users must check if another IRQ is also asserted, then clear current IRQ to allow the next IRQ occurring.

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. The sources of INT1 and INT2 are selective by the Interrupt Control (ISC) Register.

Because of dual interrupt system, for example, you can use FIFO half-full and external interrupt at the same time if your software ISR can distinguish these two events.

4.2.4Interrupt Source Control

There are two bits to control the IRQ sources of INT1 and INT2. Refer to section 3.10 for the details of the bits. In addition, the PCI controller itself can also control the using of the interrupt. For manipulating the interrupt system more easily, ADLINK recommend you to 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 you disable all the two IRQ sources without change the initial condition of the PCI controller, the PCI BIOS still assigns an IRQ level to the PCI card and it will occupy the PC resource. It is not suggested to re-design the initial condition of the PCI card by users‘ own application software. If users want to disable the IRQ level, please use the ADLINK’s software utility to change the power on interrupt setting.

4.3Extended Digital I/O Port

There are 4 extended digital input (EDI) signals and 4 extended digital output (EDO) signals on CN3 connector. The 4 EDI signals are dedicated used as input signal, however the 4 EDO signals can be used as digital input (Mode 1), digital output (Mode 2) or channel number output (Mode 3).

For power on safety, the EDO channel is set to be input when power on initial. To modify the configuration of the usage of the signals, please use the “_9111_Set_EDO_Function” in the library.

Note that w hen set the EDO function as channel number output (Mode 3), it presents the high nibble (4 MSBs) of the channel number no matter manual scan or auto scan mode.

32 ∙ Operation Theorem