ADLINK ACL-8454/12 - Manual (Page 24)

16 • Installation & 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 named as ACL8454/12. On which 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’
2.9 Clock Source Configurations
For every independent counter, four signals can be chosen as clock source
by jumper setting. The clock source of counter #n comes from either
CLOCK1, CLOCK2, the external clock source (ECLK n), or the cascaded
counter output. Note that the clock sources of the cascaded counters
(counter #5, #6, #11 and #12) are fixed.
CLOCK1
CLK n
COUT x
CLOCK2
ECLK n
Figure 2.12 Clock Source of Counter #n