comedi_data_read — read single sample from channel
#include <comedilib.h>
int comedi_data_read( | comedi_t * device, |
| unsigned int subdevice, | |
| unsigned int channel, | |
| unsigned int range, | |
| unsigned int aref, | |
lsampl_t * data); |
Reads a single sample on the channel specified by the Comedi
device device, the subdevice
subdevice, and the channel
channel.
For the A/D conversion (if appropriate),
the device is configured to use range specification
range and (if appropriate) analog
reference type aref.
Analog reference types that are not supported
by the device are silently ignored.
The function comedi_data_read reads one data value from
the specified channel and stores the value in
*.
data
WARNING: comedi_data_read does not do any pausing to
allow multiplexed analog inputs to settle before
starting an analog to digital conversion. If you are
switching between different channels and need to allow
your analog input to settle for an accurate reading,
use
comedi_data_read_delayed,
or set the
input channel at an earlier time with
comedi_data_read_hint.
Data values returned by this function are unsigned integers
less than or equal to the maximum sample value of the channel,
which can be determined using the function
comedi_get_maxdata.
Conversion of data values to physical units can be performed
by the functions comedi_to_phys (linear conversion) or comedi_to_physical (non-linear polynomial conversion).