STM32CubeIDE C++ the simplest example with cin and cout

Table of Contents

• 1. Create a new STM32 project
• 2. Start programming
• 3. references

Refer to STM32CubeIDE Input/Output on STM32 Nucleo Board in advance for basics.

1 Create a new STM32 project

In STM32CubeIDE, create a new STM32 project.

In Setup STM32 project window, select C++ for the Targeted Language.

In Project Explorer, right click on main.c and rename to main.cpp.

2 Start programming

Include standard library header <iostream>.

#include <iostream>

In the main loop, we print messages standard character output and scan an integer from the standard character input.

int i;
setvbuf(stdin, NULL, _IONBF, 0);
while (1)
{
  std::cout << "cout helo" << std::endl;
  std::cin >> i;
  std::cout << "i = " << i << std::endl;
  HAL_Delay(500);
}

Similarly, we implement __io_putchar() and __io_getchar().

extern "C"
{
  int __io_putchar(int ch)
  {
    HAL_UART_Transmit(&huart2, (uint8_t *)&ch, 1, HAL_MAX_DELAY);
    return 0;
  }
  int __io_getchar(void)
  {
    uint8_t ch = 0;
    __HAL_UART_CLEAR_OREFLAG(&huart2);
    HAL_UART_Receive(&huart2, &ch, 1, HAL_MAX_DELAY);
    HAL_UART_Transmit(&huart2, &ch, 1, HAL_MAX_DELAY);
    return ch;
  }
}

Note that they are enclosed in extern "C".

This is to stop name mangling on functions __io_putchar() and __io_getchar(), so that the C program (syscalls.c) will be able to see their symbols when linking.

In the end, the whole main.cpp looks like:

When building the project, we will see arm-none-eabi-g++ being invoked instead of arm-none-eabi-gcc to compile C++ files and link.

The sample results will be something like :

3 references

• How to Use C++ with STM32CubeIDE
• stackoverflow
  • STM32 C++ and Retargeting std::cout to UART
  • What is the effect of extern "C" in C++?
• Arm Developer
  • Redefining low-level library functions to enable direct use of high-level library functions in the C library
  • The C library functions fread(), fgets() and gets()
• cppreference
  • Standard library header <iostream>
  • std::cout, std::wcout
  • std::cin, std::wcin
• How to use C++ with STM32 HAL