Looking to enhance MIDI -> control voltage conversion for his x0xb0x synth/sequencer, Robin designed and built his own converter using Arduino and a 16-bit DAC chip –

Having looked around the Arduino forums I found a lot of people using the PWM outputs on the Arduino and just running them through a low pass RC filter to get a smooth variable DC voltage out. This has the benefit of being quick to make but the downside of non-linearity across the domain of the duty cycly and the range of voltage out and the small portamento this approach will neccessarily come with. Having decided against using the PWM out and having recently been introduced to the analog devices catalogue by an a electronics friend I decided to get hold of one of their AD5668 DAC chips and dive into the world of surface mount chips and SPI. I’m not claiming to be the first to hook up a DAC chip to the Arduino as there’s a fair amount of evidence people have taken the same approach when building their own cv boxes but the approach worked and I’m pretty pleased with the results.

Homebrew midi-cv box