Re: PCIDAS 4020/12 ext trigger/clock

I'm finally able to get back to this task.  Below is my attempt to do an 
insn for the external trigger and clock.  I know I'm supposed to set 
command's scan_begin_src to TRIG_OTHER, which I know how to do in the 
cmd program but don't know how to do with insn.  Do I use a INSN_CONFIG 
instruction?  If so, how?
When I run this code I get the error:
/dev/comedi0: invalid argument

most of my insn.c:

int main(int argc, char *argv[])
{
 int ret,i;
 comedi_insn insn[4];
 comedi_insnlist il;
 struct timeval t1,t2;
 lsampl_t data[MAX_SAMPLES];

 n_scan = 10; /* override default n_scan value to something more suitable */
 parse_options(argc,argv);
 if( n_scan > MAX_SAMPLES ){
  fprintf( stderr, "Requested too many samples, reducing to %i\n", MAX_SAMPLES );
  n_scan = MAX_SAMPLES;
 }

 device=comedi_open(filename);
 if(!device){
  comedi_perror(filename);
  exit(0);
 }

 if(verbose){
  printf("measuring device=%s subdevice=%d channel=%d range=%d analog reference=%d\n",
   filename,subdevice,channel,range,aref);
 }

 /* Set up a the "instruction list", which is just a pointer
  * to the array of instructions and the number of instructions.
  */
 il.n_insns=4;
 il.insns=insn;

 /* Instruction 0: perform a gettimeofday() */
 insn[0].insn=INSN_GTOD;
 insn[0].n=2;
 insn[0].data=(void *)&t1;

 /* Instruction 1: perform a timer config */
 insn[1].insn=INSN_CONFIG;
 insn[1].n=2;
 data[0]=INSN_CONFIG_TIMER_1;
 data[1]=COMEDI_EV_SCAN_BEGIN;
 data[2]=0;
 data[3]=0x04;
 data[4]=2;
 insn[1].data=data;

 /* Instruction 2: do 10 analog input reads */
 insn[2].insn=INSN_READ;
 insn[2].n=n_scan;
 insn[2].data=data;
 insn[2].subdev=subdevice;
 insn[2].chanspec=CR_PACK(channel,range,aref);

 /* Instruction 3: perform a gettimeofday() */
 insn[3].insn=INSN_GTOD;
 insn[3].n=2;
 insn[3].data=(void *)&t2;

 ret=comedi_do_insnlist(device,&il);
 if(ret<0){
  comedi_perror(filename);
  exit(0);
 }

 printf("initial time: %ld.%06ld\n",t1.tv_sec,t1.tv_usec);
 for(i=0;i<n_scan;i++){
  printf("%d\n",data[i]);
 }
 printf("final time: %ld.%06ld\n",t2.tv_sec,t2.tv_usec);

 printf("difference (us): %ld\n",(t2.tv_sec-t1.tv_sec)*1000000+
   (t2.tv_usec-t1.tv_usec));

 return 0;
}

thanks - nick

}



Frank Mori Hess wrote:

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>On Monday 20 December 2004 11:49 am, Nick Iorio wrote:
>  
>
>>I've posted this question at comedi.org and not received a response.  My
>>boss keeps bugging me to get this external clock code working but I
>>don't know how to do it.
>>I found a reference to this INSN_CONFIG_TIMER_1 since I sent this email
>>which helps some but still leaves a lot of questions.  Now, I guess the
>>data structures should look like:
>>
>>data[0]=INSN_CONFIG_TIMER_1;
>>data[1]=COMEDI_EV_SCAN_BEGIN;  correct?
>>    
>>
>
>Yes.  And you want to set your command's scan_begin_src to TRIG_OTHER.
>
>  
>
>>data[2]= ???  trigger negative edge (digital, not analog trigger)
>>    
>>
>
>That would be "channel_number | CR_INVERT | CR_EDGE".  The driver doesn't 
>care though.  I assume I ignored that parameter in the driver because the 
>hardware doesn't let you configure that.  I really should have added some 
>verification that the hardware behaves the way you are requesting it to 
>though.
>
>  
>
>>data[3]=0x04;
>>data[4]=???  divisor for 10Mhz clock
>>    
>>
>
>If you set the divisor to N, then the board will trigger on every Nth clock 
>signal it receives from your external clock.  The hardware's minimum 
>divisor is 2.
>
>  
>
>>As you can see I'm still guessing on some of this.  If there's any
>>documentation that would help me please point me to it.
>>
>>    
>>
>
>there isn't any, aside from what you already found, and the driver source 
>code.
>
>- -- 
>Frank
>
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