OpenBCI_Python

The Python software library designed to work with OpenBCI hardware.

Please direct any questions, suggestions and bug reports to the github repo at: https://github.com/OpenBCI/OpenBCI_Python

##Dependancies:

Python 2.7 or later (https://www.python.org/download/releases/2.7/) Numpy 1.7 or later (http://www.numpy.org/)

OpenBCI 8 and 32 bit board with 8 channels.

This library includes the main open_bci_v3 class definition that instantiates an OpenBCI Board object. This object will initialize communication with the board and get the environment ready for data streaming. This library is designed to work with iOS and Linux distributions. To use a Windows OS, change the init function in open_bci_v3.py to establish a serial connection in Windows.

For additional details on connecting your board visit: http://docs.openbci.com/tutorials/01-GettingStarted

##Audience:

This python code is meant to be used by people familiar with python and programming in general. It's purpose is to allow for programmers to interface with OpenBCI technology directly, both to acquire data and to write programs that can use that data on a live setting, using python.

If this is not what you are looking for, you can visit http://openbci.com/downloads and browse other OpenBCI software that will fit your needs.

##Functionality:

The startStreaming function of the Board object takes a callback function and begins streaming data from the board. Each packet it receives is then parsed as an OpenBCISample which is passed to the callback function as an argument.

OpenBCISample members: -id: int from 0-255. Used to tell if packets were skipped.

-channel_data: 8 int array with current voltage value of each channel (1-8)

-aux_data: 3 int array with current auxiliary data. (0s by default)

###User.py

For initial testing, this code provides a simple user interface (called user.py). To use it, connect the board to your computer using the dongle (see http://docs.openbci.com/tutorials/01-GettingStarted for details).

Then simply run the code given as an argument the port your board is connected to: Ex Linux:

$python user.py -p /dev/ttyUSB0

The program should establish a serial connection and reset the board to default settings. When a '-->' appears, you can type a character (character map http://docs.openbci.com/software/01-OpenBCI_SDK) that will be sent to the board using ser.write. This allows you to change the settings on the board.

A good first test is to try is to type '?':

--> ?

This should output the current configuration settings on the board.

Another test would be to change the board settings so that all the pins in the board are internally connected to a test (square) wave. To do this, type:

--> [

Alternatively, there are 6 test signals pre configured:

--> /test1 (connect all pins to ground)

--> /test2 (connect all pins to vcc)

--> /test3 (Connecting pins to low frequency 1x amp signal)

--> /test4 (Connecting pins to high frequency 1x amp signal)

--> /test5 (Connecting pins to low frequency 2x amp signal)

--> /test6 (Connecting pins to high frequency 2x amp signal)

The / is used in the interface to execute a pre-configured command. Writing anything without a preceding '/' will automatically write those characters, one by one, to the board.

For example, writing

-->x3020000X will do the following:

‘x’ enters Channel Settings mode. Channel 3 is set up to be powered up, with gain of 2, normal input, removed from BIAS generation, removed from SRB2, removed from SRB1. The final ‘X’ latches the settings to the ADS1299 channel settings register.

Pre-configured commands that use the / prefix are:

test (As explained above)

--> /test4

csv (Set the start command to record data to a CSV file)

--> /csv

start (Start EEG streaming using the most recently defined callback, printData by default)

--> /start

Adding the argument "T:number" will set a timeout on the start command. For example, to record CSV data for 5 seconds type:

-->/csv

-->/start T:5

To use your own function as a callback just define your function and substitute in line 31 like so:

		fun = yourFunction()

Useful commands:

Writting to SD card a high frequency square wave (test5) for 3 seconds:

$ python user.py -p /dev/ttyUSB0
User serial interface enabled...
Connecting to  /dev/ttyUSB0
Serial established...
View command map at http://docs.openbci.com.
Type start to run. Type exit to exit.

--> 
OpenBCI V3 8bit Board
Setting ADS1299 Channel Values
ADS1299 Device ID: 0x3E
LIS3DH Device ID: 0x33
Free RAM: 447
$$$
--> /test5
Warning: Connecting pins to high frequency 2x amp signal

--> a
Corresponding SD file OBCI_18.TXT$$$
--> /start T:3

NOTES:

When writing to the board and expecting a response, give the board a second. It sometimes lags and requires the user to hit enter on the user.py script until you get a response.