Seemingly random disconnect after around 1 minute

[Marne]

I am using a NRF52 Devkit with S140 to connect to a NRF51 running S110. 

Initially this works as expected and I can connect, discover services read, write etc...

However after around 1 minute the connection is dropped. This always happens. 

The NRF51 (peripheral) reports that the reason was 0x0016 (BLE_HCI_LOCAL_HOST_TERMINATED_CONNECTION), and the NRF52 (central) reports 0x0013 (BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION). So it is the NRF51 that is disconnecting, if I understand correctly. 

There are no calls to disconnect in the NRF51-code however, so I don't understand why this happens. If I am connected using BLE on my PC or my Phone I don't get disconnected. This only happens on the NRF52 using S140. 

Sniffing with wireshark did not reveal anything. Communication looks normal (I do writes and notifications every second between the devices) up until the NRF51 sends a LL_TERMINATE_IND and the connection shuts down.

Any help is greatly appriciated.

[Hieu]

Hi Marne,

Given your description, I think your nRF52 device might be having clock drifting. What is the low frequency clock source in your nRF52 setup?

If you are using the internal RC oscillator as the source, you could refer to the following answer from my colleague Simon:  RE: BLE Disconnection right after connection - nRF52832 with SDK ble_app_blinky_pca10040_s132 example 

Hieu

[Marne]

I am already using the suggested values in the linked thread. I have been running the code on either a nRF52832 dev kit (the one with built-in JLink) and a nRF52840 dongle, with the same results.

[Hieu]

Could you please share the sniffer log that you got?