ENGINE=granular (default) · src/engine/granular/ (~50 files: adapter granular_engine.{h,cpp} + DSP) · class GranularEngine

The original instrument and the default build: a two-deck granular looper/sampler with recording, overdub, feedback, a per-deck step sequencer, FX, and CV/MIDI. This is the largest engine; this page is an orientation. Deeper material lives in docs/architecture.md, docs/engine-layout.md, and the refactor-history docs.

Implementation, the DSP graph, and the file map live in docs/dev/granular-impl.md.

Modes (the routing/sequencer behavior the manual describes)

• Slice — playback and recording are synced to the clock.

• Reel / Drift — playback and recording are unsynced (free).

• When the sequencer is engaged, the clock drives playback in all modes.

These per-mode decisions live inside Deck; the engine forwards every transport tick to every deck and the deck's mode logic decides whether to act (see the transport-decoupling note below).

Transport

Granular Core subscribes to the platform transport (ITransport::set_on_tick) and fans each tick out to the decks / panner / modulators / metronome click (the Core::_on_transport_tick sink — the granular half of the old Driver, which was split into the platform Transport + this sink). It also reads is_key_sub_quarter() for sequencer arming. Tempo, tap, clock-source, key-interval, and clock-out are platform-owned (see README).

Controls

Granular is the engine the platform's knob/modifier grammar was designed around, so it uses the full surface (the modifier columns in the README routing table): the direct knobs (Size/Pos/Speed/Mix/Env), the Flux/Grit FX-pad layers, the Alt layer (Feedback, PolySlice, mod sync), and the tap-hold layer (Tempo, KeyInterval, ClickMix, Pan). Pads drive record / play / reverse / sequencer-arm / FX, and MIDI notes trigger pitched grains. The mode/route switches go through set_config.

For the exhaustive control reference, the device's user manual is the authority (see the project spotykach-manual notes); docs/architecture.md covers the platform/engine seam.

Persistence

Storage saves/loads loop audio and config.txt on the SD card via the engine's byte-range audio port (audio_data / audio_recorded_bytes / ...); Settings persists smaller settings. Granular advertises the tape-storage capability.