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Foreword

You can refrain from downloading anything on the linked websites unless it is in the Installation section, we have set up a template package that already contains most of the libraries and it should be straightforward to get set up on the rest of the development environment. This guide is meant to help you understand the layout of the template and understand the toolchain required for developing embedded software for the solar car. It aims to be a comprehensive guide to getting you to the point where you can start developing as soon as you feel comfortable with the C paradigms for embedded programming. 

Prework

Before we get started if you have not yet done so, please read up on Software in particular, the Coding Standards! These will be necessary to actually do any development on the car. It is also recommended that you spend some time working with the MSP430 launchpads which were part of the architecture from the previous vehicle MSXI and will provide a good basis for getting started. 

Architecture and Libraries

The architecture we will be using on MSXII is the stm32f0xx variant of the ARM Cortex M0 MCU. This architecture is supported by both the CMSIS ARM Core M0 Library and STM Peripherals Library. Specific documentation for these libraries can be found on the Software Resources page of confluence. 

Supported Development Toolchain

  • Compiler: GCC ARM
    • A compiler builds human readable source code into a machine readable target language, usually a machine executable or binary for a specific architecture. GCC ARM compiles C code into machine readable .elf, .hex or .bin files which can be flashed onto the MCU. GCC ARM is the standard open source compiler for ARM architecture. Compilers are powerful and often catch typos, errors, and warnings; they also optimize code for efficiency or size. The compiler flags set these behaviors of the compiler.
  • Build Tools: GNU Make and GNU Linker aka ld
    • Build tools usually instruct the compiler on where the source files it is building are located and which files to look at in order to build the target program. Often a Linker will be used with a Makefile to build a collection of C and header files into a standard library which can be included in your program. GNU Make and Linker are long-standing open source standard build tools used by many developers, although many alternatives do exist.
  • Linter: cpplint (modified)
    • A linter is a program that checks the style of source code for errors. Some linters also perform static analysis, ours does not, which look to catch programming errors before the code is executed. cpplint is Google's open source linter for C/C++ programs, note that our Coding Standards closely follow Google's and as a result, this linter works well for us. The linter has been modified to support some slightly different standards and will be less pedantic.
  • Flasher: st-link/GDB or OpenOCD
    • A flasher will transfer firmware (our compiled program) onto the MCU. Typically, this is done with a special cable or by a chip on the PCB and requires flashing software to transfer the contents of the source code into the memory of the MCU. For our purposes, we will be using st-link with GDB for debug which is the chip manufacturer supported method or OpenOCD the open source version.
  • IDEs: Eclipse or any text editor (Core members like: Vim, Sublime Text and Visual Studio Code)
    • Anyone just starting out and especially those using Windows are strongly encouraged to use the Eclipse IDE which is one of the few ways to get a working Toolchain on a Windows machine. Note that we will not be supporting any issues you may encounter using other methods on Windows although, we will also support Linux if you want a VM or dual boot but you will need to figure out the install on your own. 
  • Source Control: GitHub
    • We use GitHub for our source and versioning control. In order to contribute to the codebase, you will also need to start using GitHub. If you are new to GitHub you may want to check out these guides. We have tight controls on out git repositories and require all commits to come from pull requests and that they are squashed prior to submitting. We are also now using Git Hooks, for now these will be run locally but web hooks may be enforced.

Installation

General Instructions:

Step 1: If you don't already have one, get a GitHub account!

Step 2: Join our GitHub organization uw-midsun

Step 3: Download Vagrant and Virtual Box

Step 4: Install the Vagrant image

Step 5: Start the Vagrant box

$ vagrant up

(this may take a while) and

$ vagrant ssh

into the box

Step 6: Change directory into the firmware folder 

$ cd ~/env/firmware

Step 7: Run make 

Optional: learn more bash shell commands if you want

Project Template

The package template contains seven directories, a Makefile, a linter and a README. Use this for starting new projects only. Existing projects will have their own repositories which will share a copy of libraries, linker, and extra. 

Linting

As mentioned linting checks to ensure code meets our style guides. A custom version of cpplint.py is included in the package template it has been altered to support our styleguide. Calder Kitagawa is the maintainer so if you think there is a bug or style violation it is too pedantic/permissive reach out and ask. A Git hook will prevent you from pushing any code with errors so lint often you don't want to rewrite a whole file just because you messed up on style! The Git Hook in the hooks directory should be copied into .git/hooks directory so that you auto-lint when you submit code.

$ make lint
OR
$ python2 lint.py <file(s)>

Running make lint executes cpplint on all files in src and inc. If you want to just lint specific files use python cpplint. Note the cpplint will accept wildcards in the file definitions.

Makefile

As mentioned, a Makefile tells the compiler what to build and where to find those items. This Makefile is no different, it automatically links and builds a file called main.elf and the STM Peripheral library (THIS LIBRAY FEATURES A HAL DO NOT USE IT WE ARE MAKING OUR OWN) which is located in the libraries directory. The libraries can be included without needing a relative path as can any header files you write and place in the inc directory. The linker directory contains the linker files to build the libraries. The extra folder contains configuration options for making an OpenOCD binary. Any program files you create should go in the src directory and any drivers should go into inc. The README will contain more detailed information and the Makefile does have options for selecting source files.

Usage (Linux and OSX)

$ make

Builds the package assuming it isn't built already or modified


$ make all

Same as make


$ make clean

Removes the .elf, .map and .bin files from the bin folder of the package


$ make reallyclean

In addition to doing what make clean does it also cleans the library from the /libraries driectory


$ make program

Builds the OpenOCD binary (may be broken right now)

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