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?

[Edvin]

The PCA10056 is not yet supported. The PCA10040 and PCA10028 (and PCA10031) is currently supported.

 

However, you got the sniffer up and running. Could you send the entire snifferlog (.pcapng file) ?

 

Best regards,

Edvin

[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.