From TSG Doc
Revision as of 16:03, 29 January 2015 by P.dewater (talk | contribs)
Jump to navigation Jump to search


The buttonbox is used for time accurate(1ms) button press registration. We use it to register buttonpresses, soundkey, voicekey signals and to send tone onset, analog output, triggers with the BITSI protocol. It is suitable for Behavioral, EEG, MEG, and fMRI experiments. The buttonbox is connected to a computer with a usb connection.

Image: 200 pixels Image: 200 pixels

The output connector has two binary eight bit ports: input and output. The two ports can be used for responses (input) and stimulus triggers (output). Two 8 bits analog outputs and three 8 bits analog inputs. The output connector has a sound and voicekey which triggers when a amplitude reaches a threshold. By using the serial port, the BITSI can be used platform independently: it works on Windows, Linux and Mac OSX. Most programming environments and stimulus packages support serial communication. 

BITSI Protocol

BITSI stands for Bits to Serial Interface. Because the BITSI is designed to interface both in- and output signals, the 'protocol' is asymmetric: the input and output protocols differ. 


The input port can be used to interface eight buttons maximally. Button presses are translated to serial output characters/bytes according to the following table:

Signal / Button

ASCII (rising / falling)

Code (rising / falling)


A / a

65 / 97


B / b

66 / 98


C / c

67 / 99


D / d

68 / 100


E / e

69 / 101


F / f

70 / 102


G / g

71 / 103


H / h

72 / 104


S / s

83 / 115


V / v

86 / 118

This means that when signal 1 gets active(button press), a capital A will be sent to the serial port. A lowercase 'a' will be sent when the signal is deactivated(button release). Mechanical buttons can be connected directly.


Output knows two protocols: BITSI simple or BITSI extended. To enter a certain protocol two buttons have to be pressed when the BITSIbox is powered. Press button H and A for simple mode and H and B for extended mode.

If no button is pressed when powered it boots the last known protocol. In the simple protocol every byte sent to the BITSI over the serial port, is represented at the 8 bit output.

The extended protocol uses two bytes(or two characters), this combination can access two analog outputs and a tone generator. The first byte selects the output. The second byte determines the value written to this output.


Byte 1 (ASCII / code)

Byte 2

Marker out

M / 77

Marker value

Pulse out

P / 80

Marker value

Pulse time

T / 88

ms before pulse reset

Analog out 1

Y / 89

Analog output value

Analog out 2

Z / 90

Analog output value


T / 84

Start tone

Detect Sound


S / 83

Detect Voice

D /

V / 83

Calibrate Sound

C /


Calibrate Voice

C /


Analog in 1

A /


Analog in 2

A /


Analog in 3

A /


Analog in 4

A /


LEDs off

L /


LEDs input

L /


LEDs output

L /


Trigger port settings


The 25 pins female connector has 8 inputs and 8 outputs, respectively 1-8 are inputs and 9-16 are outputs. Three analog input with an analog to digital convertor of 12 bit, pins 17,18,20 and 21. Two analog outputs with an digital to analog convertor of 12 bits on pins 22 and 23.

Serial port settings

Our hardware design allows to be connected to the computers USB and emulates a serial communication Port.





Data bits


Stop bits


Flow control


USB-Com port settings

1.Connect the BITSIbox to your computer using the USB cable.

2.When you connect the BITSIbox, Windows should initiate the driver installation process (if you haven't used the computer with an BITSIbox board before).

3.On Windows Vista/7, the driver should be automatically downloaded and installed.

4.On Windows XP, the Add New Hardware wizard will open:

  • When asked Can Windows connect to Windows Update to search for software? select No, not this time. Click next.
  • Select Install from a list or specified location (Advanced) and click next.
  • Make sure that Search for the best driver in these locations is checked; uncheck Search removable media; check Include this location in the search and browse to the c:/beheer/arduino/drivers directory.
  • The wizard will search for the driver and then tell you that a "USB Serial Converter" was found. Click finish.
  • The new hardware wizard will appear again. Go through the same steps and select the same options and location to search. This time, a "USB Serial Port" will be found.

How to Check the Com Port settings(important!)

  • From the Start menu, open the Control Panel.
  • From the control panel, open the System window.
  • From the system properties window, go to the Hardware tab and click the Device Manager button.
  • From the Device Manager window, click Ports (Com&LPT). You should now be able to see which Com Port the USB adapter is assigned to.
  • If the Com Port is 10 or higher, you will have to change it to a lower port.
  • From the Device Manager window, click on USB Serial Port (Com#). Click the Port Settings tab of the USB Serial Port Properties window, and then click the Advanced button.
  • In the Advanced Settings window, use the scroll input to select a Com Port (select 10 or lower). Change Receive (bytes) and Transmit (bytes) to 64. Change the Latency Timer to 1.
  • Click the OK button.

