The Arduboy MSX Cartridge is a DIY project that puts Arduboy-compatible electronics in an MSX cartridge assembly. An MSX joystick can control games running on the Arduboy hardware, and a separate I2C connection lets MSX software exchange data with it. Asuka Kuroda documented the design on Hackster.io on June 30, 2021; it is a build project, not a verified off-the-shelf cartridge.
What the Arduboy MSX Cartridge does
The cartridge combines an Arduino Pro Micro based on the ATmega32U4 with an SSD1306 SPI OLED. Kuroda selected those components to support existing Arduboy-compiled games. The assembly does not have its own game buttons: instead, an MSX joystick supplies directional input and two action-button states.
The MSX runs software that reads the joystick and writes six button bits to an I/O port. Decoder and logic chips in the cartridge translate those bits into simulated button presses at the Arduino’s Arduboy inputs. The MSX is therefore part of the control path; this is not simply a display or joystick adapter that works without software on the host.
How the I2C connection works
A second interface uses a PCF8584 controller to bridge the MSX 8-bit I/O bus to I2C. In the documented setup, the MSX acts as the I2C master and the Arduboy as the slave. Kuroda’s example sends text from the MSX to the OLED and returns a coordinate value from the Arduboy to the MSX.
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Joystick control and I2C are distinct features. The project says ordinary joystick input does not require changes to an Arduboy game. For I2C communication, however, the Arduino sketch must enable the I2C pins because the Arduboy2 library disables them during its normal setup.
Parts and tools in the documented build
The project’s bill of materials and tool list includes the following. This is a component inventory, not a guarantee that any particular substitute or board revision will fit or behave identically.
Hardware
- Arduino Pro Micro (an Arduino Micro clone using the ATmega32U4)
- SSD1306 SPI OLED
- MSX cartridge prototyping board with a 50-pin edge connector
- Small breadboards
- PCF8584 DIP-20 I2C-to-8-bit-bus controller and a 3 MHz oscillator
- 74LS682 address decoder, 74LS32, and 74LS05 open-collector logic chip
- GAL16V8 programmable logic and a DIP switch for selecting the MSX I/O port address
- Reset button (listed by the project as unnecessary with an Arduino Micro)
- Buzzer, ceramic and electrolytic capacitors, and I2C pull-up resistors
Software and equipment
- Arduino IDE for the Arduboy-side sketches
- Fusion-C v1.2 for MSX and SDCC
- WinCupl 5.30.4 and a GAL programmer
- Fritzing for the schematic, plus an MSX computer
The project documentation provides a Fritzing schematic/file and code for the Arduboy demo, GAL, joystick control, and I2C demo. The MSX cartridge slot is a standard expansion connector with a 50-pin pinout, but host machines can vary; the existence of a standard slot does not establish that this particular assembly works on every MSX model.
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- ✅Compliation Collection: 520 or 468 genre-diverse games with save progress functionality. Includes a protective case.
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Using the cartridge for a game
- Flash the Arduboy game to the Pro Micro using a normal Arduboy flashing method.
- With the MSX powered off, insert the cartridge.
- Start the MSX and run the supplied joystick program from MSX-DOS.
- Connect and use a joystick in MSX port 1.
For the I2C demonstration, flash the supplied Arduboy demo sketch and run the corresponding MSX demo instead. The project’s instructions specifically say to switch off the MSX when flashing a new game.
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Compatibility and practical caveats
Game compatibility is an aim, not a universal test result
Kuroda writes, “There is no Arduboy code change necessary to make the joystick control work, so all Arduboy games should work.” That is the author’s compatibility claim based on the chosen hardware and unchanged joystick input path. The published material does not establish testing across every compiled Arduboy game or every MSX host model, so treat broad compatibility as an intention rather than a guarantee.
Startup input states can affect the display
The author reports that some inputs may register as pressed at power-up, producing an all-white OLED. Running the joystick program can clear the states; the suggested next step is to reset the Arduino.
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- 3 IN 1 TOY FOR KIDS – LEGO Creator 3 in 1 Retro Gaming Console (31380) building toy lets boys and girls ages 8 years old and up construct 3 gaming toys from 1 set of LEGO bricks
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Pro Micro power depends on the board
The build may power a clone Pro Micro from the MSX slot’s 12 V supply through the board’s RAW input, but Kuroda warns that this depends on the quality of the clone’s regulator. The documentation does not establish that every Pro Micro clone can safely handle that arrangement.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How it differs from official Arduboy hardware
Arduboy’s official FX-C is a separate handheld product: its specifications list an ATmega32u4, 128×64 monochrome OLED, 16 MB external flash, six buttons, USB-C, I2C link support, and more than 300 included games. Arduboy Jr is described as a DIY development board with an ATmega32u4, external flash, and broken-out GPIO; a compatible 128×64 OLED and six buttons are needed to make it a complete game system. Neither product is the MSX cartridge or evidence that the cartridge design is compatible with it.
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The practical distinction is purpose. The MSX project integrates Arduboy-style play with an MSX joystick and MSX-to-Arduboy data exchange, at the cost of sourcing components, assembling electronics, programming logic, and having an MSX host. The official devices are useful ecosystem comparisons, not substitutes for that MSX integration.
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