ADLINK Technology NuDAQ ACL-8454, Руководство пользователя

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Installation
be used as interrupt source. See ‘Interrupt Sources’ section for
details. The following figure demonstrates a set of cascaded
counter - counter #5 and #6.
1 MHz COUT5
Counter #5
COUT5
COUT6
Counter #6
8254 Chip #2
C
G
C
G
O
O
'H'
'H'
Figure 2.10 Example of ‘cascaded counter’
User Configurable Cascaded Counters
Although there are two cascaded counter on board, users may need
more cascaded counters. User can configure the jumper for the
clock source of every independent counters. Therefore, the
independent counter output can be cascaded to the next counter's
clock source by jumper setting. Figure 2.11 demonstrate an
example of the user configurable cascaded counter. Refer to next
section for details of the clock source setting.
Multi-Configurations
The ACL-8454 provides multi -configurations for many situations.
Users may need more independent counters for some applications.
Users can installed one more 8254 to chip #3(U3) by yourself to get
3 more independent counters. It is also possible to install one more
8254 chip to #4(U4) and get one more set of cascaded counter or to
get another internal interrupt source(refer to section 2.11).
The versatile configurations of ACL-8454 depend on user‘s
applications. You may also order the extent version which named as
ACL8454/12 that all four chips are installed when shipping.
CLK1
COUT1
GATE1
Counter #1
8254 Chip #1
C
G
O
CLK2
COUT2
GATE2
Counter #2
C
G
O
VCC
VCC
CLOCK1
Cascaded
Counters
Output
Jumper 'CK2'
Figure 2.11 Example of ‘user configurable cascaded counters’