Data Translation DT9812 Series, User Manual

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Wiring Signals to the Module
41
Edge-to-Edge Measurement
Figure 15 shows how to connect counter/timer signals to the module to perform an
edge-to-edge measurement operation on one signal source. The counter measures the number
of counts between the start edge (in this case, a rising edge on the Counter 0 Gate signal) and
the stop edge (in this case, another rising edge on the Counter 0 Gate signal).
You specify the start edge and the stop edge in software. Refer to page 74 for more
information.
Figure 15: Connecting Counter/Timer Signals for an
Edge-to-Edge Measurement Operation
You can use edge-to-edge measurement to measure the following characteristics of a signal:
• Pulse width – The amount of time that a signal pulse is in a high or a low state, or the
amount of time between a rising edge and a falling edge or between a falling edge and a
rising edge. You can calculate the pulse width as follows:

Pulse width = Number of counts/24 MHz
• Period – The time between two occurrences of the same edge (rising edge to rising edge,
or falling edge to falling edge). You can calculate the period as follows:

Period = 1/Frequency

Period = Number of counts/24 MHz
• Frequency – The number of periods per second. You can calculate the frequency as
follows:

Frequency = 24 MHz/Number of Counts
Signal Source
Counter 0 Gate
Ground
19
16
In this example, the software
returns the number of counts
between the two rising edges
DT9812, DT9813, or
DT9814 Series Module