Real Time Devices AD1200 User Manual page 18

F i g . 1 - 8 a :
Factory Setting
t - ; ; ; - - - - - - ' l
8254
or2
ET
EOC
DMA
IRQT
IRQ6
IRQ5
IRQ4
IRQ3
IRQ2
G
Fig. 1-8b: Interrupt Source
OT2 Connected to lRe3
1 2 0 0
I / O C O N N E C T O R
or2
ET
EOC
DMA
IRQT
IRQ6
IRQ5
lR04
IRQ3
IRQ2
G
TO A/D
T R I G G E R
XTAL
E C 1
F 8
M H z
E X T C L K
EXT GATE 1
I
p t t { g g l 1 p l 6 6 g p
1 x
P I N
T / C O U T I
o - _ 8
M H z
EXT GATE 2
T/C OUT 2
Fig. 1-7 -8254 Timer/Counter Circuit Block Diagram
P8 - Interrupt Source and Channet (Factory Setting: Jumpers on OT2 & G; Interrupt Channels Disabled)
This header connector, shown in Figure 1-8, lets you connect any one of four intemrpt sources to any of six
interrupt channels, IRQ2 (highest priority channel) through IRQT (lowest priority channel). To activate a channel,
you must install a jumper vertically across the desired IRQ channel. Figure 1-8a shows the facory setting; Figure
1-8b shows intenupt source OT2 connected tro IRQ3.
I
ozl
o T l
XTAL
EC2
P8
P8
Fig. 1-8 - Interrupt ChannelJumper, pg
On the right side of the header, you can select any one of four signal sources to generate an intemrpt. An
intemtpt source is chosen by placing a jumper across the desired pair of.pins. The intemrpt sources available are the
A/D end-of-convert (EOC), DMA done (DMA), extemal rigger @T), and rhe outpur of timer/counter 2 (OT2).
T I M E R /
C O U N T E R
C L K
2
GATE
A r r i
l-6