========================
Playing with a Mind Flex
========================
:CreationDate: 2015-10-23 13:11:34
:Id: HW/mindflex
:tags: - hardware
       - software

Some time ago I bought a `Mind Flex`_, with the idea of interfacing it
to some motors, and control a thing **with my mind**!. As for the
"thing", I bought a `Keepon`_.

Of course they sat unused for years.

Then I got myself a `MicroView`_, because it was pretty.

Of course it, too, sat unused for years.

I've finally started putting the three together.

.. _`Mind Flex`: http://store.neurosky.com/products/mindflex
.. _`Keepon`: http://www.mykeepon.com/
.. _`MicroView`:
   http://learn.microview.io/Intro/general-overview-of-microview.html

Software setup
==============

First of all, I had to set up the Arduino IDE + compilers. On a Gentoo
system it used to be a bit tricky (although there is `a very clear post on the
Apollo NG site`_ that helped), but now it's just::

  emerge arduino crossdev dev-java/rxtx

  USE="multilib cxx" crossdev --target avr

These additional symlinks are probably still needed, though::
  
  ln -nsf /usr/x86_64-pc-linux-gnu/avr/lib/ldscripts \
          /usr/avr/lib/ldscripts

  ln -nsf /usr/x86_64-pc-linux-gnu/avr/lib/ldscripts \
          /usr/x86_64-pc-linux-gnu/avr/binutils-bin/2.20.1/ldscripts

  cd /usr/avr/lib

  ln -nsf avr5/crtm328p.o .
  ln -nsf avr6/crtm2561.o .
  ln -nsf avr6/crtm2560.o .

.. _`a very clear post on the Apollo NG site`:
   https://apollo.open-resource.org/mission:log:2015:01:20:gentoo-crossdev-compile-avr-gcc-for-arduino-and-cura

Arduino libraries
-----------------

I needed two libraries: the one to `read the Neurosky EEG data`_, and
the one to `control the MicroView hardware`_.

I cloned them in my "sketchbook" directory::

  mkdir -p ~/sketchbook/libraries
  cd ~/sketchbook/libraries

  git clone git@github.com:geekammo/MicroView-Arduino-Library.git \
      MicroView

  git clone git@github.com:kitschpatrol/Brain

Note that the MicroView library needs to be in a folder called
``MicroView``, not ``MicroView-Arduino-Library``: the Arduino IDE
really dislikes dashes in library names.

I also copied code from `BeatBots' GitHub repository`_.

.. _`read the Neurosky EEG data`:
   https://github.com/kitschpatrol/Brain
.. _`control the MicroView hardware`:
   https://github.com/geekammo/MicroView-Arduino-Library/
.. _`BeatBots' GitHub repository`:
   https://github.com/beatbots/mykeepon

Hardware setup
==============

I followed the instruction at `Frontier Nerds`_, soldering a wire to
the "T" pin of the Neurosky board, one wire to ground, and (my
addition) one wire to battery "+". This way I can power the MicroView
from the same batteries as the Mind Flex: when I tried powering them
separately, the Neurosky board seemed to have serious difficulty
getting a signal, probably because of noise on the power line.

I then connected (currently via a small breadboard) the MicroView to
the wires: ground to ground, power to VIN, signal to pin Rx.

.. _`Frontier Nerds`: http://www.frontiernerds.com/brain-hack

For the Keepon, I connected four wires as explained by BeatBots:
ground to ground, power to A0 (to read when the Keepon is turned on),
clock to A5, data to A4.

The program
===========

You can `browse the repository for the program`_; I'm using EMACS and the
`Arduino Makefile`_, instead of the normal IDE, because I like
command-line interfaces better than point&click, and also because my
C++ is so rusty that the real-time feedback of Flymake is necessary.

Currently working:

* read from the Neurosky
* get control of the Keepon every time it's turned on
* queue commands to the Keepon
* show all status on the MicroView

Future work:

* read the status of the Keepon (button presses, sensors, maybe ever
  microphone?)
* write some more interesting logic to map brain readings to movements

.. _`browse the repository for the program`:
   https://www.thenautilus.net/cgit/keepon-eeg/tree/
.. _`Arduino Makefile`: https://github.com/sudar/Arduino-Makefile