RHS USB/FPGA Interface: RhythmStim

To facilitate the development of electrophysiology interface systems using the RHS series of stimulation/amplifier microchips, Intan Technologies provides the following open-source USB/FPGA interface for developers. Designated RhythmStim, the interface consists of Verilog HDL code and a C++ API written for the commercially-available Opal Kelly XEM6010 USB interface module. RhythmStim configures the Xilinx FPGA on the Opal Kelly module to communicate with up to eight RHS2116 chips (128 channels, maximum) over SPI buses and to stream data from these chips to a host computer over a USB 2.0 interface.

Independent stimulation protocols with biphasic or triphasic constant-current stimulation pulses may be set for all 128 stimulator channels. The host computer may set the RHS2116 per-channel sampling rate to 20, 25, or 30 kS/s.

The RhythmStim API supports multi-platform development under Windows, Mac, or Linux. All API software is written in C++ to facilitate rapid development. The RhythmStim interface is used at the core of the RHS stim/recording controller software, which offers a quick way to evaluate the performance and operation of RHS chips with a plug-and-play USB interface and open-source GUI software written in C++/Qt.


  • Open-source Verilog HDL code configures a Xilinx FPGA to communicate with multiple RHS stimulator/amplifier chips
  • Verilog code is written for a commercially-available Opal Kelly XEM6010 module with integrated high-speed USB 2.0 interface
  • Up to 128 simultaneous amplifier channels supported at sample rates from 20 kS/s to 30 kS/s per channel
  • Biphasic and triphasic current pulses generated with timing resolution as fine as 33.3 ┬Ás
  • Independent or coordinated stimulation sequences on all channels triggered by digital inputs or software commands
  • Open-source host computer C++ API for multi-platform support


  • Windows, Mac, or Linux-based electrophysiology signal acquisition systems
  • Rapid prototyping of Intan Technologies RHS-based products
  • Starting point for the development of custom interfaces to RHS chips
Opal Kelly XEM6010 module
Opal Kelly XEM6010 module used for the RhythmStim interface. This device, along with the RhythmStim Verilog/C++ code, allows up to 128 channels from multiple RHS chips to be controlled and sampled by a host computer.

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