Not able to bond a BLE thermoter with a random passkey

[Daniela_A]

Hello all,

Currently I´m developing a code to be load to the SDK to act as a master in a BLE communication. The peripheral is a BLE thermoter that, in order to preform bonding, displays a random pin to be entered. When the event BLE_GAP_EVT_AUTH_KEY_REQUEST happens, I rise a flag that stops the infinite loop in the main and receive the passkey via UART. Using the function sd_ble_gap_auth_key_reply, I  send the corresponding pin and then the bond should be established. However, nothing happens and I get the following errors:

<info> app: Error code: 3002
<info> peer_manager_handler: Connection security failed: role: Central, conn_handle: 0x0, procedure: Bonding, error: 1
<debug> app: PM_EVT_CONN_SEC_FAILED
<info> app: BLE_GAP_EVT_AUTH_STATUS: status=0x1 bond=0x0 lv4: 0 kdist_own:0x0 kdist_peer:0x0
<info> app: Disconnected, reason 0x13.

I am attaching the main of the code so you can take a better look

int main(void)
{
    bool erase_bonds;
    uint8_t i = 0;
    uint8_t therm_passkey [6] = {};
    
    // Initialize.
    log_init();
    uart_init();
    timer_init();
    power_management_init();
    buttons_leds_init(&erase_bonds);
    ble_stack_init();
    gatt_init();
    peer_manager_init();
    db_discovery_init();

    hrs_c_init();
    bas_c_init();
    hts_c_init();

    scan_init();

    pairing_init(&m_scan);

    // Start execution.
    NRF_LOG_INFO("Health Thermometer collector example started.\n");
    scanning_start(&erase_bonds);

    // Enter main loop.
    for (;;)
    {
        /* This part of the code will be called once the event: "BLE_GAP_EVT_AUTH_KEY_REQUEST" is triggered. */ 
        if(f_pin)
        {   
            uint32_t err_code;
            uint8_t cr;
            while (app_uart_get(&cr) != NRF_SUCCESS);
            while (app_uart_put(cr) != NRF_SUCCESS);
            
            if (cr == '\r' || cr == '\n')
            {
                printf("PASSWORD %.6s \n",(char *) therm_passkey);
                f_pin = false;
                err_code = sd_ble_gap_auth_key_reply(g_p_ble_evt->evt.gap_evt.conn_handle,BLE_GAP_AUTH_KEY_TYPE_PASSKEY,therm_passkey);
                NRF_LOG_INFO("Error code: %x", err_code);
                i = 0;
                continue;
            }
            
            therm_passkey[i++] = cr;
        }

        idle_state_handle();

    }
}

[Amanda Hsieh]

Hi, 

Try to reply to the key in the BLE_GAP_EVT_AUTH_KEY_REQUEST event instead of the main loop. 

Regards,
Amanda

[Daniela_A]

I tried doing that too. The problem is that when the event happens, an interruption triggers and the part of receiving the key via UART doesn´t work 

[Amanda Hsieh]

Hi, 

The error code 0x3002 corersponds to BLE_ERROR_INVALID_CONN_HANDLE. Is it returned by sd_ble_gap_auth_key_reply() function? If so, How you set this, "g_p_ble_evt->evt.gap_evt.conn_handle"?

-Amanda

[Daniela_A]

Yes, it is returned by the function. What do you mean by how do I set  "g_p_ble_evt->evt.gap_evt.conn_handle"?

PS: Thank you for your help

[Amanda Hsieh]

Hi, 

yes, You need to check the input conn_handle of  sd_ble_gap_auth_key_reply() because the error code indicates BLE_ERROR_INVALID_CONN_HANDLE. 

-Amanda

[Daniela_A]

Hello,

Now I understand what you are telling me.

Since I need to use the conn_handle of the ble_evt in the main, what I do is that I am declaring a global variable in the first lines of the program like this:

ble_evt_t * g_p_ble_evt;  

Later, when the event triggers, I´m passing the information of the p_ble_evt to g_p_ble_evt

 

 case BLE_GAP_EVT_AUTH_KEY_REQUEST:
            NRF_LOG_INFO("BLE_GAP_EVT_AUTH_KEY_REQUEST");
            f_pin = true;
            g_p_ble_evt=p_ble_evt;
            break;