RM0033 Rev 9 1235/1381
RM0033 USB on-the-go high-speed (OTG_HS)
1260
4. The receive FIFO packet status readout indicates one of the following:
a) Global OUT NAK pattern:
PKTSTS = Global OUT NAK, BCNT = 0x000, EPNUM = Don’t Care (0x0),
DPID = Don’t Care (0b00).
These data indicate that the global OUT NAK bit has taken effect.
b) SETUP packet pattern:
PKTSTS = SETUP, BCNT = 0x008, EPNUM = Control EP Num, DPID = D0.
These data indicate that a SETUP packet for the specified endpoint is now
available for reading from the receive FIFO.
c) Setup stage done pattern:
PKTSTS = Setup Stage Done, BCNT = 0x0, EPNUM = Control EP Num,
DPID = Don’t Care (0b00).
These data indicate that the Setup stage for the specified endpoint has completed
and the Data stage has started. After this entry is popped from the receive FIFO,
the core asserts a Setup interrupt on the specified control OUT endpoint.
d) Data OUT packet pattern:
PKTSTS = DataOUT, BCNT = size of the received data OUT packet
(0 ≤ BCNT ≤ 1 024), EPNUM = EPNUM on which the packet was received,
DPID = Actual Data PID.
e) Data transfer completed pattern:
PKTSTS = Data OUT Transfer Done, BCNT = 0x0, EPNUM = OUT EP Num
on which the data transfer is complete, DPID = Don’t Care (0b00).
These data indicate that an OUT data transfer for the specified OUT endpoint has
completed. After this entry is popped from the receive FIFO, the core asserts a
Transfer Completed interrupt on the specified OUT endpoint.
5. After the data payload is popped from the receive FIFO, the RXFLVL interrupt
(OTG_HS_GINTSTS) must be unmasked.
6. Steps 1–5 are repeated every time the application detects assertion of the interrupt line
due to RXFLVL in OTG_HS_GINTSTS. Reading an empty receive FIFO can result in
undefined core behavior.
Figure 389 provides a flowchart of the above procedure.
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