Cyton

The OpenBCI Cyton PCBs were designed with Design Spark, a free PCB capture program.

Cyton Board Specs:

• Power with 3-6V DC Battery ONLY

• PIC32MX250F128B Micrcontroller with chipKIT UDB32-MX2-DIP bootloader

• ADS1299 Analog Front End

• LIS3DH 3 axis Accelerometer

• RFduino BLE radio

• Micro SD card slot

• Voltage Regulation (3V3, +2.5V, -2.5V)

• Board Dimensions 2.41 x 2.41 (octogon has 1 edges) [inches]

• Mount holes are 1/16 ID, 0.8 x 2.166 on center [inches]

Data Format

Binary Format

Byte No	Description
1	Start byte, always 0xA0
2	Sample Number
3-26	EEG Data, values are 24-bit signed, MSB first
27-32	Aux Data
33	Footer, 0xCX where X is 0-F in hex

EEG Data for 8 channels

24-Bit Signed.

Byte No	Description
3-5	Data value for EEG channel 1
6-8	Data value for EEG channel 2
9-11	Data value for EEG channel 3
12-14	Data value for EEG channel 4
15-17	Data value for EEG channel 5
18-20	Data value for EEG channel 6
21-23	Data value for EEG channel 7
24-26	Data value for EEG channel 8

EEG Data for 16 channels

24-Bit Signed.

Received		Upsampled board data	Upsampled daisy data
sample(3)		avg(sample(1),sample(3))	sample(2)
	sample(4)	sample(3)	avg(sample(2),sample(4))
sample(5)		avg(sample(3),sample(5))	sample(4)
	sample(6)	sample(5)	avg(sample(4),sample(6))
sample(7)		avg(sample(5),sample(7))	sample(7)
	sample(8)	sample(7)	avg(sample(6),sample(8))

This transmission only applies to Cyton + Daisy and RFduino, if WiFi shield is used then all data is transmitted, and is not necessary to interpolate.

Aux Data

16-Bit Signed.

Stop Byte (33)	Byte 27	Byte 28	Byte 29	Byte 30	Byte 31	Byte 32	Name
0xc0	AX1	AX2	AY1	AY2	AZ1	AZ2	Standard with accel
0xC1	UDF	UDF	UDF	UDF	UDF	UDF	Standard with raw aux
0xC2	UDF	UDF	UDF	UDF	UDF	UDF	User defined
0xC3	AC	AV	T3	T2	T1	T0	Time stamped set with accel
0xC4	AC	AV	T3	T2	T1	T0	Time stamped with accel
0xC5	UDF	UDF	T3	T2	T1	T0	Time stamped set with raw aux
0xC6	UDF	UDF	T3	T2	T1	T0	Time stamped with raw aux

Aux Data

16-Bit Signed.

Byte 27	Byte 28
X	AX1
x	AX0
Y	AY1
y	AY0
Z	AZ1
z	AZ0

class openbci_stream.acquisition.cyton.Cyton(mode: Literal['serial', 'wifi', None], endpoint: Optional[Union[str, List]] = None, host: Optional[str] = None, daisy: Optional[List[Literal['auto', True, False]]] = None, montage: Optional[Union[list, dict]] = None, streaming_package_size: int = 250, capture_stream: Optional[bool] = False, number_of_channels: List = [])

Cyton is a shortcut for CytonRFDuino or CytonWiFi:

>>> Cyton('serial', ...)

is equals to:

>>> CytonRFDuino(...)

and

>>> Cyton('wifi', ...)

the same that do:

>>> CytonWiFi(...)

Parameters

• mode – serial or wifi

• endpoint – Serial port for RFduino or IP address for WiFi module.

• host – IP address for the server that has the OpenBCI board attached, by default its assume that is the same machine where is it executing, this is the localhost.

• daisy – Daisy board can be detected on runtime or declare it specifically.

• montage – A list means consecutive channels e.g. [‘Fp1’, ‘Fp2’, ‘F3’, ‘Fz’, ‘F4’] and a dictionary means specific channels {1: ‘Fp1’, 2: ‘Fp2’, 3: ‘F3’, 4: ‘Fz’, 5: ‘F4’}.

• streaming_package_size – The streamer will try to send packages of this size, this is NOT the sampling rate for data acquisition.

• capture_stream – Indicates if the data from the stream will be captured in asynchronous mode.

