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  • Case ID: 319187
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After bonding, I receive write events from the central, but after reconnecting, the write events no longer come through.

keigo.imaizumi

Nice to meet you.

I'm looking to embark on BLE development using nrf52840.
The requirements include one-to-one communication with one central and one peripheral, and pairing using LE Secure Connection is necessary (just works).
I will be developing the peripheral side of this. The BLE requirements are based on the specifications of the central side.

Now, initially, I tried implementing it myself based on various online information and samples.
I have successfully paired, and I can receive write events from the central side.
However, when I turn off the power on the central side, then turn it back on and perform a reconnection, I no longer receive write events from the central side.

Specifically, I am manipulating the central device to perform a write operation on the peripheral.
However, I only receive BLE_GAP_EVT_CONN_PARAM_UPDATE, and no other events.

First, let me share the logs!
If there's anything suspicious, please let me know. I can also provide the code.
Thank you.

SEGGER J-Link V7.88j - Real time terminal output
SEGGER J-Link (unknown) V1.0, SN=1050228242
Process: JLinkGDBServerCLExe
<info> app_timer: RTC: initialized.
<info> app: ble_stack__init
<info> app: Service UUID:0000, UUID Type: 2
<info> app: Erase bonds.
<info> peer_manager_handler: All peers deleted.
<info> app: PM_EVT_PEERS_DELETE_SUCCEEDED
<info> app_timer: RTC: initialized.
<info> app: ble_stack__init
<info> app: Service UUID:0000, UUID Type: 2
<info> app: Erase bonds.
<info> peer_manager_handler: All peers deleted.
<info> app: PM_EVT_PEERS_DELETE_SUCCEEDED
<info> app: PM_EVT_CONN_CONFIG_REQ
<info> app: BLE_GAP_EVT_CONNECTED
<info> app: PM_EVT_CONN_SEC_START
<info> app: PM_EVT_CONN_SEC_PARAMS_REQ
<info> app: BLE_GAP_EVT_SEC_PARAMS_REQUEST
<info> app: BLE_GAP_EVT_LESC_DHKEY_REQUEST
<info> nrf_ble_lesc: Calling sd_ble_gap_lesc_dhkey_reply on conn_handle: 0
<info> app: BLE_GAP_EVT_CONN_SEC_UPDATE
<info> app: Security mode: 1. Security level: 2
<info> peer_manager_handler: Connection secured: role: Peripheral, conn_handle: 0, procedure: Bonding
<warning> app: PM_EVT_CONN_SEC_SUCCEEDED
<info> app: BLE_GAP_EVT_AUTH_STATUS: status=0x0, bond=0x1, kdist_own:0x3 kdist_peer:0x2
<info> peer_manager_handler: Peer data updated in flash: peer_id: 0, data_id: Bonding data, action: Update
<info> app: PM_EVT_PEER_DATA_UPDATE_SUCCEEDED
<info> app: Writing or overwriting the data.
<info> app: Flash changed.
<info> app: New Bond, add the peer to the whitelist if possible
<info> app: whitelist_peer_cnt 1, MAX_PEERS_WLIST 8
<info> app: Bonded to a new peer, add it to the whitelist.
<info> peer_manager_handler: Peer data updated in flash: peer_id: 0, data_id: Peer rank, action: Update
<info> app: PM_EVT_PEER_DATA_UPDATE_SUCCEEDED
<info> app: Writing or overwriting the data.
<info> app: Flash changed.
<info> app: PM_PEER_DATA_ID_PEER_RANK
<info> peer_manager_handler: Peer data updated in flash: peer_id: 0, data_id: Local database, action: Update
<info> app: PM_EVT_PEER_DATA_UPDATE_SUCCEEDED
<info> app: Flash changed.
<info> app: PM_PEER_DATA_ID_GATT_LOCAL
<warning> app: ble_evt_handler:53
<info> app: BLE_GATTS_EVT_WRITE
<info> app: Notification enabled
<info> peer_manager_handler: Peer data updated in flash: peer_id: 0, data_id: Central address resolution, action: Update
<info> app: PM_EVT_PEER_DATA_UPDATE_SUCCEEDED
<info> app: Writing or overwriting the data.
<info> app: Flash changed.
<info> app: PM_PEER_DATA_ID_CENTRAL_ADDR_RES
<info> peer_manager_handler: Peer data updated in flash: peer_id: 0, data_id: Local database, action: Update
<info> app: PM_EVT_PEER_DATA_UPDATE_SUCCEEDED
<info> app: Writing or overwriting the data.
<info> app: Flash changed.
<info> app: PM_PEER_DATA_ID_GATT_LOCAL
<info> app: BLE_GATTS_EVT_WRITE
<info> app: command_char_handles
<info> app:  01 00 02 00 1E 00 1A 00|........
<info> app:  01 61 C6 00 54 53 11 00|.a..TS..
<info> app:  A5 16 FF 00            |....    
<info> app: BLE_GATTS_EVT_WRITE
<info> app: command_char_handles
<info> app:  01 01 FF FF 00 00 A7 0B|........
<info> app:  AF 16 00 01 00 00 00 52|.......R
<info> app:  7C 07                  ||.      
<info> app: BLE_GATTS_EVT_WRITE
<info> app: command_char_handles
<info> app:  01 00 02 00 1E 00 1A 00|........
<info> app:  01 61 C6 00 54 53 11 00|.a..TS..
<info> app:  A5 16 FF 00            |....    
<info> app: BLE_GATTS_EVT_WRITE
<info> app: command_char_handles
<info> app:  01 01 FF FF 00 00 A7 0B|........
<info> app:  AF 16 00 01 00 00 00 52|.......R
<info> app:  7C 07                  ||.      
<info> app: BLE_GATTS_EVT_WRITE
<info> app: command_char_handles
<info> app:  01 00 02 00 1E 00 1A 00|........
<info> app:  01 61 C6 00 54 53 11 00|.a..TS..
<info> app:  A5 16 FF 00            |....    
<info> app: BLE_GATTS_EVT_WRITE
<info> app: command_char_handles
<info> app:  01 01 FF FF 00 00 A7 0B|........
<info> app:  AF 16 00 01 00 00 00 52|.......R
<info> app:  7C 07                  ||.      
<info> app: BLE_GATTS_EVT_WRITE
<info> app: command_char_handles
<info> app:  01 00 02 00 1E 00 1A 00|........
<info> app:  01 61 C6 00 54 53 11 00|.a..TS..
<info> app:  A5 16 FF 00            |....    
<info> app: BLE_GATTS_EVT_WRITE
<info> app: command_char_handles
<info> app:  01 01 FF FF 00 00 A7 0B|........
<info> app:  AF 16 00 01 00 00 00 52|.......R
<info> app:  7C 07                  ||.     