Always connect the usb device to the same port and your settings will be remembered.

TSG ButtonBox hardware 2013

Find the hardware design here Buttonbox_2013_Hardware

TSG ButtonBox software 2013

Find the code here Media:BITSI_tempalte2015_duemilanove.zip

Presentation Settings

The experiment files needs a few settings for the device to work:

  • In the settings tab: port -> input port -> 1 must be the device that identifies itself as "Arduino Uno" in the device manager. Note that the port must have a number not higher than 10 (COM1-COM10). Use re-enumerate if it is higher.
  • Rate must be set 115200, Parity to None, Data Bits to 8 and Stop Bits to 1, Uncheck FIFO Interrupt.

Buttonbox in Python and PsychoPy

Download this site package to use the buttonbox: rusocsci

Example using buttons from the buttonbox in Python:

#!/usr/bin/env python

# import the rusocsci.buttonbox module
from rusocsci import buttonbox 

# make a buttonbox
bb = buttonbox.Buttonbox()

# wait for a single button press
b = bb.waitButtons()

# print the button pressed
print("b: {}".format(b)) 

Example using markers with the buttonbox in Python:

#!/usr/bin/env python

# import the rusocsci.buttonbox module
from rusocsci import buttonbox 

# make a buttonbox
bb = buttonbox.Buttonbox()

# wait for a single button press
bb.sendMarker(val=100)    #This is your marker code, range code 1-255 

Example using the Buttonbox in PsychoPy:

#!/usr/bin/env python

# import psychopy and rusocsci
from psychopy import core, visual 
from rusocsci import buttonbox

## Setup Section
win = visual.Window(monitor="testMonitor")
bb = buttonbox.Buttonbox()
text = visual.TextStim(win, "Press a button on the buttonbox")

## Experiment Section
# show text
# wait for response
b = bb.waitButtons()
# show response
text.setText("you pressed: {}".format(b))

## Cleanup Section

Matlab Settings

 % ===================================================================================================
 function handle = serial_buttonbox_common(cmd,varargin)
 % NOTE: this is a functional example, please adapt code according to your needs. 
 % to initialize connection:
 % handle = serial_buttonbox_common('open',se)
 % settings (se):
 % define settings as a structure, i.e.:
 % se.Device = 'COM2';
 % se.BaudRate = 115200;
 % se.DataBits = 8;
 % se.StopBits = 1;
 % se.Parity = 0;
 % se.PTBPath = 'c:\toolboxes\PsychToolbox'
 % to run:
 % serial_buttonbox_common('run')
 % to close the connection:
 % serial_buttonbox_common('close',handle);
 persistent old_hdl
 % set defaults
 se.Device = 'COM2';
 se.BaudRate = 115200;
 se.DataBits = 8;
 se.StopBits = 1;
 se.Parity = 0;
 se.PTBPath = 'c:\toolboxes\PsychToolbox';
 if nargin < 1
 cmd = 'open';
 if nargin > 1
 % user overwrites default settings
 flds = fields(varargin{1});
 for n = 1 : numel(flds)
 se.(flds{n}) = varargin{1}.(flds{n});
 switch cmd
 case 'open'
 % get handle to serial device
 handle = open_buttonbox(se.Device);
 case 'close'
 handle = varargin{1};
 case 'run'
 % read incoming data
 if isempty(old_hdl)
 help serial_buttonbox_common
 error('Buttonbox not yet initialized');
 handle = old_hdl;
 fprintf('Unknown option %s\n',cmd);
 % only gets here when cmd = 'run'
 while 1 
 % start polling for characters (indicating start of scan)
 navailable = IOPort('BytesAvailable', handle);
 if navailable
 data = [];
 while navailable
 % read incoming data
 [newdata, ~, err] = IOPort('Read', handle, 0, navailable);
 if ~isempty(err), disp(err); end
 data = [data newdata];
 %pause(0.001); % if possible just add a small pause to not claim entire core
 navailable = IOPort('BytesAvailable', handle);
 if numel(data)>1
 fprintf('\nReceived characters: %d\n',numel(data));
 for n = 1 : numel(data)
 % disp(char(data(n)));
 fprintf('incoming: %d\t%s\n',data(n),char(data(n)));
 end %while 1
 function hdl = open_buttonbox(device)
 % open handle to serial device (mini buttonbox)
 hdl = IOPort('OpenSerialPort',device,['BaudRate=' num2str(se.BaudRate)]);
 if ~isempty(old_hdl)
 hdl = IOPort('OpenSerialPort',device,['BaudRate=' num2str(se.BaudRate)]);
 old_hdl = hdl;
 fprintf('Wait for device buttonbox....\n');
 while ~IOPort('BytesAvailable', hdl) && toc<10
 % wait for welcome message device
 % clear buffer
 %IOPort('flush', hdl);
 IOPort('purge', hdl);