Forgot to add file for new demo.
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Frank Mori Hess
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demo/gpct_buffered_counting.c
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demo/gpct_buffered_counting.c
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/*
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* NI general-purpose counter example. Makes the counter
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* do buffered event counting using comedi_command().
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* Different clock sources can be chosen
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* with the choose_clock demo. The gate source is
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* set to PFI1 (which is assumed to already be configured as
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* an input). The gate source latches the count
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* into the data stream, and possibly resets it (for
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* non-cumulative buffered counting).
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* Part of Comedilib
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*
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* Copyright (c) 2007 Frank Mori Hess <fmhess@users.sourceforge.net>
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*
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* This file may be freely modified, distributed, and combined with
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* other software, as long as proper attribution is given in the
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* source code.
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*/
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/*
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* Requirements: A board with a National Instruments general-purpose
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* counter, and comedi driver version 0.7.74 or newer.
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*/
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#define _GNU_SOURCE
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#include <assert.h>
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#include <stdio.h>
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#include <comedilib.h>
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#include <math.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include <getopt.h>
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#include <ctype.h>
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#include "examples.h"
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int ni_gpct_configure_buffered_event_counting(comedi_t *device, unsigned subdevice)
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{
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int retval;
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lsampl_t counter_mode;
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static const unsigned gate_pfi_channel = 1;
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static const unsigned initial_count = 0;
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retval = reset_counter(device, subdevice);
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if(retval < 0) return retval;
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retval = set_gate_source(device, subdevice, 0, NI_GPCT_PFI_GATE_SELECT(gate_pfi_channel) /*| CR_EDGE*/);
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if(retval < 0) return retval;
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retval = set_gate_source(device, subdevice, 1, NI_GPCT_DISABLED_GATE_SELECT | CR_EDGE);
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if(retval < 0)
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{
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fprintf(stderr, "Failed to set second gate source. This is expected for older boards (e-series, etc.)\n"
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"that don't have a second gate.\n");
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}
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counter_mode = NI_GPCT_COUNTING_MODE_NORMAL_BITS;
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// output pulse on terminal count (doesn't really matter for this application)
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counter_mode |= NI_GPCT_OUTPUT_TC_PULSE_BITS;
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/* Don't alternate the reload source between the load a and load b registers.*/
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counter_mode |= NI_GPCT_RELOAD_SOURCE_FIXED_BITS;
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/* Reload counter on gate. Do not set if you want to do cumulative buffered counting. */
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counter_mode |= NI_GPCT_LOADING_ON_GATE_BIT;
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/* Make gate start/stop counting */
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counter_mode |= NI_GPCT_EDGE_GATE_STARTS_STOPS_BITS;
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// count up
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counter_mode |= NI_GPCT_COUNTING_DIRECTION_UP_BITS;
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// don't stop on terminal count
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counter_mode |= NI_GPCT_STOP_ON_GATE_BITS;
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// don't disarm on terminal count or gate signal
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counter_mode |= NI_GPCT_NO_HARDWARE_DISARM_BITS;
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retval = set_counter_mode(device, subdevice, counter_mode);
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if(retval < 0) return retval;
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/* Set initial counter value by writing to channel 0.*/
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retval = comedi_data_write(device, subdevice, 0, 0, 0, initial_count);
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/* Set value of "load a" register by writing to channel 1.*/
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retval = comedi_data_write(device, subdevice, 1, 0, 0, initial_count);
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return 0;
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}
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int ni_gpct_send_command(comedi_t *device, unsigned subdevice, unsigned n_counts)
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{
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comedi_cmd cmd;
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static const unsigned num_chan = 1;
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lsampl_t chanlist[num_chan];
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int retval;
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memset(&cmd, 0, sizeof(cmd));
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cmd.subdev = subdevice;
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cmd.flags = 0;
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cmd.flags |= TRIG_WAKE_EOS;
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/* Wake up at the end of every scan, reduces latency for slow data streams.
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Turn off for more efficient throughput. */
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cmd.flags |= TRIG_WAKE_EOS;
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cmd.start_src = TRIG_NOW;
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cmd.start_arg = 0;
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/* TRIG_OTHER will use the already configured gate source to latch counts. Can also use
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TRIG_EXT and specify the gate source as the scan_begin_arg */
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cmd.scan_begin_src = TRIG_OTHER;
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cmd.scan_begin_arg = 0;
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cmd.convert_src = TRIG_NOW;
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cmd.convert_arg = 0;
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cmd.scan_end_src = TRIG_COUNT;
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cmd.scan_end_arg = num_chan;
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cmd.stop_src = TRIG_COUNT;
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cmd.stop_arg = n_counts;
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cmd.chanlist = chanlist;
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cmd.chanlist_len = num_chan;
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chanlist[0] = 0;
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retval = comedi_command_test(device, &cmd);
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if(retval)
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{
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fprintf(stderr, "comedi_command_test() failed.\n");
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return -1;
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}
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retval = comedi_command(device, &cmd);
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if(retval)
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{
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fprintf(stderr, "comedi_command() failed.\n");
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return -1;
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}
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return 0;
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}
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int ni_gpct_read_and_dump_counts(comedi_t *device, const char *device_filename, unsigned subdevice)
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{
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char subdevice_filename[100];
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int retval;
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int fd;
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static const unsigned buffer_size = 1000;
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lsampl_t buffer[buffer_size];
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//TODO: allow subdevice file name to be specified as a command-line option (with sensible default)
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#if 0
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retval = snprintf(subdevice_filename, sizeof(subdevice_filename), "%s_sub%i", device_filename, subdevice);
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assert(retval < sizeof(subdevice_filename));
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fd = open(subdevice_filename, O_RDONLY);
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if(fd < 0)
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{
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fprintf(stderr, "error opening subdevice file \"%s\".\n", subdevice_filename);
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perror("open");
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return -errno;
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}
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#endif
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fd = comedi_fileno(device);
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retval = read(fd, buffer, buffer_size * sizeof(lsampl_t));
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while(retval > 0)
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{
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unsigned num_counts = retval / sizeof(lsampl_t);
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unsigned i;
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for(i = 0; i < num_counts; ++i)
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{
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printf("%i\n", buffer[i]);
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}
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retval = read(fd, buffer, buffer_size * sizeof(lsampl_t));
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}
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if(retval < 0)
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{
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fprintf(stderr, "error reading from subdevice file \"%s\".\n", subdevice_filename);
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perror("read");
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return -errno;
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}
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return 0;
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}
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int main(int argc, char *argv[])
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{
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comedi_t *device;
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int retval;
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struct parsed_options options;
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init_parsed_options(&options);
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parse_options(&options, argc, argv);
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device = comedi_open(options.filename);
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if(!device)
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{
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comedi_perror(options.filename);
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exit(-1);
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}
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/*FIXME: check that device is counter */
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printf("Running buffered event counting on subdevice %d.\n", options.subdevice);
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retval = ni_gpct_configure_buffered_event_counting(device, options.subdevice);
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if(retval < 0) return retval;
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retval = ni_gpct_send_command(device, options.subdevice, options.n_scan);
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if(retval < 0) return retval;
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retval = ni_gpct_read_and_dump_counts(device, options.filename, options.subdevice);
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if(retval < 0) return retval;
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return 0;
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}
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