Disconnect nrf51822 when the correct connection interval is not negotiated with the phone

[ua09]

Hi Sometimes the nrf the central does not accept my connection interval of 7.5ms. I want to disconnect nrf51822 when the correct connection interval is not negotiated with the phone.just want to know if the if statement at the end of the code is the correct way to do this

static void conn_params_init(void)
{
 uint32_t err_code;
 ble_conn_params_init_t cp_init;

 memset(&cp_init, 0, sizeof(cp_init));

 cp_init.p_conn_params = NULL;
 cp_init.first_conn_params_update_delay = FIRST_CONN_PARAMS_UPDATE_DELAY;
cp_init.next_conn_params_update_delay = NEXT_CONN_PARAMS_UPDATE_DELAY;
cp_init.max_conn_params_update_count = MAX_CONN_PARAMS_UPDATE_COUNT;
cp_init.start_on_notify_cccd_handle = BLE_GATT_HANDLE_INVALID;
cp_init.disconnect_on_fail = true;
cp_init.evt_handler = on_conn_params_evt;
cp_init.error_handler = conn_params_error_handler;

err_code = ble_conn_params_init(&cp_init);


APP_ERROR_CHECK(err_code);
}

This is my conn_params_negotiation function. I believe the app_start_timer is called in the right position

static void conn_params_negotiation(void) {

// Start negotiation if the received connection parameters are not acceptable
if (!is_conn_params_ok(&m_current_conn_params))
{
    uint32_t err_code;
    uint32_t timeout_ticks;

    if (m_change_param)
    {
        // Notify the application that the procedure has failed
        if (m_conn_params_config.evt_handler != NULL)
        {
            ble_conn_params_evt_t evt;

            evt.evt_type = BLE_CONN_PARAMS_EVT_FAILED;
            m_conn_params_config.evt_handler(&evt);
        }
    }
    else
    {
        if (m_update_count == 0)
        {
            // First connection parameter update
            timeout_ticks = m_conn_params_config.first_conn_params_update_delay;
        }
        else
        {
            timeout_ticks = m_conn_params_config.next_conn_params_update_delay;
        }

        err_code = app_timer_start(m_conn_params_timer_id, timeout_ticks, NULL);
        if ((err_code != NRF_SUCCESS) && (m_conn_params_config.error_handler != NULL))
        {
            m_conn_params_config.error_handler(err_code);
        }
    }
}
else
{
    // Notify the application that the procedure has succeded
    if (m_conn_params_config.evt_handler != NULL)
    {
        ble_conn_params_evt_t evt;

        evt.evt_type = BLE_CONN_PARAMS_EVT_SUCCEEDED;
        m_conn_params_config.evt_handler(&evt);
    }
}
m_change_param = false;

}

This is my conn_params_change_conn_params

uint32_t ble_conn_params_change_conn_params(ble_gap_conn_params_t * new_params) {

uint32_t err_code;

m_preferred_conn_params = *new_params;
// Set the connection params in stack
err_code = sd_ble_gap_ppcp_set(&m_preferred_conn_params);
if (err_code == NRF_SUCCESS)
{
    if (!is_conn_params_ok(&m_current_conn_params))
    {
        m_change_param = true;
        err_code = sd_ble_gap_conn_param_update(m_conn_handle, &m_preferred_conn_params);
        m_update_count = 1;
    }
    else
    {
        // Notify the application that the procedure has succeded
        if (m_conn_params_config.evt_handler != NULL)
        {
            ble_conn_params_evt_t evt;

            evt.evt_type = BLE_CONN_PARAMS_EVT_SUCCEEDED;
            m_conn_params_config.evt_handler(&evt);
        }
        err_code = NRF_SUCCESS;
    }
}
return err_code;

}

[Hung Bui]

Hi,

I don't understand why you check for the return code of ble_conn_params_init() and then call disconnect if it's not success.

ble_conn_params_init() is not really the place to check if the connection interval is not accepted by peer device. ble_conn_params_init() is where you configure the parameter with the ble_conn_params.c module. It only configure the parameter locally, and at that moment you don't know if the peer device will accept or reject the request.

What you should do is to configure the disconnect_on_fail parameter. If you set it to true, later when the negotiation is failed, the ble_conn_params.c module will disconnect. Please have a look at the update_timeout_handler() function in the file.

I can see that disconnect_on_fail is already set, did you see the behaviour that the peripheral disconnect after connection parameter update request failed ?

[ua09]

Hi Thanks for the reply. I removed the if statement ( and changed it in the question as well) and tried to implement this with cp_init.disconnect_on_fail = true; but it still does not work. when a connection interval of 7.5ms is not accepted a default of 48.75ms is accepted and the data slows down

[Hung Bui]

@ua09: Could you try to debug and see if the update_timeout_handler() is triggered ? If you can provide a sniffer trace it could be very helpful.

Which was the max connection interval and min connection interval you requested ?

[ua09]

Both max and min are set to 7.5ms

[Hung Bui]

@ua: Please make sure m_conn_params_timer_id timer is started and update_timeout_handler() is triggered on each timeout.