AT32F425
Series Reference Manual
2022.03.30
Page 350
Ver 2.01
request queue before starting to write to the the transmit FIFO. The application must always write to the
transmit FIFO in DWORDs. If the packet size is not aligned with DWORD, the application must use
padding. The OTGFS host determines the actual packet size according to the programmed maximum
packet size and transfer size.
Figure 20-3 Writing the transmit FIFO
Wait for
GAHBCFG.NPTXFEMPLVL or
GAHBCFG.PTXFEMPLVL
interrupt
Read GNPTXSTS/
HPTXSIZ registers for
available FIFO and queue
spaces
1 MPS or
LPS FIFO is space
available?
Write 1 packet data
to Transmit FIFO
More packets to
send?
Start
Done
No
No
Yes
Yes
MPS
:
Max Packet Size
LPS
:
Last Packet Size
No
Reading the receive FIFO
shows the flow chart of reading the receive FIFO. The application must ignore all packet
statuses other than IN data packet (0x0010)