
Chapter 1
36
• output duty cycle = (output pulse width) / (output period)
For example, if the output pulse width is 222.2 ns and the output pulse period is 333.3 ns,
then the output duty cycle is .66 (66%).
Counter/Timer Operation Modes
DT9840 Series modules support the following counter/timer operation modes:
• Standard counting (this includes event counting and rate generation)
• Measure
• Continuous measure
• Up/down counting
• One-shot
• Repetitive one-shot
You specify the mode using software. The following subsections describe these modes in
more detail.
Standard Counting
Specify standard counting if you want to use the counter/timer to count events or generate a
rate based on a count.
In event counting applications, the counter/timer counts pulses from an external C/T clock
when the enabled gate signal (software, external normal, or external inverted) is active. Refer
to
for more information on the external C/T clock source; refer to
information on gate types.
Since each counter/timer is 32 bits, you can count from 1 to FFFFFFFFh events before the
counter rolls over to 0 and starts counting again. You can read the value of the counter at any
time.
Using the period count, described on
, you can specify the initial count that is loaded
into the counter/timer; the counter/timer starts counting from this value. Using the pulse
width count, described on
, you can specify the count at which the counter/timer
stops counting; when the counter reaches this value, a pulse is output from the counter/timer.
You can specify the polarity of this output pulse, as described on
.
shows an example of an event counting operation using an normal external gate type.
Summary of Contents for DT9840 Series
Page 1: ...DT9840 Series UM 19197 T User s Manual Title Page ...
Page 4: ......
Page 44: ...Chapter 1 44 ...
Page 76: ...Chapter 2 76 ...
Page 98: ...Appendix A 98 ...
Page 124: ...Appendix B 124 ...