LLPM questions

[Hannibalhz]

Dear Nordic Engineer

Our costomer has developed a keyboard using LLPM in NCS.Now Now they have encountered some problems.We have been working with them for a long time but there still no good solution to these problems.

1、When using the WIN 10 Version 20H2 or higher the PC will be connected to the keyboard.After working for a period of time the Caps and Num indicator lights will not light up.Our research found that the reason is that the PC did't issue instuctions to the keyboard.In this case,the "keyboard_leds_handler"  does not resond.Because the communication data encrtpted we can't capture the data packet,so this problem is shelved and we can't solve it.

2、 In wired mode, the keyboard uses a USB cable to connect to the PC.The keyboard can't wake up the PC while it's sleeping.Our research found that when the PC is sleeping,we call "usb_wakeup => usb_wakeup_request"  and the D+ line of the USB will generate a signal.We measured the duration an oscilloscope to be about 10ms, but this did not wake the PC.

Please give us some good suggestions.

Best regard.

[Sigurd Hellesvik]

Hi Hannibal

Is this the case for the LLPM sample without any changes as well?

I will ask our developers for solutions.

Since it is the holidays vacations for many, I might not get answer this week.
But I will return with an answer in the first week of January.

Regards,
Sigurd Hellesvik

[Hannibalhz]

Dear Sigurd

Ok waiting for your good news.

Happy New Year and best regard.

[Sigurd Hellesvik]

Hi

Have there been made any changes to the LLPM sample?

Regards,
Sigurd Hellesvik

[Kenneth]

Hi,

I am taking over this case, to help you on these issues we need to understand if the issue is also observed on the original project delivered by Nordic? Please also describe which NCS version and sample project you are using.

Regarding debugging, you can use CONFIG_BT_DEBUG_KEYS and CONFIG_BT_USE_DEBUG_KEYS to use the Bluetooth debug keys to encrypt the connection. Then sniffers such as Ellisys should be able to automatically decrypt the connection (the nRF Sniffer should also be able to decrypt the conenction I believe).

Best regards,
Kenneth

[Hannibalhz]

Dear Kenneth

1、Use the NCS(1)1.7.1 nrf_desktop program as the keyboard, define the two buttons on the NRF52833 DK as the NUM and CAP keys, and do not make other modifications, this problem will be reproduced when connected to a laptop with win 10 20H2 version for a period of time.

2、Use NCS1.6.1\nrf\applications \desktop\nrf52840gmouse_nrf52840, close sensor-3360, use NRF52840 DK, and connect the computer with the NRF_USB port of DK. Wake up the computer when the computer sleeps for 30 minutes. This problem can be reproduced by repeating the test a few times.