Error BT_BTM: Device not found after few seconds after successful connection

Xavi92
Posts: 36
Joined: Thu Mar 28, 2019 2:26 pm

Error BT_BTM: Device not found after few seconds after successful connection

Postby Xavi92 » Tue May 19, 2020 12:12 pm

Hello,

I want to implement secure communications between an ESP32 and a smartphone using BLE. Since the board with the ESP32 does not have display or input capabilities, I guess ECDH key exchange with no MITM protection (OOB is not an option) is the safest level. OTOH, I am not interested in storing LTK (bonding) as many devices will access the ESP32, so it is fine to repeat the pairing process every time.

After a few seconds after an apparently successful connection, an error from the BLE stack is triggered and the ESP32 disconnects from the paired device.

Code: Select all

I (1182) btc_spp: event ESP_SPP_INIT_EVT received
I (1202) gatts: event ESP_GATTS_REG_EVT received
I (1202) gatts: event ESP_GATTS_CREAT_ATTR_TAB_EVT received
I (1202) ble_gap: event ESP_GAP_BLE_ADV_DATA_RAW_SET_COMPLETE_EVT received
I (1212) gatts: event ESP_GATTS_START_EVT received
I (1212) ble_gap: event ESP_GAP_BLE_ADV_START_COMPLETE_EVT received
I (21262) gatts: event ESP_GATTS_CONNECT_EVT received
I (21262) ble_gap: Remote address:
I (21262) ble_gap: 0x3ffd4382   7e 9d 66 67 62 15                                 |~.fgb.|
W (21272) BT_SMP: Non bonding: No keys will be exchanged
I (22002) ble_gap: event ESP_GAP_BLE_UPDATE_CONN_PARAMS_EVT received
W (24582) BT_L2CAP: L2CA_EnableUpdateBleConnParams - unknown BD_ADDR 7e9d66676215
E (24592) BT_BTM: Device not found

I (24592) gatts: event ESP_GATTS_DISCONNECT_EVT received
I (24602) ble_gap: event ESP_GAP_BLE_AUTH_CMPL_EVT received
E (24602) ble_gap: authentication failed, reason=0x66
I (24612) ble_gap: event ESP_GAP_BLE_ADV_START_COMPLETE_EVT received

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