Provided by: libcomedi-dev_0.8.1-5ubuntu6_amd64 bug


       comedi_apply_calibration - set hardware calibration from file


       #include <comedilib.h>

       int  comedi_apply_calibration  (comedi_t  *device,  unsigned  int  subdevice, unsigned int
       channel, unsigned int range, unsigned int aref, const char *file_path);




       This function sets the calibration of the specified subdevice so  that  it  is  in  proper
       calibration  when  using  the specified channel, range and aref.  It does so by performing
       writes to the appropriate channels of the board's calibration subdevice(s).  Depending  on
       the  hardware,  the calibration settings used may or may not depend on the channel, range,
       or aref.  Furthermore, the calibrations appropriate for different channel, range, and aref
       parameters  may not be able to be applied simultaneously.  For example, some boards cannot
       have their analog  inputs  calibrated  for  more  than  one  input  range  simultaneously.
       Applying  a  calibration  for  range  1 may blow away a previously applied calibration for
       range 0.  Or, applying a calibration for  analog  input  channel  0  may  cause  the  same
       calibration  to  be  applied  to  all  the other analog input channels as well.  Your only
       guarantee is that calls to comedi_apply_calibration() on  different  subdevices  will  not
       interfere with each other.

       In  practice,  their  are some rules of thumb on how calibrations behave.  No calibrations
       depend on the aref.  A multiplexed analog input will have calibration settings that do not
       depend  on  the  channel,  and applying a setting for one channel will affect all channels
       equally.  Analog outputs, and analog inputs with independent a/d converters for each input
       channel,  will have calibrations settings which do depend on the channel, and the settings
       for each channel will be independent of the other channels.

       If you wish to investigate exactly  what  comedi_apply_calibration()  is  doing,  you  can
       perform  reads  on your board's calibration subdevice to see which calibration channels it
       is changing.  You can also try to decipher the calibration  file  directly  (it's  a  text

       The  file_path  parameter  can  be used to specify the file which contains the calibration
       information.  If file_path is NULL, then comedilib will use a default file location.   The
       calibration information used by this function is generated by the comedi_calibrate program
       (see its man page).

       The  functions  comedi_parse_calibration_file(),  comedi_apply_parsed_calibration(),   and
       comedi_cleanup_calibration() provide the same functionality at a slightly lower level.


       Zero on success, a negative number on failure.

                                         28 October 2007              COMEDI_APPLY_CALIBRATION(3)