse I am currently developing that cannot connect to a Linux machine.

RE: Linux-enabled BLE HID peripheral

Edvin — Fri, 28 Nov 2025 15:02:27 GMT

Indeed. I agree.

Can you try to add these to your prj.conf?

CONFIG_BT_HIDS_SECURITY_ENABLED=n
CONFIG_BT_SMP=y

It still requires

But perhaps that is default in the ubuntu OS. Let me know if it doesn't work.

Best regards,

Edvin

RE: Linux-enabled BLE HID peripheral

DX_HK — Fri, 28 Nov 2025 03:01:13 GMT

I thought about it for a bit...

peripheral_hids_mouse sample performs MITM authentication by displaying a key on the mouse device.

However, mouse generally do not have the ability to display text. Linux machines also assume this,

so I think they are configured not to perform MITM authentication with mice.

It should probably work if you change the settings on your Linux machine and enable MITM regardless of the device.
Fundamentally, the specification of peripheral_hids_mouse is probably incorrect.

RE: Linux-enabled BLE HID peripheral

Edvin — Thu, 27 Nov 2025 14:34:35 GMT

This is what I got from my attempt connecting to my computer:

Using nRF Connect for Desktop, I got a popup for a split second, but then I saw that I needed to check of these options:

Does it work in that case?

If so, then the issue is probably that the OS (Ubuntu) doesn't use MITM for HID Mouse, and hence it doesn't bond successfully.

Let me know what you see, and we can look into it.

Best regards,

Edvin

RE: Linux-enabled BLE HID peripheral

DX_HK — Thu, 27 Nov 2025 09:30:50 GMT

devzone.nordicsemi.com/.../flash_5F00_dump.hex

The hex file has been dumped. Please check it.

I'm using the nRF52833DK (an old 1.1.0 board, but that shouldn't be an issue here)

RE: Linux-enabled BLE HID peripheral

Edvin — Thu, 27 Nov 2025 09:06:22 GMT

In that case, we can rule out that this is a linux issue, if the behavior is the same when trying to pair with the nRF Connect for Desktop -> Bluetooth Low Energy.

Can you replicate the issue once more, and after you have done that, can you read out the flash on the nRF (the one acting as a hids_mouse)?

To read it out, you can use one of these commands:

nrfjprog --readcode flash_dump.hex

nrfutil device dump-to-file flash_dump.hex

And upload that flash_dump.hex file here? Also, let me know what device (nRF52833 or nRF52840) the flash dump is coming from.

Best regards,

Edvin

RE: Linux-enabled BLE HID peripheral

DX_HK — Wed, 26 Nov 2025 10:59:01 GMT

Sorry, I left it set to test mode for another device (the device I'm developing on).

However, even when I changed it to "Keyboard And Display", the result was the same.

Note: The target board has been changed to the nRF52833DK due to a lack of board.

Analysis using a BLE sniffer seems a bit time-consuming. I'll check it tomorrow.

RE: Linux-enabled BLE HID peripheral

Edvin — Wed, 26 Nov 2025 10:22:07 GMT

Does the log from the nRF say the same when you attempted using nRF Connect for Desktop -> Bluetooth Low Energy?

I noticed that you are using "No keyboard, no display" in nRF Connect for Desktop -> Bluetooth Low Energy.

Can you please try to use "Keyboarrd And Display"?

Does that change anything?

A sniffer trace could still be helpful.

Best regards,

Edvin

RE: Linux-enabled BLE HID peripheral

DX_HK — Wed, 26 Nov 2025 10:10:48 GMT

Erasing the board makes no difference.
I have also confirmed that there is no pair information using bluetoothctrl on a Linux machine.

To check that the DK buttons are not malfunctioning, I set it to output a log when num_comp_reply() is called, but there is no sign of a malfunction.

Setting up the sniffer takes some time, so I tested it using Bluetooth Standalone.

Also, my setup is a standard development kit and sample code, except for the Linux host machine.
The Linux machine (T14s gen2, Ubuntu 24.04) is also a very standard environment.
Would it be possible for Nordic to test it?

RE: Linux-enabled BLE HID peripheral

Edvin — Wed, 26 Nov 2025 08:51:38 GMT

And are you are not pressing button 2 on the DK while trying to connect? Or shorting P0.12 to GND?

BR,
Edvin

RE: Linux-enabled BLE HID peripheral

Edvin — Wed, 26 Nov 2025 08:49:59 GMT

It could be that one of the devices (the nRF or your computer) have the bonding data stored, but the other one doesn't.

Make sure that you remove the device from your computer (if you tried another sample on the DK previously, look for that device as well), and remove it from "known/paired" devices.

Then make sure the flash on your nRF52840 is empty. You can use either of these:

nrfutil device erase

nrfjprog --eraseall

And then flash the application again. If the same issue still occurs, can you please try to capture a sniffer trace of the connection? You can use the nRF Sniffer for Bluetooth LE for this.

