Thank you so much for the clarification and assistance! Greatly appreciated! This is the reason that I love using NI instruments so much. The support provided through the Discussion Forum is simply awesome!!!
There is one more improvement that I would really want to make for this small project. This improvement is called an odd-ball paradigm. In all the previous attempts of my DAQmx programming codes, there is only one stimulus and that stimulus gets presented repeatedly. In an odd-ball paradigm, some of the stimulus presentations will be using a different stimulus (i.e., an odd-ball stimulus). For example, we can use a 100 Hz tone as the primary stimulus and use a 50 Hz tone as an odd-ball stimulus. And for example, through the 10 stimulus presentations, the 100 Hz tone will be used for the 1, 2, 4, 5, 6, 8, 9, and 10th stimulus presentations, whereas the 50 Hz tone will be used for the 3rd and 7th stimulus presentations.
In order to implement this odd-ball paradigm in this program, I spent one whole day today and wrote a program (please see below) to the best of my ability. The program compiled, but it gave me an error code -200547. I think I may have made some horrible mistakes.
If anyone could give me some suggestions or directions to go, I would greatly appreciate it.
Thank you so much in advance for your time and kindness to help me out!
#include <stdio.h>
#include <NIDAQmx.h> // DAQmx 9.3
#include <math.h>
#define DAQmxErrChk(functionCall) if( DAQmxFailed(error=(functionCall)) ) goto Error; else
#define PI 3.141592653589793238
// function prototypes
int32 CVICALLBACK EveryNCallback(TaskHandle taskHandleAI, int32 everyNsamplesEventType, uInt32 nSamples, void *callbackData);
void StopTaskAOAI();
// initialize parameters at a global scope, so they are accessible inside any subroutine functions.
const unsigned int N = 10000; // number of data points (This number refers to the number of data points per sweep, which include the stimulus duration and silent interval data points)
const unsigned int BUFFER_SIZE = N; // buffer size in data points, [default 1000].
// declare nSweeps parameters
const unsigned int N_SWEEPS_TARGET = 10; // number of sweeps to be obtained (i.e., the targeted number of sweeps to be obtained after the user has initiated the AI task)
unsigned int nSweepsRecorded = 0; // number of sweeps that have been obtained via AI task
// declare and initialize an error code and error buffer. This will be used for both the AO and AI tasks.
int32 error = 0; // error code
char errBuff[2048] = {'\0'}; // error message
// create and initialize AO and AI task handles
TaskHandle taskHandleAO = 0;
TaskHandle taskHandleAI = 0;
// create two stimuli
float64 stimulus1[N]; // stimulus 1 (e.g., a 100 Hz tone)
float64 stimulus2[N]; // stimulus 2 (e.g., a 50 Hz tone)
// arbitrarily define a presentation sequence
int sequence[N_SWEEPS_TARGET] = {1, 1, 2, 1, 1, 1, 2, 1, 1, 1}; // 1 for stimulus 1, and 2 for stimulus 2
int main(void)
{
// prepare two sine waves that will be delivered via an AO channel
double frequency1 = 100; // frequency in Hz, for stimulus 1
double frequency2 = 100; // frequency in Hz, for stimulus 2
double amplitude = 1.0; // baseline-to-peak amplitude of a sine wave (roughly in volts). Should be between +- 10 volts.
