2012-12-18

Necomimi EEG on the inside

I'm trying to connect a TGAM1 EEG sensor to a R0cket badge for 29C3 / Chaos Communication Congress of the Chaos Computer Club.

Because I have not found and photos online:
This is what the Necomimi EEG toy looks like on the inside.
Below the sticker. Are 4 PH0 bolts.
A main PCB on top of a breakout-board and a

The large breakout PCB is secured by 2 PH00 bolts.
This is the 60Hz US Version.
Beware of the third PH00 securing the tiny main board below.

The main board looks to be a
Thinkgear TGAM1

So to convert the notch filter to european 50Hz interference:
"Tie the M pad to VCC pad to select 60Hz, and to GND pad to select 50Hz notch Filtering frequency."
The M pad being on the hidden side of the board.
M=TP7 has 100KOhm to P4-1(square)=VCC and 1MOhm to P4-2(round)=GND .
So M is indeed tied to VCC for 60Hz.
B1=GND
B0=VCC
So we have " 57.6k Baud with Normal* + Raw Output Mode"
"Normal Output mode includes the following output: poor quality value, EEG value, Attention value and Meditation value.".
Thus maybe it's enoug to sniff the existing serial communication instead of replacing/reprogramming the original microcontroller.

There is a surprisingly large solder-bridge below TP1 and R12. No idea about it's purpose.


Interestingly P4=power is not connected. Instead the GND and VCC on P3=serial communication are used.
All test points are easily accessible, so attaching a microcontroller should be easy.

I don't know if the boards are permanently connected or if this is a very tight socket as there is some black plastic beweet the board where they connect.
I also can't see the microcontroller used as it's hidden by the TGAM1 board.
...stay tuned (My Multimeter battery is dead, so I can't continue to check how the solder bridges are wired.)

The protocol seems to be 57600bps UART at 3.3V as documented and is described here and here linking here.
(frame structure: 2x 0xAA sync, 1x payload-length, payload, 1 byte checksum (sum payload, lowest 8 bit, inverted))

18.12.12
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