Signal connections & applications • 35, Figure 4.5 example of frequency measurement (1) – ADLINK ACL-8454/12 User Manual
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Signal Connections & Applications
• 35
COUT5
COUT6
Counter #6
8254 Chip #2
C
G
O
'H'
COUT1
Counter #1
8254 Chip #1
C
G
O
Jumper
CK1
/COUT6
frequency to
be measured
Precise
Time
Interval
'H' enable counter #1
Jumper
G1
Figure 4.5 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 necessarily coming from the internal
source. The gate can be generated 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.