Windows Quick Start

Installing the required software

Miosix Toolchain

To be able to compile the Miosix kernel and your application, you need a patched version of the GCC compiler called Miosix toolchain, you can find the link to download it here. At the end of the installation you will need to reboot your computer (sorry, it's Windows...)

Git

To download the Miosix kernel and keep it up to date, you need the git version control system.

It is recommended to install it from git-scm.com. Please do not uncheck the Windows Explorer integration feature during the installation, as you will need it to install the kernel sources.

Perl

The Perl programming language is used by the Miosix build system. Unlike on GNU/Linux computers where Perl is pre-installed, for Windows you'll need to install it separately.

Strawberry perl is the recomended Perl version for Miosix on Windows.

Flashing tool

With the installed Miosix toolchain you'll be able to compile the kernel, but you'll also need a way to transfer it to your microcontroller. This operation is usually called 'flashing' the microcontroller. Miosix can work with any flashing utility that accepts as input raw binary files, and on Windows you'll usually want to install the flashing tool provided by your chip vendor.

For STM32 chips, you can use the STLink utility available here.

Text editor or IDE

It is recommended to download a better text editor than Notepad, as you will need it to edit the Miosix configuration files. Notepad++ is a good option, but many other options exist. Just don't use Notepad, because it does not recognize Unix line-endings and will show you Miosix source files as if they were composed of a single line of text.

As an alternative to Notepad++, you may want to use an IDE.

Serial port viewer

Miosix redirects stdin/stdout to a serial port by default on most boards, so to see the boot log and the output of printf() in your application you need a program to interact with the serial port. PuTTY is an option, although old fashioned. TODO: There are likely better options for Windows too.

Downloading and configuring the Miosix kernel

This section is a stripped down guide with the bare minimum to get you started, we also have a full guide about Miosix and git workflow. Following the tutorial in this page, your project directory will not be under version control (git). The Miosix and git workflow page shows how to create a git repository for your project and add the Miosix kernel as a git submodule.

Before downloading the kernel, however, you first have to create a directory for your project (in this case, the hello world), and then clone the kernel as a subdirectory.

Using the Windows explorer, create a hello directory, double click on it. Then right-click on the empty directory. Select Git bash to open a git shell. This opens a shell where you can type the commands to download the kernel.

Note that it is possible to paste commands in the shell (so as to avoid typing them, which can be tedious and lead to typos), but you have to do it one line of text at a time, and to paste you need to use the Shift+Ins shortcut, not the usual Ctrl+V one. The last command, exit, will close the shell.

git clone https://github.com/fedetft/miosix-kernel.git
exit

Note that there is also a Git GUI in the right click menu, but git is best used from a command line interface, you're on your own if you choose to use git from the GUI.

Initializing a Miosix project

For reasons explained in depth in the Miosix and git workflow page, you'll need to copy the Miosix configuration directory from the kernel sources to your project directory, as well as create a template project where you can start writing code. This can be automated with a Perl script called init_project_out_of_git_tree.pl. To run it, you need to open a Windows terminal (which is a different terminal than the git bash we used before), which can be done by Shift+Right click and selecting Open command window here:

Then, type the following command:

perl miosix-kernel/tools/init_project_out_of_git_tree.pl

Leave the terminal open as you'll need it later.

You should run the script from the directory where you want to initialize your empty project, such as the hello directory in this tutorial. A successful run of the script produces the following output:

Successfully created Miosix project
Target directory: hello
Kernel directory: hello/miosix-kernel/miosix

Your project directory should now look like the following picture, with the miosix-kernel directory containing the kernel sources, the config directory with the kernel configuration, the empty main.cpp and the build files for the two alternative build systems supported by Miosix: Makefile and CMake:

For this tutorial, we'll use the Makefile build system, have a look at the CMake page to learn how to use CMake instead.

Configuring the kernel

The minimum configuration required to compile the kernel is to select a board, as the kernel needs to build the appropriate board support package for it.

The Miosix kernel has several other build-time configuration options, to enable optional components (filesystem, userspace processes), select algorithms such as the scheduler and trade feature support for code size, but these won't be covered here. The kernel is configured by editing files in the config directory, the two most important ones are Makefile.inc and miosix_settings.h.

To select a board, using Notepad++ open the first one, config/Makefile.inc. Look for the OPT_BOARD section of the file, which contains the list of boards officially supported by the kernel. In this section, all boards appear commented out (the # sign is a comment in Makefile syntax), so you need to uncomment the line corrsponding to your board. Porting the kernel to a new board is an advanced topic not covered here, so we'll assume you'll want to use an officially supported board. As an example, in this tutorial we'll use the stm32f746zg_nucleo board:

...
#OPT_BOARD := stm32f469ni_stm32f469i-disco
OPT_BOARD := stm32f746zg_nucleo
#OPT_BOARD := stm32f765ii_marco_ram_board
...

