/*********************************************************************
*
* ANSI C Example program:
*    DigPulseTrain-Var.c
*
* Example Category:
*    CO
*
* Description:
*    This example demonstrates how to generate a continuous digital
*    pulse train from a Counter Output Channel. The Frequency, Duty
*    Cycle, and Idle State are all configurable.
*
*    This example shows how to configure the pulse in terms of
*    Frequency/Duty Cycle, but can easily be modified to generate a
*    pulse in terms of Time or Ticks.
*
* Instructions for Running:
*    1. Select the Physical Channel which corresponds to the counter
*       you want to output your signal to on the DAQ device.
*    2. Enter the Frequency and Duty Cycle to define the pulse
*       parameters. You can also change the Idle State to determine
*       the beginning and end states of the output. If the Idle State
*       is High, the generation will use inverted logic.
*       Additionally, you can set the Initial Delay (in seconds)
*       which will delay the beginning of the pulse train from the
*       start call; this is currently set to 0.0 in the code.

*    Note: Use the Measure Period example to verify you are
*          outputting the pulse train on the DAQ device.
*
* Steps:
*    1. Create a task.
*    2. Create a Counter Output channel to produce a Pulse in terms
*       of Frequency. If the Idle State of the pulse is set to low,
*       the state of the line will begin low and remain low after the
*       generation is stopped.
*    3. Call the timing function to configure the duration of the
*       pulse generation.
*    4. Call the Start function to arm the counter and begin the
*       pulse
*    train generation.
*    5. For continuous generation, the counter will continually
*       generate the pulse train until stop button is pressed.
*    6. Call the Clear Task function to clear the Task.
*    7. Display an error if any.
*
* I/O Connections Overview:
*    The counter will output the pulse train on the output terminal
*    of the counter specified in the Physical Channel I/O control.
*
*    This example uses the default output terminal for the counter of
*    your device. To determine what the default counter pins for you
*    device are or to set a different output terminal, refer to the
*    Connecting Counter Signals topic in the NI-DAQmx Help (search
*    for "Connecting Counter Signals").
*
*********************************************************************/

#define MIN_RATE (0.001)
#define MAX_RATE (20.0e6)
#define MIN_SLEEP 1
#define MAX_SLEEP 3600
#include <unistd.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <NIDAQmx.h>

#define DAQmxErrChk(functionCall) if( DAQmxFailed(error=(functionCall)) ) goto Error; else

int32 CVICALLBACK DoneCallback(TaskHandle taskHandle, int32 status, void *callbackData);

int main(int argc, char* argv[])
{
  int         error=0;
  TaskHandle  taskHandle=0;
  char        errBuff[2048]={'\0'};
  char*       base_ptr = "";
  char*       range_ptr = "";
  char*       sleep_ptr = "";
  double      range = 1000.0;
  double      base_rate = 0.0;
  int         sleep_time = MAX_SLEEP;
  int         idx = 1;
  char        device[100] = "Dev1/Ctr1";

  if (argc > idx
      && toupper(argv[idx][0]) == 'D'
      && toupper(argv[idx][1]) == 'E'
      && toupper(argv[idx][2]) == 'V')
  {
    strncpy(device, argv[idx], sizeof(device));
    ++idx;
  }
  if (argc > idx)
  {
    range_ptr = argv[idx];
    range = (double) atof(range_ptr);
    ++idx;
  }
  if (range < MIN_RATE)
    range = MIN_RATE;
  if (range > MAX_RATE)
    range = MAX_RATE;
  if (argc > idx)
  {
    base_ptr = range_ptr;
    base_rate = range;
    range_ptr = argv[idx];
    range = (double) atof(range_ptr);
    if (base_rate + range > MAX_RATE)
      range = MAX_RATE - base_rate;
    ++idx;
    sleep_time = MIN_SLEEP;
  }
  printf("Input of '%s' gives base of %g\n", base_ptr, base_rate);
  printf("Input of '%s' gives range of %g\n", range_ptr, range);
  if (argc > idx)
  {
    sleep_ptr = argv[idx];
    sleep_time = atoi(sleep_ptr);
    if (sleep_time < MIN_SLEEP)
      sleep_time = MIN_SLEEP;
    if (sleep_time > MAX_SLEEP)
      sleep_time = MAX_SLEEP;
    ++idx;
  }
  else if (range == 0)
    sleep_time = MAX_SLEEP;
  printf("Input of '%s' gives loop time of %d\n", sleep_ptr, sleep_time);

  /*********************************************/
  // DAQmx Configure Code
  /*********************************************/
  while (1)
  {
    double this_rate;
    double rval;
    rval = (double) random() / (double) RAND_MAX;
    this_rate = range * rval;
    this_rate += base_rate;
    if (this_rate < MIN_RATE)
      this_rate = MIN_RATE;
    printf("Pulse train on %s at %f Hz.\n", device, this_rate);
    DAQmxErrChk (DAQmxCreateTask("",&taskHandle));
    DAQmxErrChk (DAQmxCreateCOPulseChanFreq(taskHandle,
          device,
          "",
          DAQmx_Val_Hz,
          DAQmx_Val_Low,
          0.0,
          this_rate,
          0.50));
    DAQmxErrChk (DAQmxCfgImplicitTiming(taskHandle,DAQmx_Val_ContSamps,1000));

    DAQmxErrChk (DAQmxRegisterDoneEvent(taskHandle,0,DoneCallback,NULL));

    /*********************************************/
    // DAQmx Start Code
    /*********************************************/
    DAQmxErrChk (DAQmxStartTask(taskHandle));

    do {
      sleep(sleep_time);
    } while (range == 0);

    DAQmxStopTask(taskHandle);
    DAQmxClearTask(taskHandle);
    taskHandle = 0;
  }

Error:
  if( DAQmxFailed(error) )
    DAQmxGetExtendedErrorInfo(errBuff,2048);
  if( taskHandle!=0 ) {
    /*********************************************/
    // DAQmx Stop Code
    /*********************************************/
    DAQmxStopTask(taskHandle);
    DAQmxClearTask(taskHandle);
  }
  if( DAQmxFailed(error) )
    printf("DAQmx Error: %s\n",errBuff);
  printf("End of program, press Enter key to quit\n");
  getchar();
  return 0;
}

int32 CVICALLBACK DoneCallback(TaskHandle taskHandle, int32 status, void *callbackData)
{
	int32   error=0;
	char    errBuff[2048]={'\0'};

	// Check to see if an error stopped the task.
	DAQmxErrChk (status);

Error:
	if( DAQmxFailed(error) ) {
		DAQmxGetExtendedErrorInfo(errBuff,2048);
		DAQmxClearTask(taskHandle);
		printf("DAQmx Error: %s\n",errBuff);
	}
	return 0;
}