Uf2 Decompiler
Many devices use UF2 for Over-The-Air (OTA) updates. If the extracted binary looks like noise (high entropy), the payload is likely encrypted or compressed (LZMA/Zlib).
When you ask for a "UF2 decompiler," you are actually asking for two distinct, sequential operations:
You can convert a .uf2 back to a .bin file.
If you do not know the source chip, check the original UF2 header magic numbers using a hex editor: : Family ID 0xe48bff56 ESP32 : Family ID 0x1c5f21b0 STM32F4 : Family ID 0x57755a57 uf2 decompiler
Use uf2conv.py (part of microsoft/uf2 or makerdiary/uf2utils) to convert the file.uf2 to file.bin . python3 uf2conv.py -u input.uf2 output.bin Use code with caution. Note: The -u flag instructs it to u npack the file.
In the modern world of microcontroller development, particularly with boards like the Raspberry Pi Pico (RP2040) or Adafruit Feather series, the file format has become a standard for drag-and-drop programming. While efficient for flashing, these .uf2 files are opaque containers, holding compiled machine code, not human-readable source code.
| Tool | Purpose | |------|---------| | uf2conv.py | Convert UF2 ↔ bin / hex | | arm-none-eabi-objdump | Disassemble ARM binary | | Ghidra | Decompiler to C‑like pseudocode | | radare2 / Cutter | Interactive disassembly + decompilation | | picotool | Inspect UF2 on RP2040 hardware | Many devices use UF2 for Over-The-Air (OTA) updates
arm-none-eabi-objdump -D -b binary -m armv6s-m binary.bin > assembly.s Use code with caution. 4. Alternative Tools and Resources
Here is the general workflow to reverse engineer a UF2 file:
Stripping the UF2 container wrappers to reconstruct the continuous raw binary image exactly as it sits in the microcontroller's memory. If you do not know the source chip,
Your UF2 file likely contains only your code plus fragments of the C standard library or Arduino core. It does not contain the source for printf() – only its compiled machine code. The decompiler will show the machine code of printf() , but not its original implementation.
Metadata indicating file properties, such as whether the block belongs to a specific family of microcontrollers (e.g., RP2040, ESP32, STM32).
Usually, the tool is used to convert bin-to-uf2. To reverse it, you typically use the Python utility logic or simply utilize the uf2conv.py script with the --convert flag (though this is often for bin->uf2).
Use a Python script (example with uf2utils or manual parsing). UF2 records have a 0x0B start marker; you strip the 512‑byte records and write raw data at specified addresses.