If you do not yet have a board, you can follow along and get to the compiled firmware anyway. If you're looking for suggestions on which board to get, consider that most boards currently supported by Miosix are for STM32 microcontrollers. Here's a basic guide:

• Nucleo STM32 boards produced by ST are good for beginners, as they allow to power the board, flash it, debug it and access the serial port all through a single USB connection with your computer. The stm32f401re_nucleo and stm32f411re_nucleo are realtively low cost.
• Discovery STM32 boards are also good, but they don't include an USB to serial adapter so you'll have to buy it separately and you'll end up having to connect two USB cables, one for power/programming/debugging and one for the serial port.
• Third party STM32 boards such as the stm32f411ce_blackpill are cheaper and great to embed in your hardware project, but you'll have to [solder] the pin header yourself, and you'll need to attach a separate USB to serial adapter, and if you want in-circuit debugging you'll need an STLink adapter, so you'll end up having to run up to three separate USB cables from your computer to the board for power/programming, serial port and debugging.
• Venturing outside of STM32, the RP2040 is a good choice. Also in this case, you'll need a separate USB to serial adapter and some soldering skills, though.

Writing your first Miosix program

Hello world

With Notepad++ open the main.cpp file with your IDE or text editor of choice, and replace its content with the following program:

#include <cstdio>
#include <thread>
#include <miosix.h>
#include <interfaces/bsp.h>

using namespace std;
using namespace miosix;

int main()
{
    for(;;)
    {
        iprintf("Hello world\n");
        ledOn();
        this_thread::sleep_for(500ms);
        ledOff();
        this_thread::sleep_for(500ms);
    }
}

At this point, it's good to have a quick walkthrough of this hello world program. Miosix is based on a Fluid kernel architecture: in a nutshell it's a kernel that supports writing applications both inside the kernel, and inside userspace programs. In this tutorial, we're using it as a unikernel. This means when power is applied to the board, the kernel will boot, and then start running the main() function you just wrote in kernelspace. This means you have both support for C/C++ standard libraries and unrestricted hardware access.

This main() function will print "Hello world" and blink an LED approximately every second. The printing is done with the iprintf() function. If you expected just printf() without the i, the reason is that Miosix uses the Newlib C standard library that provides both printf() and iprintf(), an optimized version that is smaller in code size but incapable of printing floating point numbers. So you can also use printf() if you wish, but this optimization is worth knowing from the start.

Sleeping to blink the LED is done with the sleep_for() function from the C++ standard library. Miosix supports other sleeping APIs, such as nanosleep() from POSIX, or Thread::sleep(), a native Miosix function. All these functions do the same thing: they tell the scheduler to stop the currently running thread, run some other thread, and resume execution after a given time interval. Miosix is a preemptive multithreading operating system, so you should get comfortable with the fact that the code you're writing lives in a thread and shares the CPU with other threads.

Many (but not all!) board support packages define the ledOn() and ledOff() functions to control one of the LED on the board. This should be true for all the boards that have at least one software-accessible LED. This is true for the stm32f746zg_nucleo board we selected, but if you selected a different board with no LEDs, then compiling will fail with an error related to ledOn() and ledOff(). You can comment out those two lines in this case, your hello world will only print to the serial port.

Compiling

In the same terminal you used to run Perl, type make to build the kernel.

make

If all goes well, the result should look like this.

Otherwise, compiler errors will appear in the shell. The number that appears under text in the make output is the size in bytes of your application plus the kernel. Don't worry about the 42KBytes code size, you're compiling with the default Miosix options, if you want you can play around with the options later to reduce the code size.

Flashing

The procedure to flash the microcontroller board on Windows depends on the vendor-provided flashing tool. They usually provide a GUI where you can load the .bin file and then connect to the board and flash it. For Miosix the file is named main.bin if you're not using processes, or image.bin if you are using processes. For this tutorial, look for main.bin in the hello directory.

If you correctly flashed the board, the LED will start blinking.

Accessing the serial port

The USB to serial port adapter will appear on Windows as a randomly numbered COM port. To figure out the right number, you'll have to open Devices from the control panel:

Today, on my computer, Windows decided to assign the STM32 board to COM3.

Next up, open PuTTY and configure it to open the right COM port. Starting from Miosix v3.00, all boards use by default a baud rate of 115200bit/s, so input 115200 in the Speed field:

Finally, click Open and you should see the serial port messages from the microcontroller. Since the board will be already running when you connect, you can press the RESET button on the board to reboot it and see the boot logs:

A note on uninstalling software

To uninstall the Miosix Toolchain, you can find the uninstaller in the start menu under Miosix Toolchain. Note that the other tools such as Git, Perl and the STLink utility have their own uninstallers.