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GD32F403xx User Manual
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29:28
Reserved
Must be kept at reset value.
27
SNAK
Set NAK
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
TXFNUM[3:0]
Tx FIFO number
Defines the Tx FIFO number of IN endpoint 0.
21
STALL
STALL handshake
Software can set this bit to make USBFS sends STALL handshake when receiving
IN token. USBFS will clear this bit after a SETUP token is received on the
corresponding OUT endpoint 0. This bit has a higher priority than NAKS bit in this
register and GINS bit in USBFS_DCTL register. If both STALL and NAKS bits are
set, the STALL bit takes effect.
20
Reserved
Must be kept at reset value.
19:18
EPTYPE[1:0]
Endpoint type
This field is fixed to
‘00’ for control endpoint.
17
NAKS
NAK status
This bit controls the NAK status of USBFS when both STALL bit in this register
and GINS bit in USBFS_DCTL register are cleared:
0: USBFS sends data or handshake packets according to the status of the
endpoint
’s Tx FIFO.
1: USBFS always sends NAK handshake to the IN token.
This bit is read -only and software should use CNAK and SNAK in this register to
control this bit.
16
Reserved
Must be kept at reset value.
15
EPACT
Endpoint active
This field is fixed to
‘1’ for endpoint 0.
14:2
Reserved
Must be kept at reset value.
1:0
MPL[1:0]
Maximum packet length
This field defines the maximum packet length for a control data packet. As
described in USB 2.0 protocol, there are 4 kinds of length for control transfers:
00: 64 bytes
01: 32 bytes
10: 16 bytes
11: 8 bytes