*
* This demo uses an analog output subdevice with an
* asynchronous command to generate a waveform. The
- * waveform in this example is a sine wave (surprise!),
- * but this can be easily changed to make a generic
- * function generator.
+ * demo hijacks for -n option to select a waveform from
+ * a predefined list. The default waveform is a sine
+ * wave (surprise!). Other waveforms include sawtooth,
+ * square, triangle and cycloid.
*
* The function generation algorithm is the same as
* what is typically used in digital function generators.
sampl_t data[BUF_LEN];
void dds_output(sampl_t *buf,int n);
-void dds_init(double waveform_frequency, double update_frequency);
-
-/* This define determines which waveform to use. */
-#define dds_init_function dds_init_sine
+void dds_init(double waveform_frequency, double update_frequency, int fn);
void dds_init_sine(void);
void dds_init_pseudocycloid(void);
-void dds_init_sawtooth(void);
+void dds_init_cycloid(void);
+void dds_init_ramp_up(void);
+void dds_init_ramp_down(void);
+void dds_init_triangle(void);
+void dds_init_square(void);
+void dds_init_blancmange(void);
+
+static void (* const dds_init_function[])(void) = {
+ dds_init_sine,
+ dds_init_ramp_up,
+ dds_init_ramp_down,
+ dds_init_triangle,
+ dds_init_square,
+ dds_init_cycloid,
+ dds_init_blancmange,
+};
+
+#define NUMFUNCS (sizeof(dds_init_function)/sizeof(dds_init_function[0]))
int main(int argc, char *argv[])
{
comedi_range *rng;
int ret;
struct parsed_options options;
+ int fn;
init_parsed_options(&options);
options.subdevice = -1;
+ options.n_chan = -1; /* waveform */
parse_options(&options, argc, argv);
+ /* Use n_chan to select waveform (cheat!) */
+ fn = options.n_chan;
+ if(fn < 0 || fn >= NUMFUNCS){
+ fprintf(stderr,"Use the option '-n' to select another waveform.\n");
+ fn = 0;
+ }
+
/* Force n_chan to be 1 */
options.n_chan = 1;
if(options.subdevice < 0)
options.subdevice = comedi_find_subdevice_by_type(dev, COMEDI_SUBD_AO, 0);
- maxdata = comedi_get_maxdata(dev, options.subdevice, 0);
- rng = comedi_get_range(dev, options.subdevice, 0, 0);
+ maxdata = comedi_get_maxdata(dev, options.subdevice, options.channel);
+ rng = comedi_get_range(dev, options.subdevice, options.channel, options.range);
offset = (double)comedi_from_phys(0.0, rng, maxdata);
amplitude = (double)comedi_from_phys(1.0, rng, maxdata) - offset;
memset(&cmd,0,sizeof(cmd));
cmd.subdev = options.subdevice;
- cmd.flags = 0;
+ cmd.flags = CMDF_WRITE;
cmd.start_src = TRIG_INT;
cmd.start_arg = 0;
cmd.scan_begin_src = TRIG_TIMER;
cmd.chanlist_len = options.n_chan;
chanlist[0] = CR_PACK(options.channel, options.range, options.aref);
- chanlist[1] = CR_PACK(options.channel + 1, options.range, options.aref);
+ //chanlist[1] = CR_PACK(options.channel + 1, options.range, options.aref);
- dds_init(waveform_frequency, options.freq);
+ dds_init(waveform_frequency, options.freq, fn);
- dump_cmd(stdout,&cmd);
+ if (options.verbose)
+ dump_cmd(stdout,&cmd);
err = comedi_command_test(dev, &cmd);
if (err < 0) {
"See the --write-buffer option of comedi_config\n", n);
exit(1);
}
- printf("m=%d\n",m);
+ if (options.verbose)
+ printf("m=%d\n",m);
ret = comedi_internal_trigger(dev, options.subdevice, 0);
if(ret < 0){
perror("write");
exit(0);
}
- printf("m=%d\n",m);
+ if (options.verbose)
+ printf("m=%d\n",m);
n-=m;
}
total+=BUF_LEN;
unsigned int acc;
unsigned int adder;
-void dds_init(double waveform_frequency, double update_frequency)
+void dds_init(double waveform_frequency, double update_frequency, int fn)
{
adder = waveform_frequency / update_frequency * (1 << 16) * (1 << WAVEFORM_SHIFT);
- dds_init_function();
+ (*dds_init_function[fn])();
}
void dds_output(sampl_t *buf,int n)
}
}
+/* Defined for x in [0,1] */
+static inline double triangle(double x)
+{
+ return (x > 0.5) ? 1.0 - x : x;
+}
void dds_init_sine(void)
{
int i;
+ double ofs = offset;
+ double amp = 0.5 * amplitude;
+ if(ofs < amp){
+ /* Probably a unipolar range. Bump up the offset. */
+ ofs = amp;
+ }
for(i=0;i<WAVEFORM_LEN;i++){
- waveform[i]=rint(offset+0.5*amplitude*cos(i*2*M_PI/WAVEFORM_LEN));
+ waveform[i]=rint(ofs+amp*cos(i*2*M_PI/WAVEFORM_LEN));
}
}
}
}
-void dds_init_sawtooth(void)
+void dds_init_cycloid(void)
+{
+ enum { SUBSCALE = 2 }; /* Needs to be >= 2. */
+ int h, i, ni;
+ double t, x, y;
+
+ i = -1;
+ for (h = 0; h < WAVEFORM_LEN * SUBSCALE; h++){
+ t = (h * (2 * M_PI)) / (WAVEFORM_LEN * SUBSCALE);
+ x = t - sin(t);
+ ni = (int)floor((x * WAVEFORM_LEN) / (2 * M_PI));
+ if (ni > i) {
+ i = ni;
+ y = 1 - cos(t);
+ waveform[i] = rint(offset + (amplitude * y / 2));
+ }
+ }
+}
+
+void dds_init_ramp_up(void)
{
int i;
}
}
+void dds_init_ramp_down(void)
+{
+ int i;
+
+ for(i=0;i<WAVEFORM_LEN;i++){
+ waveform[i]=rint(offset+amplitude*((double)(WAVEFORM_LEN-1-i))/WAVEFORM_LEN);
+ }
+}
+
+void dds_init_triangle(void)
+{
+ int i;
+
+ for (i = 0; i < WAVEFORM_LEN; i++) {
+ waveform[i] = rint(offset + amplitude * 2 * triangle((double)i / WAVEFORM_LEN));
+ }
+}
+
+void dds_init_square(void)
+{
+ int i;
+
+ for (i = 0; i < WAVEFORM_LEN / 2; i++) {
+ waveform[i] = rint(offset);
+ }
+ for ( ; i < WAVEFORM_LEN; i++) {
+ waveform[i] = rint(offset + amplitude);
+ }
+}
+
+void dds_init_blancmange(void)
+{
+ int i, n;
+ double b, x;
+
+ for (i = 0; i < WAVEFORM_LEN; i++) {
+ b = 0;
+ for (n = 0; n < 16; n++) {
+ x = (double)i / WAVEFORM_LEN;
+ x *= (1 << n);
+ x -= floor(x);
+ b += triangle(x) / (1 << n);
+ }
+ waveform[i] = rint(offset + amplitude * 1.5 * b);
+ }
+}
projects / comedilib.git / blobdiff