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open_bci_v3.py
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open_bci_v3.py
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"""
Core OpenBCI object for handling connections and samples from the board.
EXAMPLE USE:
def handle_sample(sample):
print(sample.channels)
board = OpenBCIBoard()
board.print_register_settings()
board.start(handle_sample)
NOTE: If daisy modules is enabled, the callback will occur every two samples, hence "packet_id" will only contain even numbers. As a side effect, the sampling rate will be divided by 2.
FIXME: at the moment we can just force daisy mode, do not check that the module is detected.
"""
import serial
import struct
import numpy as np
import time
import timeit
import atexit
import logging
import threading
import sys
import pdb
import glob
SAMPLE_RATE = 250.0 # Hz
START_BYTE = 0xA0 # start of data packet
END_BYTE = 0xC0 # end of data packet
ADS1299_Vref = 4.5 #reference voltage for ADC in ADS1299. set by its hardware
ADS1299_gain = 24.0 #assumed gain setting for ADS1299. set by its Arduino code
scale_fac_uVolts_per_count = ADS1299_Vref/float((pow(2,23)-1))/ADS1299_gain*1000000.
scale_fac_accel_G_per_count = 0.002 /(pow(2,4)) #assume set to +/4G, so 2 mG
'''
#Commands for in SDK http://docs.openbci.com/software/01-Open BCI_SDK:
command_stop = "s";
command_startText = "x";
command_startBinary = "b";
command_startBinary_wAux = "n";
command_startBinary_4chan = "v";
command_activateFilters = "F";
command_deactivateFilters = "g";
command_deactivate_channel = {"1", "2", "3", "4", "5", "6", "7", "8"};
command_activate_channel = {"q", "w", "e", "r", "t", "y", "u", "i"};
command_activate_leadoffP_channel = {"!", "@", "#", "$", "%", "^", "&", "*"}; //shift + 1-8
command_deactivate_leadoffP_channel = {"Q", "W", "E", "R", "T", "Y", "U", "I"}; //letters (plus shift) right below 1-8
command_activate_leadoffN_channel = {"A", "S", "D", "F", "G", "H", "J", "K"}; //letters (plus shift) below the letters below 1-8
command_deactivate_leadoffN_channel = {"Z", "X", "C", "V", "B", "N", "M", "<"}; //letters (plus shift) below the letters below the letters below 1-8
command_biasAuto = "`";
command_biasFixed = "~";
'''
class OpenBCIBoard(object):
"""
Handle a connection to an OpenBCI board.
Args:
port: The port to connect to.
baud: The baud of the serial connection.
daisy: Enable or disable daisy module and 16 chans readings
"""
def __init__(self, port=None, baud=115200, filter_data=True,
scaled_output=True, daisy=False, log=True, timeout=None):
self.log = log # print_incoming_text needs log
self.streaming = False
self.baudrate = baud
self.timeout = timeout
if not port:
port = self.find_port()
self.port = port
print("Connecting to V3 at port %s" %(port))
self.ser = serial.Serial(port= port, baudrate = baud, timeout=timeout)
print("Serial established...")
time.sleep(2)
#Initialize 32-bit board, doesn't affect 8bit board
self.ser.write(b'v');
#wait for device to be ready
time.sleep(1)
self.print_incoming_text()
self.streaming = False
self.filtering_data = filter_data
self.scaling_output = scaled_output
self.eeg_channels_per_sample = 8 # number of EEG channels per sample *from the board*
self.aux_channels_per_sample = 3 # number of AUX channels per sample *from the board*
self.read_state = 0
self.daisy = daisy
self.last_odd_sample = OpenBCISample(-1, [], []) # used for daisy
self.log_packet_count = 0
self.attempt_reconnect = False
self.last_reconnect = 0
self.reconnect_freq = 5
self.packets_dropped = 0
#Disconnects from board when terminated
atexit.register(self.disconnect)
def getSampleRate(self):
if self.daisy:
return SAMPLE_RATE/2
else:
return SAMPLE_RATE
def getNbEEGChannels(self):
if self.daisy:
return self.eeg_channels_per_sample*2
else:
return self.eeg_channels_per_sample
def getNbAUXChannels(self):
return self.aux_channels_per_sample
def start_streaming(self, callback, lapse=-1):
"""
Start handling streaming data from the board. Call a provided callback
for every single sample that is processed (every two samples with daisy module).
