marles77 / openbci-brainflow-lsl

Use BrainFlow to read data from Open BCI board and send it as Lab Streaming Layer streams

OpenBCI-Brainflow-LSL

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Uses Python, BrainFlow, and pylsl to read data from Open BCI board and send it as Lab Streaming Layer (LSL) streams.

Dependencies

Install dependencies in your environment with:

pip install --upgrade numpy brainflow pylsl pyserial PyYAML

Usage

Steps:

1. Set up your own settings file. An example of such file is included in this repo as settings8.yml. If you are not going to use Arduino as a source of triggers, just comment out lines 25-33. To see what channel commands (sent to Cyton board) mean, go to Cyton channels commands. A full description can be found in Open BCI docs. In this examplary file only channels 1-6 are powered up. Default commands are defined as a constant in obci_brainflow_lsl.py
2. Set up your EEG (and Arduino if needed), check signal quality using OpenBCI GUI
3. Run the script with a command including one required argument --set with the name of a YAML file containing settings: python obci_brainflow_lsl.py --set settings8.yml and continue with the steps (initiating the session, sending commands, commencing the stream) until the LSL stream is established
4. Record all your LSL streams (continuous data and markers) using e.g. Lab Recorder to one *.XDF file
5. View and analyze your data using free software e.g. EEGLab or Python MNE library

My Cyton setup:

Channel nr	Electrode(s) position	Cyton Board Pin	Board command
1	-VEOG	Bottom N1P	x1040100X
	+VEOG	Top N1P
2	Fz	Bottom N2P	x2060110X
3	C3	Bottom N3P	x3060110X
4	C4	Bottom N4P	x4060110X
5	P3	Bottom N5P	x5060110X
6	P4	Bottom N6P	x6060110X
7	-	-	x7161000X
8	-	-	x8161000X
REF	A1	Bottom SRB (SRB2)	-
BIAS	AFz	Bottom BIAS	-

My Arduino circuit:

Features

The script (written in Python 3.8) enables to stream in parallel several types of data via LSL:

• Open BCI board channels such as EXG/EEG and AUX (accelerometer; if you want to use it, just uncomment line 13 in the settings file)
• Triggers/markers from serial port connected to Arduino board, e.g. photosensors, switch etc. (an example of a simple sketch is included in trigger_photo.ino file)

Limitations and known issues

The script has been tested only on Windows with Cyton + Dongle and Cyton + Daisy + Dongle, for now. Any feedback from tests performed on other platforms will be much appreciated.

Acknowledgments

This program is based on a script originally created by @retiutut. I was also inspired by a similar project OpenBCI_LSL

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Cyton channels commands

	CHANNEL	POWER_DOWN	GAIN_SET	INPUT_TYPE_SET	BIAS_SET	SRB2_SET	SRB1_SET
x	1-8*	0-1	0-6	0-7	0-1	0-1	0-1	X
			0 Gain 1	0 NORMAL
			1 Gain 2	1 SHORTED
			2 Gain 4	2 BIAS_MEAS
			3 Gain 6	3 MVDD
			4 Gain 8	4 TEMP
			5 Gain 12	5 TESTSIG
			6 Gain 24	6 BIAS_DRP
				7 BIAS_DRN
x	1	0	4	0	0	0	0	X
x	2	0	6	0	1	1	0	X
x	7	1	6	1	0	0	0	X

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*channels 9-16 are labeled Q,W,E,R,T,Y,U,I