NAME

       egd_open - Open an EEG device

SYNOPSIS

       #include <eegdev.h>

       struct eegdev* egd_open(const char* devstring);

DESCRIPTION

       egd_open()  opens  a  EEG  device  according to the devstring description. If devstring is
       NULL, the first device supported by the library will be opened.

       The devstring argument specifies the type of EEG device required  to  be  opened  and  the
       parameters  parameters  which  the  system  should be configured with (overriding defaults
       settings). The syntax of the string is defined in eegdev-open-options(5).

       The syntax may change in future releases and programs should not rely on it  to  configure
       the  device.  It  is  provided only to users of the programs to select the EEG acquisition
       device and configure it. Programs using the eegdev library should pass the string provided
       by the users untouched.

       devstring  is  not  the only way to provides configuration information about the device to
       open. The configuration is read from the configuration files.  The  final  values  of  the
       settings  provided  to  the  opening function are defined (and overriden) in the following
       order:

        * default values

        * shared configuration file

        * device specific configuration file

        * devstring

       This order indicates that a setting value specified in devstring will always override  any
       setting value defined by other mean.

RETURN VALUE

       The  function  returns  a  pointer to the opened EEG device in case of success.  Otherwise
       NULL is returned errno is set accordingly.

ERRORS

       egd_open() will fail if:

       ENOSYS the device part of devstring does not refer to a device supported  by  any  of  the
              installed eegdev plugin modules.

       EINVAL one of the option specified in devstring is unknown.

       ENODEV The specified device is not connected.

       EBUSY  The specified device is already in use.

       ECHILD The  specified device needs an auxiliary child process whose executable file cannot
              be found.

ENVIRONMENT

       EEGDEV_PLUGINS_DIR
           This variable controls which folder should be  search  to  find  plugin  modules.   If
           unset, they will be searched in the subfolder eegdev of the installation folder of the
           libraries.

       EEGDEV_CONF_DIR
           This variable controls which folder should be search to find the configuration  files.
           If unset, they will be searched in /etc/eegdev.

SEE ALSO

       egd_close(3), eegdev-open-options(5)