m33mu

m33mu is an embedded microcontroller emulator for ARMv8-M Cortex-M33 targets. It is used to test, debug, and demonstrate firmware without any physical hardware.

It can run as:

• an interactive terminal UI with --tui
• a pure command-line emulator
• a tool inside automated tests and CI jobs

What It Does

• Emulates Cortex-M33 / ARMv8-M firmware with TrustZone awareness
• Runs firmware images directly from your host machine
• Supports debugging through a built-in GDB remote server
• Can load multiple images, including Secure and Non-secure firmware combinations
• Exposes UART, SPI flash, TPM, USB, Ethernet, and other target-specific peripherals

Documentation Index

• Getting started
• Supported CPUs
• Loading images
• Command-line usage
• CI and automated testing

Screenshots for TUI mode

m33mu TUI, stopped, stepping with GDB:

m33mu TUI, running in secure domain:

m33mu TUI, running in non-secure domain:

Reporting Issues

Please report issues to the GitHub issue tracker.

Include, if possible, a full capture using --capstone, a reproducer firmware image, and a clear explanation of how to reproduce the problem.

Copyright / License

Copyright (c) Daniele Lacamera 2025.

Released under AGPLv3. See LICENSE.