ADLINK Technology NuDAQ ACL-8454, User Manual

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Applications
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Figure 4.4 Example of frequency measurement (1)
The ACL-8454 can
synchronously measure frequency from four
channels because the internal gate control is connected to 4
counters (#1~4) in the same time. Furthermore, as the gate signal
goes low, an interrupt is generated. The user can write an ISR to
sample and calculate the frequency of all the 4 channels. This
feature is very useful in control system.
COUT n
Counter #n
8254 Chip #m
C
G
O
'H'
COUT1
Counter #1
8254 Chip #1
C
G
O
Jumper
CK1
frequency to
be measured
external gate control
Figure 4.6 Example of frequency measurement (2)
Note that the precise gate signal is not nessarily coming from the
internal source. The gate can be generate by any counter and route
to gate of counters externally (refer Figure 4.6. ). The frequency
measurement application is quit complicate. User should also be
care of the frequency range to be measured then design a system
according to the system specification.