Re: 24 channel EEG

Take everything I say here with a big spoonful of salt, as I'm still trying
to come to grips with the theory and design of openeeg.

As I understand it, the channel limitation is largely because of the
processor; the ATMega used on the digital board is only 8 bits, which iirc
actually reduces the limit to 5 since the 10-bit processor that was used in
the original design is harder to find. According to the firmware
(here)<http://openeeg.sourceforge.net/doc/modeeg/firmware/modeeg-p3.c>though,
the software's packets could support more than 6 channels if you
had the hardware to support it. So (and I'm really going out on a limb
here) if you wanted to use a different processor, maybe a 16 or 32-bit
ATMega, you could just change the firmware's packet format to use 3 more
bytes for every 2 channels you want to add.

But if you wanted to do that, you'd also have to redesign the digital board
to support more inputs as well, right? I guess that's why you want to daisy
chain them together and use software to get the whole signal. Going back to
the packet format, there is an opportunity to use a unique identifier
string for each of the devices you want to use in conjunction. It looks
like each packet has a byte of auxiliary information, and part of the
auxiliary sequence is an identifying string which is sent over a number of
packets, currently "mEEGv1.0". You could change it in the firmware of each
device to read something like, "mEEGn001", "mEEGn002", etc. You'd need to
set the software up to interpret that though, and I don't think that
electricGuru was ever open-sourced so that could be an issue. There are
probably a few other design problems with that which I'm not seeing, but I
do think it'd be possible.

Could anybody else chime in on how far off I am with that?

---
On Mon, Jan 6, 2014 at 12:23 AM, Justin Pampalone <[email protected]
> wrote:

> I see the design for the multi-channel EEG only allows 6 channels. Is
> there a way to have 4 of them easily attach to a computer and run smoothly
> with software? I'm planning on building one at a time, but I just want to
> know if it's even possible to synchronize them.
>
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