Args:
callback: A callback function -- or a list of functions -- that will receive a single argument of the
OpenBCISample object captured.
"""
if not self.streaming:
self.ser.write(b'b')
self.streaming = True
start_time = timeit.default_timer()
# Enclose callback funtion in a list if it comes alone
if not isinstance(callback, list):
callback = [callback]
#Initialize check connection
self.check_connection()
while self.streaming:
# read current sample
sample = self._read_serial_binary()
# if a daisy module is attached, wait to concatenate two samples (main board + daisy) before passing it to callback
if self.daisy:
# odd sample: daisy sample, save for later
if ~sample.id % 2:
self.last_odd_sample = sample
# even sample: concatenate and send if last sample was the fist part, otherwise drop the packet
elif sample.id - 1 == self.last_odd_sample.id:
# the aux data will be the average between the two samples, as the channel samples themselves have been averaged by the board
avg_aux_data = list((np.array(sample.aux_data) + np.array(self.last_odd_sample.aux_data))/2)
whole_sample = OpenBCISample(sample.id, sample.channel_data + self.last_odd_sample.channel_data, avg_aux_data)
for call in callback:
call(whole_sample)
else:
for call in callback:
call(sample)
if(lapse > 0 and timeit.default_timer() - start_time > lapse):
self.stop();
if self.log:
self.log_packet_count = self.log_packet_count + 1;
"""
PARSER:
Parses incoming data packet into OpenBCISample.
Incoming Packet Structure:
Start Byte(1)|Sample ID(1)|Channel Data(24)|Aux Data(6)|End Byte(1)
0xA0|0-255|8, 3-byte signed ints|3 2-byte signed ints|0xC0
"""
def _read_serial_binary(self, max_bytes_to_skip=3000):
def read(n):
b = self.ser.read(n)
if not b:
self.warn('Device appears to be stalled. Quitting...')
sys.exit()
raise Exception('Device Stalled')
sys.exit()
return '\xFF'
else:
return b
for rep in range(max_bytes_to_skip):
#---------Start Byte & ID---------
if self.read_state == 0:
b = read(1)
if struct.unpack('B', b)[0] == START_BYTE:
if(rep != 0):
self.warn('Skipped %d bytes before start found' %(rep))
rep = 0;
packet_id = struct.unpack('B', read(1))[0] #packet id goes from 0-255
log_bytes_in = str(packet_id);
self.read_state = 1
#---------Channel Data---------
elif self.read_state == 1:
channel_data = []
for c in range(self.eeg_channels_per_sample):
#3 byte ints
literal_read = read(3)
unpacked = struct.unpack('3B', literal_read)
log_bytes_in = log_bytes_in + '|' + str(literal_read);
#3byte int in 2s compliment
if (unpacked[0] >= 127):
pre_fix = bytes(bytearray.fromhex('FF'))
else:
pre_fix = bytes(bytearray.fromhex('00'))
literal_read = pre_fix + literal_read;
#unpack little endian(>) signed integer(i) (makes unpacking platform independent)
myInt = struct.unpack('>i', literal_read)[0]
if self.scaling_output:
channel_data.append(myInt*scale_fac_uVolts_per_count)
else:
channel_data.append(myInt)
self.read_state = 2;
#---------Accelerometer Data---------
elif self.read_state == 2:
aux_data = []
for a in range(self.aux_channels_per_sample):
#short = h
acc = struct.unpack('>h', read(2))[0]
log_bytes_in = log_bytes_in + '|' + str(acc);
if self.scaling_output:
aux_data.append(acc*scale_fac_accel_G_per_count)
else:
aux_data.append(acc)
self.read_state = 3;
#---------End Byte---------
elif self.read_state == 3:
val = struct.unpack('B', read(1))[0]
log_bytes_in = log_bytes_in + '|' + str(val);
self.read_state = 0 #read next packet
if (val == END_BYTE):
sample = OpenBCISample(packet_id, channel_data, aux_data)
self.packets_dropped = 0
return sample
else:
self.warn("ID:<%d> <Unexpected END_BYTE found <%s> instead of <%s>"
%(packet_id, val, END_BYTE))
logging.debug(log_bytes_in);
self.packets_dropped = self.packets_dropped + 1
"""
Clean Up (atexit)
"""
def stop(self):
print("Stopping streaming...\nWait for buffer to flush...")
