STMicroelectronics STM32F407 - Figure 397. Receive FIFO Read Task

USB on-the-go full-speed (OTG_FS) RM0090
1328/1731 DocID018909 Rev 11
• Reading the receive FIFO
The application must ignore all packet statuses other than IN data packet (bx0010).
Figure 397. Receive FIFO read task
• Bulk and control OUT/SETUP transactions
A typical bulk or control OUT/SETUP pipelined transaction-level operation is shown in
Figure 398. See channel 1 (ch_1). Two bulk OUT packets are transmitted. A control
SETUP transaction operates in the same way but has only one packet. The
assumptions are:
– The application is attempting to send two maximum-packet-size packets (transfer
size = 1, 024 bytes).
– The non-periodic transmit FIFO can hold two packets (128 bytes for FS).
– The non-periodic request queue depth = 4.
• Normal bulk and control OUT/SETUP operations
The sequence of operations in (channel 1) is as follows:
a) Initialize channel 1
b) Write the first packet for channel 1
c) Along with the last Word write, the core writes an entry to the non-periodic request
queue
d) As soon as the non-periodic queue becomes non-empty, the core attempts to
send an OUT token in the current frame
e) Write the second (last) packet for channel 1
RXFLVL
interrupt ?
Read the received
packet from the
Receive FIFO
Read
OTG_FS_GRXSTSP
PKTSTS
0b0010?
Yes
Yes
Unmask RXFLVL
interrupt
BCNT > 0?
No
Mask RXFLVL
interrupt
Yes
Unmask RXFLVL
interrupt
No
No
Start
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