1EGD_OPEN(3)                  EEGDEV library manual                 EGD_OPEN(3)
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NAME

6       egd_open - Open an EEG device
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SYNOPSIS

9       #include <eegdev.h>
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11       struct eegdev* egd_open(const char* devstring);
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DESCRIPTION

14       egd_open()  opens  a EEG device according to the devstring description.
15       If devstring is NULL, the first device supported by the library will be
16       opened.
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18       The  devstring argument specifies the type of EEG device required to be
19       opened and the parameters parameters which the system should be config‐
20       ured  with  (overriding defaults settings). The syntax of the string is
21       defined in eegdev-open-options(5).
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23       The syntax may change in future releases and programs should  not  rely
24       on it to configure the device. It is provided only to users of the pro‐
25       grams to select the EEG acquisition device and configure  it.  Programs
26       using  the  eegdev library should pass the string provided by the users
27       untouched.
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29       devstring is not the only way  to  provides  configuration  information
30       about the device to open. The configuration is read from the configura‐
31       tion files. The final values of the settings provided  to  the  opening
32       function are defined (and overriden) in the following order:
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34        * default values
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36        * shared configuration file
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38        * device specific configuration file
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40        * devstring
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42       This  order  indicates that a setting value specified in devstring will
43       always override any setting value defined by other mean.
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RETURN VALUE

46       The function returns a pointer to the opened EEG device in case of suc‐
47       cess.  Otherwise NULL is returned errno is set accordingly.
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ERRORS

50       egd_open() will fail if:
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52       ENOSYS the  device  part  of  devstring does not refer to a device sup‐
53              ported by any of the installed eegdev plugin modules.
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55       EINVAL one of the option specified in devstring is unknown.
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57       ENODEV The specified device is not connected.
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59       EBUSY  The specified device is already in use.
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61       ECHILD The specified device needs an auxiliary child process whose exe‐
62              cutable file cannot be found.
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ENVIRONMENT

65       EEGDEV_PLUGINS_DIR
66           This variable controls which folder should be search to find plugin
67           modules.  If unset, they will be searched in the  subfolder  eegdev
68           of the installation folder of the libraries.
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70       EEGDEV_CONF_DIR
71           This  variable  controls  which folder should be search to find the
72           configuration  files.  If  unset,  they   will   be   searched   in
73           /etc/eegdev.
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SEE ALSO

76       egd_close(3), eegdev-open-options(5)
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80EPFL                                 2010                          EGD_OPEN(3)
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