GETTING STARTED: The 904: Compact fORP Package

The new 904 fORP system is a low cost, high feature package for subject response in fMRI. It's really easy to use. Simply attach the handheld to the interface (with or without the removable bundle), attach the USB cable and you're ready to go. There are two trigger inputs (optical and TTL) for syncing your data with the scanner.


  • Interface
  • 8-fiber removable bundle
  • 4-button response pad
  • USB cable.

Front Panel

The USB connection is made to the small USB connector on the front panel, shown here on the right (as P1).

The front panel also has 5 LED indicators, for trigger and button status.


Rear Panel

The optical connections are made to the rear panel. You can connect most optical handheld devices directly to the optical port (P4), or through long removable bundle to that port.

The 904 will also accept TTL and optical trigger inputs on ports P3 and P2, shown here.


The TTL input is positive edge-triggered and has a weak internal pullup resistor (47 k ohm). There is no minimum pulse width for the TTL input.

Set Up

  1. Attach the handheld to the interface with or without the removable fiber optic bundle to P4.
  2. Attach the USB cable from P1 to a computer.
  3. Optional: connect trigger-in cable to the TTL SMB (P3) or Main.Optical HFBR connector (P2).

The interface is powered by the USB port and automatically adjusts the light levels for use with or without the bundle.

User Tips

  1. Attach the handheld before attaching to the computer.
  2. If it's not working properly, detach and reattach the USB.
  3. Make sure the connectors are fully attached.
  4. Each time the USB is attached the interface is powered up and it sets its optical gain based on what is connected. If you add the removable bundle, you will need to reset the gain by reattaching the USB.

Standard Output

If you are using the 904 with a button box, and have not requested special outputs, this is what will be sent over the USB connection:

Button Keycode
Blue 1
Yellow 2
Green 3
Red 4
TTL trigger 5
Optical Trigger 6


If you have any questions or suggestions, please contact us here:

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Current Designs, Inc.
3950 Haverford Ave.
Philadelphia PA 19104 \
Phone: 215 387-5456
Fax: 215 386-4857
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Topic revision: r2 - 23 Feb 2021, BenDugan
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