--- /dev/null
+/*
+ * NI general-purpose counter example. Configures the counter to
+ * produce a continuous pulse train. The argument specifies the
+ * number of nanoseconds the output pulse should remain high.
+ * The example assumes the board has already been configured to
+ * route the output signal of the counter to an appropriate
+ * location (you may need to route it to a PFI output line
+ * for example).
+ * Part of Comedilib
+ *
+ * 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: A board with a National Instruments general-purpose
+ * counter, and comedi driver version 0.7.74 or newer.
+ */
+
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <comedilib.h>
+#include <math.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <getopt.h>
+#include <ctype.h>
+#include "examples.h"
+
+/*FIXME: move helper functions to common.c so they can be used on other (mostly counter) examples*/
+
+int arm(comedi_t *device, unsigned subdevice, lsampl_t source)
+{
+ comedi_insn insn;
+ lsampl_t data[2];
+ int retval;
+
+ memset(&insn, 0, sizeof(comedi_insn));
+ insn.insn = INSN_CONFIG;
+ insn.subdev = subdevice;
+ insn.chanspec = 0;
+ insn.data = data;
+ insn.n = sizeof(data) / sizeof(data[0]);
+ data[0] = INSN_CONFIG_ARM;
+ data[1] = source;
+
+ retval = comedi_do_insn(device, &insn);
+ if(retval < 0)
+ {
+ fprintf(stderr, "%s: error:\n", __FUNCTION__);
+ comedi_perror("comedi_do_insn");
+ return retval;
+ }
+ return 0;
+}
+
+/* This resets the count to zero and disarms the counter. The counter output
+ is set low. */
+int reset_counter(comedi_t *device, unsigned subdevice)
+{
+ comedi_insn insn;
+ lsampl_t data[1];
+ int retval;
+
+ memset(&insn, 0, sizeof(comedi_insn));
+ insn.insn = INSN_CONFIG;
+ insn.subdev = subdevice;
+ insn.chanspec = 0;
+ insn.data = data;
+ insn.n = sizeof(data) / sizeof(data[0]);
+ data[0] = INSN_CONFIG_RESET;
+
+ retval = comedi_do_insn(device, &insn);
+ if(retval < 0)
+ {
+ fprintf(stderr, "%s: error:\n", __FUNCTION__);
+ comedi_perror("comedi_do_insn");
+ return retval;
+ }
+ return 0;
+}
+
+int set_counter_mode(comedi_t *device, unsigned subdevice, lsampl_t mode_bits)
+{
+ comedi_insn insn;
+ lsampl_t data[2];
+ int retval;
+
+ memset(&insn, 0, sizeof(comedi_insn));
+ insn.insn = INSN_CONFIG;
+ insn.subdev = subdevice;
+ insn.chanspec = 0;
+ insn.data = data;
+ insn.n = sizeof(data) / sizeof(data[0]);
+ data[0] = INSN_CONFIG_SET_COUNTER_MODE;
+ data[1] = mode_bits;
+
+ retval = comedi_do_insn(device, &insn);
+ if(retval < 0)
+ {
+ fprintf(stderr, "%s: error:\n", __FUNCTION__);
+ comedi_perror("comedi_do_insn");
+ return retval;
+ }
+ return 0;
+}
+
+int set_clock_source(comedi_t *device, unsigned subdevice, lsampl_t clock, lsampl_t period_ns)
+{
+ comedi_insn insn;
+ lsampl_t data[3];
+ int retval;
+
+ memset(&insn, 0, sizeof(comedi_insn));
+ insn.insn = INSN_CONFIG;
+ insn.subdev = subdevice;
+ insn.chanspec = 0;
+ insn.data = data;
+ insn.n = sizeof(data) / sizeof(data[0]);
+ data[0] = INSN_CONFIG_SET_CLOCK_SRC;
+ data[1] = clock;
+ data[2] = period_ns;
+
+ retval = comedi_do_insn(device, &insn);
+ if(retval < 0)
+ {
+ fprintf(stderr, "%s: error:\n", __FUNCTION__);
+ comedi_perror("comedi_do_insn");
+ return retval;
+ }
+ return 0;
+}
+
+int set_gate_source(comedi_t *device, unsigned subdevice, lsampl_t gate_index, lsampl_t gate_source)
+{
+ comedi_insn insn;
+ lsampl_t data[3];
+ int retval;
+
+ memset(&insn, 0, sizeof(comedi_insn));
+ insn.insn = INSN_CONFIG;
+ insn.subdev = subdevice;
+ insn.chanspec = 0;
+ insn.data = data;
+ insn.n = sizeof(data) / sizeof(data[0]);
+ data[0] = INSN_CONFIG_SET_GATE_SRC;
+ data[1] = gate_index;
+ data[2] = gate_source;
+
+ retval = comedi_do_insn(device, &insn);
+ if(retval < 0)
+ {
+ fprintf(stderr, "%s: error:\n", __FUNCTION__);
+ comedi_perror("comedi_do_insn");
+ return retval;
+ }
+ return 0;
+}
+
+int ni_gpct_start_pulse_generator(comedi_t *device, unsigned subdevice, unsigned period_ns, unsigned up_time_ns)
+{
+ int retval;
+ lsampl_t counter_mode;
+ const unsigned clock_period_ns = 50; /* 20MHz clock */
+ unsigned up_ticks, down_ticks;
+/*
+FIXME:
+How is output initialized to known state for toggling (reset?)
