Blacklisted issue in STM32WBA

Question

Title: STM32WBA BLE: Device Gets Blacklisted on Wrong PIN Entry (Guard Timer Issue)

Description:

I am working with an STM32WBA BLE SoC where the TCU (Telematics Control Unit) is advertising its services. When an iOS/Android device tries to connect, a popup appears asking for the BLE PIN. If the user enters the wrong PIN or cancels the popup, the device gets blacklisted.

Observed Behavior:

If the user enters the correct PIN, the connection works as expected.

If the user enters the wrong PIN or cancels the pairing request, the iOS/Android device gets blacklisted.

According to STM32WBA BLE logs, the second connection attempt from the phone comes after 10 seconds.

The Guard Timer behavior is internal to the STM32WBA BLE stack and is not configured manually by me.

Despite this, the iOS device remains blacklisted and cannot reconnect.

If I disable CFG_SC_SUPPORT (LE Secure Connections), this issue does not occur.

However, I must keep LE Secure Connections enabled for security reasons.

Configuration:

LE Secure Connections (CFG_SC_SUPPORT): Enabled

Pairing Method: PIN entry (numeric comparison)

I tried disabling then LE Secure then it works proper But i want to keep it on

Stopping ADV Lpw Pwr Timer
[00029.406:5115]==>> aci_gap_set_non_discoverable - Success
[00029.406:5115]==>> aci_gap_set_discoverable - Success
[00029.406:5115]==>> Success: Start Advertising
[00034.290:5952]
Stopping ADV Lpw Pwr Timer
[00034.290:5952]INIT SECURITY TIMER
[00034.290:5952]
supervision timeout less
[00034.290:5952]==>> aci_l2cap_connection_parameter_update_req - Success
[00034.406:5968]RTCTM386D43A2
[00034.696:6020]>>== HCI_LE_CONNECTION_UPDATE_COMPLETE_SUBEVT_CODE
[00034.696:6020]     - Connection Interval:   45.00 ms
     - Connection latency:    0
     - Supervision Timeout:   5000 ms
[00034.870:6045]STATUS [0]
[00034.870:6045]Periph security request cmd success
[00035.290:6122]  MTU exchanged size = 512
[00035.290:6122]>>== MTU_size = 512
[00035.290:6122]
[00035.290:6122]
>>== CONNECTION READY
[00035.348:6135]RTCTM386D43A3
[00035.812:6209]>>== ACI_GAP_PASS_KEY_REQ_VSEVT_CODE
[00035.812:6209]==>> aci_gap_pass_key_resp : Success
[00039.232:6785]TCU Sendng the heartbeat ...
[00039.232:6785]pData->p_Payload[0] = 0
[00039.232:6785]pData->p_Payl`your text`oad[1] = 1
[00039.290:6802]RTCTM386D43A6
[00039.406:6820]>>== ACI_GAP_PAIRING_COMPLETE_VSEVT_CODE
[00039.406:6820]     - Pairing KO
     - Status: 0x02
     - Reason: 0x01
[00039.406:6820]Pairing Failed: Disconnecting !!!!
[00039.406:6820]Stopping Connection - APP_BLE_CONNECTED_SERVER
[00039.406:6820]==>> aci_gap_terminate : Success
[00039.522:6835]>>== HCI_DISCONNECTION_COMPLETE_EVT_CODE
[00039.522:6836]     - Connection Handle:   0x01
     - Reason:    0x16
[00039.522:6836]==>> aci_gap_set_discoverable - Success
[00039.522:6836]==>> Success: Start Advertising
[00039.522:6836]
Starting ADV Lpw Pwr Timer
[00047.812:8245]
Stopping ADV Lpw Pwr Timer
[00047.812:8245]INIT SECURITY TIMER
[00047.812:8245]
supervision timeout less
[00047.812:8245]==>> aci_l2cap_connection_parameter_update_req - Success
[00048.116:8303]RTCTM386D43AF
[00048.174:8314]>>== HCI_LE_CONNECTION_UPDATE_COMPLETE_SUBEVT_CODE
[00048.174:8314]     - Connection Interval:   45.00 ms
     - Connection latency:    0
     - Supervision Timeout:   5000 ms
[00048.406:8345]STATUS [89]
[00048.406:8345]Periph security request hdl: 1 cmd failure: 0x59
[00048.812:8416]  MTU exchanged size = 512
[00048.812:8416]>>== MTU_size = 512
[00048.812:8416]
[00048.812:8416]
>>== CONNECTION READY
[00049.116:8470]RTCTM386D43B0
[00049.928:8613]>>== ACI_GAP_PAIRING_COMPLETE_VSEVT_CODE
[00049.928:8613]     - Pairing KO
     - Status: 0x02
     - Reason: 0x09
[00049.928:8613]Pairing Failed: Disconnecting !!!!
[00049.928:8613]Stopping Connection - APP_BLE_CONNECTED_SERVER
[00049.928:8613]==>> aci_gap_terminate : Success
[00050.058:8628]>>== HCI_DISCONNECTION_COMPLETE_EVT_CODE
[00050.058:8628]     - Connection Handle:   0x01
     - Reason:    0x16
[00050.058:8629]==>> aci_gap_set_discoverable - Success
[00050.058:8629]==>> Success: Start Advertising
[00050.058:8629]
Starting ADV Lpw Pwr Timer
[00051.058:8804][               imu thread]RunCnt:00000773,ST:006
[00051.058:8804][               CAN`