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Installation
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2.14 Interrupt System
The PCI-8554‘s interrupt system is a powerful and flexible system,
which is suitable for many applications. The system is a
Dual
Interrupt System
. The dual interrupt means the hardware can
generate two interrupt request signals at the same time and the
software can service these two request signals by ISR. Note that the
dual inte rrupt do not mean the card occupy two IRQ levels. These
two interrupt request signals (INT1 and INT2) comes from external
interrupt signal
EXTINT
and the timer / counter #12 output. Fig 2.14
show you the structure of interrupt system.
COUT12
Counter #12
8254 Chip #4
Counter #11
8254 Chip #4
'H'
'H'
8MHz
IRQ
Flip-
Flops
IRQ
Flip-
Flops
P
Controller
INT #A
INT1
INT2
Clear by "8554_CLR_IRQ1"
Clear by "8554_CLR_IRQ2"
EXTINT
E_INT
debounce
system
DB_CLK
JP11
Fig 2.14 Dual Interrupt System of PCI-8554
There is only one IRQ level used by this card although it is a dual
interrupt system. This card uses INT #A interrupt request signal to
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 setting by software
library. Refer the section 5.4.
The PCI controller of PCI-8554 can receive two hardware IRQ
sources. However, a PCI controller can generate only one IRQ to
Содержание PCI-8554
Страница 1: ...NuDAQ PCI 8554 Multi functions Counter Timer Card User s Guide Recycled Paper...
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Страница 11: ...Introduction 3 The second interrupt source comes from external source 100 pin SCSI II female connector PCI Bus...
Страница 13: ...Introduction 5 Humidity 5 95 non condensing Power Consumption 5 V 350 mA typical Dimension 134mm L X 107mm W...