4.
Interrupt request register 1 (IRR1)
IRR1 is an 8-bit read/write register, in which a corresponding flag is set to 1 when a timer A or
IRQ
4
to IRQ
0
interrupt is requested. The flags are not cleared automatically when an interrupt is
accepted. It is necessary to write 0 to clear each flag.
Bit 7: Timer A interrupt request flag (IRRTA)
Bit 7
IRRTA
Description
0
Clearing conditions:
(initial value)
When IRRTA = 1, it is cleared by writing 0
1
Setting conditions:
When the timer A counter value overflows from H'FF to H'00
Bit 6: Reserved bit
Bit 6 is a readable/writable reserved bit. It is initialized to 0 by a reset.
Bit 5: Reserved bit
Bit 5 is reserved; it is always read as 1 and cannot be modified.
Bits 4 to 0: IRQ
4
to IRQ
0
interrupt request flags (IRRI4 to IRRI0)
Bit n
IRRIn
Description
0
Clearing conditions:
(initial value)
When IRRIn = 1, it is cleared by writing 0
1
Setting conditions:
When pin
IRQn
is designated for interrupt input and the designated signal edge is input
(n = 4 to 0)
Bit
Initial value
Read/Write
7
IRRTA
0
R/W
6
—
0
R/W
5
—
1
—
4
IRRI4
0
R/W
3
IRRI3
0
R/W
0
IRRI0
0
R/W
2
IRRI2
0
R/W
1
IRRI1
0
R/W
*
*
*
*
*
*
*
Note:
*
Only a write of 0 for flag clearing is possible
72