ADLINK Technology NuDAQ ACL-8454, User Manual

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Installation
COUT12
IRQ 3 5 6 7 9
JP2
IRQ 10 11 12 15 X
JP1
/COUT6
JP3
High IRQ Level
Low IRQ Level
Ext.Int.
(ECLK10)
Figure 2.15. Block diagram of interrupt system
Dual interrput example
The dual interrupt system is very useful in some application. For
example, most of the application needs a watchdog timer to monitor
the system pereodicly, hence, one IRQ channel is used. In addition,
the emergency control may be necessary, an additional external IRQ
channel is helpful to handle the situation. Therefore, dual interrupt
levels are necessary.
/COUT6
Counter #6
8254 Chip #2
C
G
O
IRQ channel : Watchdog Interrupt
JP1
COUT12
JP2
IRQ channel : External Interrupt
JP3
COUT12
Ext.Clk
Figure 4.8 Example of dual interrupt system
Internal or External Interrupt Selection
The interrupt system is very flexible. No matter under any system
configuration, it is possible to generate interrupt internally or
externally.
In fact, when chip #4 are not installed, the
COUT12 are floating and
it's corresponding pin in the connector can be used as digital input
pin or external interrupt source. Whenever 8254 chip #4 is installed,
it is an internal interrupt source, otherwise, it is used as an external
clock source or just a digital input signal. The following table lists
the combinations of the interrupt sources. The label
‘I’ means
‘internal’ source and the label ‘ e ’ means ‘ext ernal’ source. The label