PUMPBOY / PHYSICAL CARTRIDGE KIT
The factory.
On original hardware.
A separate Game Boy ROM, Pico adapter firmware, and browser companion. Your handheld creates and confirms the token; your computer handles the network and wallet.
Hardware prototype. Software and emulator checks have passed. Electrical timing, flash cartridge compatibility and real transactions still need testing with physical hardware. Start with practice mode.
What you need
- Original Game Boy (DMG) and a compatible flash cartridge for 128 KB MBC1 games (no save battery needed).
- Original Raspberry Pi Pico (RP2040), USB data cable, and a DMG link-cable breakout.
- A suitable 5 V/3.3 V logic interface: two signals into the Pico and one signal back to the Game Boy, plus common ground.
- Desktop Chrome or Edge with Web Serial. Phantom or Solflare is needed for live launches.
A retail Game Boy cartridge cannot simply be rewritten, and a passive USB cable or ordinary USB-UART adapter will not work.
Connect the hardware
Do not wire Game Boy signals directly to Pico GPIO. The Pico uses 3.3 V logic. Use proper level translation, verify the connector orientation, and power off both devices before wiring. An electronics builder should check the interface. This kit does not include a validated PCB design.
| Game Boy port signal | Translation | Pico |
|---|---|---|
| Pin 2 · SOUT | 5 V → 3.3 V | GP0 / physical pin 1 |
| Pin 3 · SIN | 3.3 V → 5 V | GP1 / physical pin 2 |
| Pin 5 · Clock | 5 V → 3.3 V | GP2 / physical pin 4 |
| Pin 6 · Ground | Common ground | GND / physical pin 3 |
Leave the Game Boy's power pin and pin 4 disconnected. The Game Boy supplies the serial clock. Cable data wires may cross; identify signals back to the console's port, not by wire color. See connector orientation and the full guide.
Your launch desk
Create token details and pixel artwork, connect a wallet, and review the launch from the cartridge. Select opens dev buy, creator/holder rewards, social links, description, slippage and priority-fee settings. Walking around the Zelda village is optional.
Your first physical launch
- Copy
pumpboy-link.gbto the flash cartridge using its manufacturer's instructions. - Hold the Pico's BOOTSEL button while connecting USB. Copy
pumpboy_link.uf2to the RPI-RP2 drive. This replaces its firmware; use a dedicated Pico. - Verify the translated wiring and power both devices. Open the USB companion, click Connect USB adapter, and choose the Pico.
- Wait several seconds for the link handshake. On the Game Boy, edit the token and logo, keep PRACTICE selected, then choose Review/Launch, press A for cost review, release A, and hold A to confirm.
- Confirm that PRACTICE COMPLETE appears on the real screen before trying live mode.
For live mode, configure upload or metadata credentials and RPC in Connection settings. Approve wallet signing on the computer. Keep the companion open while processing. The ROM-only cartridge does not save artwork across power-off; browser draft saving makes a local copy on the computer.
Recovery and limits
The prototype exchanges approximately 60 bytes per second to preserve the game loop; updates can lag several seconds. Reconnecting creates a new session and does not replay an old launch. If a cable disconnects after a transaction is sent, check its status on the computer before starting another launch.
Private keys and upload credentials stay off the cartridge and cable. The adapter is a byte transport; it does not hold a wallet.
Source, build instructions and the protocol specification are in the kit. For hardware details, see Raspberry Pi Pico documentation and Game Boy serial documentation.