comedilib/demo/tut3_part.c

129 lines
3.5 KiB
C

/* open the device */
dev = comedi_open(options.filename);
if(!dev){
comedi_perror(options.filename);
exit(1);
}
// Print numbers for clipped inputs
comedi_set_global_oor_behavior(COMEDI_OOR_NUMBER);
/* Set up channel list */
for(i = 0; i < options.n_chan; i++){
chanlist[i] = CR_PACK(options.channel + i,
options.range,
options.aref);
range_info[i] = comedi_get_range(dev,
options.subdevice,
options.channel, options.range);
maxdata[i] = comedi_get_maxdata(dev,
options.subdevice,
options.channel);
}
/* prepare_cmd_lib() uses a Comedilib routine to find a
* good command for the device. prepare_cmd() explicitly
* creates a command, which may not work for your device. */
prepare_cmd_lib(dev,
options.subdevice,
options.n_scan,
options.n_chan,
1e9 / options.freq, cmd);
/* comedi_command_test() tests a command to see if the
* trigger sources and arguments are valid for the subdevice.
* If a trigger source is invalid, it will be logically ANDed
* with valid values (trigger sources are actually bitmasks),
* which may or may not result in a valid trigger source.
* If an argument is invalid, it will be adjusted to the
* nearest valid value. In this way, for many commands, you
* can test it multiple times until it passes. Typically,
* if you can't get a valid command in two tests, the original
* command wasn't specified very well. */
ret = comedi_command_test(dev, cmd);
if(ret < 0){
comedi_perror("comedi_command_test");
exit(1);
}
ret = comedi_command_test(dev, cmd);
if(ret < 0){
comedi_perror("comedi_command_test");
exit(1);
}
fprintf(stderr,"second test returned %d (%s)\n", ret,
cmdtest_messages[ret]);
if(ret!=0){
fprintf(stderr, "Error preparing command\n");
exit(1);
}
/* start the command */
ret = comedi_command(dev, cmd);
if(ret < 0){
comedi_perror("comedi_command");
exit(1);
}
subdev_flags = comedi_get_subdevice_flags(dev, options.subdevice);
while(1){
ret = read(comedi_fileno(dev),buf,BUFSZ);
if(ret < 0){
/* some error occurred */
perror("read");
break;
}else if(ret == 0){
/* reached stop condition */
break;
}else{
static int col = 0;
int bytes_per_sample;
total += ret;
if(options.verbose)fprintf(stderr, "read %d %d\n", ret, total);
if(subdev_flags & SDF_LSAMPL)
bytes_per_sample = sizeof(lsampl_t);
else
bytes_per_sample = sizeof(sampl_t);
for(i = 0; i < ret / bytes_per_sample; i++){
if(subdev_flags & SDF_LSAMPL) {
raw = ((lsampl_t *)buf)[i];
} else {
raw = ((sampl_t *)buf)[i];
}
print_datum(raw, col);
col++;
if(col == options.n_chan){
printf("\n");
col=0;
}
}
}
}
}
/*
* This prepares a command in a pretty generic way. We ask the
* library to create a stock command that supports periodic
* sampling of data, then modify the parts we want. */
int prepare_cmd_lib(comedi_t *dev, int subdevice, int n_scan, int n_chan,
unsigned scan_period_nanosec, comedi_cmd *cmd)
{
int ret;
memset(cmd,0,sizeof(*cmd));
/* This comedilib function will get us a generic timed
* command for a particular board. If it returns -1,
* that's bad. */
ret = comedi_get_cmd_generic_timed(dev, subdevice, cmd, n_chan, scan_period_nanosec);
if(ret<0){
printf("comedi_get_cmd_generic_timed failed\n");
return ret;
}
/* Modify parts of the command */
cmd->chanlist = chanlist;
cmd->chanlist_len = n_chan;
if(cmd->stop_src == TRIG_COUNT) cmd->stop_arg = n_scan;
return 0;
}