self.streaming = False
self.ser.write(b's')
if self.log:
logging.warning('sent <s>: stopped streaming')
def disconnect(self):
if(self.streaming == True):
self.stop()
if (self.ser.isOpen()):
print("Closing Serial...")
self.ser.close()
logging.warning('serial closed')
"""
SETTINGS AND HELPERS
"""
def warn(self, text):
if self.log:
#log how many packets where sent succesfully in between warnings
if self.log_packet_count:
logging.info('Data packets received:'+str(self.log_packet_count))
self.log_packet_count = 0;
logging.warning(text)
print("Warning: %s" % text)
def print_incoming_text(self):
"""
When starting the connection, print all the debug data until
we get to a line with the end sequence '$$$'.
"""
line = ''
#Wait for device to send data
time.sleep(1)
if self.ser.inWaiting():
line = ''
c = ''
#Look for end sequence $$$
while '$$$' not in line:
c = self.ser.read().decode('utf-8')
line += c
print(line);
else:
self.warn("No Message")
def openbci_id(self, serial):
"""
When automatically detecting port, parse the serial return for the "OpenBCI" ID.
"""
line = ''
#Wait for device to send data
time.sleep(2)
if serial.inWaiting():
line = ''
c = ''
#Look for end sequence $$$
while '$$$' not in line:
c = serial.read().decode('utf-8')
line += c
if "OpenBCI" in line:
return True
return False
def print_register_settings(self):
self.ser.write(b'?')
time.sleep(0.5)
self.print_incoming_text();
#DEBBUGING: Prints individual incoming bytes
def print_bytes_in(self):
if not self.streaming:
self.ser.write(b'b')
self.streaming = True
while self.streaming:
print(struct.unpack('B',self.ser.read())[0]);
'''Incoming Packet Structure:
Start Byte(1)|Sample ID(1)|Channel Data(24)|Aux Data(6)|End Byte(1)
0xA0|0-255|8, 3-byte signed ints|3 2-byte signed ints|0xC0'''
def print_packets_in(self):
while self.streaming:
b = struct.unpack('B', self.ser.read())[0];
if b == START_BYTE:
self.attempt_reconnect = False
if skipped_str:
logging.debug('SKIPPED\n' + skipped_str + '\nSKIPPED')
skipped_str = ''
packet_str = "%03d"%(b) + '|';
b = struct.unpack('B', self.ser.read())[0];
packet_str = packet_str + "%03d"%(b) + '|';
#data channels
for i in range(24-1):
b = struct.unpack('B', self.ser.read())[0];
packet_str = packet_str + '.' + "%03d"%(b);
b = struct.unpack('B', self.ser.read())[0];
packet_str = packet_str + '.' + "%03d"%(b) + '|';
#aux channels
for i in range(6-1):
b = struct.unpack('B', self.ser.read())[0];
packet_str = packet_str + '.' + "%03d"%(b);
b = struct.unpack('B', self.ser.read())[0];
packet_str = packet_str + '.' + "%03d"%(b) + '|';
#end byte
b = struct.unpack('B', self.ser.read())[0];
#Valid Packet
if b == END_BYTE:
packet_str = packet_str + '.' + "%03d"%(b) + '|VAL';
print(packet_str)
#logging.debug(packet_str)
#Invalid Packet
else:
packet_str = packet_str + '.' + "%03d"%(b) + '|INV';
#Reset
self.attempt_reconnect = True
else:
print(b)
if b == END_BYTE:
skipped_str = skipped_str + '|END|'
else:
skipped_str = skipped_str + "%03d"%(b) + '.'
