RM0090: Reference manual - STMicroelectronics

RM0090 USB on-the-go full-speed (OTG_FS)
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
f) The core generates the XFRC interrupt as soon as the last transaction is
completed successfully
g) In response to the XFRC interrupt, de-allocate the channel for other transfers
h) Handling non-ACK responses
Doc ID 018909 Rev 3 1114/1416