Menu
▾
▴
Re: [Openeeg-list] OpenEEG Questions
|
From: Jordan <joc...@gm...> - 2020-09-24 20:15:34
|
Can you remove me from your mailing list? *Jordan Harris, Ph.D, LPC, LMFT* Trauma Therapist and Couples Counselor https://medium.com/@informedsimplicity Cell: (410) 300 3461 On Wed, Sep 23, 2020 at 2:43 PM Yonah Elorza <yo...@gm...> wrote: > Hello all, > > Thank you all so much for your great advice. I'm starting prototyping with > one channel for now, to test my schematics and ICs, as well as my control > mechanisms. If I make any headway with my changes, I'll make sure to reach > out to you all and give you an update! > > On Mon, Sep 21, 2020 at 5:44 AM Blago Gmail <don...@gm...> wrote: > >> Hello Yonah, >> >> Your idea for developing upgraded hardware for OpenEEG is definitely good! >> >> I wonder how many users feel "performance constrained" with current >> version? >> >> Here are you points: >> >>> -Designing better noise cancelling to reduce commons noise, >> >>> as well as noise between electrodes. >> You can gain significant improvements over signal to noise ratio if you >> "integrate" the signal processing chain down to the ADC - the so called >> Analog Front-End (AFE). What I mean under integration is to choose from >> available options multi-channel AFE implemented as integrated circuit >> (ASIC) - Texas-instruments, Analog-devices, Linear.... Those AFE chips >> are coming with TIA (first amplification, in Damian's terms) and PGA >> (second amplification) amplifiers + different type (single-ended or >> differential) and resolution, ADC inside. All of them requires some kind >> of external digital control + reading out converted data samples (they >> don't memory buffers or storage place inside) >> >> >>> -Integrating an FPGA into the design which acts as a >> >>> hardware Fast Fourier Transform >> I think you are underestimating the FPGAs. Despite the good use for >> signal processing, FPGA are good for implementing timing engines (the >> control signals needs to drive properly your AFE circuit). >> >> Imagine you are picking up an FPGA such as ZYNQ, who comes with dual >> core ARM processor inside... you are pretty much done with the >> configurable hardware you want. The firmware whiten for the ATMega >> should be ported to ARM but this will come with reward to have much more >> powerful processing unit. The FPGA fabric can be used for signal >> processing and controlling the external AFE. As you will end-up with >> good amount of data samples, better consider USB3/USB2 as interface with >> the PC. >> >> >>> -Making the circuit modular enough that you can stack >> >>> multiple together to have 4, 8, 16, etc. electrodes reading >> >>> at the same time. >> If you go the FPGA way, you will have ability to have reconfiguration on >> PCB and IC levels. >> >> >> >>> -Long term: modifying the design of the circuit to work >> >>> without the AT processor, instead having hardware control >> >>> from the GPIO of a Raspberry Pi, and all data being fed raw >> >>> to either the GPIO or USB interface of the Pi. >> Raspberry Pi is good platform but OpenEEG is too hardware specific that >> I am afraid that platforms as Raspberry Pi or Begalbone or Arduino are >> too generic for this project. >> >> Kind regards, >> >> Blagomir Donchev >> >> >> >> >> >> On 20/09/2020 23:46, Damián Filo wrote: >> > I am not, really... :D >> > Can you please define "leads"? Do you mean channels? >> > And what challenges? >> > >> > OpenEEG is in default built as bipolar EEG. That means for each channel >> > you need to connect two electrodes. The output is difference of voltage >> > between those two electrodes. But even with two electrodes you won't >> > need to make two amplfication circuits. The difference of voltages is >> > processed in the instrumentation amplifier (first amplifier) and then >> > the one difference signal is amplified further, so it can be reliably >> > converted to digital data. So you will need an amplification circuit >> > (cascade) for each channel (2 electrodes). >> > OpenEEG with v2 protocol and baud rate 115200 can support up to 6 >> > channels, although ATmega16 can support 8. If there is need for more >> > channels, you would have to rewrite the firmware and change the baud >> > rate. But with that you would lose compatibility with software >> > supporting OpenEEG (like BrainBay). >> > I simply chose not to face those challenges and I stuck to the >> > specifications concerning OpenEEG compatibility. I use olimex v2 >> > protocol firmware with ATmega16L. >> > >> > >> > >> > On Sun, Sep 20, 2020, 23:18 Steve Sterling <acu...