if self.attempt_reconnect and (timeit.default_timer()-self.last_reconnect) > self.reconnect_freq:
self.last_reconnect = timeit.default_timer()
self.warn('Reconnecting')
self.reconnect()
def check_connection(self, interval = 2, max_packets_to_skip=10):
#check number of dropped packages and establish connection problem if too large
if self.packets_dropped > max_packets_to_skip:
#if error, attempt to reconect
self.reconnect()
# check again again in 2 seconds
threading.Timer(interval, self.check_connection).start()
def reconnect(self):
self.packets_dropped = 0
self.warn('Reconnecting')
self.stop()
time.sleep(0.5)
self.ser.write(b'v')
time.sleep(0.5)
self.ser.write(b'b')
time.sleep(0.5)
self.streaming = True
#self.attempt_reconnect = False
#Adds a filter at 60hz to cancel out ambient electrical noise
def enable_filters(self):
self.ser.write(b'f')
self.filtering_data = True;
def disable_filters(self):
self.ser.write(b'g')
self.filtering_data = False;
def test_signal(self, signal):
if signal == 0:
self.ser.write(b'0')
self.warn("Connecting all pins to ground")
elif signal == 1:
self.ser.write(b'p')
self.warn("Connecting all pins to Vcc")
elif signal == 2:
self.ser.write(b'-')
self.warn("Connecting pins to low frequency 1x amp signal")
elif signal == 3:
self.ser.write(b'=')
self.warn("Connecting pins to high frequency 1x amp signal")
elif signal == 4:
self.ser.write(b'[')
self.warn("Connecting pins to low frequency 2x amp signal")
elif signal == 5:
self.ser.write(b']')
self.warn("Connecting pins to high frequency 2x amp signal")
else:
self.warn("%s is not a known test signal. Valid signals go from 0-5" %(signal))
def set_channel(self, channel, toggle_position):
#Commands to set toggle to on position
if toggle_position == 1:
if channel is 1:
self.ser.write(b'!')
if channel is 2:
self.ser.write(b'@')
if channel is 3:
self.ser.write(b'#')
if channel is 4:
self.ser.write(b'$')
if channel is 5:
self.ser.write(b'%')
if channel is 6:
self.ser.write(b'^')
if channel is 7:
self.ser.write(b'&')
if channel is 8:
self.ser.write(b'*')
if channel is 9 and self.daisy:
self.ser.write(b'Q')
if channel is 10 and self.daisy:
self.ser.write(b'W')
if channel is 11 and self.daisy:
self.ser.write(b'E')
if channel is 12 and self.daisy:
self.ser.write(b'R')
if channel is 13 and self.daisy:
self.ser.write(b'T')
if channel is 14 and self.daisy:
self.ser.write(b'Y')
if channel is 15 and self.daisy:
self.ser.write(b'U')
if channel is 16 and self.daisy:
self.ser.write(b'I')
#Commands to set toggle to off position
elif toggle_position == 0:
if channel is 1:
self.ser.write(b'1')
if channel is 2:
self.ser.write(b'2')
if channel is 3:
self.ser.write(b'3')
if channel is 4:
self.ser.write(b'4')
if channel is 5:
self.ser.write(b'5')
if channel is 6:
self.ser.write(b'6')
if channel is 7:
self.ser.write(b'7')
if channel is 8:
self.ser.write(b'8')
if channel is 9 and self.daisy:
self.ser.write(b'q')
if channel is 10 and self.daisy:
self.ser.write(b'w')
if channel is 11 and self.daisy:
self.ser.write(b'e')
if channel is 12 and self.daisy:
self.ser.write(b'r')
if channel is 13 and self.daisy:
self.ser.write(b't')
if channel is 14 and self.daisy:
self.ser.write(b'y')
if channel is 15 and self.daisy:
self.ser.write(b'u')
if channel is 16 and self.daisy:
self.ser.write(b'i')
def find_port(self):
# Finds the serial port names
if sys.platform.startswith('win'):
ports = ['COM%s' % (i+1) for i in range(256)]
elif sys.platform.startswith('linux') or sys.platform.startswith('cygwin'):
ports = glob.glob('/dev/ttyUSB*')
elif sys.platform.startswith('darwin'):
ports = glob.glob('/dev/tty.usbserial*')
else:
raise EnvironmentError('Error finding ports on your operating system')
openbci_port = ''
for port in ports:
try:
s = serial.Serial(port= port, baudrate = self.baudrate, timeout=self.timeout)
s.write(b'v')
openbci_serial = self.openbci_id(s)
s.close()
if openbci_serial:
openbci_port = port;
except (OSError, serial.SerialException):
pass
if openbci_port == '':
raise OSError('Cannot find OpenBCI port')
else:
return openbci_port
class OpenBCISample(object):
"""Object encapulsating a single sample from the OpenBCI board."""
def __init__(self, packet_id, channel_data, aux_data):
self.id = packet_id;
self.channel_data = channel_data;
self.aux_data = aux_data;