GD32VF103 User Manual
526
Software sets this bit to set NAKS bit in this register.
26
CNAK
Clear NAK
Software sets this bit to clear NAKS bit in this register.
25:22
Reserved
Must be kept at reset value
21
STALL
STALL handshake
Software can set this bit to make USBFS sends STALL handshake during an OUT
transaction. This bit has a higher priority than NAKS bit in this register and GINAK
in USBFS_DCTL register. If both STALL and NAKS bits are set, the STALL bit takes
effect.
For control OUT endpoint:
Only USBFS can clear this bit when a SETUP token is received on the
corresponding OUT endpoint. Software is not able to clear it.
For interrupt or bulk OUT endpoint:
Only software can clear this bit.
20
SNOOP
Snoop mode
This bit controls the snoop mode of an OUT endpoint. In snoop mode, USBFS
doesn
’t check the received data packet’s CRC value.
0:Snoop mode disabled
1:Snoop mode enabled
19:18
EPTYPE[1:0]
Endpoint type
This field defines the transfer type of this endpoint:
00: Control
01: Isochronous
10: Bulk
11: Interrupt
17
NAKS
NAK status
This bit controls the NAK status of USBFS when both STALL bit in this register and
GONS bit in USBFS_DCTL register are cleared:
0: USBFS sends handshake packets according to the status of the endpoint
’s Rx
FIFO.
1: USBFS always sends NAK handshake to the OUT token.
This bit is read-only and software should use CNAK and SNAK in this register to
control this bit.
16
EOFRM
DPID
Even/odd frame (For isochronous OUT endpoints)
For isochronous transfers, software can use this bit to control that USBFS only
receives data packets in even or odd frames. If the current frame number
’s parity
doesn
’t match with this bit, USBFS just drops the data packet.
0: Only sends data in even frames
1: Only sends data in odd frames
Endpoint data PID (For interrupt/bulk OUT endpoints)