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)