SPI Communication

STM32 NUCLEO-C031C6 to Arduino Bare-Metal Implementation

This repository demonstrates a bare-metal C implementation of SPI communication between an STM32 Nucleo-C031C6 (Controller) and Arduino Uno (Peripheral). The Nucleo sends the Arduino a number, and in response, the Arduino returns the same number added by 10. For the Nucleo, STM32's CubeMX is used to configure SWD/debug and clock initialization. All GPIO,timer, USART, and SPI manipulation are performed via direct memory-mapped register access. Similarly for the Arduino, all SPI parameters are configured using direct memory-mapped register access. The Arduino library is only used to initialize and utilize the serial port.

Wiring

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⚡ 5V to 3.3V Bi-directional Logic Converter

• Nucleo Side (Low Voltage):
  • 3V3/GND leads connected to LV / GND respectively.
  • SCK (PA5) connected to LV1.
  • MISO/CIPO (PA6) connected to LV2.
  • MOSI/COPI (PA7) connected to LV3.
  • NSS (PB0) connected to LV4.
• Arduino Side (High Voltage):
  • 5V/GND leads connected to HV / GND respectively.
  • SCK (PB5) connected to HV1.
  • MISO/CIPO (PB4) connected to HV2.
  • MOSI/COPI (PB3) connected to HV3.
  • SS (PB2) connected to HV4.

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🔵 STM32 Nucleo Setup

Category	Details
Hardware	NUCLEO-C031C6 (ARM Cortex-M0+)
Debugger	ST-LINK V2-1 (SWD interface)
IDE	STM32CubeIDE 2.0.0
Toolchain	GNU Tools for STM32 (13.3.rel1)
Libraries	STM32 LL, CMSIS STM32C0xx, CMSIS STM32C031xx

How to Run

1. Import: Import the "STM32C031C6_SPI_Controller" sub-folder as an STM32CubeIDE project.
2. Setup (Optional): Review and adjust the error handler logging and error indicator settings within error_check_utilities.h.
3. Build: Select Project > Build Project.
4. Flash: Use the Run or Debug icons.
5. Run:
   • Ensure that the Arduino has been initialized before the Nucleo. Otherwise, reset the Nucleo using the reset button on the board.
   • Open serial terminal and set to 9600 Baud.
   • Observe the controller transmitting a number to the Arduino and receiving a response. Due to the nature of SPI the response by the Arduino is behind by one cycle with respect to the Nucleo.

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🟢 Arduino Uno Setup

Category	Details
Hardware	Arduino Uno R3 (Atmega 328p)
IDE	Visual Studio Code + PlatformIO
Toolchain	avr-gcc, AVR Dude (via PlatformIO)
Libraries	Arduino.h (Used for Serial UART)

How to Run

1. Open Folder: Select File > Open Folder, then select the "Arduino_SPI_Periph" folder.
2. Build: Select PlatformIO: Build.
3. Flash: Select PlatformIO: Upload.
4. Run:
   • Open serial terminal and set to 9600 Baud.
   • Observe the Arduino receiving a number from the controller and transmitting a response. Due to the nature of SPI the response by the Arduino is behind by one cycle with respect to the Nucleo.