I'm sending a continuous data stream from uC to PC via VCP which is implemented as CDC. During stream every responded IN token for EP1 generates DIEPINT_XFRC, so I'm seeing interrupts:
DIEPINT_XFRC
DIEPINT_XFRC
DIEPINT_XFRC
...
Now I send something to uC and get these interrupts:
1. GINTSTS_RXFLVL (GRXSTS_PKTSTS_OUT_DATA_RECEIVED)
2.GINTSTS_RXFLVL (GRXSTS_PKTSTS_OUT_TRANSFER_COMPLETED)
3. GINTSTS_OEPINT (DOEPINT_TRANSFER_COMPLETED)
thereafter again, the stream to PC
...
DIEPINT_XFRC
DIEPINT_XFRC
...
But sometimes (I thing if the OUT token is received at some wrong uC USB stage) i get:
1. GINTSTS_RXFLVL (GRXSTS_PKTSTS_OUT_DATA_RECEIVED) //ok
2. GINTSTS_RXFLVL (GRXSTS_PKTSTS_OUT_TRANSFER_COMPLETED) //ok
3. GINTSTS_OEPINT (DOEPINT_TRANSFER_COMPLETED) //ok
4. GINTSTS_RXFLVL (SETUP_DATA_PACKET_RECEIVED)
5. GINTSTS_RXFLVL (SETUP_COMPLETED)
6. GINTSTS_OEPINT (USB_REQUEST_CLEAR_FEATURE) <---
Why clear feature? It seems that the core is not acknowledging the last OUT transfer and PC tries to reset the device.
With limited transmission blocks from uC to PC:
send command from PC to uC-> receive data block
send command from PC to uC-> receive data block
...
everything is working fine.
