Paper

ENF Technical Note 03

This technical note specifies a reference architecture for Embedded Neural Firmware (ENF)- a sealed, deterministic embedded intelligence stack designed for MCU-class devices operating without an operating system, cloud dependency, telemetry, or over-the-air updates. The architecture is structured across six layers: (1) a constrained hardware substrate (MCU-scale Flash/SRAM) with hierarchical power domains; (2) an energy-qualified execution model using analog threshold gating, supercapacitor buffering, and interrupt-free finite-state control; (3) firmware-sealed neural inference using statically compiled INT8 models with fixed memory layout, bounded latency, and no dynamic allocation; (4) a security and trust architecture anchored in PUF-derived identity and a ROM-sealed secure boot measurement chain; (5) deterministic safety and fallback behavior based on voltage gating, watchdog deadline enforcement, fail-dormant sink states, and cold-reset atomicity; and (6) a modular multi-node topology supporting deterministic interconnects (e.g., MBus/SPI-class buses) with ROM- encoded addressing, slot-timed signaling, passive reception, and provenance-bound messaging. The note emphasizes auditability, reproducibility, and attack-surface minimization through architectural finality, while explicitly acknowledging tradeoffs: reduced adaptability, no post-deployment patching, and strict task-bounded model scope.