KOSMOS screenshot 1

KOSMOS

Shipped

Multi-stage phaser pedal with deep modulation control, stereo output, and MIDI sync.

CTO at Keystone Musical Instruments. Sole engineer and technical decision-maker.

Company→

Tech Stack

MCU: STM32H750 (ARM Cortex-M7, 480MHz) via Daisy SeedMemory: 128KB Flash + 480KB SRAM + 64MB SDRAM + 8MB QSPI FlashAudio: 24-bit/96kHz stereo codec, DMA-managed buffersLanguages: C++, ARM assembly (VTOR/FPU setup)Build: GNU Make, ARM GCC toolchainLibraries: libDaisy, DaisySP, CMSIS-DSPI/O: 6 pots, 2 footswitches, 3 rotary switches, MIDI (5-pin DIN + USB), expression pedal, RGB LEDs

Stats

2–8 poles
Phaser stages
0.1Hz – 10Hz
LFO rate
100Hz – 2kHz
Center frequency
3 (Mono / Stereo / Wide)
Width modes
128
Presets
9
MIDI CCs

Overview

A hardware multi-stage phaser pedal built on the STM32H750 (ARM Cortex-M7, 480MHz) via Daisy Seed. Features configurable phaser stages with modulation depth, rate, and feedback control. 128 presets, expression pedal mapping via APEX mode, and configurable I/O modes (mono true bypass, mono-to-stereo, stereo buffered). 24-bit/96kHz stereo audio with custom QSPI bootloader for OTA firmware updates. Part of the Keystone Musical Instruments pedal line, launched January 2026.

Engineering Highlights

  1. 01Cross-platform DSP core — Same C++ phaser algorithm compiles for both STM32H750 firmware (ARM) and VST3 plugin (x86_64/ARM64) without modification.
  2. 02Custom QSPI bootloader — Firmware exceeds 128KB internal flash, boots from 8MB QSPI. OTA updates via USB MIDI SysEx.
  3. 03APEX expression pedal learning — Runtime parameter mapping without recompilation. Users assign expression pedal to any parameter with custom min/max/inversion, saved to flash.
  4. 04Hardware-agnostic parameter smoothing — ParameterSmoother class provides audio-rate interpolation preventing zipper artifacts.