Restart Scanning failed - SD140 6.1.0

[lolek]

Hi 

I'm facing a problem since I've upgraded to SD140 6.1 . 

I'm running as multilink central, and want to keep scanning even after connection. I scan with the following parameters:

static ble_gap_scan_params_t m_scan_params =
    {
        .active = 0,
        .extended = 1,
        .report_incomplete_evts = 0,
        .scan_phys = BLE_GAP_PHY_1MBPS | BLE_GAP_PHY_CODED,
        .interval = 0x00A0,
        .window = 0x0050,
        .timeout = 0,
        .filter_policy = BLE_GAP_SCAN_FP_ACCEPT_ALL};

I have a peripheral set to CODED who advertise with whitelist that doesn't include the current central, but it advertises in its surroundings and with the same name that the scanner is looking for.

when the central gets adv_report from this sensor, it tries to connect (usually what happens is that it connects to the peripheral, and then fails on security check):

    err_code = sd_ble_gap_connect(&p_adv_report->peer_addr, &m_scan_params, &m_connection_param, APP_BLE_CONN_CFG_TAG);

it returns NRF_SUCCESS, but I don't get any event back from  ble_evt_handler() (as far as I know, once I called sd_ble_gap_connect(), it has to call back...).

inside  ble_evt_handler() , I call scan_start() to restart scanning. but as nothing was returned the scan didn't restarted. so I moved the call to right after sd_ble_gap_connect().

inside scan_start(), when I call:

        err_code = sd_ble_gap_scan_start(&m_scan_params, &m_scan_buffer);

I get an error: NRF_ERROR_INVALID_STATE

I then try to stop and start:

err_code = sd_ble_gap_scan_stop();
APP_ERROR_CHECK(err_code);
err_code = sd_ble_gap_scan_start(&m_scan_params, &m_scan_buffer);
APP_ERROR_CHECK(err_code);

but I get NRF_ERROR_INVALID_STATE from sd_ble_gap_scan_stop()

my questions are:

1. why I'm not getting any event after connecting?
2. why both sd_ble_gap_scan_start() and sd_ble_gap_scan_stop() returns NRF_ERROR_INVALID_STATE? as far as I understand, sd_ble_gap_scan_start() returns that error if a scan is already running (i tried to run it with scan_params = NULL and got NRF_ERROR_INVALID_STATE, so I'm guessing the only reason is that scan is already running), and sd_ble_gap_scan_stop() will return that error if scan is not running, so it doesn't makes sense...

thanks for the help

[lolek]

I found a solution for the problem above - I changed the Advertising timeout from infinite to 1 min.

if the corrupted sensors tries to connect, after the advertising time out I get BLE_GAP_TIMEOUT_SRC_CONN instead of BLE_GAP_TIMEOUT_SRC_SCAN and then start scanning again.

it seems like a bug...

[Kenneth]

Hi,

I can see that you have already found the problem and the solution. Here you can find the message sequence chart for sd_ble_gap_connect():
http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.s132.api.v6.0.0/group___b_l_e___g_a_p___c_e_n_t_r_a_l___c_o_n_n___m_s_c.html 

You will either get the BLE_GAP_EVT_CONNECTED or the BLE_GAP_EVT_TIMEOUT event, however if you set timeout to infinite (e.g. .timeout = 0), then you may become stuck forever if the peripheral device is no longer present by the time you call sd_ble_gap_connect(). So it is recommended to set a reasonable timeout (e.g. a few seconds to a minute) in case the peripheral device is no longer present.

Best regards,
Kenneth