Gameboy camera printer shield

Game Boy Camera Reader + Pocket Printer Shield

An Arduino Uno R4 WiFi shield (KiCad project) for dumping DMG/GBC cartridges — especially the Game Boy Camera — and printing to the Game Boy Pocket Printer.

With an Arduino Uno R4 WiFi (5V logic, RA4M1) this shield lets you:

• Read the ROM header of DMG/GBC cartridges
• Dump the Game Boy Camera's SRAM (128 KB of photos) to a .sav file
• Print images to the Pocket Printer over the link cable

Key design points:

• Everything runs at 5V, so no level shifters are required
• The 16-bit address bus is driven by two cascaded 74HC595 shift registers; the 8-bit data bus connects directly to GPIO
• PHI (cartridge pin 2) control is mandatory for the Game Boy Camera (Low for ROM access / High for RAM access). Regular cartridges ignore pin 2, so they can be read with the same setup
• The Pocket Printer is driven over the 3 link-cable lines (SCK/SOUT/SIN) with bit-banged SPI mode 3

Repository Contents

Required Libraries

Opening the schematic/PCB requires these external KiCad libraries in addition to the bundled Arduino_MountingHole.pretty:

• Gekkio/gekkio-kicad-libs — Game Boy related symbols and footprints (cartridge connector, link port)
• willdurand/kicad-libs — Arduino Uno shield symbols and footprints

Clone them and register the symbol/footprint libraries in KiCad (Preferences → Manage Symbol/Footprint Libraries) before opening the project.

Bill of Materials

No level shifters or crystal oscillator needed — PHI is just toggled statically Low/High from a GPIO; no clock generation is required.

Arduino Pin Assignment

Wiring

1. 74HC595 ×2 (fixed pins)

2. Address lines (595 outputs → cartridge)

595 outputs: Q0 = pin 15, Q1–Q7 = pins 1–7.

(Bit order: Q0 = LSB. Sending the high byte first, then the low byte over SPI puts the low byte in U1 and the high byte in U2.)

3. Data, control, and power (Arduino ↔ cartridge)

4. Capacitor placement (decoupling / bulk)

Rule of thumb: 0.1 µF right at each IC's power pins, plus one 10 µF on the power rail.

Keep the 0.1 µF caps as close as possible to the IC/connector pins — long leads defeat the purpose. The circuit will work without them, but they provide noise margin and dump stability.

Pocket Printer (link cable, printer-side connector)

The Arduino acts as clock master and bit-bangs SPI mode 3 (SCK idles High, data updated on the falling edge, sampled on the rising edge, MSB first) at ~8 kHz.

Bus Control Logic

• Idle state: /RD, /WR, /CS = High.
• PHI: High when accessing the RAM region (0xA000–0xBFFF), Low otherwise (ROM/registers). Without this the Game Boy Camera's ROM returns high-Z garbage and its RAM is inaccessible. Regular cartridges ignore pin 2.

SRAM (Photo) Dump Procedure

1. Write 0x0A to 0x0000 (enable RAM)
2. Write bank number 0x00–0x0F to 0x4000 (select RAM bank)
3. With PHI = High, read 0xA000–0xBFFF
4. Repeat for all 16 banks → 128 KB
5. Write 0x00 to 0x0000 (disable RAM)

Concatenate the hex dump on a PC and convert it with bytes.fromhex() into a 131,072-byte .sav file. Photos can then be extracted with a GB Camera save viewer or an emulator.

Fabrication

Ready-to-order files for JLCPCB are in jlcpcb/production_files/ (Gerber zip, BOM, and CPL for SMT assembly).

License

This project is licensed under CC BY-SA 4.0.

The parts derived from the external libraries listed in Required Libraries (Gekkio/gekkio-kicad-libs and willdurand/kicad-libs) remain subject to their respective licenses.