Some UF2 images are not linear. They may have gaps for QSPI flash caches. The raw binary may be correct, but the decompiler sees jumps to addresses that have no code. Use binwalk -E to detect entropy and find real code sections.
[ UF2 File ] ---> ( Extraction Tool ) ---> [ Raw Binary / .bin ] ---> ( Decompiler ) ---> [ C-Like Pseudocode ] Step 1: Converting UF2 to Binary (.bin)
Most UF2-compatible chips utilize an architecture (Thumb-2 instruction set). Step 3: Loading the Binary into a Decompiler
: The official Microsoft utility. While primarily used to create UF2 files, it can be used to convert them back to binaries. uf2 decompiler
| Tool | Purpose | How to Get It | | :--- | :--- | :--- | | | Official conversion tool to extract binary from UF2 | Included in Microsoft's uf2 GitHub repository | | uf2l | Alternative Rust tool for packing/unpacking and flashing | GitHub ( cbiffle/uf2l ) | | uf2utils | Python library for inspecting and extracting UF2 contents | PyPI ( pip install uf2utils ) | | Ghidra | Powerful, free decompiler for analyzing the extracted binary | GitHub ( NationalSecurityAgency/ghidra ) | | IDA Pro | Industry-standard commercial disassembler/decompiler | hex-rays.com | | UF2-IDA-Loader | Loads UF2 files directly into IDA Pro | GitHub ( kjcolley7/UF2-IDA-Loader ) | | SVD Files | Provide register maps to enhance decompiler output | Find them in your MCU vendor's SDK or on GitHub |
Because the actual firmware code is fragmented across these 256-byte payloads, you cannot feed a raw .uf2 file directly into a decompiler. Doing so will corrupt the analysis, as the decompiler will attempt to interpret the UF2 headers as executable machine instructions. Step 1: Converting UF2 to Raw Binary (.bin)
What is the family? (e.g., RP2040, ESP32, SAMD21) Some UF2 images are not linear
Unlike an ELF file, a raw binary does not have an entry point header telling the decompiler where main() is. You must find it manually.
The first step in the decompilation process is stripping away the UF2 container. You can accomplish this using command-line utilities or Python scripts. Option A: Using the Official UF2 Utilities
You want to understand how a library works or identify security vulnerabilities in a firmware image. Use binwalk -E to detect entropy and find real code sections
And if you are a developer shipping UF2 files: A UF2 file is a great delivery mechanism, but a terrible archive format.
Debug symbols are usually stripped from final production UF2 files, making the assembly difficult to interpret.
The most standard tool for working with UF2 files is uf2conv.py , provided by Microsoft and often maintained in repositories like makerdiary/uf2utils . Step 1: Install Required Tools
For developers and power users who need programmatic control, uf2utils is a flexible Python library. It goes beyond simple conversion, offering features like: