Hello,
Most DAQ boards can sample at higher speed due to some
intelligent controller on board which allows fast DAQ
even under non real time OSes by scaning channels in a
loop. However, aquiring single consequtive samples from
different channels is then obviously more time consuming
as the respective controller has to be programmed for
any DAQ.
In my real time application there are sequences like:
/* in the control thread @ 1kHz
*/
:
board_aget(3,&xxx);
some_calcs();
board_aset(0, yyy);
:
/* in the measurment thread @ 400 Hz
*/
:
board_aget(1,&xxx);
board_aget(10,&xxx);
:
/* the SPP isr is used for synchronized measures
*/
:
board_aget(0,&xxx);
:
Therefore I needed a DAQ board which allows something like
int board_aget( unsigned short int channel,
unsigned short int *value )
{
/* Select channel directly !
*/
outw( (char)(channel), base_io+CHANNEL_REG );
/* Start ADC
*/
outw( ADC_START, base_io+SW_ADC_REG );
/* Busy wait for EOC not too bad for 3usec ADC
*/
if ( board_wait_while( ADC_BUSY, ADC_TIMEOUT ) < 0 )
return -ETIME;
*value = inw( base_io+DATA_REG );
return 0;
}
Therefore I needed a board which gives me quickly an analog
value on demand for any channel. The board I had until now
cannot do this, it is even slower than an old ISA board for
single values.
Any hints?
peterw
--
Dr. Peter Wurmsdobler
CTM - Centre de Transfert des Microtechniques
39, av. de l'Observatoire, BP-1445, 25007 Besancon CEDEX 3
TELEPHONE: +33 3 81 47 70 20 TELECOPIE: +33 3 81 47 70 21
E-mail: [EMAIL PROTECTED]
Ceterum censeo MIRCOSOFTem esse delendam.
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