ADLINK ACL-8454/12 - Manual (Page 44)

36 • Signal Connections & Applications
4.8 Event Counter
Example : To count external event in 1 sec
step 1: This application needs one counter to generate a time base of
1 sec and the second counter to count the event. The
cascaded counter #5, #6 can perform the watchdog timer.
Counter #1 is used as an example to count external event. The
clock source of counter #1 is the event signal and the
frequency is not fixed.
step 2~6: Skip these steps.
step 7: The gate source is always enabled and the external gate must
be removed.
step 8: Connect the signal according to Figure 4.7.
step 9: Write the control program. Please refer the ‘DEMO5.C’ source
code.
COUT1
Counter #1
8254 Chip #2
C
G
O 'H'
Jumper
CK1
COUT6
Counter #6
8254 Chip #2
C
G
O
IRQ channel : Watchdog Interrupt
JP1
Event signal
Figure 4.7 Example of event counter