Re: How to get the sampled values on asynchronous aquisition (kernel space)

From: Pecenin <mpecenin_at_yahoo.com.br> · Date: Thu, 21 Jul 2005 14:02:14 -0300 (ART)

Yes, it work. I use the test below.

Thanks a lot!!!

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/comedi.h>
#include <linux/comedilib.h>

const char *dev_path = "/dev/comedi0";
comedi_t *dev = NULL;
unsigned int subd = 0;
void *ptr = NULL;

int do_cmd(void)
{
	int ret;

	comedi_cmd cmd;
	unsigned int chanlist[1];

	cmd.subdev = subd;
	cmd.flags = 0;

	cmd.start_src = TRIG_NOW;
	cmd.start_arg = 0;

	cmd.scan_begin_src = TRIG_TIMER;
	cmd.scan_begin_arg = 10000000;

	cmd.convert_src = TRIG_TIMER;
	cmd.convert_arg = 0;

	cmd.scan_end_src = TRIG_COUNT;
	cmd.scan_end_arg = 1;

	cmd.stop_src = TRIG_COUNT;
	cmd.stop_arg = 1000000000;

	cmd.chanlist = chanlist;
	cmd.chanlist_len = 1;

	chanlist[0] = CR_PACK(0,0,0);

	cmd.data=0;
	cmd.data_len=0;

	ret = comedi_command_test(dev,&cmd);
	printk("command test returned %d\n",ret);

	cmd.chanlist = chanlist;
	cmd.chanlist_len = 1;
	cmd.data=0;
	cmd.data_len=0;

	ret = comedi_command_test(dev,&cmd);
	printk("command test returned %d\n",ret);

	cmd.chanlist = chanlist;
	cmd.chanlist_len = 1;
	cmd.data=0;
	cmd.data_len=0;

	ret = comedi_command(dev,&cmd);
	printk("command returned %d\n",ret);

	return ret;
}

int callback(unsigned int i,void *arg)
{
	int ret, ofs;

	ofs = comedi_get_buffer_offset(dev, subd);
	ret = comedi_get_buffer_contents(dev, subd);

	rt_printk("sample: %d\n", *(sampl_t *)(ptr + ofs));

	ret = comedi_mark_buffer_read(dev, subd,
sizeof(sampl_t));
	return 0;
}

int init_module(void)
{
	int ret;

	dev = comedi_open(dev_path);
	printk("comedi_open: %d\n",(int)dev);

	ret = comedi_lock(dev,subd);
	printk("comedi_lock: %d\n",ret);

	ret = comedi_map(dev, subd, &ptr);
	printk("comedi_map ret: %d, ptr: %d\n", ret,
(int)ptr);

comedi_register_callback(dev,subd,COMEDI_CB_EOS,callback,NULL);

	do_cmd();

	return 0;
}

void cleanup_module(void)
{
	int ret;

	ret = comedi_cancel(dev,subd);
	printk("comedi_cancel: %d\n",ret);

	ret = comedi_unmap(dev, subd);
	printk("comedi_unmap ret: %d\n", ret);

	ret = comedi_unlock(dev,subd);
	printk("comedi_unlock: %d\n",ret);

	ret = comedi_close(dev);
	printk("comedi_close: %d\n", ret);
}

Pecenin

--- Andrés Cascallana Alvarez
<acascallana_at_simulare.com> escreveu:

> This code snippet is from a kernel module where 16
> bits samples are being
> adquired. I think that i got that from the
> mailing-list.
> On this example, a callback function is called each
> time an adquisition
> ends.That is done with  comedi_register_callback()
> on init_module() before
> launching the comedi command, with the COMEDI_CB_EOS
> flag.
> I hope this helps.
> Regards,
> 
> Andrés
> 
>
//--------------------------------------------------------------------------
> -------------
> Global variables:
> 
> comedi_t *dispositivo_comedi;
> void *map, *front;
> 
>
//--------------------------------------------------------------------------
> -------------
> On init_module() :
> 
>  dispositivo_comedi =
> comedi_open(datablocks->comediai.device);
>  if (dispositivo_comedi==NULL)
>  {
>   printk("Error en comedi_open.\n");
>   return -1;
>  }
> 
>  ret=comedi_map(dispositivo_comedi,0,&map); // Call
> comedi_unmap() on
> cleanup_module()
>  if( ret < 0 )
>  {
>   printk("Error en mmap.\n");
>   return -1;
>  }
> 
>  front = (void *)comedi_get_buf_head_pos
> (dispositivo_comedi, 0);
> 
>
//--------------------------------------------------------------------------
> -------------
> On the callback:
> 
>
ret=comedi_get_buffer_contents(dispositivo_comedi,0);
>  if (ret==-1)
>   rt_printk("callback: Error en
> comedi_get_buffer_contents:
> %s\n",comedi_strerror(ret));
> 
>  if (ret!=-1)
>  {
>   front =
> comedi_get_buffer_offset(dispositivo_comedi, 0);
> 
>   for (i=0;i<ret/2;i++)
>   {
>    sample = *((lsampl_t *)(map + front + i*2));
>    rt_printk("%04x ",sample);
>   }
> 
>  rt_printk("\n");
> 
>  
>
ret=comedi_mark_buffer_read(dispositivo_comedi,0,ret);
>   if (ret==-1)
>    rt_printk("callback: Error en
> comedi_get_buffer_contents:
> %s\n",comedi_strerror(ret));
>  }
> 
> 
> _______________________________________________
> comedi mailing list
> comedi_at_comedi.org
>
https://cvs.comedi.org/cgi-bin/mailman/listinfo/comedi
> 

_______________________________________________________ 
Yahoo! Acesso Grátis - Internet rápida e grátis. 
Instale o discador agora! http://br.acesso.yahoo.com/