Adds the first board-less SEQUENTIAL gallery example (digital-ripple-counter-4bit):
four T flip-flops chained into a ripple counter, LEDs showing the binary count,
clocked by a slide switch. Impossible on the SPICE engine (no edge detection at
DC) - it runs on the digital gate engine.
Controller fix (found by testing the counter live): the controller rebuilt the
network on every change, which reset flip-flop state so a counter never counted.
Now the network is built once and KEPT ALIVE; a switch toggle applies
incrementally via setSwitch (preserving sequential state), and a rebuild happens
only on a structural change (components/wires). Correct for combinational AND
sequential circuits.
examples-digital.test.ts: flip-flop examples are digital-engine-only, so they are
exempt from the SPICE-mapping / has-a-gate / netlist checks (the "logic" check
now accepts a gate OR a flip-flop). digitalgate-engine-examples: a correctness
test clocks the real counter example and asserts it counts 1..15,0 in binary.
Verified live (?digitalgates default ON): the counter counts 0..6 on the canvas;
and the complex examples all work - comparator-4bit (A=B correct), decoder-3to8
(perfect one-hot x8), alu-slice-1bit (32 combos deterministic), multiplier-2x2
(3*3=9, 7 distinct products), adder-subtractor-4bit (5+3=8).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Board-less digital circuits (logic gates + switches + LEDs) run today as ngspice
analog B-sources, which is fragile for deep logic: a 4-bit ripple adder re-solves
but never lights its result LEDs live. This adds an event-driven digital motor
that reuses the multichip-bus settle kernel, so the same engine that boots a Z80
over a chip bus evaluates a gate network exactly and instantly.
Phases 0-2 (project/digital-gate-engine/), all behind ?digitalgates=on (default
OFF — flag off is byte-for-byte the old behaviour):
- digitalGateEngine.ts: buildDigitalNetwork(components, wires) does union-find
over the wires (merging pass-through resistors), identifies the rail/gnd from
the signal-generator, registers drivers (rail STRONG-1, gnd 0, pull resistors
PULL, slide-switch as a pass-gate) and event-driven gates (reusing the
LogicGateParts boolean semantics), settles on busKernel, and exposes
setSwitch / readLed / netOf. Tolerant of both the raw example `type` and the
store `metadataId`. Returns {ok:false} for any non-primitive, so mixed/analog
circuits stay entirely on ngspice.
- digitalGateController.ts + a SimulatorCanvas useEffect: when the flag is on and
the circuit is all-digital, rebuild from the store on switch-toggle / load
(rAF-coalesced) and paint the wokwi-led DOM. CircuitSimulationService.tick()
skips the SPICE solve for all-digital circuits when the flag is on, so the two
motors never fight over the LEDs.
Tests: digitalgate-kernel (22 — single gates -> half/full adder -> 4-bit
adder/subtractor -> exhaustive ADD 256 -> mux/decoder/comparator/parity/
multiplier) and digitalgate-engine-examples (6 — the real gallery data for
and/or/xor/not + the full adder/subtractor). Verified live: ?digitalgates=on
lights the adder's result LEDs that the SPICE path leaves dark. Full suite
2117 pass / 5 pre-existing unrelated fails.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
David Montero Crespo