I ported a USBX using the stm32H5 development board, and then created a task to send data using FreeRtos, but the task runs three times before it successfully sends data once. I tried debugging with STLink, but it didn’t find the problem, where should I troubleshoot?

Here is my porting process

First I configured the USB using the STM32CubeMX

Then I added the USBX code and header files

After that I modify the code in usb.c to start the USB controller

I’m using USBX in STANDALONE mode, so run ux_system_tasks_run() in FreeRTOS.

void StartDefaultTask(void *argument)
{
  /* USER CODE BEGIN defaultTask */
  /* Infinite loop */
  for(;;)
  {
        /*==============LED===========================*/
        HAL_GPIO_WritePin(GPIOC, GPIO_PIN_12, GPIO_PIN_SET);
        vTaskDelay(500);
        HAL_GPIO_WritePin(GPIOC, GPIO_PIN_12, GPIO_PIN_RESET);
        vTaskDelay(500);
        
        /* call usbx system fuc*/
        ux_system_tasks_run();
        
  }
  /* USER CODE END defaultTask */
}

Next I used another task to send data via USB

static void SPILCDTaskFunction( void *pvParameters )
{
    char buf[100];
    int cnt = 0;
    while (1)
    {
        cnt ++;
        sprintf(buf, "LCD Task Test : %drn", cnt);
        //Draw_String(0, 0, buf, 0x0000ff00, 0);
        
        /* use usb send data */
        int ux_device_cdc_acm_send(uint8_t *datas, uint32_t len, uint32_t timeout);
        ux_device_cdc_acm_send((uint8_t *)buf, strlen(buf), 1000);
        
        vTaskDelay(1000);
        
    }
}

I was expecting to receive consecutive numbers per second on the serial port, but I didn’t get one for 3 seconds.

[14:07:59.126]收←◆LCD Task Test : 79

[14:08:02.119]收←◆LCD Task Test : 82

[14:08:05.102]收←◆LCD Task Test : 85

[14:08:08.094]收←◆LCD Task Test : 88

[14:08:11.077]收←◆LCD Task Test : 91

[14:08:14.072]收←◆LCD Task Test : 94

[14:08:17.052]收←◆LCD Task Test : 97

[14:08:32.993]收←◆LCD Task Test : 100

I used ST-Link debugging and found that this task is running fine, that is to say the Variable cnt grows continuously, but the ux_device_cdc_acm_send() function is called every three times before the data is successfully sent once

ux_device_cdc_acm_send() function

int ux_device_cdc_acm_send(uint8_t *datas, uint32_t len, uint32_t timeout)
{
    if (cdc_acm)

    {
        if (UX_SUCCESS == ux_device_class_cdc_acm_write_with_callback(cdc_acm, datas, len))
        {
            
        }
        else
        {
            return -1;
        }
    }
    else
    {
        return -1;
    }
        return 0;
}

I’m using the serial debugging assistant to send data to the board and he’s receiving it fine.

I don’t know where to look next to troubleshoot the error