Frequent disconnection with reason 8

[Mikah S.]

I am currently struggling with the issue of the Bluetooth board disconnecting in irregular intervals ranging from 30 seconds to 10 minutes. The disconnection message is reason 8 for these disconnects.

I thought originally that the issue was because my bluetooth board did not have a 32.768kHz clock attached and was instead using the RC with the 500ppm setting, so I had a second revision of the board made with a 32.768kHz clock but the issue still occurred with the usage of the 32.768kHz clock.

Some additional details that may be relevant: The chip is actively using usb through out the duration of its run time. I'm using the the third-party component E73-2G4M08S1C which uses nRF52840 revision 2.0 (it shows on visual studio code as NRF52840_xxAA_REV2 which I assume means that it is revision 2.0).

Thank you

[Simonr]

Hi

Do you by chance have an nRF52840 DK to try and reproduce this on? Or is it only reproducible on the board you have. How have you loaded the 32.768 kHz, disconnect reason 8 should be a connection timeout if I'm not mistaken, and could indeed point to a drifting LF clock or HF clock source. Although the disconnect intervals of up to 10 minutes seems like a bit much.

Can you share some details on what your application is doing exactly, what connection parameters are you operating with, and what is the central you're connecting to when seeing these disconnects? Are your boards both central and peripheral here, or just one of the roles? What SDK are you using for development?

Best regards,

Simon

[Mikah S.]

I do have an nRF52840 DK but have been unable to reproduce the issue with the DK. The 32.768 kHz clock has a 12pF capacitor on both XL1 and XL2 lines (I was unable to get 12.5pF capacitors). My application is a Bluetooth keyboard with customizable keys. The connection parameters are not any different than the peripheral_hids_keyboard example in the sdk. I am using the v2.6.1 sdk. I don't know if this is meaningful but before each disconnect the following log message is displayed: bas: blvl_ccc_cfg_changed: BAS Notifications disabled. The board is always acting as a peripheral, and any programming/customizing of keys is done over usb.