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Firmware Flashing System

3 posts · May 2026 – Aug 2026

What this trail covers

Ignition, a Temporal-powered system for flashing firmware onto devices at scale, has been further refined. The system manages distributed workflows for individual device flashing, handles device re-enumeration and retries, and provides detailed state tracking for each device. The latest iteration focuses on robust handling of USB re-enumeration issues, improved carrier-based workflow boundaries, and detailed per-badge lifecycle management with granular failure reporting. The system demonstrated the ability to coordinate the manufacturing and distribution of 2,000 custom hardware badges for a conference, involving complex supply chain management, hardware development, and firmware deployment.

All Temporal trails
  1. Ignition: Flashing 2,300 conference badges with TemporalThis post details the evolution of the Ignition firmware flashing system, specifically focusing on its application to flashing 2,300 conference badges. Key technical contributions include: robust handling of USB re-enumeration issues by recognizing QA firmware's behavior and dynamically rebuilding device identity post-reset; defining a carrier as a Workflow boundary (`FlashBadgesWorkflow`) with per-badge child Workflows (`BadgeFlashWorkflow`) to manage physical assembly lines; implementing a per-badge durable state machine with distinct phases (USB identity resolution, firmware flashing, boot verification, clock synchronization) and retry policies for each; resolving hardware-specific issues like incorrect filesystem offsets by parsing partition tables directly; using Activity heartbeats for progress reporting instead of large state payloads; and the architectural decision to run self-contained, local Temporal development servers on each flashing station for improved resilience and isolation.
  2. I built 2,000 badges for Replay and I’m not sure I’ve slept since DecemberThis post details the author's personal experience building 2,000 custom hardware badges for the Replay conference, leveraging generative AI (Claude, Codex) for firmware development in C. It highlights the challenges of scaling from a single prototype to mass production, including coordinating manufacturing in Shenzhen, managing PCB fabrication, and developing firmware for an ESP32-S3 microcontroller with various peripherals. The author emphasizes the role of AI in enabling them to undertake firmware development despite lacking prior experience, using extensive testing (Playwright, unit tests) to validate AI-generated code. The post also touches upon the inspiration from DEF CON badges and the generosity of Pimoroni in sharing their expertise. While not directly describing the Ignition system, it showcases a complex, large-scale hardware deployment orchestrated and managed using Temporal principles, demonstrating the platform's capability to handle intricate, multi-stage projects with external dependencies and physical product manufacturing.