User`s guide

Operation Theory • 45
4.2.3 Dual Interrupt System
The PCI controller of the PCI-9111 can receive two hardware IRQ sources.
However, a PCI controller can generate only one IRQ on the PCI bus, the two
IRQ sources must be distinguished by the ISR of the application software if the
two IRQ are both used.
The application software can use the “_9111_Get_Irq_Status” function to
distinguish which interrupt is inserted. After servicing an IRQ signal, users
must check if another IRQ is also asserted, then clear the current IRQ to allow
the next IRQ to occur.
The two IRQs are named as INT1 and INT2. INT1 comes from AD EOC or the
FIFO half-full flag. INT2 comes from timer‘s pacer output or the external
interrupt request or when the pre-trigger counter reaches to 0. The sources of
INT1 and INT2 are selective by the Interrupt Control (ISC) Register.
Because the PCI-9111 is a dual interrupt system, you can use the FIFO
half-full and external interrupt at the same time if your software ISR can
distinguish these two events.
4.2.4 Interrupt Source Control
There are three bits to control the IRQ sources of INT1 and INT2. Refer to
section 3.10 for details of these bits. In addition, the PCI controller itself can
also control the usage of the interrupt. To manipulate the interrupt system
more easily, ADLINK recommends you use the function
_9111_INT_Source_Control to control the IRQ source so that you can disable
one or two of the IRQ sources.
Note that even if you disable both IRQ sources without changing the initial
condition of the PCI controller, the PCI BIOS will still assign an IRQ level to the
PCI card and will still occupy the PC’s resources. It is not recommended that
the PCI cards initial condition be re-design with a users‘ application software.
If users wish to disable the IRQ level, use the ADLINK software utility to
change the interrupt settings.