__getattribute__(attr: str) → Any

Some attributes must be acceded from RPyC.

class openbci_stream.acquisition.cyton.CytonRFDuino(port: Optional = None, host: Optional[str] = None, daisy: Literal['auto', True, False] = 'auto', montage: Optional[Union[list, dict]] = None, streaming_package_size: int = 250, capture_stream: bool = False, board_id: str = '0', parallel_boards: int = 1)

RFduino is the default communication mode for Cyton, this set a serial comunication through a USB dongle with a sample frequency of 250 Hz, for 8 or 16 channels.

Parameters

• port – Serial port.

• host – IP address for the server that has the OpenBCI board attached, by default its assume that is the same machine where is it executing, this is the localhost.

• daisy – Daisy board can be detected on runtime or declare it specifically.

• montage – A list means consecutive channels e.g. [‘Fp1’, ‘Fp2’, ‘F3’, ‘Fz’, ‘F4’] and a dictionary means specific channels {1: ‘Fp1’, 2: ‘Fp2’, 3: ‘F3’, 4: ‘Fz’, 5: ‘F4’}.

• streaming_package_size – The streamer will try to send packages of this size, this is NOT the sampling rate for data acquisition.

• capture_stream – Indicates if the data from the stream will be captured in asynchronous mode.

_get_gain() → list

Return the gains from ADS1299 register.

As defined in the datasheet

_get_serial_ports() → Optional[str]

Look for first available serial port.

Returns

String with the port name or None if no ports were founded.

Return type

str

_stream_data(size: Optional[int] = 256, kafka_context: Optional[Dict] = {}) → None

Write binary raw into a kafka producer.

This method will feed the producer while the serial device has data to be read.

Parameters

• size – The buffer length to read.

• kafka_context – Information from the acquisition side useful for deserializing and that will be packaged back in the stream.

close()

Close the serial communication.

read(size: int) → bytes

Read size bytes from the serial port.

Parameters

size – Size of input buffer.

Returns

Data read.

Return type

read

reset_input_buffer()

Clear input buffer, discarding all that is in the buffer.

start_stream() → None

Initialize a Thread for reading data from the serial port and streaming into a Kafka producer.

stop_stream() → None

Stop the data collection that runs asynchronously.

write(data: bytes) → None

Write the given data over the serial port.

class openbci_stream.acquisition.cyton.CytonWiFi(ip_address: str, host: Optional[str] = None, daisy: Literal['auto', True, False] = 'auto', montage: Optional[Union[list, dict]] = None, streaming_package_size: int = 250, capture_stream: Optional[bool] = False, board_id: str = '0', parallel_boards: int = 1)

This module implement a TCP connection for the WiFi module with a sample frequency from 250 Hz up to 16 kHz, for 8 or 16 channels (8 kHz for 16 channels).

Parameters

• ip_address – IP addres for the WiFi shield.

• host – IP address for the server that has the OpenBCI board attached, by default its assume that is the same machine where is it executing, this is the localhost.

• daisy – Daisy board can be detected on runtime or declare it specifically.

• montage – A list means consecutive channels e.g. [‘Fp1’, ‘Fp2’, ‘F3’, ‘Fz’, ‘F4’] and a dictionary means specific channels {1: ‘Fp1’, 2: ‘Fp2’, 3: ‘F3’, 4: ‘Fz’, 5: ‘F4’}.

• streaming_package_size – The streamer will try to send packages of this size, this is NOT the sampling rate for data acquisition.

• capture_stream – Indicates if the data from the stream will be captured in asynchronous mode.

_create_tcp_server() → None

Create TCP server, this server will handle the streaming EEG data.

_get_local_ip_address() → str

Get the current network IP assigned.

_start_loop()

Start the TCP server on a thread asyncore loop.

_start_tcp_client()

Connect the board to the TCP server. Sends configuration of the previously server created to the board, so they can connected to.

close() → None

Stops TCP server and data acquisition.

kafka_context() → Dict[str, Any]

Kafka contex generator.

read(size=None) → bytes

Read the response for some command.

Unlike serial mode, over WiFi there is not read and write individual commands, the response is got in the same write command. This implementation tries to emulate the the behavior of serial read/write for compatibility reasons. Not all command return a response.

start_stream() → None

Initialize a TCP client on the WiFi shield and sends the command to starts stream.

stop_stream() → None

Stop the data collection that runs asynchronously and sends the command to stops stream.

write(data: Union[str, bytes]) → None

Send command to board through HTTP protocole.

Parameters

data – Commands to send, It should not be more than 31 characters long.