hemokit

Haskell library and tool suite for the Emotiv Epoc EEG, inspired by the Emokit code.

It currently only works on Linux and Windows - patches for other platforms are welcome, they should be trivial.

Download

You can download pre-built binaries here, or build it yourself via cabal install hemokit.

Library Features

• device discovery via hidapi
• decryption of the raw data (one-to-one port from from Emokit)
• convenient access to sensor values, gyro, qualities, battery, and raw data

Programs

Hemokit comes with example programs to

• hemokit-dump print out the current EEG data
• hemokit-mouse move the cursor using the gyro

Note that we have to use sudo in most of the cases because the HIDAP-hidraw implementation reads directly from a device file.

hemokit-dump - Examples

hemokit-dump can print EEG data, format it as JSON, serve it via TCP or Websockets, and read from real devices and dump files.

• Output EEG cumulative state for an automatically found device:

  sudo hemokit-dump
  

• Select one of many connected EEGs by serial number:

  sudo hemokit-dump --serial SN...GM
  

• Output only the data the device sends (no cumulative state), and format the output as JSON:

  sudo hemokit-dump --mode packets --format json
  

  The --format flag allows you to change the way the output is printed. The output of --mode state --format spaced is especially easy to work with.

• Instead of from a real device, read data recorded to a file, and serve it via JSON over a TCP server on port 1234:

  sudo cat /dev/hidraw1 > encrypted.dump  # Dump data to a file
  sudo hemokit-dump --from-file encrypted.dump --serial SN...GM --serve 0.0.0.0:1234 --format json
  

  Here you have to specify the serial since HIDAPI is not used to obtain it automatically.

  If you prefer a Websockets server over a raw TCP server, use ws://0.0.0.0:1234 instead.

• Output decrypted raw data to stdout:

  sudo hemokit-dump --mode raw
  

• Both print the data from the EEG and store the original data for later use:

  sudo cat /dev/hidraw1 | tee >(hemokit-dump --from-file - --serial SN...GM --format json) > encrypted.dump
  

  We use tee and shell process substitution to duplicate the data stream, and tell hemokit-dump to read from - (stdin).

Connecting with other Programs

• To use Hemokit as a data source from OpenVibe, check out the corresponding entry in the Wiki
• To read Hemokit data from Matlab, I recommend publishing the data on a local socket in text format using hemokit-dump --format spaced --serve 127.0.0.1:1234. Then you can read it with code like:

t = tcpip('127.0.0.1', 1234);
fopen(t)
data = fscanf(t, '%d');