Datasheet

Table Of Contents
Section 15 Universal Serial Bus Interface (USB)
REJ09B0140-0900 Rev. 9.00 Page 525 of 846
Sep 16, 2010
H8S/2215 Group
15.3.30 USB Interrupt Flag Register 2 (UIFR2) (Only in H8S/2215R, H8S/2215T and
H8S/2215C)
UIFR2 is an interrupt flag register indicating the state of EP4i, EP4o, and EP5i. If the
corresponding bit is set to 1, the corresponding EXIRQ0 or EXIRQ1 interrupt is requested to the
CPU. EP4iTR EP5iTS and EP4iTR flags can cleared by writing 0 to them. 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. However, EP4iEMPTY
and EP4oREADY are status bits indicating the EP4i and EP4o FIFO status, and cannot be cleared.
Bit Bit Name Initial Value R/W Description
7, 6 All 0 R Reserved
These bits are always read as 0 and cannot be
modified.
5
EP5iTR
0
R/(W)
*
EP5i Transfer Request
Set to 1 if there is no valid transmit data in the FIFO
when an IN token is sent from the host to EP5i. The
corresponding interrupt output is EXIRQ0 or EXIRQ1.
4
EP5iTS
0
R/(W)
*
EP5i Transfer Complete
Set to 1 if the transmit data written in EP5i is
transferred to the host normally and the ACK
handshake is returned. The corresponding interrupt
output is EXIRQ0 or EXIRQ1.
3
EP4iALL
EMPTYS
1
R
EP4i FIFO All Empty Status
EP4i FIFO has a dual FIFO configuration. This flag is
set to 1 if both FIFOs are empty. (Corresponds to a
UDSR/EP4iDE negative-polarity signal.)
2
EP4oREADY
0
R
EP4o Data Ready
EP4o FIFO has a dual-FIFO configuration. This flag is
set if there is a valid data in at least one EP4o FIFO.
This flag is cleared to 0 if there is no valid data in EP4o
FIFO. This flag is a status flag and cannot be cleared.
The corresponding interrupt output is EXIRQ0 or
EXIRQ1.
Note: * The write value should always be 0 to clear this flag.