ESP32 (Gateway) disconnects from end devices(Nordic) after 30 seconds

[erifat]

I have problem with BLE connection. I developing a BLE Gatt client application with ESP32. There is a nordic processor in my sensor (end device).

Notify is not coming to ESP32. I can read and write without notify it, but when I need to collect data constantly, it disconnects every 30 seconds and I get an error.

How can I check the specific reason of disconnection?

Incoming message;

ESP_GATTC_DISCONNECT_EVT,reason = 19 

[Vidar Berg]

Hello,

The ESP log shows that the shows that the connection was terminated by the nRF (disconnect reason 19 corresponds to BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION).  I could be caused by GATT procedure timeout. This timeout is 30 seconds and is raised if a GATT procedure is not completed in time. 

Which SDK is your Sensor FW based on? Also, do you get the same disconnect if you connect to your sensor with the nRF connect app on android or iOS?

Best regards,

Vidar

[erifat]

Hi,

I use custom apps on Windows and iOS, but they don't make the disconnection. I use SDK 16. The system is constantly experiencing bluetooth drops(ESP32). Do you have any suggestions for solving the problem?

Best regards,

[Vidar Berg]

Hi,

OK, the fact that you don't see the disconnects with Windows and iOS indicates the problem is on the ESP. 

Are you trying to receive notifications or indications (ref. GATTS Handle Value Notification & GATTS Handle Value Indication) when you experience the timeout? Notice the indication require acknowledgement from the client to avoid GATT timeouts:

A sniffer capture (https://www.nordicsemi.com/Products/Development-tools/nrf-sniffer-for-bluetooth-le) would be helpful if we need to troubleshoot this further. 

[erifat]

Hi,

Thank you for your support. 

I saved the data with wireshark. I've looked through the data but still can't see the problem.

(ESP32 = 98:cd:ac:73:4d:d6) (Nordic : c0:ba:42:19:22:22 )  ESP32-Nordic.pcapng

This image, could that be the cause of the error? 

What are your suggestions about the problem?

Best regards,

[Vidar Berg]

Hi,

The ESP does not respond to the nRF's MTU request according to the sniffer trace which would explain the timeout. 

[erifat]

Hi, 

Nordic(Slave-Server) device is used as server and ESP(Master-Client) device is used as client.

As can be seen in the image, the Nordic device sends a request while it should send a response under normal conditions.

Why might the Nordic device be sending the request even though it is set as the server?

Nordic (Slave - Server)  ESP32 (Master - Client)

[Vidar Berg]

Even if the peripheral is primarily acting as a GATT server it can still initiate the MTU request as long as the connected peer does not do it first. The issue here is that the ESP does not respond to the request.

[erifat]

Hi,

The ESP32 cannot respond in client mode.It's not in the source code.

I shared the MTU request immediately after the nordic device was found on the ESP32 side. but it didn't work.

What is your suggestion in this case?

[Vidar Berg]

Hi,

You can change your nRF FW to not send the MTU request.

[erifat]

Hi,

Our nordic nRF devices were placed in different regions. We can't send update via dfu without solving bluetooth problem.  

Do you have any other suggestions for solving the problem?

Best regards,

[Vidar Berg]

Hi,

I understand, but then you must find a way to make the ESP respond to the MTU request. I suggest you reach out to the manufacturer to ask if there is a way to do this.