@gm... >> > <mailto:acu...@gm...>> wrote: >> > >> > You're really knowledgable about this Damian! How do you work >> > around the challenges with multiple leads, will each lead require >> > it's own circuit? >> > >> > Thanks, >> > Steve >> > >> > On Sun, Sep 20, 2020, 1:17 PM Damián Filo <nog...@gm... >> > <mailto:nog...@gm...>> wrote: >> > >> > I am sorry for the spam, but in my previous e-mail I said: "any >> > of those changes you proposed are possible" - that is false. One >> > change you mentioned was to feed raw data onto GPIO pins of RPi. >> > That will not work, because what you need to do with the signal >> > is to convert it from analog to digital data through ADC and RPi >> > doesn't have an ADCs. You can avoid using ATmega >> > microcontrollers, but you still would have to use some external >> > chip with ADC functions. And then you would have to program your >> > own firmware and protocol, so you can use the data in >> > applications running on RPi. >> > Though what you can do with RPi is to feed the data directly >> > from ATmega through native UART interface on RPi without the >> > need for USB-UART chip. But about that, I am not really sure >> > about the signalling voltage mismatch 5V/3.3V. So it is still >> > preferred to use a USB interface with UART bridge like CP2102. >> > >> > S pozdravom, >> > Damián Filo >> > >> > >> > so 5. 9. 2020 o 21:49 Yonah Elorza <yo...@gm... >> > <mailto:yo...@gm...>> napísal(a): >> > >> > Hello! >> > >> > I'm a computer engineer interested in making some >> > modifications to the OpenEEG circuit, and had a few >> > questions, if anyone is available to answer them. I've read >> > through all the documentation on the website, and have >> > worked with the OpenEEG platform for a few years now, and >> > wanted to see if the following was possible: >> > >> > -Designing better noise cancelling to reduce commons noise, >> > as well as noise between electrodes. >> > -Integrating an FPGA into the design which acts as a >> > hardware Fast Fourier Transform >> > -Making the circuit modular enough that you can stack >> > multiple together to have 4, 8, 16, etc. electrodes reading >> > at the same time. >> > -Long term: modifying the design of the circuit to work >> > without the AT processor, instead having hardware control >> > from the GPIO of a Raspberry Pi, and all data being fed raw >> > to either the GPIO or USB interface of the Pi. >> > >> > If anyone has reasons this wouldn't be possible, or if you >> > have suggestions for any of these changes, please let me >> > know. I absolutely love this project, and would love to be >> > able to contribute my own work to it. >> > >> > -- >> > Best Regards, >> > Yonah Elorza >> > Columbia School of Engineering | Class of 2018 >> > Computer Engineering >> > Tel: ( <tel:%28786%29%20205%20-%204304>305)-542-1735 >> > _______________________________________________ >> > Openeeg-list mailing list >> > Ope...@li... >> > <mailto:Ope...@li...> >> > https://lists.sourceforge.net/lists/listinfo/openeeg-list >> > Go to the above address to change your >> > subscription options, e.g unsubscribe. >> > >> > _______________________________________________ >> > Openeeg-list mailing list >> > Ope...@li... >> > <mailto:Ope...@li...> >> > https://lists.sourceforge.net/lists/listinfo/openeeg-list >> > Go to the above address to change your >> > subscription options, e.g unsubscribe. >> > >> > _______________________________________________ >> > Openeeg-list mailing list >> > Ope...@li... >> > <mailto:Ope...@li...> >> > https://lists.sourceforge.net/lists/listinfo/openeeg-list >> > Go to the above address to change your >> > subscription options, e.g unsubscribe. >> > >> > >> > >> > _______________________________________________ >> > Openeeg-list mailing list >> > Ope...@li... >> > https://lists.sourceforge.net/lists/listinfo/openeeg-list >> > Go to the above address to change your >> > subscription options, e.g unsubscribe. >> > >> >> >> _______________________________________________ >> Openeeg-list mailing list >> Ope...@li... >> https://lists.sourceforge.net/lists/listinfo/openeeg-list >> Go to the above address to change your >> subscription options, e.g unsubscribe. >> > > > -- > Best Regards, > Yonah Elorza > Columbia School of Engineering | Class of 2018 > Computer Engineering > Tel: ( <%28786%29%20205%20-%204304>305)-542-1735 > _______________________________________________ > Openeeg-list mailing list > Ope...@li... > https://lists.sourceforge.net/lists/listinfo/openeeg-list > Go to the above address to change your > subscription options, e.g unsubscribe. > |
