User`s guide

Operation Theorem  41
4.2 Interrupt System
The interrupt system of the ACL-8316/12 is very flexible for many applications.
There are four plus one (4+1) programmable interrupt sources. The interrupt
signal can be routed one of the 10 IRQ channels by jumper setting. The
following diagram shows interrupt system.
A
T Bus
interrupt
lines
External Interrupt
EOC Interrupt
Timer Interrupt
FIFO Half-Full Int.
DMA Terminal Count
Programmabl
Multiplexer
DMA Enable Signal
Jumper
Figure 4.2 The illustration of Interrupt System
The 4 programmable interrupt source is the external interrupt, end of
conversion (EOC) interrupt, 8254 timer interrupt and the FIFO half-full
interrupt. The additional one is the DMA terminal counter (TC) interrupt. As
the DMA is enable, the only one possible interrupt source is the DMA TC
interrupt because the DMA programming must use this interrupt to set the
DMA controller. However, if the DMA is disable, the other 4 signal can be
selectable by program,
Sometimes the interrupt signal may be used by combining with the data
transfer. For example, the EOC interrupt and the FIFO half-full interrupt can
startup an ISR to read data, please refer to section 4.1.5 for data transferring.
However, as the A/D data is read by software FIFO polling, the interrupt can
be reserved to be used as emergency interrupt, which comes from external,
or timer interrupt, which comes directly from the 8254 timer interrupt.
The interrupt signal is routed to one of the ten IRQ levels: 3, 4, 5, 6, 7, 9, 10,
11, 12, 15. The jumper (JP3) sets the IRQ channels. To disable the interrupt,
just remove the jumper and put the jumper to the ‘NC’ position.