7. Interrupt Handling
148
PowerSpan II User Manual
80A1010_MA001_09
Integrated Device Technology
www.idt.com
7.3.1
Interrupt Status
When an interrupt source becomes active, the relevant status bit is set in one of the interrupt status
registers. Interrupt Status is reported through two registers:
“Interrupt Enable Register 0” on page 332
“Interrupt Status Register 1” on page 329
. Interrupt Status Register 0 provides status for interrupts
resulting from normal device operation. This includes I
2
O, DMA, hardware, doorbell and mailbox
interrupts. A register description for ISR0 is provided in
All status bits are clear by default.
Table 34: Register Description for Interrupt Status Register 0
Bits
Type
Description
ISR1_ACTV
R
This bit indicates an active status bit in ISR1. This enables software to
monitor activity of the other interrupt status register while observing this
interrupt status register.
I2O_HOST
R
Indicates to the Host that there are outstanding Message Frame
Addresses in the Outbound Post List FIFO.
I2O_IOP
R/
Write 1
to Clear
Indicates to the IOP that there are outstanding Message Frame
Addresses in the Inbound Post List FIFO.
DMAx
R/
Write 1
to Clear
Status bit is set when DMAx generates an interrupt. See
Control and Status Register” on page 314
for details of DMAx interrupt
sources.
x_HW
R/
Write 1
to Clear
An interrupt is outstanding on an interrupt input (one of eight interrupt
pins, see
DBx
R/
Write 1
to Clear
Set when a doorbell register is written to in the corresponding IER0 bit.
MBOXx
R/
Write 1
to Clear
Set when there is a write to a mailbox.