The hemokit package

[ Tags: benchmark, bioinformatics, library, mit, program ] [ Propose Tags ]

This package allows reading raw data from the Emotiv EPOC EEG devices.

It is inspired and based on the code of the Emokit project (, but entirely written in Haskell.

It contains an extensive, well-documented library for connecting to devices, decrypting the stream, and parsing the relevant data out.

Data can be read from a given device via HIDAPI-hidraw or a dump file; reading from multiple devices is supported and when only one EEG is to be used, the correct device is automatically selected.

There is also an executable, hemokit-dump, that can print out

in both their plain form and as JSON, and optionally serve any of this via Websockets.

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Versions 0.4.0, 0.4.1, 0.4.2, 0.5, 0.5.1, 0.6.0, 0.6.1, 0.6.2, 0.6.3, 0.6.4, 0.6.5, 0.6.6
Dependencies aeson (>=, base (==4.*), base64-bytestring (>=, bytestring (>=, cairo (>=0.12.4), cipher-aes (>=0.2.0), conduit (>=1), deepseq (>=1.2), deepseq-generics (>=0.1), gtk (>=0.12.4), hemokit, hidapi (>=0.1.2), mtl (>=2.1.2), network-simple (>=, optparse-applicative (>=0.11), pretty-show (>=1.0), robot (>=, split (>=0.2.2), svgcairo (>=, text (>=, time (>=1.4), transformers (>=, vector (>=0.9), vector-fftw (>=, websockets (>= [details]
License MIT
Copyright 2013 Niklas Hambüchen <>, Patrick Chilton <>
Author Niklas Hambüchen <>, Patrick Chilton <>
Maintainer Niklas Hambüchen <>
Category Bioinformatics
Home page
Bug tracker
Source repository head: git clone git://
Uploaded Wed Aug 19 03:36:56 UTC 2015 by NiklasHambuechen
Distributions NixOS:0.6.6
Executables hemokit-headmap, hemokit-fft, hemokit-dump-conduit, hemokit-dump, hemokit-mouse
Downloads 2459 total (18 in the last 30 days)
Rating 0.0 (0 ratings) [clear rating]
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Status Docs available [build log]
Last success reported on 2015-08-19 [all 1 reports]
Hackage Matrix CI





Enable apps that use FFT. Needs fftw installed.


Build the headmap. Needs GUI libraries installed.


Build the app that controls the mouse with the gyroscope. Needs Xorg and related libraries installed (so it only works on Linux for now).


Use -f <flag> to enable a flag, or -f -<flag> to disable that flag. More info


Maintainer's Corner

For package maintainers and hackage trustees

Readme for hemokit-0.6.6

[back to package description]


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.


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


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 --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:// 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 Then you can read it with code like:
t = tcpip('', 1234);
data = fscanf(t, '%d');