Debugging support for ARM Cortex-M Microcontrollers with the following features:
- Highly configurable. See https://github.com/Marus/cortex-debug/blob/master/debug_attributes.md
- Support J-Link, OpenOCD GDB Server, STMicroelectronic's ST-LINK GDB server (no SWO support yet), pyOCD
- Initial support for the Black Magic Probe (This has not been as heavily tested; SWO can only be captured via a serial port)
- Partial support textane/stlink (st-util) GDB Servers (SWO can only be captured via a serial port)
- Multi-core and multi-session debugging. See https://github.com/Marus/cortex-debug/wiki/Multi-core-debugging
- Disassembly of source code available along with instruction level breakpoints and stepping. The actual disassembly window is provided and managed by VSCode. See https://github.com/Marus/cortex-debug/wiki/Disassembly-Debugging
- Cortex Core Register Viewer (integrated into Variables window since V1.2)
- In some cases the st-util GDB server can report incomplete/incorrect registers, so there may be some issues here.
- SWO Decoding - "console" text output and binary data (signed and unsigned 32-bit integers, Q16.16 fixed point integers, single precision floating point values)
- The registers that are part of the DWT, TPIU, and ITM debug components will automatically be configured and do not need to be set in firmware.
- Firmware may still need to enable the SWO output pin - as this part of the setup is microcontroller dependant.
- Decoding ETM data over the SWO pin is not currently supported.
- Live graphing of decoded ITM data.
- Support for Custom ITM Data Decoders:
- Semi-hosting Support. In the
TERMINAL tab, there will be a sub-window called
gdb-server. That terminal is bidirectional and is intended for semi-hosting. This applies to those gdb-servers that do their semi-hosting on their stdio.
- Support for SEGGER Real Time Trace (RTT) using OpenOCD and J-Link gdb-servers. All the features supported for SWO (text, binary, graphing) are also supported with RTT. See image above for console style output. SWO output also creates another section.
- Globals and Static scopes in the variables view
- Initial support for Rust code (most functionality is working; report any issues
- RTOS Thread Support in
CALL STACK window (J-Link, OpenOCD, pyOCD - RTOS supported depend on GDB server)
- As a general rule do not try to use stepping instructions before the scheduler of your RTOS has started - in many cases this tends to crash the GDB servers or leave it in an inconsistent state.
- Live Watch with supported GDB servers (tested with OpenOCD, J-Link, STLink so far - since V1.6)
- We have a set of extensions that this extension relies on for various frontend services (since V1.6)
Cortex-Debug uses a versioning system specified by Microsoft that allows distribution of pre-releases via the marketplace. You can enable (or disable) pre-releases within VSCode for this extension and you will automatically get new pre-releases. By default, pre-releases are disabled. We use pre-releases as allow testing of bug fixes and new features. They allow you participate during the formation of a feature of how an issue gets addressed. More info about pre-releases. To summarize, extensions use semantic versioning (SemVer) system which in simple terms is
major.minor.patch. With MS convention, if the
minor version is
odd, then it is a pre-release.
- ARM GCC Toolchain (https://developer.arm.com/open-source/gnu-toolchain/gnu-rm/downloads) - provides arm-none-eabi-gdb and related tools
- At least one of:
- J-Link Software Tools - provides the J-Link GDB Server for J-Link based debuggers (https://www.segger.com/downloads/jlink)
- OpenOCD - provides a GDB Server that can be used with a number of debuggers (http://openocd.org)
- NOTE: If a chip vendor ships it's own OpenOCD version, for sure use NOTHING but that
- NOTE: On macOS do not use the default version of OpenOCD provided by homebrew, this is not compatible with releases V0.2.4 and newer.
- NOTE: Some linux versions and Windows may also need a more up-to-date version of OpenOCD from the xPack releases.
- Texane's st-util GDB server - Only supports ST-Link Debug Probes (https://github.com/texane/stlink)
- ST-LINK GDB server - This server is packaged with the STM32CubeIDE which must be installed. The location of the STM32CubeIDE and related tools is automatically resolved but also can be overridden using configuration settings (
- pyOCD GDB Server - GDB server that supports the CMSIS-DAP debugger on a number of mbed boards (https://github.com/mbedmicro/pyOCD)
- Black Magic Probe
See https://github.com/Marus/cortex-debug/wiki for usage information. This needs some help from the community. See https://github.com/Marus/cortex-debug/blob/master/debug_attributes.md for a summary of all properties that are available in your
How to Build from sources
git clone https://github.com/Marus/cortex-debug.git
- Optionally switch to a branch:
git checkout <existing-branch-name>
npm run compile
- Open VSCode in the top folder and run the task
npm watch. This will compile the code and watch for any changes and auto compile. The first time, it may take a minute or so for it to watch the entire folder. You can see the output of
npm watch in the Terminal tab.
How to debug
The extension is split into two main parts.
- The front-end which is what you interact with mostly
- The backend called
debug adapter which interfaces between
vscode/front-end, and the
gdb-server. We just start the server and from then on the debug adapter only interacts with
gdb. All requests go to
gdb and the results are read back from
gdb's MI (machine interface)
If you want to debug both parts, in
launch.json use the
Extension + Debug Server configuration. It will launch a new window -- the
debuggee. In the
debuggee VSCode window, load a FW folder/workspace (VSCode remembers the last one) and add the following to
Now, launch a debug session and you wil be able to use the primary VSCode window to observe the Cortex-Debug extension
Parts of this extension are based upon Jan Jurzitza's (WebFreak) code-debug extension (https://github.com/WebFreak001/code-debug).
His project provided an excellent base for GDB MI parsing and interaction.