Data Translation DT9834 Series, User Manual

Page: 102 / 186

Chapter 5
102
• Period of a signal pulse (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/18 MHz
• Frequency of a signal pulse (the number of periods per second). You can calculate the
frequency as follows:
−
Frequency = 18 MHz/Number of Counts
Using software, specify the counter/timer mode as edge-to-edge measurement mode
(measure), the C/T clock source as internal, the start edge type, and the stop edge type.
Make sure that the signals are wired appropriately. Refer to
page 60 for an example of connecting an edge-to-edge measurement application.
Continuous Edge-to-Edge Measurement
In continuous edge-to-edge measurement mode, the counter starts incrementing when it
detects the specified start edge. When it detects the next start edge type, the value of the
counter is stored and the next edge-to-edge measurement operation begins automatically.
Every time an edge-to-edge measurement operation completes, the previous measurement is
overwritten with the new value. When you read the counter as part of the analog input data
stream, the current value (from the last edge-to-edge measurement operation) is returned and
the value of the counter is reset to 0. Refer to
page 101 for more information on edge-to-edge
measurement mode.
Note: If you read the counter before the measurement is complete, 0 is returned.
To select continuous edge-to-edge measurement mode, use software to specify the
counter/timer mode as continuous measure, the C/T clock source as internal, and the start
edge type.