
KONTINUUM
ShippedTap-tempo delay pedal with MIDI sync, flutter/wow modulation, and tempo divisions including dotted and triplet modes.
CTO at Keystone Musical Instruments. Sole engineer and technical decision-maker.
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
0.1s – 2.0s
Delay range
128
Presets
3 (MIDI / Tap / Free)
Timing modes
3 (1/4 / 1/8 / 1/16)
Tempo divisions
0% – 100%
Modulation depth
9
MIDI CCs
Overview
A hardware delay pedal built on the STM32H750 (ARM Cortex-M7, 480MHz) via Daisy Seed. Features tap tempo with MIDI clock sync, analog-modeled flutter and wow, and tempo divisions (dotted/triplet). 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
- 01Cross-platform DSP core — Same C++ delay algorithm compiles for both STM32H750 firmware (ARM) and VST3 plugin (x86_64/ARM64) without modification.
- 02Custom QSPI bootloader — Firmware exceeds 128KB internal flash, boots from 8MB QSPI. Python post-build script patches firmware header (size, CRC32, timestamp) at offset 0x400.
- 03APEX expression pedal learning — Runtime parameter mapping without recompilation. Users assign expression pedal to any parameter with custom min/max/inversion, saved to flash.
- 04Hardware-agnostic parameter smoothing — ParameterSmoother class provides audio-rate interpolation preventing zipper artifacts.