From: Joerg Hansmann (info_at_jhansmann.de)
Date: 2001-10-05 23:45:47
Hi Vladimir,
----- Original Message -----
From: Vladimir.K <gogol101_at_yahoo.com>
To: <buildcheapeeg_at_yahoogroups.com>
Sent: Thursday, October 04, 2001 6:20 PM
Subject: [buildcheapeeg] Re: comADC-EEG
...
> I've finished older variant of comADC-EEG , the gameport.
> ( I used TLC272 and 9V Battery).
> Now, I am reading gameport on old Linux box and sending to
> other machine (W98) to Electric Guru.
>
> Even some experiment with kernel Real Time extension ( KURT ) and
> altering parameters in joystick driver, results are not perfect.
What sample rate and how many bits resolution do you get ?
> It's
> only 120MHz Pentium.
>
>
> I would like to try your code for DOS, so if you can, send me, please
> it. (gogol101_at_yahoo.com)
I will send it via email.
However it is for the comADC02 hardware.
> One curiosity:
> I didnt think that 9V is dangerous, but when I mesured resitance of
> EEG electrod ( home made saline type ) I got el. shock and becaus
> I had electrode on forehead near eye so I saw light flash.
> ( I have 9V battery in Ohmmeter).
A normal ohmmeter is not very suitable for measuring electrode
impedance, because it uses DC (resulting in electrode
polarization) and probably exceeds the limits of IEC601-1
(therefore you got the electric shock and the light-effects)
> If I remember, you said that RS232EEG is limited to 8( or 6 ) channels
6 channels, because the AT90S4433 has only 6 analog multiplexer inputs.
> for limited bandwith on RS232 ( 115 kbaud).
There are other limiting factors too like ADC conversion speed.
> I was suprised when I saw on Linux possible setting for 230 and 460
> kbaud. I am curious if so high speed is real.
If the UART chip on the mainboard can handle that speed, I see no
reason why such settings should not work.
For RS232EEG however the upper limit is 115200 baud due to
xtal-frequency and minimum possible baudrate divider factor.
Regards,
Joerg
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