Chapter 4
General-Purpose Counter/Timer
©
National Instruments Corporation
4-55
DAQ-STC Technical Reference Manual
4.7.1 CTRSRC Minimum Period and Minimum Pulsewidth
Figure 4-21 and the accompanying table indicate the minimum period and minimum
pulsewidth for the general-purpose counter source signal, CTRSRC.
Figure 4-21.
CTRSRC Minimum Period and Minimum Pulsewidth
Note
If simple loop counting is the only functionality required for the counter, then the
frequency of operation may be increased. For simple loop counting, the counter
has been shown to function at CTRSRC periods as small as 33 ns.
4.7.2 CTRSRC to CTROUT Delay
Figure 4-22 and the accompanying table indicate the delay from the counter source signal
(CTRSRC) to the counter output signal (CTROUT). If the CTRSRC is selected to be the
output of the other general-purpose counter, then you must add the Tso delays from each
counter to determine the total source to output delay. For example, if general-purpose counter
0 selects OSC for its source and general-purpose counter 1 selects the output of
general-purpose 0 for its source, then the total delay (OSC to the CTROUT of
general-purpose counter 1) will be 18 + 27 = 45 (MIN) and 55 + 80 = 135 (MAX).
Name
Description
Minimum
Maximum
Tctrp
CTRSRC minimum period
50
—
Tctrpw
CTRSRC minimum pulsewidth
6
—
All timing values are in nanoseconds.
CTRSRC
Tctrp
Tctrpw
Tctrpw