double samplingRateWav = 20000.0; // sampling rate of the sine wave
for (int i = 0; i < N; i++) // generate two sine waves (i.e., stimulus 1 and stimulus 2)
{
stimulus1[i] = amplitude * sin(2.0 * PI * frequency1 * (double)(i) / samplingRateWav);
stimulus2[i] = amplitude * sin(2.0 * PI * frequency2 * (double)(i) / samplingRateWav);
}
/* --- Step 1 Create AO and AI tasks --- */
DAQmxErrChk(DAQmxCreateTask("taskAO", &taskHandleAO));
DAQmxErrChk(DAQmxCreateTask("taskAI", &taskHandleAI));
/* --- Step 2 Create and configure an Analog Output Voltage channel and an Analog Input Voltage channel --- */
DAQmxErrChk(DAQmxCreateAOVoltageChan(taskHandleAO, "Dev1/ao0", "", -10.0, 10.0, DAQmx_Val_Volts, NULL));
DAQmxErrChk(DAQmxCreateAIVoltageChan(taskHandleAI, "Dev1/ai0", "", DAQmx_Val_Cfg_Default, -10.0, 10.0, DAQmx_Val_Volts, NULL));
/* --- Step 3 Define sampling rate and related parameters for the AO task and the AI task ---*/
DAQmxErrChk(DAQmxCfgSampClkTiming(taskHandleAO, "", 20000.0, DAQmx_Val_Rising, DAQmx_Val_ContSamps, N));
DAQmxErrChk(DAQmxCfgSampClkTiming(taskHandleAI, "", 20000.0, DAQmx_Val_Rising, DAQmx_Val_ContSamps, BUFFER_SIZE));
/* --- Step 4 setup a Digital Edge, Start Trigger --- */
DAQmxErrChk(DAQmxCfgDigEdgeStartTrig(taskHandleAO, "/Dev1/ai/StartTrigger", DAQmx_Val_Rising));
/* --- Step 5 setup parameters for AI buffer ---*/
DAQmxErrChk(DAQmxRegisterEveryNSamplesEvent(taskHandleAI, DAQmx_Val_Acquired_Into_Buffer, BUFFER_SIZE, 0, EveryNCallback, NULL));
/* ---- Step 6 User presses Enter to start AO and AI tasks ----*/
printf("Press Enter to start AO and AI tasks\n");
getchar();
for (unsigned int sweep = 0; sweep < N_SWEEPS_TARGET; sweep++)
{
/* ---- Step 7 write signal via AO ---- */
switch (sequence[nSweepsRecorded])
{
case 1:
DAQmxErrChk(DAQmxWriteAnalogF64(taskHandleAO, N, 0, 10.0, DAQmx_Val_GroupByChannel, stimulus1, NULL, NULL));
break;
case 2:
DAQmxErrChk(DAQmxWriteAnalogF64(taskHandleAO, N, 0, 10.0, DAQmx_Val_GroupByChannel, stimulus2, NULL, NULL));
break;
default:
printf("Unrecognizable sequence number");
/* ---- Step 8 start AO and AI tasks --- */
DAQmxErrChk(DAQmxStartTask(taskHandleAO));
DAQmxErrChk(DAQmxStartTask(taskHandleAI));
/* --- Step 9 read data via AI ----*/
// This step is executed through EveryNCallback() function ---
/* ---- Step 10 stop AO and AI tasks --- */
DAQmxStopTask(taskHandleAO);
DAQmxStopTask(taskHandleAI);
}
}
/*--- Step 10 User presses Enter to exit the program --- */
printf("Press Enter to stop AO and AI tasks\n");
getchar();
Error:
if( DAQmxFailed(error) )
DAQmxGetExtendedErrorInfo(errBuff, 2048);
if( taskHandleAI!=0 )
{
StopTaskAOAI();
}
if( DAQmxFailed(error) )
printf("DAQmx Error: %s\n", errBuff);
printf("End of program, press Enter to quit\n");
getchar();
return 0;
}
// A function to execute when every N samples have been obtained via AI
int32 CVICALLBACK EveryNCallback(TaskHandle taskHandleAI, int32 everyNsamplesEventType, uInt32 nSamples, void *callbackData)
{
static int totalRead = 0;
int32 read = 0;
float64 data[BUFFER_SIZE];
/*********************************************/
// DAQmx Read Code
/*********************************************/
DAQmxErrChk(DAQmxReadAnalogF64(taskHandleAI, BUFFER_SIZE, 10.0, DAQmx_Val_GroupByScanNumber, data, BUFFER_SIZE, &read, NULL)); // N, N
if( read > 0 )
{
totalRead += read; // increment totalRead
nSweepsRecorded++; // increment nSweepsRecorded
printf("Sweep %d: Acquired %d samples, total %d samples.\n", nSweepsRecorded, read, totalRead);
if (nSweepsRecorded == N_SWEEPS_TARGET) // If N_SWEEPS_TARGET has been obtained, stop AO and AI tasks.
{
StopTaskAOAI();
printf("%d sweeps have been obtained. Press Enter to exit.\n", N_SWEEPS_TARGET);
}
}
Error:
if( DAQmxFailed(error) )
{
DAQmxGetExtendedErrorInfo(errBuff, 2048);
StopTaskAOAI();
printf("DAQmx Error: %s\n", errBuff); /* NOTE: If an error occurs here, the user will see the error message and will respond accordingly*/
}
return 0;
}
// A function to stop AO and AI tasks
void StopTaskAOAI()
{
/* --- Step 11 stop AI and AO tasks --- */
DAQmxStopTask(taskHandleAO);
DAQmxStopTask(taskHandleAI);
/* --- Step 12 clear AI and AO tasks --- */
DAQmxClearTask(taskHandleAO);
DAQmxClearTask(taskHandleAI);
/* --- Step 13 reset AI and AO task handles --- */
taskHandleAO = 0;
taskHandleAI = 0;
}
