iRM Embedded 2020

Embedded system development @ Illini RoboMaster

User Guide (Linux / Mac)

You can follow the instructions below to setup the necessary environments for building the source code and flashing the embedded chips.

Install ARM Toolchain

1. Go to the official download page for ARM Toolchain.

2. Download the pre-built toolchain according to your operating system.

3. Decompress it to some directory and find an absolute path to the bin directory.

   In my case: /Users/alvin/gcc-arm-none-eabi-9-2020-q2-update/bin.

4. For Linux / Mac users, add the following line (replace <path> with the actual binary path found in step 3) to ~/.bashrc for bash users or ~/.zshrc for zsh users.

   export PATH=<path>:$PATH

Compile Project

1. Go to your project root directory in a terminal.

2. Run the following command to build the entire project.

   mkdir build && cd build
   cmake -DCMAKE_BUILD_TYPE=Release ..
   make -j

   Change build type to Debug or RelWithDebInfo in order to debug with gdb. Note that Debug build could be much slower than the other two due to lack of compiler optimizations.

Flash Binary to Chip

1. Install stlink.

   1. For Mac users, brew install stlink could be a shortcut.
   2. For Linux users, either use prebuilt binaries, or build from source following their compile manual.

2. Flash one of the example programs by running make flash-<xxx> in the build/ directory created at compilation.

   e.g. make flash-example_buzzer -> and you shall hear some music (or noise)

User Guide (Windows + CLion)

TODO - waiting for the true master of Windows

Developer Guide

Use the following guide when making contributions to this repo.

Format Code

The continuous integration system will check the source code against Google C++ Style Guide. All codes are required to be formatted correctly before merging. There are several integrated build commands that can help you automatically format your changes.

Prerequisite: install clang-format (version 10 recommended)

• Windows users will need WSL and can follow the steps for Linux
• Linux users can simpliy install it using sudo apt install clang-format-10.
• Mac users need to download prebuilt binraies from here. For now, we CANNOT use version 11 or above.

With clang-format installed, you can run the following commands inside build to automatically format your changes.

1. make check-format: Check diff between current source and formatted source (without modifying any source file)
2. make format: Format all source files (Modifies file inplace)

Debug with gdb

To debug embedded systems on a host machine, we would need a remote gdb server. There are 2 choices for such server, with tradeoffs of their own.

• st-util

  This tool comes with stlink, but be aware that this is a thirdparty implementation and is not stable. The most recent release tested to be working is v1.5.1.

• OpenOCD

  This tool is much more stable but is slightly less intelligent in detecting ST-LINK version and it has not been updated since 2017. To install it,

  • brew install openocd for Mac users
  • sudo apt install openocd for Linux (Ubuntu) users

Follow the steps below to debug an executable

1. Launch a gdb server by either choice
   • st-util
   • openocd -f <project root>/debug/OpenOCD/st-link-v2-1.cfg
2. In a seperate terminal, cd into the build directory and run make debug-xxx (e.g. make debug-example_buzzer). This will open up a gdb session.
3. Run target extended-remote :<port> (or tar ext :<port> in short ) to connect to the gdb server.
   • For st-util, replace <port> with 4242.
   • For openocd, replace <port> with 3333.
4. Run load to flash the executable (Note that you can also run make here without exiting gdb to re-build the executable if you modified some source code).
5. Debug just like any regular gdb debugger: use commands like continue, run, break, watch, next, step the same way you will expect.