portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;                        
    if( SET == USART_GetITStatus( USART1, USART_IT_RXNE ) )              
    {                                                                        
        u16 b;                                                        
        USART_ClearITPendingBit( USART1, USART_IT_RXNE );                  
        b = USART_ReceiveData( USART1 );                                
        if( !(USART1->SR & (USART_FLAG_ORE | USART_FLAG_FE | USART_FLAG_PE | USART_FLAG_NE) ) )
        {                                                                    
            CB_Push( cb_rx, b );// помещает байт в конец циклического буфера
            // использую очередь для индикации "приема"
            xQueueSendFromISR( rx_q, &b, &xHigherPriorityTaskWoken);
        }                                                                      
    }                                                                          
    portEND_SWITCHING_ISR(xHigherPriorityTaskWoken);

void Task( void * pvParameters)
{
    u16 q_mes;
    for(;; )
    {
        if( pdFALSE == xQueueReceive( rx_q, (void *)&q_mes, 10 )
           || CB_GetFreeSize(cb_rx) < 100 )
        {
            // если здесь значит за 10 мс не было байт либо в буфере осталось
            // место для < 100 байт
            
        }
    }
}

void vListInsert( xList *pxList, xListItem *pxNewListItem )
{
volatile xListItem *pxIterator;
portTickType xValueOfInsertion;

    /* Insert the new list item into the list, sorted in ulListItem order. */
    xValueOfInsertion = pxNewListItem->xItemValue;

    /* If the list already contains a list item with the same item value then
    the new list item should be placed after it.  This ensures that TCB's which
    are stored in ready lists (all of which have the same ulListItem value)
    get an equal share of the CPU.  However, if the xItemValue is the same as
    the back marker the iteration loop below will not end.  This means we need
    to guard against this by checking the value first and modifying the
    algorithm slightly if necessary. */
    if( xValueOfInsertion == portMAX_DELAY )
    {
        pxIterator = pxList->xListEnd.pxPrevious;
    }
    else
    {
        for( pxIterator = ( xListItem * ) &( pxList->xListEnd ); pxIterator->pxNext->xItemValue <= xValueOfInsertion; pxIterator = pxIterator->pxNext )
        {
            /* There is nothing to do here, we are just iterating to the
            wanted insertion position. */
// <-------------- из этого цикла не выходит по причине
// pxIterator = pxIterator->pxNext, в итоге указывает на самого же себя и соотв. если
// pxIterator->pxNext->xItemValue <= xValueOfInsertion то уже и не выйдет никогда...
        }
    }

    pxNewListItem->pxNext = pxIterator->pxNext;
    pxNewListItem->pxNext->pxPrevious = ( volatile xListItem * ) pxNewListItem;
    pxNewListItem->pxPrevious = pxIterator;
    pxIterator->pxNext = ( volatile xListItem * ) pxNewListItem;

    /* Remember which list the item is in.  This allows fast removal of the
    item later. */
    pxNewListItem->pvContainer = ( void * ) pxList;

    ( pxList->uxNumberOfItems )++;
}