======
Here, intentionally turning the power of the central device OFF/ON to trigger a reconnection.
======

<info> app: Disconnected, reason 8.
<info> app: PM_EVT_CONN_CONFIG_REQ
<info> app: PM_EVT_CONN_SEC_PARAMS_REQ
<info> peer_manager_handler: Peer data updated in flash: peer_id: 0, data_id: Peer rank, action: Update, no change
<info> app: PM_EVT_PEER_DATA_UPDATE_SUCCEEDED
<info> app: Writing or overwriting the data.
<info> app: Flash not changed.
<info> app: PM_PEER_DATA_ID_PEER_RANK
<warning> app: PM_EVT_BONDED_PEER_CONNECTED
<info> app: PM_EVT_LOCAL_DB_CACHE_APPLIED
<info> app: BLE_GAP_EVT_CONNECTED
<info> app: PM_EVT_CONN_SEC_START
<info> app: BLE_GAP_EVT_SEC_INFO_REQUEST
<info> peer_manager_handler: Connection secured: role: Peripheral, conn_handle: 0, procedure: Encryption
<info> peer_manager_handler: Peer data updated in flash: peer_id: 0, data_id: Peer rank, action: Update, no change
<info> app: PM_EVT_PEER_DATA_UPDATE_SUCCEEDED
<info> app: Writing or overwriting the data.
<info> app: Flash not changed.
<info> app: PM_PEER_DATA_ID_PEER_RANK
<warning> app: PM_EVT_CONN_SEC_SUCCEEDED
<info> app: BLE_GAP_EVT_CONN_SEC_UPDATE
<info> app: BLE_GAP_EVT_CONN_PARAM_UPDATE
<info> app: connection parameters updated. min_interval:160, max_interval:160, latency:0, timeout:810
<info> app: BLE_GAP_EVT_CONN_PARAM_UPDATE
<info> app: connection parameters updated. min_interval:80, max_interval:80, latency:0, timeout:810
<info> app: BLE_GAP_EVT_CONN_PARAM_UPDATE
<info> app: connection parameters updated. min_interval:160, max_interval:160, latency:0, timeout:810
<info> app: BLE_GAP_EVT_CONN_PARAM_UPDATE
<info> app: connection parameters updated. min_interval:80, max_interval:80, latency:0, timeout:810
<info> app: BLE_GAP_EVT_CONN_PARAM_UPDATE
<info> app: connection parameters updated. min_interval:160, max_interval:160, latency:0, timeout:810

