From: jiva_at_humboldt1.com
Date: 2001-05-07 18:18:25
Iteration 5:
(this loop adds references to electrode posts)
This is a growing/evolving list of the project specs.
Feedback is requested from list members with further information. When
somewhat gelled, this can be converted to HTML format for the website.
All useful information will be included in future iterations. I'm
beginning to reference info here to posts on the mail list.
* Hardware
* The "Black Box":
Current working prototype is a design by Joerg Hansmann,
Moritz Buttlar (and others?). http://www.jhansmann.de/eeg/eeg.html
links to info on the RS232 (old and new) and a gameport
design. The new design is an entry in a Texas Instruments
analog design contest. (post #299)
( post #372)
Here are the specifications of the tested and running prototype.
Specification of RS232EEG_01 (date:010502)
----------------------------
isolated power supply:
* input voltage: 7..12V dc, or 5V dc stabilized (from PC or
mains adaptor)
| > Does this mean it might be possible to power the unit by
| > "stealing" power from the serial port?
| > No. The required current is 76mA and that is way too much for
| > the serial port. However it would be possible to get the
| > stabilized +5Vdc from the PC-gameport.
* isolated with DCDC-converter(TMA0505S):
Isolation voltage Input/Output 1'000 VDC
Isolation capacity Input/Output 60 pF typ.
Isolation resistance Input/Output >1'000 Mohm
* isolated RS232 Data-lines (opto-isolated)
2x 6N139 (RxD, TxD)
Viso > 2500 Vrms (Input-Output Momentary Withstand Voltage)
Resistance (Input-Output) Rio=10^12 ohm
Capacitance (Input-Output) Cio=0.6 pF
Microcontroller:
* Atmel AVR AT90S4433 at 7.3728Mhz
with 6 channel (multiplexed) 10 bit resolution ADC
EEG-amplifier:
* 2 channels
* about 100uVpp input range (adjustable)
* lower corner frequency: 0.25Hz
* upper corner frequency: 33.1Hz
* -3dB bandwidth: 32.9Hz
* noise: about 1uVpp over above specified bandwidth
* common-mode rejection: typ. 115dB
* Impedance, Differential 10^10ohm || 22nF
* Impedance, Common-Mode 10^10ohm || 60pF
misc.:
* 256Hz samplefrequency, (optional 200 Hz)
* 4 unused ADC-channels (input range +-2V)
* 4 TTL-inputs (for switches e.g. for marking events by the user)
* 4 LED-driver outputs (e.g. for light goggles)
* 1 PWM output
* hardware UART (RS232 transmission
parameters are: 1 startbit, 8 data bits, 1 stopbit, no parity,
57600 baud)
* on board calibration generator: 50uVpp 10Hz rectangle wave
* easy in system programmable uC-EEPROM/Flashrom
* uC-firmware written in AVR-GNU-C
At the moment communication direction is only from Atmel-processor to
PC. The hardware however supports full duplex communication. This
feature will be used in later firmware releases to support the
PWM-output and LED-Goggles.
-------------------------
Joerg's comment: "Or did you want the specs of the new design ?"
Follow up comment " The new design is not really finished. At the
moment Moritz and I are trying to develop it for the TI-competition."
-------------------------
There is interest and discussion of getting FDA approval
of the unit as a medical device.
--------------------------
There is interest and discussion of the unit being available
as a manufactured product vs "kit" form.
--------------------------
The parts list which appears not yet complete
shows a parts cost of 165 DM or about $US 75 thus far.
--------------------------
Host computer hardware requirements:
Available serial port
SVGA graphics
--------------------------
Host computer requirements to run ElectricGuru host software
(from post #393, 394)
OS: Win9x (what about NT, W2K, etc?)
CPU: feedback suggests a 200mhz cpu or greater will run the
software,
Output can be scaled back for slower machines.
---------------------------
Benefits of EEG feedback and the availability of a low cost unit
(#370)
Software support "wishlist" (#369)
----------------------------
Electrodes:
#133 - thoughts on electrodes and associated materials
#134 - "Flextrodes" and links to brainmaster site with
"A Guide to Electrode Selection, Location, and
Application for EEG Biofeedback"
"Flextrodes"
an electrode placement image
#305 - Images from Moritz of electrode and holder
#311 - Info/link East3 "goopless" design
#317 - info/link to new design patent
This archive was generated by hypermail 2.1.4 : 2002-07-27 12:28:29 BST