BLE Connection Issues with nRF52832 Multi-Device Setup

RE: BLE Connection Issues with nRF52832 Multi-Device Setup

Hung Bui — Wed, 26 Mar 2025 10:01:58 GMT

Hi Siltvm,

Error 0x28 is a bit strange because it's indicate an issue in the BLE stack timing ( BT_HCI_ERR_INSTANT_PASSED) either on the nRF52 or on the phone. Which phone did you use ?

I would need to see your sniffer trace to be to check what happens there.
You can find the guide on how to use the sniffer here: https://academy.nordicsemi.com/courses/bluetooth-low-energy-fundamentals/lessons/lesson-6-bluetooth-le-sniffer/

RE: BLE Connection Issues with nRF52832 Multi-Device Setup

siltvm — Wed, 26 Mar 2025 06:41:48 GMT

When the submaster gateway initially starts advertising, and when Iam initiates a connection from the APK, it sometimes disconnects and shows:

Peripheral disconnected. conn_handle: 0x5, reason: 0x28

The APK then shows: Connection failed: write descriptor failed.

One more thing: I am not using any kind of bonding here. So, what are the possible causes of this issue?

This issue happens only sometimes .

RE: BLE Connection Issues with nRF52832 Multi-Device Setup

Hung Bui — Fri, 21 Mar 2025 09:19:38 GMT

Hi,
I don't see a problem having a connection and then scan and establish another connection. It's our fundamental operation for multilink application. So, shouldn't be a problem.
There is no requirement on the timing. Of course two connection can't be established at the same time (like exactly the same time) they should be established based on when the scanner catch the advertising packet and send the connect request.

RE: BLE Connection Issues with nRF52832 Multi-Device Setup

siltvm — Thu, 20 Mar 2025 04:33:41 GMT

Hung Bui Okay, I will proceed as you suggested. I also have a question: are there any issues with scanning for or connecting to a central device while maintaining a peripheral connection? Additionally, what are the standard minimum delays required for a response device, sub-gateway, or super-master gateway to perform scanning and connection?

RE: BLE Connection Issues with nRF52832 Multi-Device Setup

Hung Bui — Wed, 19 Mar 2025 13:31:13 GMT

Hi,
If you want such feature, you would need to implement that. The submaster gateway shouldn't connect to the supermaster gateway as the central. This mean when the submaster scan for advertising packet, it would need a way to detect that it only connect to response node, not the supermaster. I think it's quite straight forward to do so. Just need to scan for either address, or the advertising name/data.

RE: BLE Connection Issues with nRF52832 Multi-Device Setup

siltvm — Wed, 19 Mar 2025 09:20:40 GMT

Yes, I modified the central, peripheral, and total link counts to meet my project requirements:

NRF_SDH_BLE_PERIPHERAL_LINK_COUNT=1;
NRF_SDH_BLE_CENTRAL_LINK_COUNT=5;
NRF_SDH_BLE_TOTAL_LINK_COUNT=6;

Our expectation is that the submaster gateway acts as a peripheral when a connection initiation is received from the supermaster gateway. This means the supermaster gateway should be the central (client) to the submaster gateway and all three response devices. However, the log shows that the supermaster gateway connects as a peripheral to the submaster gateway. The log output is from the supermaster gateway. We expected a central connection here, not a peripheral connection.

RE: BLE Connection Issues with nRF52832 Multi-Device Setup

Hung Bui — Wed, 19 Mar 2025 08:31:31 GMT

Hi,
The call is inside nrf_ble_gatt.c.

Could you try capturing a sniffer trace ?

Have you configured the link count to match with your need ?

NRF_SDH_BLE_PERIPHERAL_LINK_COUNT

NRF_SDH_BLE_CENTRAL_LINK_COUNT

NRF_SDH_BLE_TOTAL_LINK_COUNT

RE: BLE Connection Issues with nRF52832 Multi-Device Setup

siltvm — Wed, 19 Mar 2025 03:45:41 GMT

The given log is from the super master, and I could not find sd_ble_gatts_exchange_mtu_reply() within my super master code.

RE: BLE Connection Issues with nRF52832 Multi-Device Setup

Hung Bui — Mon, 17 Mar 2025 12:19:58 GMT

Hi,
I would suggest to use a sniffer to try debugging. You can find why the connection is terminated.

You can also find the termination reason on the device when it's disconnected.

Please focus on this:
<error> nrf_ble_gatt: sd_ble_gatts_exchange_mtu_reply() returned NRF_ERROR_INVALID_STATE.

Where do you call sd_ble_gatts_exchange_mtu_reply() ?

Was the log from the Super master or the Sub master ?

RE: BLE Connection Issues with nRF52832 Multi-Device Setup

siltvm — Mon, 17 Mar 2025 11:05:38 GMT

When I disconnect power from all response devices, submaster gateways, and supermaster gateways, and then initially power on the supermaster gateway followed by the submaster gateway, I encounter an error. I believe this is causing disconnections. However, if I power on the submaster gateway and the nearest response devices before powering on the supermaster gateway, the issue does not occur. What could be the reason for this difference?


<info> app: Connected to target F41493782DCD

<info> app: Peripheral connected

<info> app: Connected device MAC: F4:14:93:78:2D:CD

<info> app: Flash memory is empty. Accepting any device.

<error> nrf_ble_gatt: sd_ble_gatts_exchange_mtu_reply() returned NRF_ERROR_INVALID_STATE.

<info> app: Fast advertising.

<info> app: Peripheral disconnected. conn_handle: 0x5, reason: 0x13