Best regards,

Edvin

RE: Linux-enabled BLE HID peripheral

DX_HK — Wed, 26 Nov 2025 05:10:08 GMT

*** Booting nRF Connect SDK v3.0.2-89ba1294ac9b ***
*** Using Zephyr OS v4.0.99-f791c49f492c ***
[00:00:00.024,871] <inf> main: Starting Bluetooth Peripheral HIDS mouse sample
[00:00:00.039,337] <inf> fs_nvs: 2 Sectors of 4096 bytes
[00:00:00.045,288] <inf> fs_nvs: alloc wra: 0, ef8
[00:00:00.050,720] <inf> fs_nvs: data wra: 0, 17c
[00:00:00.056,182] <inf> bt_sdc_hci_driver: SoftDevice Controller build revision: 
                                            89 9a 50 8a 95 01 9c 58  fc 39 d2 c1 10 04 ee 02 |..P....X .9......
                                            64 ce 25 be                                      |d.%.             
[00:00:00.089,599] <inf> bt_hci_core: HW Platform: Nordic Semiconductor (0x0002)
[00:00:00.097,747] <inf> bt_hci_core: HW Variant: nRF52x (0x0002)
[00:00:00.104,522] <inf> bt_hci_core: Firmware: Standard Bluetooth controller (0x00) Version 137.20634 Build 2617349514
[00:00:00.116,546] <inf> bt_hci_core: No ID address. App must call settings_load()
[00:00:00.124,847] <inf> main: Bluetooth initialized
[00:00:00.132,263] <inf> bt_hci_core: Identity: D7:27:30:94:0A:33 (random)
[00:00:00.139,892] <inf> bt_hci_core: HCI: version 6.0 (0x0e) revision 0x10f3, manufacturer 0x0059
[00:00:00.149,658] <inf> bt_hci_core: LMP: version 6.0 (0x0e) subver 0x10f3
[00:00:00.159,973] <inf> main: Direct advertising to 14:5A:FC:4B:71:00 (public) started
[00:00:01.440,277] <inf> main: Direct advertising to 14:5A:FC:4B:71:00 (public) timed out
[00:00:01.450,744] <inf> main: Regular advertising started
[00:00:20.254,913] <inf> bas: BAS Notifications enabled
[00:00:20.261,169] <inf> main: Connected 14:5A:FC:4B:71:00 (public)
[00:00:20.268,249] <inf> main: Conn details (post-connect): 14:5A:FC:4B:71:00 (public) role peripheral interval 36 latency 0 timeout 42 sec_level 1 key_size 0
[00:00:20.285,705] <inf> main: Regular advertising started
[00:00:20.870,758] <inf> main: Passkey for 14:5A:FC:4B:71:00 (public): 636211
[00:00:20.878,631] <inf> main: Press Button 1 to confirm, Button 2 to reject.
[00:00:21.590,209] <inf> main: Security failed: 14:5A:FC:4B:71:00 (public) level 1 err 9 
[00:00:21.599,365] <inf> main: Conn details (security cb): 14:5A:FC:4B:71:00 (public) role peripheral interval 36 latency 0 timeout 42 sec_level 1 key_size 0
[00:00:21.614,532] <inf> main: Pairing failed conn: 14:5A:FC:4B:71:00 (public), reason 9 
[00:00:21.623,596] <inf> main: Conn details (pairing failed): 14:5A:FC:4B:71:00 (public) role peripheral interval 36 latency 0 timeout 42 sec_level 1 key_size 0
[00:00:21.639,038] <inf> bas: BAS Notifications disabled
[00:00:21.645,294] <inf> main: Disconnected from 14:5A:FC:4B:71:00 (public), reason 0x08 
[00:00:21.655,609] <inf> main: Direct advertising to 14:5A:FC:4B:71:00 (public) started
[00:00:22.935,699] <inf> main: Direct advertising to 14:5A:FC:4B:71:00 (public) timed out
[00:00:22.946,166] <inf> main: Regular advertising started

Here's the log:

Security error is 9
Pairing error is 9
disconnection reason is 8

A connection attempt is made from a Linux machine about 10 seconds after startup.
On the Linux machine, a key code popup appears for about 0.5 seconds and then disappears immediately.

I would appreciate any advice you can give me.

RE: Linux-enabled BLE HID peripheral

DX_HK — Wed, 26 Nov 2025 05:00:17 GMT

Thank you for your response.
As you said, I tried nRF Desktop.
I found that it works without any problems.

On the other hand, nRF Desktop is an application-level implementation and is too complex as sample code.
Is there any simpler BLE sample code that has been verified to work?

RE: Linux-enabled BLE HID peripheral

Edvin — Tue, 25 Nov 2025 14:54:00 GMT

Hello,

Does the log from the nRF say anything when it disconnects? Particularly, what is the "reason" parameter in the disconnected event? And does the log say anything about "security change"?

Best regards,

Edvin

RE: Linux-enabled BLE HID peripheral

Lorenzo Amicucci — Tue, 25 Nov 2025 13:36:02 GMT

yes, have you tried "nRF Desktop" application in nRF Connect SDK?

Lorenzo