Midi-to-CV

From the desk of Malte Steiner: 

"My favorite microcontrollers are from the STM32 ARM family, which offers a wide range of integrated peripherals. Recently, I developed a MIDI-to-CV converter for the DIY modular synthesizer system I have been working on over the past few years. It generates three control voltages (CVs) and several digital gate signals from incoming MIDI messages. 

The STM32 Nucleo board, pictured in the foreground, provides three independent DAC channels, so I didn't need any external converters for this design. The circuitry includes a standard 5-pin DIN MIDI input with an optocoupler providing galvanic isolation before the signal reaches the microcontroller's UART. This prevents ground loops, as recommended in the original MIDI specification. 

I developed the firmware using STM32CubeIDE. However, I'm also considering a more affordable variant based on the Seeed Studio XIAO SAMD21, using multiple MCP DAC chips connected via SPI. This would allow me to generate additional independent control voltages and control more synthesizer parameters."