rewrite

demo/mode2.c

@@ -1,15 +1,17 @@
 /*
-   A little input demo for mode 2
+   A little input demo for mode 4
 
-   Mode 2 uses two different timers to convert samples.
-   The primary timer determines the time between scans,
-   and the secondary timer determines the time between
-   samples in a scan.
+   Mode 4 uses an external trigger to repeatedly trigger a
+   scan of samples.  (This is different from mode 3, which
+   triggers an individual sample.)  Thus, for each external
+   trigger, n_chan samples are converted.
 
-   The time between scans is in trigval; the time
-   between samples is selected by trigval1.  Conversion
-   from seconds or Hz is done using the standard timer
-   routines.
+   If you have multiple external trigger lines, the
+   particular trigger line is selected by trigval.
+
+   The time between samples in a scan is selected
+   by trigval1.  Conversion from seconds or Hz is done
+   using the standard timer routines.
 
  */
 
@@ -22,42 +24,63 @@
 #include <getopt.h>
 #include <ctype.h>
 
-#define N_SCANS		10
-#define N_CHANS		16
+#define N_SCANS		4
+#define N_CHANS		4
 
 int subdevice = 0;
-int chan=0;
-int range = 0;
-int aref = AREF_GROUND;
+int channels[N_CHANS] = { 0, 1, 2, 3 };
 double freq = 1000;
+int range = 0;
+int aref = 3;
+int external_trigger_number = 0;
 
-#define N_SAMPLES	1000
+#define N_SAMPLES	(N_CHANS*N_SCANS)
 
-double data[N_SAMPLES];
+sampl_t data[N_SAMPLES];
 
 
 int main(int argc, char *argv[])
 {
 	char *fn = NULL;
-	int i;
+	comedi_trig it;
+	int err;
+	int n,i;
 	comedi_t *dev;
+	double actual_freq;
+	unsigned int chan[N_CHANS];
 
-	fn = "/dev/comedi0";
+	fn = "/dev/comedi3";
 
 	dev = comedi_open(fn);
 
-#if 0
-	for(i=0;i<10;i++){
-		range=comedi_find_range(dev,subdevice,chan,0,-i,i);
-		printf("%d\n",range);
-	}
-#endif
-	comedi_timed_1chan(dev,subdevice,chan,range,aref,freq,N_SAMPLES,data);
+	it.subdev = 0;
+	it.mode = 2;
+	it.flags = 0;
+	it.n_chan = 1;
+	it.chanlist = chan;
+	it.data = data;
+	it.n = N_SCANS;
+	it.trigsrc = 0;
+	it.trigvar = 10000;
+	it.trigvar1 = 10000;
 
-	for(i=0;i<N_SAMPLES;i++){
-		printf("%g\n",data[i]);
+	/* pack the channel list */
+	for(i=0;i<N_CHANS;i++){
+		chan[i] = CR_PACK(channels[i], range, aref);
 	}
 
+	if ((err = comedi_trigger(dev, &it)) < 0) {
+		perror("ioctl");
+		exit(1);
+	}
+
+	if((n=read(comedi_fileno(dev),data,N_SAMPLES*sizeof(sampl_t)))<0){
+		perror("read");
+		exit(1);
+	}
+	printf("number of samples read=%d\ndata[0]=%d\ndata[N-1]=%d\n",
+		n/sizeof(sampl_t),data[0],data[N_SAMPLES-1]);
+
 	return 0;
 }