,这就奇怪了.我看了一下STM32的资料说可以一个包的字节是maximum-packet-size packets 或者是a single short packet.为什么只能发送 maximum-packet-size (64字节)的数据包呢?
我的发送函数:
uint16_t VCP_DataTx (uint8_t* Buf, uint32_t Len)
{
uint8_t i;
for (i=0;i<64;i++) //这里如果不是64,就不能发送成功,必须是64的倍数,
{
APP_Rx_Buffer[APP_Rx_ptr_in] = g_ucaHeartbeat;
APP_Rx_ptr_in++;
/* To avoid buffer overflow */
if(APP_Rx_ptr_in == APP_RX_DATA_SIZE)
{
APP_Rx_ptr_in = 0;
}
}
return USBD_OK;
}
usb_cdc_core.c里面的代码我没修改,使用的是ST公司的USB库2.0版本.
/**
* @brief usbd_audio_SOF
* Start Of Frame event management
* @param pdev: instance
* @param epnum: endpoint number
* @retval status
*/
static uint8_t usbd_cdc_SOF (void *pdev)
{
static uint32_t FrameCount = 0;
if (FrameCount++ == CDC_IN_FRAME_INTERVAL)
{
FrameCount = 0;
/* Check the data to be sent through IN pipe */
Handle_USBAsynchXfer(pdev);
}
return USBD_OK;
}
/**
* @brief Handle_USBAsynchXfer
* Send data to USB
* @param pdev: instance
* @retval None
*/
static void Handle_USBAsynchXfer (void *pdev)
{
uint16_t USB_Tx_ptr;
uint16_t USB_Tx_length;
if(USB_Tx_State != 1)
{
if (APP_Rx_ptr_out == APP_RX_DATA_SIZE)
{
APP_Rx_ptr_out = 0;
}
if(APP_Rx_ptr_out == APP_Rx_ptr_in)
{
USB_Tx_State = 0;
return;
}
if(APP_Rx_ptr_out > APP_Rx_ptr_in) /* rollback */
{
APP_Rx_length = APP_RX_DATA_SIZE - APP_Rx_ptr_out;
}
else
{
APP_Rx_length = APP_Rx_ptr_in - APP_Rx_ptr_out;
}
#ifdef USB_OTG_HS_INTERNAL_DMA_ENABLED
APP_Rx_length &= ~0x03;
#endif /* USB_OTG_HS_INTERNAL_DMA_ENABLED */
if (APP_Rx_length > CDC_DATA_IN_PACKET_SIZE)
{
USB_Tx_ptr = APP_Rx_ptr_out;
USB_Tx_length = CDC_DATA_IN_PACKET_SIZE;
APP_Rx_ptr_out += CDC_DATA_IN_PACKET_SIZE;
APP_Rx_length -= CDC_DATA_IN_PACKET_SIZE;
}
else
{
USB_Tx_ptr = APP_Rx_ptr_out;
USB_Tx_length = APP_Rx_length;
APP_Rx_ptr_out += APP_Rx_length;
APP_Rx_length = 0;
}
USB_Tx_State = 1;
DCD_EP_Tx (pdev,
VL8461_IN_EP,
(uint8_t*)&APP_Rx_Buffer[USB_Tx_ptr],
USB_Tx_length); //这里的 USB_Tx_length 只要不是 64,就发送不成功????
}
}
|
楼主
