From: Moritz von Buttlar (info_at_baltic-microsolutions.de)
Date: 2001-12-20 07:33:15
Hi Sade !
Nice post :)
I'm also in favor using PCB-Pool now.
>I have used BBrown ADS1211 4 diff channel A/D part in some projects,
>and would think that such part would allow using just single stage
>of the INA114's, and make the analog section much smaller, and
>perhaps boost the noise-performance, provided someone better than
>me routed the guardings/shieldings, though, I would like to learn
>more of how to route high-quality low-noise analog microvoltage
>input stages. I used ADS1211 in interfacing to pressure sensors
>and RTD's that provide very low voltage when driven with precision
>constant current generators, and it just is superior to many other
>A/D parts. I am sure that combining it with something like INA114
>and good routing techniques could somehow boost the analog section
>yet, and not cost much more to speak off.
Yeah, that one is nice. There are also much higer speed parts at amazing
low price
like ADS1252. I like the idea of using heavy oversampling instead of analog
filters
to solve the aliasing problem. Price the same, performance better. Slightly
more
difficult if the ADC is outside the uC. Also for delta-sigma converters
multiplexing
different channels is a problem because the first 6 samples or so after
switching the
channel are worthless.
After that, would throw in possibly either some small risc
>flash microcontroller with hw multiplier, or, consider
>some of the nicer versions of the TI flash DSP's, combined
>with a USB controller chip from some company FTDI, who provide
>a good way to solve the driver problems, and then approach
Maybe a DSP would be overkill. But a risc controller in combination with
the FTDI parts would certainly also be nice. I always thought USB would be
overkill. But now I'm working on a laboratory measuring instrument for
plasma physics using USB and since I learned about the FTDI parts
I think it's very easy :)
But for now, let's stick to RS232 and try to get the modularEEG going.
Moritz
---------------------------------------------------
Moritz von Buttlar
Flash uC/DSP Development http://www.baltic-microsolutions.de
Free EEG Design http://openeeg.sf.net
This archive was generated by hypermail 2.1.4 : 2002-07-27 12:28:35 BST