CV Input Signal Types #0 — About
Control Voltage (CV) is the universal language of Eurorack synthesizers. Every patch cable carries a voltage signal that controls some aspect of sound — pitch, volume, timbre, timing, or any other parameter a module exposes.
But not all CV signals are created equal. A trigger is fundamentally different from a pitch signal, and an audio-rate FM input demands entirely different hardware and firmware treatment than a slow macro-parameter knob.
This series catalogs 20 distinct CV input signal types encountered in Eurorack module design. Each entry covers the electrical characteristics, typical use cases, Eurorack examples, and — crucially — the hardware and firmware requirements for correctly receiving and processing the signal in a digital module.
The entries are organized from simple logical signals (triggers, gates, clocks) through pitch and modulation signals to specialized types like feedback CV and audio exciters. The hardware references are based on a design using an STM32G4 microcontroller with an ADS8866 external ADC, MCP6004 op-amps, and a PCM5102A DAC — the architecture of the fragesymo Eurorack module.
Whether you are designing your own Eurorack module or simply want to understand what happens inside the modules you already own, this reference should help you make informed decisions about input stage design, ADC routing, and firmware signal processing.