The Bluetooth connection is made and immediately disconnected.

[jwcheon]

Hello,

I am creating a project through the MultiLink example.

One problem occurred. If the device is attached to NRF52DK, the connection will be disconnected immediately after the DICONNECTED event occurs.

-----------------log----------------------

<info> app: Start scanning for device name Nordic_Blinky.
<info> app: LBS central link 0x0 disconnected (reason: 0x3E)
<info> ble_lbs_c: BLE_GAP_EVT_DISCONNECTED Type [59]
<info> ble_lbs_c: BLE_GAP_EVT_DISCONNECTED Type [59]
<info> ble_lbs_c: BLE_GAP_EVT_DISCONNECTED Type [59]
<info> ble_lbs_c: BLE_GAP_EVT_DISCONNECTED Type [59]
<info> app: Start scanning for device name Nordic_Blinky.
<info> app: Connection 0x0 established, starting DB discovery.
<debug> ble_db_disc: Starting discovery of service with UUID 0x19F1 on connection handle 0x0.
<debug> ble_gatt: Requesting to update ATT MTU to 127 bytes on connection 0x0.
<debug> ble_gatt: sd_ble_gattc_exchange_mtu_request() on connection 0x0 returned busy, will retry.
<debug> ble_gatt: Requesting to update data length to 131 on connection 0x0.

-----------------------------------

Logging occurs as above.

What part am I missing? Help.

For reference, I use SDK14.1, S140, NRF52840, and SD 5.0.0-2.

[Edvin]

Hello,

What do you mean by: "If the device is attached to NRF52DK, the connection will be disconnected immediately after the DISCONNECTED event occurs."?

By "attached", do you mean connected via BLE?

 

Disconnect reason 0x3E is BLE_HCI_CONN_FAILED_TO_BE_ESTABLISHED. What device are you trying to connect to the nRF52DK? Do you have a sniffer trace?

 

Best regards,

Edvin

[jwcheon]

Hi,
Fortunately for me, I had a PCA10028 board, installed the sniffer and observed the packets.

I think this part is probably what I said.

Do you think you know what the problem is?

[jwcheon]

connect_failed.pcapng

Here it is.

[Edvin]

Thank you. It doesn't seem like the peripheral responds at all. May I ask what kind of device the peripheral is? Is it something you are developing, or is it a product already on the marked?

If it is something that you are developing, are you able to debug that device and see if you get a connection event?

 

From the sniffer log, it looks like the connection is never established (as is confirmed by the 0x3E disconnect reason). But the peripheral has a break in the advertisements after the CONNECT_REQ packet, so something is happening, but the peripheral goes silent for a few seconds, then it continues to advertise.

 

Out of curiosity, can you try to change to the following (in sdk_config.h)

#define NRF_SDH_BLE_PERIPHERAL_LINK_COUNT 0
#define NRF_SDH_BLE_CENTRAL_LINK_COUNT 1
#define NRF_SDH_BLE_TOTAL_LINK_COUNT 1

And see if anything changes in the sniffer log?

 

Best regards,

Edvin

[jwcheon]

hi, Edvin.

I will confirm that you have advised and will test.
I will leave a comment after the test.

[jwcheon]

Hi, Edvin.

I am currently migrating from SDK14.1 to SDK15. After migrating, we'll try this test and contact you again if we get an error. Thank you.

[jwcheon]

Hi,
After migrating to SDK15
This error seems to have been resolved.
Thanks.

[strengthstrong]

What is the problem and how is sdk14.2 solved? Multiple connections cannot set NRF_SDH_BLE_CENTRAL_LINK_COUNT 1 to 1
  Isn't it only connected to one device?

[jwcheon]

Hi strengthstrong,

Rather than being resolved by switching to SDK14.2 -> SDK15,
It only adjusts the connection time.
It seems that the interval time that was applied to the existing 14.2 was short and the phenomenon occurred.
I did not test NRF_SDH_BLE_CENTRAL_LINK_COUNT by setting it to 1. I always set it to 4 and proceeded to test.