STM32 Development Info

MCU Info

  • The STM32 board that we are currently evaluating is the Nucleo-F413ZH.
  • The target STM32 variant used in our PCBs is the STM32G473CE.
  • The STM32G473CE was chosen for its 3 built-in CAN 2.0B controllers and its small pin count package size (48 pins).
  • There are many other variants in the STM32 family; if needed, low power or dual core versions of the STM32 such as the STM32H745 could also be considered.

RTOS Info

  • A real-time operating system (RTOS) is currently being considered to allow for better modularity and multiple task scheduling.
  • The RTOS currently being considered is Mbed OS.
    • Open source
    • Many built-in libraries (especially for connectivity)
    • Developed and backed by ARM
    • Many options for toolchains/development environments
    • Code written for Mbed can be run on a large number of supported ARM hardware

Development Environment

Software

  • PlatformIO Extension for Visual Studio Code (reccommended)
  • PlatformIO Core/CLI if not using VSCode (NOT recommended)
    • Required for base installation. Using the CLI tool by itself is NOT recommended, as it will be installed by the PlatformIO VSCode Extension.
    • On MacOS, this can simply be installed using the “platformio” package available in Homebrew.
    • On Arch Linux, this can simply be installed using the PlatformIO AUR package.
    • For other platforms, please refer to this guide.

Configuration

  • Getting started with the IDE
    • Or, if you want to go the NOT reccommended route, getting started with the CLI
    • The platform for STM32 is ststm32.
    • The evaluation board is nucleo_f413zh.
    • The framework is mbed.
    • If using the RTOS features in the Mbed API, an extra build flag option should be specified in the platformio.ini file with a value of build_flags = -D PIO_FRAMEWORK_MBED_RTOS_PRESENT.
  • The default behavior for PlatformIO with Mbed OS is to recompile the entire RTOS every time a project is built with the PIO_FRAMEWORK_MBED_RTOS_PRESENT compiler flag. This can lead to extremely long build times.

Serial Terminal

During development, there will almost certainly be a need to use a serial terminal to view text output or do text input to the device. Several different methods can be used to access the serial terminal, depending on what computer is used:

  • On Linux, either GNU Screen or many other terminal emulators can be used.
    • The most straightforward one is GNU Screen, which can be installed from almost all repositories. The command to use it to access the terminal is screen /dev/ttyACM0 9600, where /dev/ttyACM0 and 9600 are the default device and baudrate and can be changed. To exit screen, use Ctrl-A \ or Ctrl-A and type :quit.
    • Another good option is picocom, which can be installed from most repositories, including Arch and Debian. To access the serial terminal, use picocom -b 9600 /dev/ttyACM0. Again, the settings can be changed from the defaults.
  • On MacOS, screen is also available, and is used similarly to the one in Linux. However, the device path will be different.
  • On Windows, the most popular option is PuTTY. On Linux and MacOS, the device path can be found using the command ls /dev/tty* before and after plugging in the STM32 board. The new device is the STM32. On Windows, the COM port used can be found using Device Manager in a similar manner. It will be listed in the “Ports (COM & LPT)” section.

Alternatively, the PlatformIO extension for VSCode has a built-in Serial Monitor that can be accessed from the blue toolbar on the bottom of the IDE. This link shows the toolbar and what each button does. Click on the 8th button from the left (Serial Monitor, looks like a plug) to open up the built-in Serial Terminal.

Helpful References

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