RM0090: Reference manual - STMicroelectronics

RM0090 USB on-the-go full-speed (OTG_FS)
De-allocate Channel
}
else if (STALL)
{
Transfer Done = 1
Unmask CHH
Disable Channel
}
else if (NAK or TXERR )
{
Rewind Buffer Pointers
Unmask CHH
Disable Channel
if (TXERR)
{
Increment Error Count
Unmask ACK
}
else
{
Reset Error Count
}
}
else if (CHH)
{
Mask CHH
if (Transfer Done or (Error_count == 3))
{
De-allocate Channel
}
else
{
Re-initialize Channel
}
}
else if (ACK)
{
Reset Error Count
Mask ACK
}
The application is expected to write the data packets into the transmit FIFO as and
when the space is available in the transmit FIFO and the Request queue. The
application can make use of the NPTXFE interrupt in OTG_FS_GINTSTS to find the
transmit FIFO space.
b) Bulk/Control IN
Unmask (TXERR/XFRC/BBERR/STALL/DTERR)
if (XFRC)
{
Reset Error Count
Unmask CHH
Disable Channel
Doc ID 018909 Rev 3 1116/1416