87
5.2.3 IRQ Status Register (ISR)
ISR is an 8-bit readable/writable register that indicates the status of IRQ
0
, IRQ
1
, IRQ
4
, and IRQ
5
interrupt requests.
Bit
Initial value
Read/Write
7
—
0
—
These bits indicate IRQ
5
and IRQ
4
interrupt request status
Note: Only 0 can be written, to clear flags.
*
6
—
0
—
5
IRQ5F
0
R/(W)
*
4
IRQ4F
0
R/(W)
*
3
—
0
—
2
—
0
—
1
IRQ1F
0
R/(W)
*
0
IRQ0F
0
R/(W)
*
IRQ to IRQ flags
5
4
These bits indicates IRQ
1
and IRQ
0
interrupt request status
IRQ , IRQ flags
1
0
Reserved bits
Reserved bits
ISR is initialized to H'00 by a reset and in hardware standby mode.
Bits 7, 6, 3 and 2—Reserved: These bits cannot be modified and are always read as 0.
Bits 5, 4, 1 and 0—IRQ
5
, IRQ
4
, IRQ
1
and IRQ
0
Flags (IRQ5F, IRQ4F, IRQ1F, and IRQ0F):
These bits indicate the status of IRQ
5
, IRQ
4
, IRQ
1
and IRQ
0
interrupt requests.
Bits 5, 4, 1, and 0
IRQ5F, IRQ4F, IRQ1F,
and IRQ0F
Description
0
[Clearing conditions] (Initial value)
0 is written in IRQnF after reading the IRQnF flag when IRQnF = 1.
IRQnSC = 0,
IRQ
n input is high, and interrupt exception handling is
carried out.
IRQnSC = 1 and IRQn interrupt exception handling is carried out.
1
[Setting conditions]
IRQnSC = 0 and
IRQ
n input is low.
IRQnSC = 1 and
IRQ
n input changes from high to low.
Note: n = 5, 4, 1 and 0