Cynthion is an all-in-one tool for building, testing, monitoring, and experimenting with USB devices. Built around a unique FPGA-based architecture, Cynthion’s digital hardware can be fully customized to suit the application at hand. As a result, it can act as a no-compromise High-Speed USB protocol analyzer, a USB-hacking multi-tool, or a USB development platform.

Out-of-the-box, Cynthion acts as a USB protocol analyzer capable of capturing and analyzing traffic between a host and any Low-, Full-, or High-Speed (“USB 2.0”) USB device. It works seamlessly with our open-source analysis software.

Combined with our LUNA gateware and Facedancer libraries, Cynthion becomes a versatile USB-hacking and development tool. Facedancer makes it quick and easy to create or tamper with real USB devices—not just emulations—even if you don’t have experience with digital-hardware design, HDL, or FPGA architecture!

Documentation + Technical Information

Documentation for Cynthion is on Read the Docs and in the repository wiki.

Hardware design files for Cynthion are available in the cynthion-hardware repository. For a schematic PDF, assembly diagrams, bill of materials, component position file, and Gerber files, please download a repository release.

Read the latest news about Cynthion in the Cynthion-tagged blog posts.

Getting Help

For assistance with Cynthion use or development, please look at the issues on the Cynthion GitHub project. This is the preferred place to ask questions so that others may locate the answer to your question in the future. For hardware issues use the cynthion-hardware repository.

Join the Great Scott Gadgets community discussions on Discord. Note that while technical support requests are welcome there, they do not have support staff on duty at all times and your questions are not guaranteed to be answered. Be sure to also submit an issue on GitHub if you’ve found a bug or if you want to ensure that your request will be tracked and not overlooked.