added poll example
This commit is contained in:
David Schleef
parent
ad4ee57f18
commit
d4b04cd828
2 changed files with 234 additions and 1 deletions
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@ -8,7 +8,7 @@ LDFLAGS = -L../lib/ -lcomedi -lm
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BINS=tut1 tut2
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MBINS=inp inpn sv eeprom_dump info outp insn antialias ao_waveform \
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dio mmap ledclock receiver sigio select sender cmd
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dio mmap ledclock receiver sigio select sender cmd poll
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all: $(BINS) $(MBINS)
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233
demo/poll.c
Normal file
233
demo/poll.c
Normal file
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@ -0,0 +1,233 @@
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/*
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* poll.c - Example of using comedi_poll() with Comedi
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* Part of Comedilib
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*
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* Copyright (c) 1999,2000 David A. Schleef <ds@schleef.org>
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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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* An example for using comedi_poll() in asynchronous input,
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* so you can ask the driver to pull samples that may be waiting
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* on the board into the buffer (so they can be read).
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*/
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#include <stdio.h>
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#include <comedilib.h>
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#include <fcntl.h>
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#include <unistd.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 <string.h>
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#include <sys/time.h>
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#include "examples.h"
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#define N_SCANS 10
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#define N_CHANS 16
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double freq = 1000;
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#define BUFSZ 1000
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sampl_t buf[BUFSZ];
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int n_chans = 1;
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int n_scans = 10;
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unsigned int chanlist[4];
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comedi_t *device;
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void prepare_cmd(comedi_t *dev,comedi_cmd *cmd);
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void do_cmd(comedi_t *dev,comedi_cmd *cmd);
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#define sec_to_nsec(x) ((x)*1000000000)
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#define sec_to_usec(x) ((x)*1000000)
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#define sec_to_msec(x) ((x)*1000)
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#define msec_to_nsec(x) ((x)*1000000)
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#define msec_to_usec(x) ((x)*1000)
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#define usec_to_nsec(x) ((x)*1000)
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int comedi_poll(comedi_t *dev,unsigned int subdev)
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{
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return ioctl(comedi_fileno(dev),COMEDI_POLL,subdev);
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}
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int main(int argc, char *argv[])
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{
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comedi_cmd cmd;
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int i;
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parse_options(argc,argv);
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device = comedi_open(filename);
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if(!device){
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perror(filename);
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exit(1);
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}
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fcntl(comedi_fileno(device),F_SETFL,O_NONBLOCK);
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for(i=0;i<n_chans;i++){
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chanlist[i]=CR_PACK(channel+i,range,aref);
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}
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prepare_cmd(device,&cmd);
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do_cmd(device,&cmd);
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return 0;
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}
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void do_cmd(comedi_t *dev,comedi_cmd *cmd)
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{
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int total=0;
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int ret;
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int go;
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fd_set rdset;
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struct timeval timeout;
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ret=comedi_command_test(dev,cmd);
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printf("test ret=%d\n",ret);
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if(ret<0){
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printf("errno=%d\n",errno);
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comedi_perror("comedi_command_test");
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return;
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}
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dump_cmd(cmd);
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ret=comedi_command_test(dev,cmd);
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printf("test ret=%d\n",ret);
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if(ret<0){
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printf("errno=%d\n",errno);
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comedi_perror("comedi_command_test");
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return;
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}
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dump_cmd(cmd);
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ret=comedi_command(dev,cmd);
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printf("ret=%d\n",ret);
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if(ret<0){
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printf("errno=%d\n",errno);
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comedi_perror("comedi_command");
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return;
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}
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go=1;
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while(go){
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FD_ZERO(&rdset);
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FD_SET(comedi_fileno(device),&rdset);
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timeout.tv_sec = 0;
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timeout.tv_usec = 50000;
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ret = select(comedi_fileno(dev)+1,&rdset,NULL,NULL,&timeout);
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//printf("select returned %d\n",ret);
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if(ret<0){
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perror("select");
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}else if(ret==0){
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/* hit timeout */
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printf("timeout, polling...\n");
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ret = comedi_poll(device,0);
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printf("poll returned %d\n",ret);
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}else if(FD_ISSET(comedi_fileno(device),&rdset)){
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/* comedi file descriptor became ready */
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//printf("comedi file descriptor ready\n");
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ret=read(comedi_fileno(dev),buf,sizeof(buf));
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printf("read returned %d\n",ret);
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if(ret<0){
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if(errno==EAGAIN){
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go = 0;
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perror("read");
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}
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}else if(ret==0){
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go = 0;
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}else{
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int i;
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total+=ret;
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//printf("read %d %d\n",ret,total);
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for(i=0;i<ret/sizeof(sampl_t);i++){
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printf("%d\n",buf[i]);
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}
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}
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}else{
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/* unknown file descriptor became ready */
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printf("unknown file descriptor ready\n");
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}
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}
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}
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/*
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* This part of the demo measures channels 1, 2, 3, 4 at a rate of
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* 10 khz, with the inter-sample time at 10 us (100 khz). The number
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* of scans measured is 10. This is analogous to the old mode2
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* acquisition.
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*/
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void prepare_cmd(comedi_t *dev,comedi_cmd *cmd)
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{
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memset(cmd,0,sizeof(*cmd));
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/* the subdevice that the command is sent to */
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cmd->subdev = subdevice;
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/* flags */
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cmd->flags = 0;
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/* each event requires a trigger, which is specified
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by a source and an argument. For example, to specify
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an external digital line 3 as a source, you would use
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src=TRIG_EXT and arg=3. */
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/* In this case, we specify using TRIG_NOW to start
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* acquisition immediately when the command is issued.
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* The argument of TRIG_NOW is "number of nsec after
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* NOW", but no driver supports it yet. Also, no driver
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* currently supports using a start_src other than
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* TRIG_NOW. */
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cmd->start_src = TRIG_NOW;
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cmd->start_arg = 0;
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/* The timing of the beginning of each scan is controlled
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* by scan_begin. TRIG_TIMER specifies that scan_start
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* events occur periodically at a rate of scan_begin_arg
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* nanoseconds between scans. */
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cmd->scan_begin_src = TRIG_TIMER;
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cmd->scan_begin_arg = msec_to_nsec(100);
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/* The timing between each sample in a scan is controlled
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* by convert. Like above, TRIG_TIMER specifies that
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* convert events occur periodically at a rate of convert_arg
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* nanoseconds between scans. */
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cmd->convert_src = TRIG_TIMER;
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cmd->convert_arg = msec_to_nsec(1);
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/* The end of each scan is almost always specified using
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* TRIG_COUNT, with the argument being the same as the
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* number of channels in the chanlist. You could probably
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* find a device that allows something else, but it would
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* be strange. */
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cmd->scan_end_src = TRIG_COUNT;
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cmd->scan_end_arg = n_chans; /* number of channels */
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/* The end of acquisition is controlled by stop_src and
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* stop_arg. The src will typically be TRIG_COUNT or
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* TRIG_NONE. Specifying TRIG_COUNT will stop acquisition
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* after stop_arg number of scans, or TRIG_NONE will
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* cause acquisition to continue until stopped using
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* comedi_cancel(). */
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cmd->stop_src = TRIG_COUNT;
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cmd->stop_arg = n_scans;
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/* the channel list determined which channels are sampled.
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In general, chanlist_len is the same as scan_end_arg. Most
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boards require this. */
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cmd->chanlist = chanlist;
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cmd->chanlist_len = n_chans;
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}
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