Gakken SX-150 Mk II - USB MIDI Mod
This project provides a standalone MIDI interface for the Gakken SX-150 synthesizer, and provides useable firmwares/sketches for the Arduino UNO r3 as well as the Leonardo or Pro Micro. The interface is simple to use: Simply plug the USB connector from your workstation to the MCU, and connect the remaining cables to your Gakken to provide CV.
As the interface itself is a fully class compliant USB MIDI device, the unit is fully standalone. No drivers are needed, and there is no client-side software to install or run- just plug and play! This interface has been successfully tested on macOS and iOS.
This project draws heavily from the work of:
- Initial inspiration and SPI code for the MCP4921: Controlling a Gakken SX-150 synth with Arduino (Mrbook.org)
- HIDuino, which provides hardware support for USB MIDI on Arduino UNO and Mega 2560
- The wonderful Arduino Midi Library
Also of note is the wonderful SendMIDI utility, which is very useful for debugging.
A great deal of background information on the SX-150, including schematics, can be found in
More information, including wiring schematics for the interface, setup/build instructions, and more are forthcoming. The project is functional and very near complete, but remains a work in progress at the moment.
See it in action:
- Gakken SX-150 MIDI Mod: Sound Demo
- Gakken SX-150 MIDI Mod: Sequencing and Control Demo
- Gakken SX-150 MIDI Mod: Pitch Bend Controls! (and effects)
Tuning is way out of whack! (I'll need to bust out the multimeter and fiddle around)seems fixed in the Pro Micro version!