KNXduino - KNX bus compatible DIY device based on STM32G071 MCU with Arduino flavour

Testing Boards

• DEPRECATED (will be replaced by STM32G0 Nucleo board): Nucleo-F303RE

  • Connections:
    • KNX RX voltage divider 33k:2k -> PB0 (COMP4_INP)
    • PB1 (COMP4_OUT) -> PA6 (TIM3_CH1)
    • PA7 (TIM3_CH2) -> TX MOSFET (shorting 68R to GND, 10k pull-down on gate)
    • KNX- <-> GND

• KNXduino One

  • Note: make sure to connect NRST along with SWO, SWD and GND to ST-LINK while using OpenOCD

Development Environment

Testing IDE: Visual Studio Code + Arduino plugin + Cortex-Debug plugin

or Arduino IDE 1.8.5.

Testing Arduino Core: Additional URL https://github.com/stm32duino/BoardManagerFiles/raw/master/STM32/package_stm_index.json version 1.6.1

"Blink via KNX" sketch currently compiles to approx. 28072 bytes of Flash (without bootloader, size-optimized, without hard-coded addresses, no EEPROM emulation thus not configurable at all yet). Sketch consumes approx. 4mA while powered from KNX bus without any power optimizations. Bootloader is currently approx. 9kB. Thus perfectly OK for 128kB devices.

Development Environment for Bootloader

Use Atollic TrueSTUDIO for STM32

Steps to compile application (sketch)

• Use KNXduino library
• Copy hardware folder to your sketches folder (eg. ~/Arduino)
• Select KNXdunino board, and KNXduino Nucleo F303RE with 32kB bootloader in your IDE (eg. vscode or Arduino IDE)
• Select U(S)ART support: Enable (no generic 'Serial')
• Optional: Select Optimize menu according to your preferences

Known issues in vscode

• Fix hardcoded arduinoPath path in .vscode/c_cpp_properties.json file
• ~~Fix hardcoded cortex-debug.openocdPath path in .vscode/settings.json file~~ build OpenOCD and install in PATH (see below)
• Fix hardcoded cortex-debug.armToolchainPath path in .vscode/settings.json file
• Fix hardcoded path to st_nucleo_g0.cfg in .vscode/launch.json file
• Arduino: Upload command does not work because of output option in .vscode/arduino.json file. Use Arduino: Verify followed by Debug: Continue (F5) instead.

Note on building OpenOCD for STM32G0:

• git clone --recurse-submodules https://repo.or.cz/openocd.git
• patch http://openocd.zylin.com/gitweb?p=openocd.git;a=patch;h=dcec354bfc756c4a4e1034c9461b5d3f4e55a63e
• ./bootstrap
• ./configure --disable-werror
• make
• make sure you've uninstalled package-managed openocd from system (sudo apt-get remove openocd)
• sudo make install

Steps to compile bootloader

Use Atollic TrueSTUDIO for STM32, open and build bootloader project.

TODO

• ? Migrate to PlatformIO.org when it will fully support official ST's STM32duino Core (which we use here). PlatformIO.org has much better build and dependency management (configurable preprocessor defines, local references to particular Arduino Core, libraries,...). Watch https://github.com/platformio/platform-ststm32/issues/76

Acknowledgement

• This project is based on Selfbus project.
• This work is supported by hkfree.org community network.