greybadge25

GreyCTF 2025 Badge (Greymecha Army)

1. Instruction Manual
2. Slides for Badge Talk

Repository Structure

.
├── firmware
│   ├── circuitpython_frozen_leaky.uf2  # CircuitPython firmware to flash
│   ├── ecp5                            # FPGA-related files                   
│   └── rp2350
│       ├── art                         # Greycat animation files (thanks shuqing!)
│       ├── filesystem                  # Filesystem to copy into CircuitPython (includes challenges)
│       ├── solutions                   # Solution scripts
│       └── src_chall                   # Raw challenge files for reference
├── hardware
│   ├── artwork                         # Artwork used on the PCB (thanks shuqing!)
│   ├── fpga_placement.svg              # High level reference for how the FPGA pins were used
│   ├── greybadge_pcb                   # KICAD files
│   ├── JLCPCB.kicad_dru
│   └── kicad_libraries
└── README.md

To view the schematic, find the pcb/prototype3 release and get the schematic pdf from there

Firmware Set Up Guide

1. Connect the PCB to your computer. It will mount as a USB drive named RPI_RP2.
2. From the /firmware folder, drag & drop the file circuitpython_frozen_leaky.uf2 onto the RPI_RP2 drive.
3. This should restart the badge and it will appear as a new USB drive called CIRCUITPYTHON.
4. Open /firmware/rp2350/filesystem on your computer and copy everything inside that folder to the CIRCUITPYTHON drive.
5. Your badge is set up!

Hardware Ordering Guide

Refer to Prototype 3 Order under Releases.

Feel free to update the BOM to remove the oscillator for the FPGA as it is expensive and not strictly necessary.

Ordering on JLCPCB:

1. Upload the GERBER into the order page.
2. For the PCB Fab options, we recommend mostly using the defaults, but keep the following options in mind:
   • Finishing: HASL (HASL is fine, though we recommend ENIG for higher quantities as the extra cost scales well and is better for BGA soldering.)
   • To customize the main PCB colour, update the soldermask colour.
   • To have it assembled, tick the option below. You would likely want to choose to assemble both sides, which requires the standard assembly (not economic assembly).
3. Select the BOM/CPL if you chose to have it assembled.

There are several things you will need to order separately (and solder on).

1. Screen: Taobao Link, choose the 焊接12P option.
2. Battery: You can either use a LIPO with JST-PH connector or solder 3x AA batteries.
   • LiPo Battery: Taobao Link We chose the 603040-750mAh option. If you want to have the plug rather than soldering the battery, contact the seller to install the 2.0-2P 反向公插 header (2.0mm pitch, 2 pin, reverse-orientation), which is essentially JST-PH, on the battery.
   • AA Battery Holder: Taobao Link.
   • 90 Degree Pinout Headers (or just solder wires)

FPGA Tooling

A sample FPGA project is in /firmware/ecp5/uart_coprocessor. The tooling needed to be installed is as such

sudo apt install openFPGALoader # only needed if you use an external fpga jtag programmer
sudo apt install yosys
sudo apt install nextpnr-ecp5
sudo apt install fpga-trellis

Afterwards, you can just run make clean and make to generate the bitstream.

You can upload through the RP2350 in the hardware.fpga libraries