ADLINK PCI-7396 - Manual (Page 34)

26
• Operation Theorem
4.3 Interrupt Circuit
4.3.1 System Architecture
The PCI-7396‘s interrupt system is powerful and flexible, which is suitable
for many applications. It is a Dual Interrupt System. The dual interrupt
means the hardware can generate two interrupt request signals in the same
time and the software can service these two request signals by ISR. Note
that the dual interrupt do not mean the card occupy two IRQ levels.
The two interrupt request signals (INT1 and INT2) comes from digital inputs
or the timer/counter outputs. Two multiplexers (MUX) are used to select the
IRQ sources. Fig 4.4 shows the interrupt system.
4.3.2 IRQ Level Setting
There is only one IRQ level needed in the PCI-7396, although it is a dual
interrupt system. This card uses INT #A interrupt request signal on PCI bus.
The mother board circuits will transfer INT #A to one of the AT bus IRQ
levels. The IRQ level is set by the PCI plug and play BIOS and saved in the
PCI controller. It is not necessary for users to set the IRQ level. Users can
get the IRQ level by software library.