# Great Scott Gadgets Cynthion

> Inspect USB traffic while developing a keyboard or other USB device.

- **Category:** Instruments
- **Availability:** Listed by maker
- **Price:** US$150 without enclosure / US$200 with aluminium enclosure (at shop.hak5.org), checked 2026-09-16
- **Good for:** Find enumeration or report problems in your own USB firmware.
- **You'll need:** Packetry host, Cynthion tools and separately supplied USB data cables.
- **Trade-off:** USB 2.0 analysis; cable layout and target power need checking.
- **Page:** https://gadgets.sh/devices/great-scott-gadgets-cynthion/

## Where to buy

| Shop | Status | Link |
|---|---|---|
| Great Scott Gadgets | Orderable | https://greatscottgadgets.com/cynthion/?utm_source=gadgets.sh&utm_medium=referral&utm_campaign=great-scott-gadgets-cynthion&utm_content=api |
| Hak5 | Orderable | https://shop.hak5.org/products/cynthion?utm_source=gadgets.sh&utm_medium=referral&utm_campaign=great-scott-gadgets-cynthion&utm_content=api |
| Hacker Warehouse | Orderable | https://hackerwarehouse.com/product/cynthion/?utm_source=gadgets.sh&utm_medium=referral&utm_campaign=great-scott-gadgets-cynthion&utm_content=api |
| Crowd Supply | Orderable | https://www.crowdsupply.com/great-scott-gadgets/cynthion?utm_source=gadgets.sh&utm_medium=referral&utm_campaign=great-scott-gadgets-cynthion&utm_content=api |

## Blueprint

**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.

### Design files

- schematic: [Top-level schematic (cynthion.kicad_sch)](https://github.com/greatscottgadgets/cynthion-hardware/blob/main/cynthion.kicad_sch) (KiCad)
- pcb: [PCB layout (cynthion.kicad_pcb)](https://github.com/greatscottgadgets/cynthion-hardware/blob/main/cynthion.kicad_pcb) (KiCad)

### Source repositories

- [greatscottgadgets/cynthion-hardware](https://github.com/greatscottgadgets/cynthion-hardware) — hardware, CERN-OHL-P-2.0, ★113
- [greatscottgadgets/cynthion](https://github.com/greatscottgadgets/cynthion) — firmware, BSD-3-Clause, ★199
- [greatscottgadgets/luna](https://github.com/greatscottgadgets/luna) — sdk, BSD-3-Clause, ★1140

### Key parts

| Part | Role | Datasheet |
|---|---|---|
| Lattice ECP5 (LFE5U-12F-6BG256C) | FPGA | https://www.latticesemi.com/Products/FPGAandCPLD/ECP5 |
| Microchip ATSAMD11D14A-M | debug/control MCU |  |
| Cypress/Infineon S27KS0641 | HyperRAM (working memory) |  |
| Microchip USB3343 | USB PHY |  |

_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.).

### Raw source files

Direct links an agent or KiCad can open (the viewer on the page reads the same files).

- KiCad project **Top-level schematic (cynthion.kicad_sch)** (greatscottgadgets/cynthion-hardware): [cynthion.kicad_pro](https://raw.githubusercontent.com/greatscottgadgets/cynthion-hardware/main/cynthion.kicad_pro), [aux_port.kicad_sch](https://raw.githubusercontent.com/greatscottgadgets/cynthion-hardware/main/aux_port.kicad_sch), [bank0_1.kicad_sch](https://raw.githubusercontent.com/greatscottgadgets/cynthion-hardware/main/bank0_1.kicad_sch), [bank2_3.kicad_sch](https://raw.githubusercontent.com/greatscottgadgets/cynthion-hardware/main/bank2_3.kicad_sch), [bank6_7.kicad_sch](https://raw.githubusercontent.com/greatscottgadgets/cynthion-hardware/main/bank6_7.kicad_sch), [bank8_configuration.kicad_sch](https://raw.githubusercontent.com/greatscottgadgets/cynthion-hardware/main/bank8_configuration.kicad_sch), [clock_misc.kicad_sch](https://raw.githubusercontent.com/greatscottgadgets/cynthion-hardware/main/clock_misc.kicad_sch), [control_port.kicad_sch](https://raw.githubusercontent.com/greatscottgadgets/cynthion-hardware/main/control_port.kicad_sch), [cynthion.kicad_sch](https://raw.githubusercontent.com/greatscottgadgets/cynthion-hardware/main/cynthion.kicad_sch), [debugger.kicad_sch](https://raw.githubusercontent.com/greatscottgadgets/cynthion-hardware/main/debugger.kicad_sch), [expansion.kicad_sch](https://raw.githubusercontent.com/greatscottgadgets/cynthion-hardware/main/expansion.kicad_sch), [indicators_buttons.kicad_sch](https://raw.githubusercontent.com/greatscottgadgets/cynthion-hardware/main/indicators_buttons.kicad_sch), [power_distribution.kicad_sch](https://raw.githubusercontent.com/greatscottgadgets/cynthion-hardware/main/power_distribution.kicad_sch), [power_supplies.kicad_sch](https://raw.githubusercontent.com/greatscottgadgets/cynthion-hardware/main/power_supplies.kicad_sch), [ram.kicad_sch](https://raw.githubusercontent.com/greatscottgadgets/cynthion-hardware/main/ram.kicad_sch), [target_port.kicad_sch](https://raw.githubusercontent.com/greatscottgadgets/cynthion-hardware/main/target_port.kicad_sch), [type_c.kicad_sch](https://raw.githubusercontent.com/greatscottgadgets/cynthion-hardware/main/type_c.kicad_sch), [usb_phy.kicad_sch](https://raw.githubusercontent.com/greatscottgadgets/cynthion-hardware/main/usb_phy.kicad_sch), [cynthion.kicad_pcb](https://raw.githubusercontent.com/greatscottgadgets/cynthion-hardware/main/cynthion.kicad_pcb)

## 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. |

## Documentation

- [Official Cynthion product](https://greatscottgadgets.com/cynthion/)
- [Enclosed purchase option](https://www.crowdsupply.com/great-scott-gadgets/cynthion)
- [r1.4.0 production design files](https://github.com/greatscottgadgets/cynthion-hardware/releases/tag/r1.4.0)
- [Host installation and updates](https://cynthion.readthedocs.io/en/latest/getting_started.html)
- [Analyzer configuration](https://cynthion.readthedocs.io/en/latest/getting_started_packetry.html)
- [USB keyboard capture tutorial](https://cynthion.readthedocs.io/en/latest/tutorials/usb_analysis.html)
- [Ports and expansion](https://cynthion.readthedocs.io/en/latest/hardware/device_overview.html)
- [Electrical and cable limits](https://cynthion.readthedocs.io/en/latest/support/safety_information.html)
- [Packetry installation](https://packetry.readthedocs.io/en/latest/quick_start.html)
- [Maker statement on excluded cables](https://www.crowdsupply.com/great-scott-gadgets/cynthion/updates/cynthion-is-at-mouser)
- [Hardware source and license](https://github.com/greatscottgadgets/cynthion-hardware)
- [Cynthion/LUNA scope explanation](https://greatscottgadgets.com/2023/02-15-renaming-luna-hardware-to-cynthion/)

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Source: gadgets.sh · https://gadgets.sh/devices/great-scott-gadgets-cynthion/ · JSON: https://gadgets.sh/api/v1/devices/great-scott-gadgets-cynthion.json