STM32F4的USART数据接收问题

发布于 2017-02-22 13:56:26 浏览：4710 订阅该版

STM32F407VET6+RT-Thread v2.1.0 beta，工程用的是BSP包中的stm32f4xx，MDK
出现的问题：
使用USART2，DMA中断模式，每次只接收上位机发送的前64个字节，就停止了中断。如果是INT_RX模式，每次只接收1个字节，只响应3次，设置如下：

初始化
```
void usart_dev_init(void)
{
    rt_err_t res;
    
    GPS_uart = rt_device_find("uart2");
    if( GPS_uart == RT_NULL )
    {
        rt_kprintf("uart2 not found!!
");
        return;
    }
    
    rt_device_set_rx_indicate(GPS_uart, GPS_usart_rx_indicate);
    res = rt_device_open(GPS_uart, RT_DEVICE_OFLAG_RDWR | RT_DEVICE_FLAG_DMA_RX);
    if (res != RT_EOK)
    {
        rt_kprintf("open GPS uart error: 0x%x", -res);
    }
}

// 线程
static void threads_init(void)
{
    rt_thread_t usart_rx_thread;

// USART rx thread.  rx is interrupt.
    usart_rx_thread = rt_thread_create("urx", usart_rx_thread_entry, RT_NULL, 1024, 3, 5);
    rt_thread_startup(usart_rx_thread);
}
```

```
rt_err_t GPS_usart_rx_indicate(rt_device_t dev, rt_size_t size)
{
    rt_sem_release(&rx_sem);
    return RT_EOK;
}

void usart_rx_thread_entry(void *p)
{
    rt_bool_t result;

while( rt_sem_take(&rx_sem, RT_WAITING_FOREVER) == RT_EOK )
    {
        register rt_base_t temp;

// Clear the semaphore.
        temp = rt_hw_interrupt_disable();
        rx_sem.value = 0;
        rt_hw_interrupt_enable(temp);
        
        while( 1 )
        {
            int len;

// read data.
            len = rt_device_read(GPSBD_uart,  0,  rx_buf,  RX_BUF_SIZE);

usart_bytes_recv += len;

// If receive data is empty and break
            if( len == 0 )
            {
                break;
            }
        }
    }
    rt_kprintf("Error taking semaphore, usart rx exit!
");
}
```

我看usart.c的函数dma_uart_config（）中已经设置为DMA_InitStructure.DMA_Mode = DMA_Mode_Circular啦，为什么还是只响应一次中断呢？还有哪个细节没处理好吗？请高手指点指点。