Acquiring Digital Codes

It is critical that we acquire stimulus-locked digital codes so that we can bin the data according to stimulus type during analysis. This is also essential for creating event-related averages of psychophysiological data (e.g. creating ERPs from EEG data) as it gives us the precise onset time of each stimulus. Below is a description of the hardware, software, and steps necessary for sending and acquiring such codes with PsychoPy and the BioSemi ActiveTwo system.

Hardware

LabJack U3 DAQ device

The stimulus presentation computer interfaces with this device via USB. The device then outputs the 8-bit digital signal which is relayed to the MP150 via a 37-pin ribbon cable which connects to a parallel port on the ActiveTwo USB receiver.

Winford DB37 'Slim' Female Connector Breakout Board

This breakout board (aka terminal board or terminal block) gives us an easy way of wiring the output from the LabJack U3 to the ribbon cable.

ActiveTwo USB receiver I/O

USB from stimulus presentation computer 8-bit digital output from I/O lines FIO0-FIO7. A separate wire connects each line to the breakout board. Wires are connected to screw terminals on the breakout board. Each terminal is connected to a single pin of the female DB-37 connector. FIO0-FIO7 should be wired to terminals 1-8 of the breakout board. The ground should be wired to terminals 9-16 and terminal 37 of the breakout board. A 37-pin ribbon cable connects the breakout board to the ActiveTwo USB receiver.

Software

See here for information regarding sending event codes from PsychoPy.