Great Scott Gadgets Cynthion

Find enumeration or report problems in your own USB firmware.

USB analyzerFPGAPacketryFirmware debugging

Price: $150+at shop.hak5.org
Availability: Listed
Design: Open

Where to buy · 4 shops

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Bring along: Packetry host, Cynthion tools and separately supplied USB data cables.
Keep in mind: USB 2.0 analysis; cable layout and target power need checking.

Source checked · Sep 16, 2026

Image credit
Maker image · Great Scott Gadgets Cynthion with its aluminum enclosure. · Great Scott Gadgets / Crowd Supply

(02) Blueprint

Build it yourself

Open hardware

Cynthion is fully open hardware: complete KiCad schematics and PCB under CERN-OHL-P, plus open BSD-licensed host software and the Amaranth/LUNA gateware framework.

Top-level schematic (cynthion.kicad_sch)

Read straight from the maker’s repository. Open on GitHub

Top-level schematic (cynthion.kicad_sch)

GitHub

Design files 2

Source 3

git clone https://github.com/greatscottgadgets/cynthion-hardware.git

Key parts 4

Lattice ECP5 (LFE5U-12F-6BG256C)All ECP5 devicesFPGADatasheet
Microchip ATSAMD11D14A-MAll SAM D11 / D21 devicesdebug/control MCU
Cypress/Infineon S27KS0641HyperRAM (working memory)
Microchip USB3343All USB3343 devicesUSB PHY

Research notes

Verified repo existence/license via `gh api repos/greatscottgadgets/cynthion-hardware` (CERN-OHL-P-2.0, 113 stars) and by fetching raw .kicad_sch files and grepping lib_id/value fields for chip part numbers. Full KiCad source tree confirmed via git tree listing (bank*.kicad_sch, ram.kicad_sch, usb_phy.kicad_sch, etc.).

Every link checked 2026-09-27.

Hand this device to your agent. Everything on this page, as clean Markdown and JSON: specs, shops, prices, design files, parts.

Markdown JSON

Made the Great Scott Gadgets Cynthion? Put the badge on your README; it links here, with every shop that sells it.

Specifications

Hardware and revision

Selected package: Cynthion board in its CNC-milled anodized-aluminum enclosure; bare-board listing is separate.
Confirmed release: r1.4.0 is labeled the initial production hardware release.
Check your unit: Connect CONTROL and run cynthion info --force-offline to read hardware and firmware information.
Core hardware: Lattice LFE5U-12F ECP5 FPGA; Microchip SAMD11 debug controller.
Memory: 8 MiB RAM and 4 MiB SPI flash.
USB interfaces: Three USB3343 PHYs, each supporting up to 480 Mbit/s.
Expansion: Two Pmod-compatible connectors expose 16 FPGA I/O signals.
Scope: Cynthion hardware does not support SuperSpeed; LUNA gateware is a separate project.

Prepare a USB capture

Cables: Maker's shipping update says USB cables are not included; choose cables for your host and target ports.
Host software: Python 3.9+ and the cynthion package; Linux needs access rules and macOS needs native libusb.
Packetry: Documented installers: Linux AppImage, macOS Homebrew and Windows installer; source builds are also documented.
Analyzer firmware: Factory FPGA configuration is USB Analyzer. cynthion run analyzer loads it; cynthion flash analyzer makes it the default.
Update path: cynthion update updates MCU firmware and FPGA flash; record installed versions first.
Analysis connection: CONTROL → computer running Packetry; TARGET C → target host; TARGET A → device under test.
One computer: The tutorial permits one host for both roles, with CONTROL and TARGET C on different hubs.
Capture sequence: Start capture before attaching the target to include enumeration. Match the target speed if the UI requests it.
Documented result: The keyboard tutorial inspects enumeration plus key press/release transfers.

Power and development

Device supply: 5 V DC for Cynthion itself. Use USB cables no longer than 2 m.
Target supply: Pass-through supply: 5–20 V, up to 3 A; target must match voltage/current. Cynthion-supplied target load: at most 500 mA.
Expansion voltage: Pmod and mezzanine connectors must not exceed 3.3 V.
Other modes: Facedancer and LUNA provide USB-device development paths beyond Packetry analysis.
Design downloads: r1.4.0 archive includes schematics, assembly diagrams, BOM, placement and Gerber files.
Hardware license: The hardware design repository uses CERN-OHL-P-2.0.

What still needs checking

r1.4.0 is a confirmed production design release. The reviewed store does not guarantee a shipping revision; inspect the actual unit before selecting revision-specific files.
One-host capture depends on USB topology. No target, operating system, hub or USB-C cable combination was physically tested.
The keyboard tutorial uses manual speed selection while newer Packetry instructions omit that step; follow the installed version's UI.
Factory firmware version, present distributor cable bundles, current price and checkout stock remain unverified.
The hardware license does not establish permission for the storefront photo. Any published asset needs its own source, rights and attribution record.

Downloads & docs

Official Cynthion productgreatscottgadgets.com Enclosed purchase optioncrowdsupply.com r1.4.0 production design filesgithub.com Host installation and updatescynthion.readthedocs.io Analyzer configurationcynthion.readthedocs.io USB keyboard capture tutorialcynthion.readthedocs.io Ports and expansioncynthion.readthedocs.io Electrical and cable limitscynthion.readthedocs.io Packetry installationpacketry.readthedocs.io Maker statement on excluded cablescrowdsupply.com Hardware source and licensegithub.com Cynthion/LUNA scope explanationgreatscottgadgets.com

Source & revision notes

Maker listing checked Sep 16, 2026. Detailed documentation reviewed Sep 16, 2026. Not hands-on tested.

Price is a dated listing; confirm with the maker.

Primary-source claims checked independently; no hands-on testing or maker relationship. Price and checkout stock remain unverified.

Scope is Cynthion with the aluminum enclosure. r1.4.0 is the documented initial production hardware release, not a promise about a seller's shipping revision.

Price is Lab401's euro listing on 2026-09-18, not the maker's own price. Lab401 showed it out of stock on that date, so check stock before relying on the link.

Checked 2026-09-18: Lab401, which this entry linked to, had no stock at all, so the link was moved to Hak5. Hak5 had the bare board in stock at US$150; the aluminium-enclosure version at US$200 was sold out.

Independently checked against primary sources; no hands-on testing. Listed status does not guarantee stock, fulfillment, performance or accessory compatibility.

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