Parents
  • 0

    Hi Keigo, 
    It seems like the central managed to reconnect so I am not sure why the write command was not sent. 
    My suggestion is to use a sniffer to capture the communication. This would give us more insight of what could be wrong. You may have issue decrypting the paired connection with the sniffer if you secure connection, but you may consider turn off pairing for the test. 

    Please double check the code of the central to see if it actually send the write command on the 2nd connection or not. 

  • 0 in reply to Hung Bui

    Dear Mr. Hung Bui,

    Thank you very much for responding to my inquiries!

    Is it possible to communicate with the Central without pairing by turning off pairing?

    Also, since the Central receives finished products from the trading company and is not involved in the internal software, I have no knowledge of it.
    Furthermore, it seems that there are other companies creating peripherals that collaborate with this Central using Nordic.

    However, before using Nordic chips, I successfully communicated with the Central using a peripheral with Linux's BlueZ.
    At that time, even after reconnecting, the write events were received properly.
    Therefore, it seems there may be an issue with the peripheral I am trying to implement with Nordic this time.

    Thank you for your assistance.

  • 0 in reply to Hung Bui

    Hello, Hung Bui-San.

    I can now see communication between Central and Peripheral using the sniffer.

    However, I'm getting the error "Encrypted packet decrypted incorrectly (bad MIC)." Is there a solution?
    I dumped the LTK "00 04 00 20 01 0a 00" in the lower left of the image and entered it into WireShark as SC LTK with 0x00040020010a00 (or in MSB),
    but it didn't work.

  • 0 in reply to keigo.imaizumi

    Hi Keigo, 

    You would need to input the key and then try to capture a new connection (with the 2 same device, they will re-use the LTK). 

    Could you send us your sniffer trace , even though it has "Encrypted packet decrypted incorrectly (bad MIC)." Both when you first bond the 2 devices and when you re-connect. 

  • 0 in reply to Hung Bui

    I will send a packet sniffer.

    No. 2358 is the first connection and bonding. No. 2682 marks the beginning of a reconnection. If there are any suspicious points, your guidance would be greatly appreciated! I've been struggling with this issue for days and haven't been able to resolve it.

  • 0 in reply to keigo.imaizumi

    Hi Keigo, 
    I don't see anything suspicious from the sniffer trace. 
    It seems that the re-encryption worked properly and the 2 devices managed to re-connect and re-pair with no problem. 
    The question, I guess, is why the central doesn't want to send the write request on reconnection. If the link can be decrypted it would be much easier to inspect. 
    Please make sure you type the key and click the arrow button after you enter it. 

    If your central accept legacy pairing you can try disable LESC and only do legacy pairing, this way the sniffer can automatic decrypt Just Work encryption without you providing the key. 

  • 0 in reply to Hung Bui

    Hello Mr. Hung Bui,

    I'm sorry, but I'm not sure how to obtain the key.
    I'm a beginner when it comes to bonding.
    Could you please provide guidance on how to obtain the key?
    By the way, is the key you mentioned the public key that appears in the sniffer? (Is it either x or y?)

    Also, what type of key should be set in WireShark? (The part where you choose SC LTK or SC Private Key, etc.)
    I apologize for the basic nature of these questions, as this is my first time delving into protocol analysis. Your guidance would be greatly appreciated!

    Thank you.

Reply
  • 0 in reply to Hung Bui

    Hello Mr. Hung Bui,

    I'm sorry, but I'm not sure how to obtain the key.
    I'm a beginner when it comes to bonding.
    Could you please provide guidance on how to obtain the key?
    By the way, is the key you mentioned the public key that appears in the sniffer? (Is it either x or y?)

    Also, what type of key should be set in WireShark? (The part where you choose SC LTK or SC Private Key, etc.)
    I apologize for the basic nature of these questions, as this is my first time delving into protocol analysis. Your guidance would be greatly appreciated!

    Thank you.

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