Add Ble Scan to usbd_ble_uart_freertos example

[shai.c]

Hi I'm trying to change peripheral usbd_ble_uart_freertos example to central with nus_c
I added the scan and nuc_c module.
When I'm testing the application, before making a connection with the peripheral all USB events are working as expected.
After the connection is established new USB events stop working.

This is the code that is responsible for USB events

void usb_new_event_isr_handler(app_usbd_internal_evt_t const * const p_event, bool queued)
{
    BaseType_t xHigherPriorityTaskWoken = pdFALSE;
    UNUSED_PARAMETER(p_event);
    UNUSED_PARAMETER(queued);
    ASSERT(m_usbd_thread != NULL);
    /* Release the semaphore */
    vTaskNotifyGiveFromISR(m_usbd_thread, &xHigherPriorityTaskWoken);
    portYIELD_FROM_ISR(xHigherPriorityTaskWoken);
}

static void usbd_thread(void * arg)
{
    ret_code_t ret;
    static const app_usbd_config_t usbd_config = {
        .ev_isr_handler = usb_new_event_isr_handler,
        .ev_state_proc  = usbd_user_ev_handler
    };
    UNUSED_PARAMETER(arg);

    ret = app_usbd_init(&usbd_config);
    APP_ERROR_CHECK(ret);
    app_usbd_class_inst_t const * class_cdc_acm = app_usbd_cdc_acm_class_inst_get(&m_app_cdc_acm);
    ret = app_usbd_class_append(class_cdc_acm);
    APP_ERROR_CHECK(ret);
    ret = app_usbd_power_events_enable();
    APP_ERROR_CHECK(ret);

    // Set the first event to make sure that USB queue is processed after it is started
    UNUSED_RETURN_VALUE(xTaskNotifyGive(xTaskGetCurrentTaskHandle()));
    // Enter main loop.
    for (;;)
    {
        /* Waiting for event */
        UNUSED_RETURN_VALUE(ulTaskNotifyTake(pdTRUE, USB_THREAD_MAX_BLOCK_TIME));
        while (app_usbd_event_queue_process())
        {
            /* Nothing to do */
        }
    }
}

It looks that events are received in usb_new_event_isr_handler function, but usbd_thread keep waiting for the event - stuck in ulTaskNotifyTake

 

[shai.c]

Thanks Susheel feel better

[Einar Thorsrud]

Hi,

I took over this case from Susheel. I did just basic testing and then I see I get USB events even when connected. See log:

<info> app: USBD BLE UART example started.
<info> app: Connecting to target 45C36938A3C6
<info> app: ATT MTU exchange completed.
<info> app: Ble NUS max data length set to 0xF4(244)
<info> app: USB power detected
<info> app: USB ready
<info> app: USB power removed
<info> app: CDC ACM port closed

Can you elaborate on the procedure I should follow to reproduce the issue you are seeing, and explain it in a bit more detail?

[shai.c]

Hi Einar,

which SDK version are you using?

This is my log:

<info> app: USBD BLE UART example started.
<info> app: Connecting to target 4DB83F7296C5
<info> app: ATT MTU exchange completed.
<info> app: Ble NUS max data length set to 0xF4(244)
<info> app: Discovery complete.
<info> app: Connected to device with Nordic UART Service.

why i don't see in your logs the following messages:

<info> app: Discovery complete.
<info> app: Connected to device with Nordic UART Service.

Did you close the discovery module?

[Einar Thorsrud]

Hi,

I did a naive test with a dummy peripheral that did not actually implement the NUS service, so no NUS service was discovered. Then I did not see any USB issues. Testing again with a device that actually implements the NUS service and where that is discovered I also see USB events missing. I need to look more into it, though.

[Einar Thorsrud]

Hi,

The problem here is that there is a stack overflow in the BLE task (SoftDevice handler implemented in  <SDK>\components\softdevice\common\nrf_sdh_freertos.c). You can see that by setting configCHECK_FOR_STACK_OVERFLOW to 2 in FreeRTOSConfig.h and a breakpoint in vApplicationStackOverflowHook() in your main.c.

To fix the issue increase NRF_BLE_FREERTOS_SDH_TASK_STACK in nrf_sdh_freertos.c, for instance to 512.

[shai.c]

Hi Einar,

Thanks for solving the issue!!