skiria8
skiria8
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Fixed! Updated brainflow to the latest version: pin D13 is receivedData[15] or get_other_channels[3]
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I'm confused about this. According to the tutorial in the OpenBCI website, for EMG, AGND should be used instead of BIAS. I'm collecting EOG (which should be the same as EMG) with two channels (ch1 and ch5). Nothing is connected to the other channel…
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Oh yes, that makes sense. I wonder why I am still seeing interference with just the photoresistor. Analog value Im getting for the trigger is around 800 (aprox 2.5V), I can possibly increase the value of the resistor to bring it down. That's what I …
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I did a couple of more tests, using analog mode and a pulse generator (that simulates the photoresistor) to have a more controlled environment. It was connected at Pin D13. Given than analog mode is 0-1023 values (corresponding to 0-3.3V), I did two…
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I'm confused about this. I observed artifacts when I was using the simple photoresistor. I am using it as an external trigger for synchronization in a traditional p300 matrix speller to mark on/off when a row or column highlights/stops highlighting.…
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I'll double check the circuit with the electronic technician who did it for me. I don't know much about electronics. Where should the ground be connected instead? The photoresistor (photodiode + 2 resistors) is similar to the link you posted. …
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Yes, I tested it with a 33Ohm resistor (graphs above) and a 330Ohm resistor also. That'd be 5mA. This is the interference I'm getting: And this is using a different screen (trigger is every 200ms here), which is weird cause it seems trigger is…
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My board is set to digital mode on startup (using the code above). If I use the OpenBCI GUI, it automatically sets the board to analog mode when it starts. I have to go to Digital read and change it to digital. I'm afraid of damaging the board if it…
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I'm seeing artifacts in my signal too. I'm using a photoresistor with an optoisolator (as in https://docs.openbci.com/Cyton/CytonExternal/) connected in pin D13. Using it for P300-based applications. The interference is not consistent and I'm unabl…
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Thanks so much! That's very useful! I'll report progress and ask further questions!
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Makes sense. So in this case I wouldn't need the dongle, correct? When you say, test for on if the pins to be in such state, what do you mean? Do you have any example or pseudo code?
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Yes, I tried the extension cord. I'm still experiencing packet loss (although less frequent than without using it).
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I tested it in a different location and it worked fine. Seems like the problem was magnetic interference in the area.
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Ground placed on the foreground doesn't seem to help at all (as I shared in prev post). However, if I place it on the earlobe, the EOG I get with sleeve + enclosure has interference but with signal processing could be useful. Most papers place EOG o…
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I'm only using 3 electrodes (like configuration 1b). Hence, the electrode connected in SRB2 is the differential for both vertical (ch1) and horizontal (ch2) channels. My understanding of the OpenBCI board is that I'd get the same differential signa…
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I forgot to mention that. I'm actually using 3 electrodes as in this configuration https://www.mdpi.com/1424-8220/17/7/1485 for simplicity. Hence, SRB2 is my common reference for vertical and horizontal. I wasn't using the BIAS. This configuration w…
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Yes, that's correct! I noticed I had by mistake stop_stream() at the beginning of my code. First time I was calling get_board_samples(), it returned samples (so didn't throw any error), second time the buffer was empty so it threw the error. Thanks!
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I bought the TSL257 but I'm getting very high voltages (bigger than 1020, max value in OpenBCI). I can only get values around 950 if I completely cover it and apply some pressure. Do you have any idea if this can be fixed? Maybe with an extra resis…
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Hi William, That makes sense. So for EMG only I always need a min of 3 electrode ( signal electrode + reference + bias), right? What is the diffrence between the top and bottom pins of the bias in the cyton board? If I want to collect EM…
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Does Bias always need to be connected somewhere? When recording only EMG data (eg: detect muscle activation), could you deactivate the bias and use only 2 electrodes connected at N1 (bottom) +SRB2 (reference, bottom)?
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This is very useful information. Thanks so much for updating the thread! Regarding the response time of the photoresistor: Do you know if the response time is constant? If it's constant (for example with a latency of 5ms but no jitter), it's ea…
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Ups, I realized I forgot to reply. The latest openBCI GUI v.3.3.1 worked for me. The beta version (v 4.0.2 and 4.0.3) did not work. I was getting random values, both for digital and analog modes. The other problem I had was that the board was re…
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I finally figured out the problem and it works! Version 3.x GUI. To put the board on analog mode, what do you recommend? - modify the DefaultBoard example & upload it via Android IDE to have the board on Analog mode by default Or - send '/2' …
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In fact, it seems the issue might be either the board or the GUI not changing to Digital mode. I did the following test: 1) turn on digital mode via GUI (v 4.0.3 windows 64bit) 2) press PROG button for ~0.5sec 3) Stop streaming The values sh…
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I downloaded the latest release of the GUI and it's still doing the same. Since the GUI doesn't seem to work, What would be the easiest way to try it without using the GUI? In my standalone app, I read the data from the serial port. I can r…
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Yes, I'm using the widget in the OpenBCI GUI.
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Not working. It seems like it's not reding from the photoresistor. It shows very small pulses 0 to max. I have firmware v3.1and I tried testing the digital input with OpenBCI GUI and pressing the PROG button (as explained in the tutorial). It just …
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Thanks! I couldn't find the version with the '?" but 'v' returned it.
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Hi wjcroft, thanks for your quick reply No, I'm not using the same Adafruit photoresistor. I am measuring 16kOhm for a black image on screen and 2kOhm for a white image. Would 2k be a good resistor? I'm not sure how that is calculated. Anothe…
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Did you find out how to find it?