1 unstable release

0.2.0 Oct 23, 2019

#2108 in Embedded development


50K SLoC


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A debugging toolset and library for debugging ARM cores on a separate host.


The goal of this library is to provide a toolset to interact with a variety of embedded MCUs and debug probes. For starters, ARM cores will be supported through use of the CoreSight protocol. If there is high demand and more contributors, it is intended to add support for other architectures.

Similar projects like OpenOCD, PyOCD, Segger Toolset, ST Tooling, etc. exist. They all implement the GDB protocol and their own protocol on top of it to enable GDB to communicate with the debug probe. This is not standardized and also little bit unstable sometimes. For every tool the commands are different and so on.

This project gets rid of the GDB layer and provides a direct interface to the debug probe, which then enables other software, for example VisualStudio to use it's debug functionality.

What's more is that we can use CoreSight to its full extent. We can trace and modify memory as well as registers in real time.

The end goal is a complete library toolset to enable other tools to use the functionality of CoreSight.


  • The lib can connect to a DAPLink or an STLink and read and write memory.
  • It can read ROM tables and thus extract CoreSight component information.
  • It can download ELF binaries using standard ARM flash blobs.
  • Basic debugging (attach, reset, halt, step, show stacktrace, add breakpoint, halt on breakpoint) works.

Focus of the development is having a full implementation (CoreSight, Flashing, Debugging) working for the DAPLink and go from there.

Downloading a file

For downloading an ELF binary (standard cargo build output), you should use the cargo-flash utility. You can install it via cargo install cargo-flash and then use it via cargo flash or just use your own built cargo-flash. cargo flash is just an alias for cargo-flash.


Use cargo flash to build your binary and download the ELF binary to your target.

Full set of commands

You can pass some arguments you could pass to cargo build to configure your build target. Use cargo flash --help for a list of available commands.


If you do not pass a target via cargo flash --target <target-triplet> probe-rs will try to identify your target. If this doesn't succeed, please specify your target manually.


To demonstrate the functionality a small cli was written. Fire it up with

cargo run -p cli -- help

The help dialog should then tell you how to use the CLI.


  • v0.1.0
    • Basic flash downloader working with nRF51.
    • cargo-flash which can automatically build & flash the target elf file.
    • Docs
  • v0.2.0
    • Parse yaml (or anything else) config files for flash algorithm definitions, such that arbitrary chips can be added.
    • Modularize code to allow other cores than M0 and be able to dynamically load chip definitions.
    • Target autodetection.
    • M4 targets.
  • ...
    • Basic debugging for Cortex m0, m3, m4.
      • Stepping in
      • Halting
      • Breaking
      • Running
    • Basic VSCode plugin
      • Stepping in
      • Halting
      • Breaking
      • Running
      • Variable inspection
        • Structs
        • Enums
        • Basic types
      • Stackframes
    • Basic CLI
      • Stepping in
      • Halting
      • Breaking
      • Running
    • Semihosting.
    • Tracing.
    • SWD file support.


I need help!

Don't hesitate to file an issue, ask questions on matrix, or contact @Yatekii by e-mail.

How can I help?

Please have a look at the issues or open one if you feel that something is needed.

Any contibutions are very welcome!

Also have a look at CONTRIBUTING.md.


Licensed under either of


This crate contains code (the flash algorithms) that's highly based on the code of the pyOCD project. Some of this code might reside in the ocd::probe::flash module and is subject to the Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0) terms.


Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.


~1.5M SLoC