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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.