+*/
+ retval = reset_counter(device, subdevice);
+ if(retval < 0) return retval;
+
+ retval = set_gate_source(device, subdevice, 0, NI_GPCT_DISABLED_GATE_SELECT | CR_EDGE);
+ if(retval < 0) return retval;
+ retval = set_gate_source(device, subdevice, 1, NI_GPCT_DISABLED_GATE_SELECT | CR_EDGE);
+ if(retval < 0)
+ {
+ fprintf(stderr, "Failed to set second gate source. This is expected for older boards (e-series, etc.)\n"
+ "that don't have a second gate.\n");
+ }
+
+ counter_mode = NI_GPCT_COUNTING_MODE_NORMAL_BITS;
+ // toggle output on terminal count
+ counter_mode |= NI_GPCT_OUTPUT_TC_TOGGLE_BITS;
+ // load on terminal count
+ counter_mode |= NI_GPCT_LOADING_ON_TC_BIT;
+ // alternate the reload source between the load a and load b registers
+ counter_mode |= NI_GPCT_RELOAD_SOURCE_SWITCHING_BITS;
+ // count down
+ counter_mode |= NI_GPCT_COUNTING_DIRECTION_DOWN_BITS;
+ // initialize load source as load b register
+ counter_mode |= NI_GPCT_LOAD_B_SELECT_BIT;
+ retval = set_counter_mode(device, subdevice, counter_mode);
+ if(retval < 0) return retval;
+
+ /* 20MHz clock */
+ retval = set_clock_source(device, subdevice, NI_GPCT_TIMEBASE_1_CLOCK_SRC_BITS, clock_period_ns);
+ if(retval < 0) return retval;
+
+ up_ticks = (up_time_ns + clock_period_ns / 2) / clock_period_ns;
+ down_ticks = (period_ns + clock_period_ns / 2) / clock_period_ns - up_ticks;
+ /* set initial counter value by writing to channel 0 */
+ retval = comedi_data_write(device, subdevice, 0, 0, 0, down_ticks);
+ if(retval < 0) return retval;
+ /* set "load a" register to the number of clock ticks the counter output should remain low
+ by writing to channel 1. */
+ comedi_data_write(device, subdevice, 1, 0, 0, down_ticks);
+ if(retval < 0) return retval;
+ /* set "load b" register to the number of clock ticks the counter output should remain high
+ by writing to channel 2 */
+ comedi_data_write(device, subdevice, 2, 0, 0, up_ticks);
+ if(retval < 0) return retval;
+
+ retval = arm(device, subdevice, NI_GPCT_ARM_IMMEDIATE);
+ if(retval < 0) return retval;
+
+ return 0;
+}
+
+int main(int argc, char *argv[])
+{
+ comedi_t *device;
+ unsigned up_time;
+ unsigned period_ns;
+ int retval;
+ struct parsed_options options;
+
+ init_parsed_options(&options);
+ options.value = -1.;
+ parse_options(&options, argc, argv);
+ period_ns = lrint(1e9 / options.freq);
+ if(options.value < 0.)
+ up_time = period_ns / 2;
+ else
+ up_time = lrint(options.value);
+ device = comedi_open(options.filename);
+ if(!device)
+ {
+ comedi_perror(options.filename);
+ exit(-1);
+ }
+ /*FIXME: check that device is counter */
+ printf("Generating pulse train on subdevice %d.\n", options.subdevice);
+ printf("Period = %d ns.\n", period_ns);
+ printf("Up Time = %d ns.\n", up_time);
+ printf("Down Time = %d ns.\n", period_ns - up_time);
+
+ retval = ni_gpct_start_pulse_generator(device, options.subdevice, period_ns, up_time);
+ if(retval < 0) return retval;
+ return 0;
+}
+
projects / comedilib.git / commitdiff