stm32-bitbang-spi

SPI using bitbang GPIO for stm32f4

Credits

• Cmake setup from an5952-how-to-use-cmake-in-stm32cubeide-stmicroelectronics.pdf
• USB interface from Improved usb cdc interface for stm32

Motivation

This implementation can be used to:

• Compare with hardware SPI to isolate problems
• Used by processors that don't have hardware SPI
• Support features not covered by hardware implementation, eg 32-bit data size or byte-separation based on slave select.
• Used when bitbang version achieves faster speeds than hardware version

Getting Started

cmake configuration files drive either cli or gui build.

GUI

To build using gui, first download:

https://www.st.com/en/development-tools/stm32cubeide.html

Then checkout STM32CubeF4:

    cd /somewhere/to/store/repository/
    git clone https://github.com/STMicroelectronics/STM32CubeF4.git

Update the STM32CubeF4 line in CMakeLists.txt to point to this location.

Open project at stm32-bitbang-spi level and import project "slave" into your environment. You should then be able to select "Run" to build code and flash to target board.

CLI

To use cli, in addition to steps above also download:

https://www.st.com/en/development-tools/stm32cubeclt.html

Then update the PATH variable in Makefile to point to the equivalent of these 3 directories under stm32cubeide and stm32cubeclt install dirs:

com.st.stm32cube.ide.mcu.externaltools.gnu-tools-for-stm32.11.3.rel1.macos64_1.1.1.202309131626/tools/bin/
com.st.stm32cube.ide.mcu.externaltools.make.macos64_2.1.0.202305091550/tools/bin/
com.st.stm32cube.ide.mcu.externaltools.cubeprogrammer.macos64_2.1.0.202305091550/tools/bin/

cmake and ninja should also be installed and path to these updated in Makefile. To flash using cli:

> make

make targets are: clean debug release, eg:
	make release


> make clean

rm -rf Debug/ Release/

> make release

cmake -S . -B Release -DCMAKE_TOOLCHAIN_FILE=cubeide-gcc.cmake -DCMAKE_BUILD_TYPE=Release
-- The C compiler identification is GNU 11.3.1
-- The CXX compiler identification is GNU 11.3.1
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /Applications/STM32CubeIDE.app/Contents/Eclipse/plugins/com.st.stm32cube.ide.mcu.externaltools.gnu-tools-for-stm32.11.3.rel1.macos64_1.1.1.202309131626/tools/bin/arm-none-eabi-gcc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /Applications/STM32CubeIDE.app/Contents/Eclipse/plugins/com.st.stm32cube.ide.mcu.externaltools.gnu-tools-for-stm32.11.3.rel1.macos64_1.1.1.202309131626/tools/bin/arm-none-eabi-g++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- The ASM compiler identification is GNU
-- Found assembler: /Applications/STM32CubeIDE.app/Contents/Eclipse/plugins/com.st.stm32cube.ide.mcu.externaltools.gnu-tools-for-stm32.11.3.rel1.macos64_1.1.1.202309131626/tools/bin/arm-none-eabi-gcc
-- Configuring done (1.2s)
-- Generating done (0.0s)
-- Build files have been written to: /Users/deep/stm32-bitbang-spi/slave/Release
cmake --build Release --config Release
[0/2] Re-checking globbed directories...
[109/109] Linking CXX executable slave.elf
   text	   data	    bss	    dec	    hex	filename
 316272	   1528	  27760	 345560	  545d8	/Users/deep/stm32-bitbang-spi/slave/Release/slave.elf
STM32_Programmer_CLI --connect port=SWD freq=4000 mode=UR reset=HWrst --write Release/slave.elf
      -------------------------------------------------------------------
                        STM32CubeProgrammer v2.14.0
      -------------------------------------------------------------------

Dir Structure

Makefile has the cmake commands to build and flash the target board.

.
├── slave
│   ├── Makefile
│   ├── CMakeLists.txt
│   ├── Core
│   │   ├── Inc
│   │   │   ├── local.hpp
│   │   │   ├── main.h
│   │   │   ├── output.hpp
│   │   │   ├── queue.hpp
│   │   │   ├── spi.hpp   <-- spi driver lives here
│   │   │   ├── stm32_assert.h
│   │   │   ├── stm32f4xx_hal_conf.h
│   │   │   └── stm32f4xx_it.h
│   │   ├── Src
│   │   │   ├── main.cpp
│   │   │   ├── output.cpp
│   │   │   ├── spi.cpp
│   │   │   ├── stm32f4xx_hal_msp.c
│   │   │   ├── stm32f4xx_it.c
│   │   │   ├── syscalls.c
│   │   │   ├── sysmem.c
│   │   │   └── system_stm32f4xx.c
│   │   └── Startup
│   │       └── startup_stm32f407vgtx.s
│   ├── Release/
│   ├── Debug/

Coding style

Roughly following https://google.github.io/styleguide/cppguide.html except in this case all functions and variables are snake_case.

# naming conventions
MyExcitingClass, MyExcitingEnum.
a_local_variable, a_struct_data_member, a_class_data_member_.

std::string table_name;  // OK - lowercase with underscore.

class TableInfo {
  ...
 private:
  std::string table_name_;  // OK - underscore at end.
};

// global constexpr or const,
const int kDaysInAWeek = 7;

// functions should generally with a capital letter and have a capital letter for each new word.
// in this case all functions are snake_case:
int count();
void set_count(int count);

// Namespace names are all lower-case, with words separated by underscores.

Authors

• Sandeep - @d-e-e-p

License

The project is available under the MIT license. See LICENSE file for details