Datasheet

Table Of Contents
Section 15 Universal Serial Bus Interface (USB)
REJ09B0140-0900 Rev. 9.00 Page 527 of 846
Sep 16, 2010
H8S/2215 Group
15.3.31 USB Interrupt Flag Register 3 (UIFR3)
UIFR3 is an interrupt flag register indicating the USB status. If the corresponding bit is set to 1,
the corresponding EXIRQ0, EXIRQ1, or IRQ6 interrupt is requested from the CPU. VBUSi,
SPRSi, SETI, SETC, SOF, and CK48READY flags can be cleared by writing 0. Writing 1 to them
is invalid and causes no operation. Consequently, to clear only a specific flag it is necessary to
write 0 to the bit corresponding to the flag to be cleared and 1 to all the other bits. (To clear bit 5
only, write H'DF.) The bit-clear instruction is a read/modify/write instruction. There is a danger
that the wrong bits may be cleared if a new flag is set between the read and write. Therefore, the
bit-clear instruction should not be used to clear bits in this interrupt flag register. VBUSs and
SPRSs are status flags and cannot be cleared.
Bit Bit Name Initial Value R/W Description
7
CK48READY
0
R/(W)
*
USB Operating Clock (48 MHz) Stabilization Detection
Set to 1 when the 48-MHz USB operating clock
stabilization time has been automatically counted after
USB module rest mode cancellation. The
corresponding interrupt output is EXIRQ0 or EXIRQ1.
CK48READY can also operate in USB interface
software reset state (the UIFRST bit of UCTLR is set
to 1).
Note that USB operating clock stabilization time differs
according to the clock source, refer to the UCKS3 to
UCKS0 bits of the UCTLR.
6
SOF
0
R/(W)
*
Start of Frame Packet Detection
Set to 1 if the SOF packet is detected. This flag can
be used to start time stamp check, EP3i transmit data
write, or EP3o receive data read timing in EP3
isochronous transfer. The corresponding interrupt
output is EXIRQ0 or EXIRQ1.
5
SETC
0
R/(W)
*
Set_Configuration Command Detection
Set to 1 if the Set_Configuration command is
detected. The corresponding interrupt output is
EXIRQ0 or EXIRQ1.
4
SETI
0
R/(W)
*
Set_Inferface Command Detection
Set to 1 if the Set_Interface command is detected.
The corresponding interrupt output is EXIRQ0 or
EXIRQ1.