AVR Development & Reverse Engineering

AVR is a family of microcontrollers developed by Atmel (now Microchip Technology). It is most famously known as the architecture powering the original Arduino boards (Uno, Nano, Mega).

Toolchain Setup

To compile and flash C/C++ code for AVR devices without the Arduino IDE, you need the standard GNU toolchain.

# Alpine Linux installation
apk add avr-gcc avr-libc avrdude

Basic Commands

• avr-gcc: The C compiler.
• avrdude: The utility for uploading code to the microcontroller's flash memory.
• avr-objdump: For inspecting compiled binaries or hex files.

  # Disassemble a hex file for ATmega328P (avr5 architecture)
  avr-objdump -j .sec1 -d -m avr5 foo.hex

Reverse Engineering Tools

When dealing with unknown AVR binaries, the following tools are useful for disassembly and decompilation.

Disassemblers

• • twinearthsoftware/AVRDisassembler
    • C#
    • A standalone AVR disassembler.
• ODA (Online Disassembler): A web-based tool for quick disassembly of various architectures.
  • ODA Home
  • ODA Web Interface

Decompilers

• Hex-Rays / IDA Pro: The industry standard for professional binary analysis; supports AVR with specific plugins.
  • Hex-Rays Official Site
• Ghidra: NSA's open-source reverse engineering suite, which has excellent support for AVR architectures.

Resources

• AVR Instruction Set Manual
• AVR Libc Documentation