GD32F20x User Manual
940
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)
These is a data PID toggle scheme in interrupt or bulk transfer. Software should
set SD0PID to set this bit before a transfer starts and USBFS maintains this bit
during transfers following the data toggle scheme described in USB protocol.
0:
Data packet’s PID is DATA0
1:
Data packet’s PID is DATA1
15
EPACT
Endpoint active
This bit controls whether this endpoint is active. If an endpoint is not active, it
ignores all
tokens and doesn’t make any response.
Содержание GD32F20 Series
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Страница 325: ...GD32F20x User Manual 325 15 0 ALRM 15 0 RTC alarm value low ...
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Страница 523: ...GD32F20x User Manual 523 clears AERR bit by writing 0 to it ...