National Instruments 320682C FrequencyDividerConfig

Chapter 10 Easy I/O for DAQ Library

FrequencyDividerConfig

short error = FrequencyDividerConfig (short device, char counter[],

double sourceTimebase,

double timebaseDivisor,

unsigned short gateMode,

unsigned short outputBehavior,

short sourceEdge, unsigned long *taskID);

Purpose

This function configures the specified counter to count the number of signal transitions on its

SOURCE pin or on an internal timebase signal, and to strobe or toggle the signal on its OUT pin.

To divide an external TTL signal, connect it to counter's SOURCE pin, and set the

sourceTimebase parameter to USE_COUNTER_SOURCE.

To divide an internal timebase signal, set the sourceTimebase parameter to a desired valid

frequency.

Set the timebaseDivisor to the desired value. For a value of N and a pulsed output, an output

pulse equal to the period of the source or timebase signal appears on counter's OUT pin once

each N cycles of that signal. For a toggled output, the output toggles after each N cycles. The

toggled output frequency is thus half that of the pulsed output, in other words,

pulsedFrequency = sourceFrequency/N

and

toggledFrequency = sourceFrequency/(2*N)

thus, if N=3, the OUT pin would generate pulses as follows:

_ _ _ _ _ _ _ _ _ _ _ _

source _| |_| |_| |_| |_| |_| |_| |_| |_| |_| |_| |_| |

___ ___ ___ ___

pulsed _| |_______| |_______| |_______| |______

___________ ___________

toggled _| |___________| |_________

If gateMode is not UNGATED_SOFTWARE_START, connect your gate signal to counter's

GATE pin.