========================
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**!.
Of course it sat unused for years.
Then I got myself a `MicroView`_, because it was pretty.
Of course it, too, sat unused for years.
Today I finally put the two together.
.. _`Mind Flex`: http://store.neurosky.com/products/mindflex
.. _`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's a bit tricky, but thanks to `a very clear post on the
Apollo NG site`_ I got it installed::
emerge arduino crossdev dev-java/rxtx
USE="multilib -cxx" crossdev -s1 --without-headers \
--target avr \
--gcc 4.5.4 --binutils 2.21.1-r1 --libc 1.7.0
USE="multilib cxx" crossdev -s4 \
--target avr \
--gcc 4.5.4 --binutils 2.21.1-r1 --libc 1.7.0
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.
.. _`read the Neurosky EEG data`: https://github.com/kitschpatrol/Brain
.. _`control the MicroView hardware`: https://github.com/geekammo/MicroView-Arduino-Library/
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 pin 8, power to pin 16, signal to pin 9 (serial
receive).
.. _`Frontier Nerds`: http://www.frontiernerds.com/brain-hack
The program
===========
This is the very simple program I wrote::
#include <MicroView.h>
#include <Brain.h>
// the MindFlex is connected to the serial input
Brain brain(Serial);
void setup() {
// the MindFlex speaks 9600 bps
Serial.begin(9600);
// setup the MicroView display
uView.begin();
uView.clear(ALL);
// use the smallest font, 5x7
uView.setFontType(0);
}
const int hist_width=3;
const int hist_pad=1;
void loop() {
if (brain.update()) { // do we have data to show?
uView.clear(PAGE);
// print the signal quality, 0=good, 200=no signal
uView.setCursor(0,0); uView.print(brain.readSignalQuality());
// print the two "high level" signals
uView.setCursor(0,9); uView.print(brain.readAttention());
uView.setCursor(18,9); uView.print(brain.readMeditation());
// we then have 8 frequency bands
const uint32_t* power = brain.readPowerArray();
// find the maximum value, for scaling
uint32_t max_value=0;
for (int x=0;x<8;++x) {
if (power[x] > max_value) {
max_value = power[x];
}
}
// draw a simple bar chart
for (int x=0;x<8;++x) {
int x0 = (hist_width + hist_pad) * x;
// we have 30 vertical pixels
int height = power[x] * 30 / max_value;
for (int o=0;o<hist_width;++o) {
uView.lineV(x0+o,47-height,height);
}
}
// blit the buffer to the display
uView.display();
}
}
And that's it.
