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Created October 9, 2022 16:15
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This is a native python implementation to stream data from a Unicorn EEG system to LSL. It works on macOS, Linux and Windows.
#!/usr/bin/env python
# Unicorn2lsl streams data from a Unicorn Hybrid Black EEG system to LSL
# Copyright (C) 2022 Robert Oostenveld
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <>.
import serial
import struct
import string
import random
import numpy as np
from pylsl import StreamInfo, StreamOutlet
start_acq = [0x61, 0x7C, 0x87]
stop_acq = [0x63, 0x5C, 0xC5]
start_response = [0x00, 0x00, 0x00]
stop_response = [0x00, 0x00, 0x00]
start_sequence = [0xC0, 0x00]
stop_sequence = [0x0D, 0x0A]
s = serial.Serial(device, 115200, timeout=timeout)
print("connected to serial port " + device)
raise RuntimeError("cannot connect to serial port " + device)
lsl_name = 'Unicorn'
lsl_type = 'EEG'
lsl_format = 'float32'
lsl_id = ''.join(random.choice(string.digits) for i in range(6))
# create an outlet stream
info = StreamInfo(lsl_name, lsl_type, nchan, fsample, lsl_format, lsl_id)
outlet = StreamOutlet(info)
print('started LSL stream: name=%s, type=%s, id=%s' % (lsl_name, lsl_type, lsl_id))
# start the Unicorn data stream
response =
if response != b'\x00\x00\x00':
raise RuntimeError("cannot start data stream")
print('started Unicorn')
while True:
dat = np.zeros(nchan)
# read one block of data from the serial port
payload =
# check the start and end bytes
if payload[0:2] != b'\xC0\x00':
raise RuntimeError("invalid packet")
if payload[43:45] != b'\x0D\x0A':
raise RuntimeError("invalid packet")
battery = 100*float(payload[2] & 0x0F)/15
eeg = np.zeros(8)
for ch in range(0,8):
# unpack as a big-endian 32 bit signed integer
eegv = struct.unpack('>i', b'\x00' + payload[(3+ch*3):(6+ch*3)])[0]
# apply two’s complement to the 32-bit signed integral value if the sign bit is set
if (eegv & 0x00800000):
eegv = eegv | 0xFF000000
eeg[ch] = float(eegv) * 4500000. / 50331642.
accel = np.zeros(3)
# unpack as a little-endian 16 bit signed integer
accel[0] = float(struct.unpack('<h', payload[27:29])[0]) / 4096.
accel[1] = float(struct.unpack('<h', payload[29:31])[0]) / 4096.
accel[2] = float(struct.unpack('<h', payload[31:33])[0]) / 4096.
gyro = np.zeros(3)
# unpack as a little-endian 16 bit signed integer
gyro[0] = float(struct.unpack('<h', payload[27:29])[0]) / 32.8
gyro[1] = float(struct.unpack('<h', payload[29:31])[0]) / 32.8
gyro[2] = float(struct.unpack('<h', payload[31:33])[0]) / 32.8
counter = struct.unpack('<L', payload[39:43])[0]
# collect the data that will be sent to LSL
dat[0:8] = eeg
dat[8:11] = accel
dat[11:14] = gyro
dat[14] = battery
dat[15] = counter
# send the data to LSL
if ((counter % fsample) == 0):
print('received %d samples, battery %d %%' % (counter, battery))
del outlet
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I found 2 bugs in this example:

  • line 87: the sign is not flipped by eeg_channel | 0xff000000 as Python considers these as unsigned ints. It will actually add about 380 V instead. Could be resolved in two ways:
    • First pack as unsigned, then unpack again as signed int: struct.unpack('>i', struct.pack('>I', eeg_channel | 0xff000000))[0]
    • Easier solution: subtract 2**24: eeg_channel - 0x01000000
  • line 98: the indices given for the gyroscope are the same as for the accelerometer. According to the documentation of gtec, the indices of the gyroscope are 33:38

Otherwise great example, thanks!

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