Multiple FreeRTOS Softdevice Tasks not Working

[VikramB]

Hi,

I want to create 2 softdevice tasks, 1 for advertising and 1 for scanning. I have ported the dependencies and some code from the ble_app_freertos_pca10040_s132 into the ble_app_hrs_rscs_relay_pca10040_s132  example. When I call nrf_sdh_freertos_init(adv_scan_start, &erase_bonds) the board works as intended, and does both advertising and scanning correctly, as far as I can tell. When I have two calls to nrf_sdh_freertos_init, however, I get an ERROR 8 (Invalid State) on the advertising side. Why does this occur when I try to run them as 2 separate threads? 

Advertising and Scanning code:

static void scanning_start(void * p_erase_bonds)
{
   scan_start();
    
}
static void advertising_start(void * p_erase_bonds)
{
    bool erase_bonds = *(bool*)p_erase_bonds;

    if (erase_bonds)
    {
        delete_bonds();
        // Advertising is started by PM_EVT_PEERS_DELETE_SUCCEEDED event.
    }
    else
    {
        //scan_start();
        ret_code_t err_code = ble_advertising_start(&m_advertising, BLE_ADV_MODE_FAST);
        APP_ERROR_CHECK(err_code);
        //adv_scan_start();
        //ret_code_t err_code = ble_advertising_start(&m_advertising, BLE_ADV_MODE_FAST);
        //APP_ERROR_CHECK(err_code);
    }
}

Calls to create threads in Main:

    nrf_sdh_freertos_init(scanning_start, &erase_bonds);

    nrf_sdh_freertos_init(advertising_start, &erase_bonds);
    // Start FreeRTOS scheduler.
    vTaskStartScheduler();

Serial Output: 

app: ERROR 8 [NRF_ERROR_INVALID_STATE] at C:\Users\vikra\Downloads\NRFClean\nRF5_SDK_14.2.0_17b948a\examples\ble_central_and_peripheral\experimental\ble_app_hrs_rscs_relay\main.c:1367

Where the error line is line 19 in the advertising_start function.

[Susheel Nuguru]

Probably because the advertising init runs before the softdevice is initialized. The SD initialization could take many milliseconds depending on the accuracy of the LF clock you are using. If you want to run them in two different threads, you need to make sure that advertising task is blocked until SD is initialized

[VikramB]

isn't the softdevice initialized in ble_stack_init? I have called that above the included code in the main function, along with the other requisite initialization functions that are present in the ble_app_hrs_rscs_relay_pca10040_s132 example

[Susheel Nuguru]

The trick is to make sure that the advertising init isn't called until the ble is initialized. and softdevice task is created. 

Then you start advertising just before polling for events.

If you do not do it this way, It is possible that you start advertising way ahead the softdevice_has finished initializing (it could take many milliseconds after you called the softdevice_enable, since it need to calibrate the clocks if necessary)