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Section 20 USB Function Module
Rev. 4.00 Sep. 14, 2005 Page 752 of 982
REJ09B0023-0400
Bit Bit Name
Initial
Value R/W Description
2 EP3TR 0 R/W EP3 Transfer Request
This bit is set if there is no valid transmit data in the
FIFO buffer when an IN token for endpoint 3 is
received from the host. A NACK handshake is
returned to the host until data is written to the FIFO
buffer and packet transmission is enabled.
1 EP3TS 0 R/W EP3 Transmit Complete
This bit is set when data is transmitted to the host
from endpoint 3 and an ACK handshake is returned.
0 VBUS 0 R/W UBS Disconnection Detection
This bit is set to 1 when a function is connected to or
disconnected from the USB bus. Use the VBUSCNT
pin of this module to detect connection/disconnection.
20.3.3 USB Interrupt Flag Register 2 (USBIFR2)
Together with USB interrupt flag registers 0 (USBIFR0) and 1 (USBIFR1), USBIFR2 indicates
interrupt status information required by the application. When an interrupt occurs, the
corresponding bit is set to 1 and an interrupt request is sent to the CPU according to the
combination with USB interrupt enable register 2 (USBIER2). Clearing is performed by writing 0
to the bit to be cleared, and 1 to the other bits. However, CFGV is a status bit, and cannot be
cleared. USBIFR2 is initialized to H'20 by a power-on reset.
Bit Bit Name
Initial
Value R/W Description
7
6
5
4
0
0
1
0
R
R
R
R
Reserved
The write value should always be 0.
3 AWAKE 0 R/W Awake Signal Detection
This bit is set to 1 when the resume or bus reset signal
is detected on the USB bus in the suspend state with
USBCTRL/SUSPEND = 1.
2 SUSPS 0 R/W USB Suspend Signal Detection
This bit is set to 1 when the USB suspend signal is
detected with USBCTRL/SUSPEND = 1.