draft: false
Name: stretchcore
short-description: Mono sample-loop player with tempo control, timestretch, position jumps, and browser-based sample loading
summary: |
  stretchcore plays uploaded mono sample loops with internal or external tempo control,
  granular timestretch, position jumps, sample selection, and two independent slow random
  CV outputs. Its Web Serial sample manager can preview, crop, read back, and replace the
  sample bank without reflashing the firmware.
Language: C++ (Pico SDK + ComputerCard)
Creator: Infinite Digits
Version: "1.0"
Status: Released
License: MIT
Editor: https://infinitedigits.co/stretchcore/
date-created: 2026-06-02
date-updated: 2026-07-02
demo-link: https://www.youtube.com/watch?v=2qQBaFxhDwc

contact:
  email: zack@infinitedigits.co

tags:
  - sampler
  - looper
  - timestretch
  - web-serial

panel:
  inputs:
    - id: CVIn1
      name: Timestretch Mod
      description: Adds bipolar modulation to the Main knob's timestretch amount when patched
      type: cv
    - id: CVIn2
      name: Position Offset
      description: Adds a bipolar offset to the Y position when Pulse In 2 triggers a jump
      type: cv
    - id: PulseIn1
      name: External Tempo Clock
      description: Two-pulses-per-quarter-note tempo clock; overrides the X knob while active
      type: pulse
    - id: PulseIn2
      name: Jump Trigger
      description: Jumps playback to the Y position, offset by CV In 2 when patched
      type: pulse
  outputs:
    - id: AudioOut1
      name: Loop Output 1
      description: Mono playback of the selected sample loop
      type: audio
    - id: AudioOut2
      name: Loop Output 2
      description: Duplicate mono playback of the selected sample loop
      type: audio
    - id: CVOut1
      name: Random CV 1
      description: Smooth slow bipolar random modulation output
      type: cv
    - id: CVOut2
      name: Random CV 2
      description: Independent smooth slow bipolar random modulation output
      type: cv
    - id: PulseOut1
      name: Jump Pulse
      description: 20 ms trigger emitted when the switch is moved down to jump playback
      type: pulse
    - id: PulseOut2
      name: Select Pulse
      description: 20 ms trigger emitted when the switch is moved up to select a sample
      type: pulse

controls:
  switch:
    up:
      name: Select Sample
      description: Selects a sample according to the Y knob position and fires Pulse Out 2
    middle:
      name: Loop Playback
      description: Normal playback; Main controls timestretch, X controls internal tempo, and Y sets the next jump position
    down:
      name: Jump Position
      description: Jumps playback to the position selected by Y and fires Pulse Out 1
  knobs:
    - main:
        name: Timestretch
        description: Sets the timestretch amount; CV In 1 adds bipolar modulation when patched
      x:
        name: Internal Tempo
        description: Sets playback tempo from 100 to 200 BPM when no external clock is active
    - when: { z: middle }
      y:
        name: Jump Position
        description: Sets the position used by the next switch-down or Pulse In 2 jump
    - when: { z: up }
      y:
        name: Sample Select
        description: Selects one of the uploaded samples according to knob position
    - when: { z: down }
      y:
        name: Jump Position
        description: Selects the loop position to jump to

  # certainty: low — README documents overall feedback; per-LED roles are inferred from update_leds() in src/main.cpp
  leds:
    - display: list
      items:
        - id: LED0
          name: Playhead / Clock Edge
          description: First playhead segment in free-run mode; remains lit as the left edge marker with external clock
        - id: LED1
          name: Playhead Segment 2
          description: Playhead segment in free-run mode; first inner position segment with external clock
        - id: LED2
          name: Playhead Segment 3
          description: Playhead segment in free-run mode; second inner position segment with external clock
        - id: LED3
          name: Playhead Segment 4
          description: Playhead segment in free-run mode; third inner position segment with external clock
        - id: LED4
          name: Playhead Segment 5
          description: Playhead segment in free-run mode; fourth inner position segment with external clock
        - id: LED5
          name: Playhead / Clock Edge
          description: Final playhead segment in free-run mode; remains lit as the right edge marker with external clock

host:
  usb:
    - name: stretchcore Sample Manager
      role: editor
      description: Browser loader for previewing, cropping, reading back, and uploading sample banks over Web Serial
  notes: |
    The firmware exposes its sample manager over USB serial. Sample banks contain up to
    64 mono samples stored in flash as 48 kHz signed 8-bit PCM.