qwer1304
qwer1304
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@biomurphYes, that's Direct Memory Access. The way it usually works is that in the ISR (which is triggered by Data Ready) you setup the DMA registers and release it (software control). Alternatively, you could set it up so that the demand interrupt…
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@biomurphDo you use / intend to use DMA to get data off the ADS1299?
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@biomurphThat's a nice "hidden" feature I didn't know about! Perhaps worth adding to documentation?
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@biomurphThe question was about sending triggers while receiving EEG data in OpenBCI GUI. Since the GUI grabs the COM port to OpenBCI, it seems impossible to send triggers over that port from another process. Have you modified the GUI so that it's…
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@biomurph To send the trigger to OpenBCI you need to grab the serial. But the serial is used for sending EEG samples to host. How do you split the ownership of the serial at the host side? I.e., sending a trigger while OpenBCI_GUI receives samples?T…
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Thx William.Do you know how compatible with EEG this material is: polarization, DC offset, etc?
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Another thought / observation:It is an unavoidable fact that EEG recordings are riddled with artifacts that must be removed prior to processing. It is straightforward and easy to remove these by dropping (short) epochs that contain them when data i…
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Yep, it's here. See caption of Figure 2.
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After giving it more thought here's what I think:It is required to compare power of the signal rather than the psd. Assuming the response is stable in frequency and time, the signal power is fixed. But as the trial gets longer and accordingly the …
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Hi Fred,You wrote: "The higher the resolution, the more the ASSR signature gets focused on a single term and the more the noise power gets dispersed among many. The longer the recording, the higher the SNR. " Not so, IMHO. Increasing the length of…
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Hi Fred. Thx for the clarifications.I looked at the processing code and I see that you don't employ any averaging of the signal (I do see that you average the results over trials). I'm very much surprised at how high your SNR is compared to what I s…
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William, thx for this.Several observations / comments: * there're no details on what signal processing was done on the recordings and what the graphs show (They show amplitude vs frequency, but amplitude of what is that? What kind of averaging was…
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Thx William.This is why I was thinking of having an external optional (bypassable) high-pass filter. This would help folks who're not doing ILF but who struggle with high offsets that saturate the DSP. Filtering in software is fine as long as the of…
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Thanx William. I was wondering why OpenBCI doesn't include (at least as an option) DC blocking caps to block offset voltages?Since the current design leaves this to DSP, high offset voltage easily saturates the input (especially if high gain is used…
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With 32 bit board, both the dongle and board's blue LEDs come on and stay on (at least mine do )
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I managed to get ASSR with OpenBCI off myself (my wife too ).The response matches reported results by others. The "trick" is to combine many epochs (I use 160) to cancel out the noise, since the raw SNR is extremely low (well below 0 dB). For tha…
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Female headers are not easy to cut. Fortunately, it's easy to cut the extra pin off and there's enough space to squeeze in a 5-pin header.
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Notice that the spectrum panel shows the spectrum BEFORE filtering (notch included).You need to look at the spectrum AFTER filtering is applied. The time domain panel shows the signal AFTER filtering (but it's in the time-domain). Also, the saved …
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@biomurphIf you're getting into software triggers, then consider a more general solution to sync OpenBCI and PC clocks similar to how it's done in LSL. See here and links therefrom.
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There're five PIC pins exported to connectors on the OpenBCI. You could add optocouplers and use these.Alternatively, you could use an encoder, e.g. 8-3 M74HC148, to encode upto eight markers onto 3 lines. You'd still need optocouplers. Note that …
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Looking at the image and comparing it to my installation I see that your chipKit toolchain is in Roaming, while mine is in Local.Also note that that the file it's looking for is in Local. Looks like a bad installation.
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I wasn't getting this error.Looks like a configuration issue. Did you select the OpenBCI 32 board in Arduino?
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data = _spi->transfer((uint8_t)0xFF); yes it does
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I use spectrogram to calculate the power spectrum of electrode readings.You have to give spectrogram meaningful parameters (window, overlap, NFFT), otherwise spectrogram will be BS. This gives me t,f and ps. Then imagesc to plot 10*log10(ps). I l…
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Well, finally after a lot of experimenting, I'm getting meaningful SSVEP results from myself.Thx for everybody who's commented / shared their experience. Best electrode position: POz 2nd best: Oz (noisier than POz) SRB: Cz Bias: linked ears with…
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Commenting out plib.h fixed that error.There're a second group of errors. Look at my post where I describe adding casts to fix the 2nd class of errors. You need to add them in two files, maybe in several places. The fix is the same in all cases.
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What error are you getting?What version of Chipkit do you have installed? Did you try commenting plib.h out? What happened after you did?
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The pnas paper verified the method for accurately generating arbitrary frequencies and phase on a monitor with a 60 Hz refresh rate (as opposed to LEDs) using the following formula: s(f,theta,i) = 1/2 * {1 + sin(2πf * (i / RefreshRate) + theta)}, …
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Note that this is a synchronous system (i.e., you know precisely when the target begins to flash and know the user watches it), otherwise you loose the phase information. Not sure how practical this is.
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nekrodezynfekator. The paper uses AMUSE for BSS. I tried to run it from ICALAB, but it's too old for my Matlab 2015b and there're no .m sources to rebuild the .p files.Did you you AMUSE and if so - did you manage to run it in Matlab? Thx, D