From: ldean_at_metrowerks.com
Date: 2001-12-03 22:49:57
Doug,
Thank you for this post! I have been having these questions
also.
As you say, software is not going to materialize without
actual EEG units in the hands of developers.
It looks like the most difficult part of this is amplifier
design. If I can't get specs on the current amplifier
design and some sort of confidence that it is well tested,
there is no way I want to get a custom PCB made to build
this thing (no offense to the talented individuals who designed
this circuit). IMHO, if we are targeting build-it-yourselfers
we need a design with less parts. The low-partcount biosemi
design seems to have some advantages over the Brainmaster
design (reference post 1264 for details). I'm going to run
a cost analysis on parts for these two designs either tonight
or tomorrow.
The job of the microcontroller is not really very hard (for a
person with embedded programming experience ;) Just sample
the A/D and transmit the results to the serial port. This group
can provide recommendations and source code; it would be
nice if we could support a couple of different ones including
the Atmel AVR and the 68HC11. At some point we need to evaluate
the current serial spec (see post 33) and decide if it is
what we want... but right now, any EEG is better than no EEG!
IMHO, this group needs to target the build-it-yourself market
first. Otherwise, who will write the software?
Laura
--- In buildcheapeeg_at_yahoogroups.com, Doug Sutherland <wearable_at_earthlink.net> wrote:
> Hi Yaniv,
>
> > i'm looking for simple way for our group to offer a 1
> > channel, very low cost, nfb machine, both pc based and
> > stand alone.
>
> I have to say I'm a bit confused by the different versions
> that are on the OpenEEG site. There is the PDF describing
> a multi-parameter biofeedback device based on TI parts.
> Then there is the ComADC design based on 555 timers. Then
> there is the ModularEEG design using Atmel microcontrollers
> and fast IR. I also see something called RS232EEG, not
> sure if that is the same as ComADC. So where are we going
> with all of these designs?
>
> Regarding your statement above, I wonder how much thought
> has gone into target audience, who are these for, and what
> will they be used for? One thing I think is important is
> that the design doesn't go too low-end. For example not
> using a microcontroller introduces a lot of issues but
> microcontrollers are not expensive. The minimal performace
> specs might be different for someone trying to do alpha
> training vs ADD or addiction treatment vs just something
> neat to play with, or for entertainment.
>
> I like the idea of a vert cheap and also small and low
> power EEG, even for my own use. I want to try some
> experiments in long-term monitoring with me as the
> guinea pig, and I need a small/simple/low power EEG to
> do that. So I'm definitely interested in the low cost
> simple design. However, I caution not to go too low
> end, or it becomes a toy. Let's not make another HAL-4
> neat toy EEG here. HAL-4 has a frequency response that
> pretty much misses the delta and beta spectrums, and
> it has a poor sampling rate.
>
> > it's very important that the work that need to be
> > done in order to have that would be minimal , and
> > won't require expensive development tools, due to
> > the nature of volunteer groups.
>
> I'm all for that. The Atmel microcontroller tools are
> free (I think), and on the PC side I am really keen
> on working on Linux apps (GNU). However it's clear
> that windows versions are needed too, I think there
> are some free borland C tools kicking around.
>
> > so on thing to do is to start from what we have -
> > joerg's comadc, and go from there.
>
> We need a microcontroller between that and the PC.
> That design requires disabling interrupts. Joerg
> does that by running in DOS only mode, effectively
> taking over the whole machine. I don't know many
> people who want to go back to DOS. We need to remove
> that limitation or we are too low-end in my opinion.
>
> Here's what I want to understand: what are the
> specs on band width (frequency range) and sampling
> rates for these different designs? So far nobody has
> answered those questions. How does ComADC compare to
> ModularEEG in terms of band width and sampling? Is
> there perhaps a possible target in between the two?
> ModularEEG has lots of parts while ComADC has very
> few. This is just my opinion, but I think that the
> real target might be somewhere in between. The amp
> section for ModularEEG looks good, I would rather
> see a simplified version of that that ComADC.
>
> > another idea to make it much easier is that at first
> > step, it would be only pc based and be working good,
> > and very cheap, but anybody who have pc,
>
> I don't see any standalone features in any of these
> designs yet. What would be the method of feedback?
> Audio? Graphs on a small LCD? Perhaps there could be
> two boards that plug together, one is the EEG that
> plugs into PC, the other board is a feedback board
> for stand-alone operation, one simple ribbon cable/
> connector joins them.
>
> > could get from web the right development tools,
>
> Yes, I think it's important to avoid commercial
> devtools that cost, and I also think that you are
> much more likely to succeed with an open source
> type license. Anything less will discorage people
> from contributing. Look at the success of linux
> as your example.
>
> > and could develop software for the standalone
> > version and download it via pc. so in such a way,
> > the work could be shared by large group of
> > volunteers , in order to have the standalone
> > version. again empasize on cost, and minimal
> > work is very critical.
>
> Yaniv: what is the business model? Who gets the
> money and where does it go? This needs to be made
> clear before many people will dive in. I am not
> interested in money from this, but I do want to
> understand the business model if I am planning
> to contribute development time.
>
> > anybody would like to help in thinking and /or
> > designing / coding for such a thing?
>
> I am quite experienced in software, including
> embedded and microcontroller plus PC stuff, and
> I've done quite a bit of research on EEG. I am
> willing to help with the software, but there are
> the big issues for me:
>
> 1) Which design is it that we are working on?
> 2) Is the hardware in alpha, beta, or what?
> 3) We need hardware to work on this stuff, so
> 4) How can we get PCB boards made, and
> 5) How do I get the firmware?
>
> If I can get a blank PCB with the target design I can populate
> it myself with the parts. If the firmware is available I can
> easily flash the uC and start programming for the PC. Jim has
> some source code for his HC11 system, I think we can leverage
> some of that if he's willing to share it. But we really need
> to get hardware into the developer's hands before you are
> going to see much software materialize. I suggest that each
> throws in a few bucks and we do a low volume order of the
> blank PCB board from PCBexpress or a similar place. I don't
> see how you are going to get very far without producing some
> PCB boards, we will just keep talking forever. Can someone
> answer the above five questions?
>
> -- Doug
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