Irq Status Register (Isr) - Hitachi H8S/2646 Hardware Manual

5.2.5

IRQ Status Register (ISR)

Bit : 7
—
Initial value : 0
R/(W)*
R/W :
Note: * Only 0 can be written, to clear the flag.
ISR is an 8-bit readable/writable register that indicates the status of IRQ5 to IRQ0 interrupt
requests.
ISR is initialized to H'00 by a reset and in hardware standby mode.
They are not initialized in software standby mode.
Bits 7 and 6—Reserved: These bits are always read as 0.
Bits 5 to 0—IRQ5 to IRQ0 flags (IRQ5F to IRQ0F): These bits indicate the status of IRQ5 to
IRQ0 interrupt requests.
Bit n
IRQnF Description
0 [Clearing conditions] (Initial value)
•
Cleared by reading IRQnF flag when IRQnF = 1, then writing 0 to IRQnF flag
•
When interrupt exception handling is executed when low-level detection is set
(IRQnSCB = IRQnSCA = 0) and IRQn input is high
•
When IRQn interrupt exception handling is executed when falling, rising, or both-edge
detection is set (IRQnSCB = 1 or IRQnSCA = 1)
•
When the DTC is activated by an IRQn interrupt, and the DISEL bit in MRB of the
DTC is cleared to 0
1 [Setting conditions]
•
When IRQn input goes low when low-level detection is set (IRQnSCB = IRQnSCA =
0)
•
When a falling edge occurs in IRQn input when falling edge detection is set
(IRQnSCB = 0, IRQnSCA = 1)
•
When a rising edge occurs in IRQn input when rising edge detection is set
(IRQnSCB = 1, IRQnSCA = 0)
•
When a falling or rising edge occurs in IRQn input when both-edge detection is set
(IRQnSCB = IRQnSCA = 1)
108
6 5
— IRQ5F IRQ4F
0 0
R/(W)* R/(W)* R/(W)*
4 3 2
IRQ3F IRQ2F
0 0 0
R/(W)* R/(W)*
1 0
IRQ1F IRQ0F
0 0
R/(W)* R/(W)*
(n = 5 to 0)