SCNI Interface Box
In order to more efficiently and effectively route analog and digital signals within the neurophysiology recording rigs, we designed an interface box that minimizes signal paths, wire crossings, and reduces the need for BNC cables. The box allows for the connection of four key systems, allowing them to communicate analog and digital data with one another:
- VPixx DataPixx2 box (3 x DB25 connectors)
- SR Research EyeLink II (1 x 68-pin D-sub)
- TDT RZ2 bioamp (2 x DB25 connectors)
- Open Ephys board (4 x HDMI connectors)
The circuit, which is completely passive, was designed by Aidan Murphy and Bruce Pritchard and constructed by Danny Trang in the Section on Instrumentation. The LEDs on the left of the front panel draw current from the connected systems in order to indicate which systems are currently connected to the box. The full schematic diagram can be found here, and a basic overview of the signal path is given below.
The interface box houses a series of breakout boards, with the main one being a Data Translation DT330, which accepts the 68-pin D-sub cable that comes from the analog-out cards in the EyeLink PCs. The six channels of eye signal (X, Y and pupil for both left and right eyes) are routed via filtering stages (consisting of a 50 Ohm resistor and a 1uF capacitor) to the first 6 analog input channels of the DataPixx2, the TDT RZ2, and the Open Ephys board. An additional four channels of analog input are taken from the BNC connectors on the top right corner of the interface box front panel (all 4 are routed to DataPixx and TDT, while only the first 2 are routed to Open Ephys).
The four analog output channels from the DataPixx are routed to the four BNC connectors on the bottom right corner of the interface box front panel.
The first four digital output channels of the DataPixx2 are routed to both the four BNC connectors on the top left of the interface box front panel, as well as the first four digital input channels of the TDT RZ2 and the Open Ephys board. The remaining digital outputs from the DataPixx2 are routed to the remaining TDT digital inputs. The DataPixx2 receives four digital inputs from the BNC connectors on the front panel of the interface box, and four directly from the Open Ephys board's digital outputs.
