--- /dev/null
+/*
+ * Asynchronous Digital Output Example
+ * Part of Comedilib
+ *
+ * Copyright (c) 1999,2000 David A. Schleef <ds@schleef.org>
+ * Copyright (c) 2007 Frank Mori Hess <fmhess@users.sourceforge.net>
+ *
+ * This file may be freely modified, distributed, and combined with
+ * other software, as long as proper attribution is given in the
+ * source code.
+ */
+
+/*
+ * Requirements: NI M-Series board.
+ *
+ * This demo uses the digital io subdevice with an
+ * asynchronous command to generate waveforms. The
+ * waveforms in this example are square waves with
+ * varying periods depending on the digital output
+ * channel. Channel N outputs a square wave with
+ * period 2*(N+1) clocks. The command line argument chooses the
+ * clock signal for updating the outputs. As a suggestion,
+ * you might use the output of one of the general
+ * purpose counters for a clock (the default clock
+ * source is the output of general purpose counter 0),
+ * and run the gpct_pulse_generator demo to start the counter
+ * generating pulses on its output.
+ *
+ * Note, you must configure at least one of the digital channels as
+ * an output (for example by running the dio demo program)
+ * before running this program. You must also pass the dio
+ * subdevice file using the -f option, since the default write
+ * subdevice for the m-series boards is the analog output. For
+ * example, "dio_waveform -f /dev/comedi0_sub2".
+ */
+
+#include <assert.h>
+#include <comedilib.h>
+#include <ctype.h>
+#include <errno.h>
+#include "examples.h"
+#include <fcntl.h>
+#include <malloc.h>
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#define BUF_LEN 0x1000
+
+struct test_waveform_generator
+{
+ unsigned *toggle_countdowns;
+ unsigned num_channels;
+ lsampl_t last_output;
+};
+
+int init_test_waveform_generator(struct test_waveform_generator *generator, unsigned num_channels)
+{
+ unsigned i;
+
+ generator->num_channels = num_channels;
+ generator->toggle_countdowns = malloc(sizeof(unsigned) * num_channels);
+ if(generator->toggle_countdowns == NULL) return -ENOMEM;
+ for(i = 0; i < num_channels; ++i)
+ generator->toggle_countdowns[i] = i + 1;
+ generator->last_output = 0;
+ return 0;
+}
+
+void cleanup_test_waveform_generator(struct test_waveform_generator *generator)
+{
+ if(generator->toggle_countdowns)
+ {
+ free(generator->toggle_countdowns);
+ generator->toggle_countdowns = NULL;
+ }
+}
+
+void build_waveforms(struct test_waveform_generator *generator, lsampl_t *data, unsigned data_len)
+{
+ unsigned i;
+ for(i = 0; i < data_len; ++i)
+ {
+ unsigned j;
+
+ data[i] = generator->last_output;
+ for(j = 0; j < generator->num_channels; ++j)
+ {
+ if(--generator->toggle_countdowns[j] == 0)
+ {
+ generator->toggle_countdowns[j] = j + 1;
+ data[i] ^= 1 << j;
+ }
+ }
+ generator->last_output = data[i];
+ }
+}
+
+int main(int argc, char *argv[])
+{
+ comedi_cmd cmd;
+ struct parsed_options options;
+ comedi_t *dev;
+ int i;
+ struct test_waveform_generator generator;
+ lsampl_t *buffer = NULL;
+ int err;
+ int n, m;
+ int total=0;
+ unsigned int *chanlist;
+ int ret;
+
+ init_parsed_options(&options);
+ options.subdevice = -1;
+ options.n_chan = 8;
+ options.value = NI_CDIO_SCAN_BEGIN_SRC_G0_OUT;
+ parse_options(&options, argc, argv);
+
+ dev = comedi_open(options.filename);
+ if(dev == NULL){
+ fprintf(stderr, "error opening %s\n", options.filename);
+ return -1;
+ }
+ if(options.subdevice < 0)
+ options.subdevice = comedi_find_subdevice_by_type(dev, COMEDI_SUBD_DIO, 0);
+
+ memset(&cmd,0,sizeof(cmd));
+ cmd.subdev = options.subdevice;
+ cmd.flags = CMDF_WRITE;
+ cmd.start_src = TRIG_INT;
+ cmd.start_arg = 0;
+ cmd.scan_begin_src = TRIG_EXT;
+ cmd.scan_begin_arg = options.value;
+ cmd.convert_src = TRIG_NOW;
+ cmd.convert_arg = 0;
+ cmd.scan_end_src = TRIG_COUNT;
+ cmd.scan_end_arg = options.n_chan;
+ cmd.stop_src = TRIG_NONE;
+ cmd.stop_arg = 0;
+
+ chanlist = malloc(options.n_chan * sizeof(unsigned));
+ assert(chanlist);
+ cmd.chanlist = chanlist;
+ cmd.chanlist_len = options.n_chan;
+ for(i = 0; i < cmd.chanlist_len; ++i)
+ {
+ cmd.chanlist[i] = i;
+ }
+
+ dump_cmd(stdout, &cmd);
+
+ err = comedi_command_test(dev, &cmd);
+ if (err < 0) {
+ comedi_perror("comedi_command_test");
+ exit(1);
+ }
+
+ err = comedi_command_test(dev, &cmd);
+ if (err < 0) {
+ comedi_perror("comedi_command_test");
+ exit(1);
+ }
+
+ err = comedi_command_test(dev, &cmd);
+ if(err != 0) {
+ fprintf(stderr, "After 3 passes, comedi_command_test returns %i\n", err);
+ exit(1);
+ }
+
+ if ((err = comedi_command(dev, &cmd)) < 0) {
+ comedi_perror("comedi_command");
+ exit(1);
+ }
+
+ ret = init_test_waveform_generator(&generator, cmd.chanlist_len);
+ assert(ret == 0);
+ buffer = malloc(sizeof(lsampl_t) * BUF_LEN);
+ assert(buffer);
+ build_waveforms(&generator, buffer, BUF_LEN);
+ n = BUF_LEN * sizeof(buffer[0]);
+ m = write(comedi_fileno(dev), buffer, n);
+ if(m < 0){
+ perror("write");
+ exit(1);
+ }else if(m < n)
+ {
+ fprintf(stderr, "Failed to preload output buffer with %i bytes, is it too small?\n"
+ "See the --write-buffer option of comedi_config\n", n);
+ exit(1);
+ }
+ printf("m=%d\n",m);
+
+ ret = comedi_internal_trigger(dev, options.subdevice, 0);
+ if(ret < 0){
+ perror("comedi_internal_trigger\n");
+ exit(1);
+ }
+
+ while(1)
+ {
+ build_waveforms(&generator, buffer, BUF_LEN);
+ n = BUF_LEN * sizeof(buffer[0]);
+ while(n > 0)
+ {
+ m = write(comedi_fileno(dev), (void*)(buffer) + (BUF_LEN * sizeof(buffer[0]) - n), n);
+ if(m < 0){
+ perror("write");
+ exit(0);
+ }
+ printf("m=%d\n",m);
+ n -= m;
+ }
+ total += BUF_LEN;
+ //printf("%d\n",total);
+ }
+
+ cleanup_test_waveform_generator(&generator);
+ free(buffer);
+ free(chanlist);
+ return 0;
+}
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