Saturday December 29 2018

Brain Bug

Video demo:

Note that only forward/reverse is demoed; turning would require practice I don’t feel like doing. To clarify: out of all the MindFlex serial data, the data that are actually stable enough to be useful are: Attention & Meditation.  So I use attention as the fw/rv switch, and meditation as the right/left switch.  Trying to control attention is hard enough, so trying to actually navigate the toy would require practice (that I find too silly to be worth-it).  So rather than demoing both (2D) and looking like a tool, I opted to go 1D.

 

Quick Links:

General Serial Repeater Arduino Code
(repeat serial @ 9600 @ INT0/DPin2)

MindFlex Serial Repeater Arduino Code
(repeat MindFlex Serial Data Frames)

BrainBug Arduino Code

 

To make this, all you need is the following:

Tapping into the MindFlex:

This part may seem scary if you are not used to soldering, but if you can handle an iron this is easy.

Here are two high-res pics (click for high-res) to show you where to solder the GND reference (that goes to DigitalPin4) and the TX out (that goes to DigitalPin2):

 

And here are some pics of the bigger picture.

And here is a pic of the hook-up to the UNO (note that blue->blue, white->white):

 

Understanding the serial stream out of the MindFlex (General Approach):

(you can skip to the next section if you don’t care how the data is sent, I ‘wrap’ all that stuff in the code, so you can just plug-n-chug)

So now you have the MindFlex plugged into the UNO (note that you don’t need the LEDs yet).
Let us start with the Arduino Sketch: General Serial Repeater.  If you program the UNO with that and then open up the Serial Monitor (Shift+Ctrl+M), after you turn on the MindFlex headset (you don’t have to wear it) you should see bursts of numbers appear roughly every second (there’s added space to make each # 3digits, and _’s to separate #’s).

Here is a sample output (after 5 bursts, and removing the trailing null character [the last 0]):

170_170_ 32_  2_ 80_131_ 24_ 14_127_253_  5_103_163_  0_129_178_  0_227_101_  0_145_225_  4_143_145_  5_127_  6_  0_202_246_  4_  0_  5_  0_ 21_170_170_ 32_  2_ 80_131_ 24_ 21_141_210_  2_ 51_146_  0_217_222_  0_125_235_  0_ 61_ 62_  0_ 94_227_  0_ 45_ 10_  0_113_ 28_  4_  0_  5_  0_ 47_170_170_ 32_  2_ 29_131_ 24_  0_  0_ 81_  0_  0_ 50_  0_  0_ 34_  0_  0_ 29_  0_  0_ 44_  0_  0_ 48_  0_  0_ 41_  0_  0_ 39_  4_  0_  5_  0_206_170_170_ 32_  2_ 29_131_ 24_  0_  0_244_  0_  2_196_  0_  1_ 87_  0_  1_ 81_  0_  0_187_  0_  0_225_  0_  0_134_  0_  2_187_  4_  0_  5_  0_249_170_170_ 32_  2_200_131_ 24_  0_ 89_152_  0_173_ 48_  0_148_  3_  0_ 79_179_  0_ 32_225_  0_  1_206_  0_  3_ 18_  0_  2_114_  4_  0_  5_  0_209_

Now if you look closely, you can see the frame header (the special sequence that indicates a new bunch of data), it’s 170 170 32 2  (or maybe that’s header, 32bytes, ID2).  So if I use the ‘header’ I can write:

170_170_ 32_  2_ 80_131_ 24_ 14_127_253_  5_103_163_  0_129_178_  0_227_101_  0_145_225_  4_143_145_  5_127_  6_  0_202_246_  4_  0_  5_  0_ 21_
170_170_ 32_  2_ 80_131_ 24_ 21_141_210_  2_ 51_146_  0_217_222_  0_125_235_  0_ 61_ 62_  0_ 94_227_  0_ 45_ 10_  0_113_ 28_  4_  0_  5_  0_ 47_
170_170_ 32_  2_ 29_131_ 24_  0_  0_ 81_  0_  0_ 50_  0_  0_ 34_  0_  0_ 29_  0_  0_ 44_  0_  0_ 48_  0_  0_ 41_  0_  0_ 39_  4_  0_  5_  0_206_
170_170_ 32_  2_ 29_131_ 24_  0_  0_244_  0_  2_196_  0_  1_ 87_  0_  1_ 81_  0_  0_187_  0_  0_225_  0_  0_134_  0_  2_187_  4_  0_  5_  0_249_
170_170_ 32_  2_200_131_ 24_  0_ 89_152_  0_173_ 48_  0_148_  3_  0_ 79_179_  0_ 32_225_  0_  1_206_  0_  3_ 18_  0_  2_114_  4_  0_  5_  0_209_

Now we can see that there are headers, IDs (other values that don’t change, header is normally longer) and some data fields that change.  Here is the breakdown that I came up with (after recording much more than just 5 bursts, I played the game to kinda-know what I was recording; the EEG values were especially hard).

Header_32Bytes_2_Quality(200->worst, 0->best)_131_24(bit-data)_8x24 bits of info_4_Attention_5_Meditation_Checksum (very normally the last one, if any).

Figuring out what those 8 numbers in the middle were took a lot of time.  If you look at the changes across lines, and know about serial transmission of numbers larger than 1byte, you can see that each of the 8 numbers is sent as bits (out of the 24): [23:16] [15:8] [7:0].

Now if you buffer the data, sum up the number components, and only spit out info when framed, the info will make a lot more sense.  I did this for you in the Arduino Sketch MindFlex Serial Repeater.  If you program the UNO with that and open the serial monitor again you should see something like:

72_0_0_26621_15348_15441_4171_21507_-23923_3435_-4190  
72_0_0_29130_5553_10588_-28290_-19892_27131_-26438_32131  
72_0_0_-12091_-25334_13067_26995_2853_-15962_1920_1703  
72_0_0_-20029_5770_-24496_-20292_4191_29146_8210_7081  
0_0_0_-17869_12679_12118_22158_14761_-28944_-10218_25171  
0_0_0_30239_-7110_8198_20080_1258_-12942_-14191_-19068  
0_0_0_15310_-10170_12229_-1139_-32562_5733_2378_20160

Now you are at the point where you can use the MindFlex as a controller for whatever single thing you want.  Be warned that only the Signal Quality, Attention, and Meditation are useful (maybe I am still wrong about the 8 numbers in the middle).

 

Moving the Inchworm with your mind:

All you have to do is:

  • Program the Arduino UNO with the Arduino Sketch BrainBug.
  • Plug in the LEDs (shown in picture earlier in post) to DigitalPins 8->11 (their GNDs->GND).
  • Plug in the MindFlex (if not already so).
  • Startup the serial monitor (so you can get feedback), and GO.
    • Attention Up -> FW
    • Attention Dn -> RV
    • Serial: _t_  will toggle turning enabled
      • Meditation Up -> Right
      • Meditation Dn -> Left