KUTTOR screenshot 1

KUTTOR

Shipped

Beat repeater and slice shaper pedal with 3 scale modes (Pulsar/Quasar/Magnetar), 10 pitch scales, and arpeggio generation.

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

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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

1–32
Slice divisions
10
Pitch scales
3 (Pulsar / Quasar / Magnetar)
Scale modes
3
Playback directions
128
Presets
9
MIDI CCs

Overview

A hardware slice shaper and beat repeater pedal built on the STM32H750 (ARM Cortex-M7, 480MHz) via Daisy Seed. Captures audio and plays back pitch-shifted slices with three scale application modes: PULSAR (global pitch transpose), QUASAR (tempo-synced arpeggio generator with 5 patterns), and MAGNETAR (random scatter for generative textures). 10 musical scales, slice divisions from 1 to 32. 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. 01Three scale application modes — PULSAR (global transpose), QUASAR (tempo-synced arpeggio with 5 patterns), and MAGNETAR (random scatter) from a single DSP engine.
  2. 02Real-time pitch shifting — Audio capture and pitch-shifted playback with 10 musical scales and slice divisions from 1 to 32, all at 96kHz.
  3. 03Cross-platform DSP core — Same C++ algorithm compiles for both STM32H750 firmware (ARM) and VST3 plugin (x86_64/ARM64) without modification.
  4. 04Custom QSPI bootloader — Firmware exceeds 128KB internal flash, boots from 8MB QSPI. OTA updates via USB MIDI SysEx.
  5. 05APEX expression pedal learning — Runtime parameter mapping without recompilation. Users assign expression pedal to any parameter with custom min/max/inversion, saved to flash.