From: sleeper75se (sleeper75se_at_yahoo.se)
Date: 2002-01-15 00:32:21
Hi all,
I just discovered the blizzard of messages, so if anyone asked me a
question, please ask again, I may have missed it.
--- In buildcheapeeg_at_yahoogroups.com, "Jim Meissner" <jpmeissner_at_mindspring.com> wrote:
> I was hoping for the HC11 only because I know the code, but I
> think Andreas is looking at the Atmel?
Yes, the assembly language of the AVR-family is very straightforward,
and a 8-MHz AVR is actually faster than an old Amiga. :-)
--- In buildcheapeeg_at_yahoogroups.com, Doug Sutherland <wearable_at_earthlink.net> wrote:
> I held back on my digikey order of parts when I heard that
> the ModularEEG wasn't performing very well. Since then you
> posted your schematics (thanks!) and also Andreas posted
> even more schematics. Now I am really confused! I have no
> idea which of these circuits to try.
You're not the only one who's confused Doug. :-) I thought I had it
nailed with the TinyAVR, but then there's the 12-bit option, and
everything involved in the optical link... so it's time to make a
requirements/design specification. I'll make it here, because that
makes it easier for me to stick to it.
The input stage is designed, and the layout for a through-hole
version is underway. There will be no significant changes there.
Possibly new filter values, but that's a 5-minute job.
The TinyAVR micrcontroller is small, but the savings ($3) compared to
Joergs choice are not worth the limitations. For those looking for a
low cost solution, I feel that Joergs design would work best, so
maybe I should try a slightly more expensive option instead?
I think these parts would work for the ADC-board:
MAX186: 20-pin, 12-bit ADC with internal reference and 8-channel
multiplexer. Max samplerate: 133kHz. It needs a +/-5V power supply
and draws 1.5mA current. Cost: $22.
AT90S2313 microcontroller: a bit smaller than Joergs choice (20-
pins), but with similar specs. It has a UART, but no ADC. Cost: $4.
Data transmission will be over fiber, with the receiver on a separate
PCB, so that experimentation is easy.
This will cost more, but the end result will still kick some serious
commercial butt.
Datasheets:
http://www.atmel.com/atmel/acrobat/doc0839.pdf
http://pdfserv.maxim-ic.com/arpdf/MAX186-MAX188.pdf
Ok guys, whaddaya think?
/Andreas
This archive was generated by hypermail 2.1.4 : 2002-07-27 12:28:36 BST