EGD_OPEN(3)						       EEGDEV library manual						       EGD_OPEN(3)

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 con-
       figured 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 configura-
       tion 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)

EPFL
								       2010							       EGD_OPEN(3)