Embedded Rust Basics.

Programs are debugged using:

• dbg! or print! information to know the value of a variable.
• assert! expected values
• Write unit tests

To access these finer details, we can use a debugger.

Software needed

Two programs will be needed:

• GNU Debugger (gdb): inspect and stop the program as it runs.
  • Linux has gdb installed. On MacOS, install it with brew install gdb.
• OpenOCD (openocd): handles the communication with the board.

OpenOCD

Download the latest openocd for your laptop architecture from the openocd-esp32 github repo. The repo is a fork of openocd targetted at esp32 boards.

Important

Please, check the commands before executing them.

• For Linux amd-64:

  # Linux amd64. See releases page for other archs. 
  cd ${HOME} # go to home so we download in a visible place.
  OPENOCD_ZIP_NAME=openocd-esp32-linux-amd64-0.12.0-esp32-20250707.tar.gz
  DATE=v0.12.0-esp32-20250707
  wget https://github.com/espressif/openocd-esp32/releases/download/${DATE}/${OPENOCD_ZIP_NAME}
  tar -xvf ${OPENOCD_ZIP_NAME}
  

• For MacOS arm64:

  cd ${HOME}
  OPENOCD_ZIP_NAME=openocd-esp32-macos-arm64-0.12.0-esp32-20250707.tar.gz
  DATE=v0.12.0-esp32-20250707
  wget https://github.com/espressif/openocd-esp32/releases/download/${DATE}/${OPENOCD_ZIP_NAME}
  tar -xvf ${OPENOCD_ZIP_NAME}
  

Important

Below, it is assumed the output of the command above was a directory named openocd-esp32.

Modify the PATH

Let’s add a path to the PATH variable, by editing the .zshrc or .bashrc file.

Additionally, the OPENOCD_SCRIPTS variable is defined. openocd uses that variable to find the board’s configuration.

# add `openocd` to PATH
export PATH=${HOME}/openocd-esp32/bin:${PATH}
# Define openocd scripts/configs location.
export OPENOCD_SCRIPTS="${HOME}/openocd-esp32/share/openocd/scripts"

Then source the profile:

source ~/.bashrc # or ~/.zshrc

Then check it is installed with openocd --version. Now to some exercises.