AT32F425
Series Reference Manual
2022.03.30
Page 391
Ver 2.01
Bit 12
USBRST
0x0
rw1c
Accesible in device mode only
USB Reset
The controller sets this bit to indicate that a reset is
detected on the USB bus.
Bit 11
USBSUSP
0x0
rw1c
Accesible in device mode only
USB Suspend
The controller sets this bit to indicate that a suspend is
detected on the USB bus. The controller enters the
Suspend state when there is no activity on the bus for a
long period of time.
Bit 10
ERLYSUSP
0x0
rw1c
Accesible in device mode only
Early suspend
The controller sets this bit to indicate that the idle state has
been detected on the USB bus for 3 ms.
Bit 9: 8
Reserved
0x0
resd
Kept at its default value.
Bit 7
GOUTNAKEFF
0x0
ro
Accesible in device mode only
Global OUT NAK effective
This bit indicates that the Set Global OUT NAK bit in the
Device Control register (set by the application) has taken
effect. This bit can be cleared by writing the Clear Global
OUT NAK bit in the Device Control register.
Bit 6
GINNAKEFF
0x0
ro
Accesible in device mode only
Global IN Non-periodic NAK effective
This bit indicates that the Set Global Non-periodic IN NA
bit in the Device Control register (set by the application)
has taken effect. That is, the controller has sampled the
Global IN NAK bit set by the application. This bit can be
cleared by writing the Clear Global Non-periodic IN NA bit
in the Device Control register. This interrupt does not
necessarily mean that a NAK handshake signal is sent out
on the USB bus. The STALL bit has priority over the NAK
bit.
Bit 5
NPTXFEMP
0x1
ro
Accesible in both host and device modes
Non-periodic TxFIFO empty
This interrupt is generated when the Non-periodic TxFIFO
is either half or completely empty and there is enough
space for at least one request to be written to the Non-
periodic Transmit Request Queue. The half or completely
empty depends on the Non-periodic TxFIFO Empty Level
bit in the Core AHB Configuration register.
Bit 4
RXFLVL
0x0
ro
Accesible in both host and device modes
RxFIFO Non-Empty
Indicates that there is at least one packet to be read from
the receive FIFO.
Bit 3
SOF
0x0
rw1c
Accesible in both host and device modes
Start of Frame
In host mode, the controller sets this bit to indicate that an
SOF (full-speed) or Keep-Alive (low-speed) is transmitted
on the USB bus. The application must set this bit to 1 to
clear this interrupt.
In device mode, the controller sets this bit to indicate that
an SOF token has been received on the USB bus. The
application must read the Device Status register to get the
current frame number. This interrupt can be generated only
when the controller is running in FS mode. This bit is set
by the controller. The application must write 1 to clear this
bit.
Note: Reading this register immediately after power-on
reset may return the value 0x1. If this register is read as
0x1 immediately after power-on reset, it does not mean
that an SOF has been transmitted (in host mode) or
received (in device mode). The reading of this register is
valid only when an effective connection has been
established between the host and the device. If this bit is