Prerequisites
This guide assume that you have an acquisition board with all the component soldered in place—either one that you built yourself or ordered from the Open Ephys store, LabMaker, or elsewhere. If so, we'll walk you through the steps necessary to start collecting data with your board.
What you'll need
For each system that you want to use, you'll need the following:
1. One Opal Kelly FPGA module, which is used to bring data from the acquisition board to a computer. If your acquisition board has a USB connector on the back, the FPGA is already installed. If not, see the instructions for Installing the FPGA.
2. One or more headstages based on the Intan RHD2000-series amplifier chips. The options can be found on the Intan Technologies website. You can also build your own headstage (see the discussion in the Headstages section).
3. At least one RHD2000 SPI interface cable per headstage. See further information on the Cables & Tethers page. These cables can be daisy-chained up to 10 meters. Any combination of the following will work:
- 3-foot SPI interface cable - $215.00 (Intan Part #C3203)
- 6-foot SPI interface cable - $295.00 (Intan Part #C3206)
- Cooner wire SPI interface cable - to build it yourself, follow the instructions in this blog post and here.
4. Various components (shown with price and recommended DigiKey part numbers)
- One USB cable (either type A to B or USB 3.0)
- One 5V/6W power supply ($9.69, #SWI6-5-N-P5R)
- At least one I/O board
- One thin, passive HDMI cable (type A to type A) (perhaps something like Q398-ND)
5. A reasonably fast modern computer (desktop or laptop) running Windows, Mac, or Linux.
- A solid-state hard drive is recommended if you need to record >32 channel simultaneously
- If you're using a laptop, make sure the acquisition board is grounded to a wall outlet (or your experiment ground). See the recording noise page.
Step 1: Connecting the USB and power supply
Required components: USB cable, 5V power supply
This one's pretty straightforward, but there are a few things to keep in mind:
- IMPORTANT: make sure you're using a 5V DC power supply! Other types of power supplies will permanently damage the board.
- Use the power jack on the Acquisition Board, this is the jack set on it's own and lower on the board (not the one on the FPGA, next to the USB port). The acquisition board power jack has extra protections to avoid damage to the system that the FPGA plug lacks.
- Connect the USB cable to a USB port on your computer. If possible, using a USB 3.0-compatible port is recommended (often indicated by a blue color). USB cables longer than 2 meters are not recommended.
Step 2: Connecting the headstages
Required components: RHD2132 headstage, SPI cables
There are four headstage connectors on the front of the acquisition board. You can use any combination of the four (but you might as well start with input "A"). The connectors on the SPI cables are very small, so sometimes they can be tricky to insert. Make sure everything is properly aligned before you apply pressure, otherwise you might break the connector. Plug the opposite end of each cable (or series of daisy-chained cables) into a headstage, or a headstage Y-adapter, if you're using two headstages on one port.
Step 3: Connecting peripheral devices
External devices that generate digital or analog signals can interface with Open Ephys system through an I/O board. We use HDMI cables to connect to the I/O board, as these are cheap and have exactly the right number of shielded wires inside of them. Please note that these ports are not standard HDMI points; they will not work with any HDMI-compatible devices.
To build your own I/O board, follow the instructions here.
If you're in a hurry, you can splice together a BNC and (passive!) HDMI cable to make a one-channel I/O cable. See here for instructions.
Once your I/O board(s) or HDMI cables are ready, the HDMI connections on the acquisition board are as follows (from left to right):
 | ±5V analog output |
 | ±5V analog input |
 | 0/5V digital output |
 | 0/5V digital input |
Step 4: Operation
The software interface is covered in the documentation for the Rhythm FPGA module, but there a few things to know about the hardware itself.
Using it with a laptop
If you're using the acquisition board with a laptop that's running off battery power, you will have a "floating" ground. This will cause your signals to look extremely noisy. To fix the issue, connect the ground of the acquisition board to whatever ground you're using for your experimental setup (perhaps a wall socket or a Faraday cage). You can either do this via the BNC connector (alligator clips work well for this), or by attaching a wire to one of the two dedicated screw terminals on the side of the board. The screw terminals are preferred because someday we may do something with the BNC. If you use the BNC, ground the shell of it to the wall, not the center pin. Connecting center pin of the BNC to ground will short your board and may fry the FPGA.
ADC input range
The default setting is to have the ADCs run from -5 to +5V, although in practice the actual range is ±4.5V (up through Acquisition Board version 2.2). If you need to go up to 5V, the ADC must be switched to 0-5V mode.
To switch the ADC range, open up the case and move the jumpers near the ADC input HDMI to the two pins farther away from the edge of the board. Different channels can have different jumper settings, but make sure you record which is which! There's no way for the software to know the setting for each channel. Channel 1 is the rightmost jumper (closer to the headstage inputs), Channel 8 is the leftmost jumper.
There is also a small DC offset (~0.4 V) on the ADCs when they're in ±5V range. This offset is taken into account by the Open Ephys GUI, but since the offset can be slightly different for each channel, the traces may not be exactly centered around zero. Be sure to measure the "zero" value for each channel if you're doing any analysis that depends on absolute DC values, and applying a high-pass filter is not possible.
A note on cross-talk.If any of the ADC channels are not connected (i.e., the signal pin is floating), signals from adjacent channels will bleed through. This is expected behavior. However, channels that are properly connected should see
LEDs
The LEDs on the acquisition board will flash during normal operation. Fast flashing of the left-most LED (analog output) is expected. The digital input LED should turn green when one of the digital input channels is high, which is useful for checking whether or not your synchronization is working.
It is possible that the LEDs can create noise in your recordings for some grounding configurations. You may also want to disable them if you're performing behavioral experiments in the dark. The LEDs can be turned off by clicking the "LED" button in the Rhythm FPGA module in the Open Ephys GUI.
Software
...