README.md

Documentation Index

Open-source replacement firmware for the FNIRSI 2C53T handheld oscilloscope / multimeter / signal generator.

Start here: The project README is at the repo root. For the full RE archive, see reverse_engineering/.

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Top-Level

• Roadmap — What works, what's in progress, what's planned
• Button Manual — Physical button layout, navigation, emulator key bindings
• Hardware Test Protocol — First-flash and subsystem verification checklist

Design

Architecture, technical specs, and system design documents.

• Peripheral Map — Memory-mapped peripherals, GPIO assignments, interrupt vectors
• FFT Design — Windowing, amplitude scaling, spectrum display architecture
• FPGA Future Possibilities — Gowin GW1N-UV2 resources and enhancement opportunities
• ESP32 Coprocessor — ESP32 UART bridge for WiFi/BLE connectivity (future mod)
• Platform Architecture — HAL layer design, SDK vision
• Module API — Interface spec for self-contained modules
• Code Organization — Proposed codebase restructuring plan
• Resource Planning — RAM/flash budget, module hot-loading strategy
• Developer Experience — Multi-tier accessibility (end users, makers, developers)
• Logic Analyzer Add-On — FX2LP-based USB analyzer for 8-channel digital capture
• Custom Test Platform — Repurposing hardware as programmable test fixture

Ideas

Feature brainstorms, market research, and community feedback. These capture the vision for what the device could become.

• Feature Catalog and Industry Modules — Comprehensive feature wishlist organized by subsystem, plus trade-specific applications (automotive, HVAC, audio, ham radio, industrial, marine, and more)
• Gaps and Priorities — Original vs custom firmware comparison, implementation priority order
• Meter Ideas — Multimeter enhancements: calibration, measurement stacks, parasitic drain testing, fuse voltage drop method
• Project Ideas — Feasibility analysis for modifications and new features
• Accessories — Community-designed PCBs (RF bridge, SWR analyzer), 3D-printed panel replacement
• Landscape — Budget handheld oscilloscope market and FNIRSI product family
• Community Issues — 62 documented bugs/requests from EEVblog and forums

Reverse Engineering

RE methodology and analysis docs. The primary RE artifacts live in reverse_engineering/ — these are supplementary.

• Firmware Analysis — Binary structure, version history (V1.0.3-V1.2.0), size comparison
• Function Map — Named functions, variables, two-region string system
• RE Guide — Tools (Ghidra, binwalk), methodology, how to get started
• FreeRTOS Tasks — Task structure, flash base address offset analysis
• RTOS Analysis — FreeRTOS kernel identification via string signatures
• Reference Projects — pecostm32 FNIRSI hack, EEVblog, open-source tools

Quick Start

1. Build firmware: cd firmware && make (hardware) or make emu (emulator)
2. Flash (with bootloader): Settings > Firmware Update > make flash
3. Flash (first time / DFU): make flash-all (see README for EOPB0 setup)
4. Emulate: make renode (display-only) or make renode-interactive (with buttons)
5. Ghidra analysis: ghidraRun > Open ghidra_project/FNIRSI_2C53T
6. Read reverse_engineering/ARCHITECTURE.md for the hardware reference