ST STM32L4+ Series Reference Manual page 2214

USB on-the-go full-speed (OTG_FS)
{
De-allocate Channel
}
else
if (FRMOR)
{
Unmask CHH
Disable Channel
}
else
if (CHH)
{
Mask CHH
De-allocate Channel
}
Code sample: Isochronous IN
Unmask (TXERR/XFRC/FRMOR/BBERR)
if (XFRC or FRMOR)
{
if (XFRC and (OTG_HCTSIZx.PKTCNT == 0))
{
Reset Error Count
De-allocate Channel
}
else
{
Unmask CHH
Disable Channel
}
}
else
if (TXERR or BBERR)
else
2214/2301
{
Increment Error Count
Unmask CHH
Disable Channel
}
if (CHH)
{
Mask CHH
if (Transfer Done or (Error_count == 3))
{
De-allocate Channel
}
RM0432 Rev 6
RM0432