Chapter 1
42
One-Shot
Use one-shot mode to generate a single pulse output signal from the counter when the
operation is enabled by a either an external normal or inverted gate type. Refer to
more information on gate types. You can use this pulse output signal as an external digital
(TTL) trigger to start other operations, such as an analog input operation.
When the operation is enabled, the counter begins incrementing. When the counter
increments to the pulse width count, described on
, the value of the counter is output.
The output stays active until the counter rolls over to 0 (the terminal count).
When the counter reaches the terminal count, the output is deactivated and the counter is
automatically reloaded with the period count, described on
. The pulse output then
stays inactive, and the counter stays disabled. All subsequent clock and gate signals are
ignored.
You can specify the polarity of the output signal; refer to
for more information.
In one-shot mode, the internal C/T clock source is more useful than an external C/T clock
source. Refer to
for more information on the internal C/T clock source.
Note:
In the case of a one-shot operation, use a duty cycle as close to 100% as possible to
output a pulse immediately. Using a duty cycle closer to 0% acts as a pulse output delay.
shows an example of a one-shot operation using an external normal gate signal, a
period count FFFFFFFEh, a low-to-high output pulse polarity, and a pulse width count of
FFFFFFFEh to achieve a duty cycle of 66%.
Figure 10: Example of One-Shot Mode
Pulse
Output
Signal
External
Gate
Signal
66% duty cycle
One-Shot Operation
Starts
166.666 ns period
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 ...