The Crumar DS2 is an old synthesizer which was used around the 1980s. It comes close to a Minimoog, with its own characteristics. It was very unstable at the time.

After more than 30 years this synthesizer was modified to be part of a modern Cubase setup. All internals were removed and instead of using its own (unstable) sound sources it now uses VSTs (Virtual Instruments) and controls them. This was accomplished by building a bridge between the Crumar and Cubase consisting of the following parts:

• Extensive hardware modification of the Crumar
• Arduino Mega 2560 microcontroller with extended inputs/outputs (over 100 I/Os)
• Arduino software for managing all knobs.
• PC USB software which acts as a bridge between Arduino and the Virtual Controller System.
• Crumar original hardware: Replaced the very unhandy joystick with a Steinberg CMC-FD which enables Pitch bend, modulation wheel, realtime control of all parameters. Moreover it is possible to select 4 VSTs and perform program changes.
• Web interface to show the settings of the CMC-FD.

In the design the Arduino part is dumb. It just serves as an interface between the PC and the hardware. The PC software controls the Arduino so that all calibration computations can be done on the Arduino, without knowing internals. This way, calibration (using some logarithm mathematics) can be performed easily from the PC.

Techniques Used:

• Arduino software written in C++.
• Arduino Serial (modified), SPI, I2C libraries
• PC Serial or LibusbK interfaces
• Midi based
• Design patterns like Model View Controller, Dependency Injection
• Webinterface build with NodeJS, Express, JQuery, Javascript, easyUI