This project maintains redirecting the printf() function to an UART. Also, it supports printing debug messages depending on the debug verbose level (DEBUG_LEVEL).

• printf() UART redirection
• Printing debug messages depending on the verbose level

• STM32 HAL library

1. In order to use this feature, copy all *.c and *.h files into your project or add the repository as submodule.

git submodule add https://github.com/NyankoTear/printf-utils.git

2. Of course, you must activate at least one UART peripheral.

3. The printf_config.h needs usart.h, Check Generate peripheral initalization as a pair of '.c/.h' files per peripheral in Project Manager -> Code Generator -> Generated files from a STM32CubeMX application.

Note: If you don't want to use this option or not using the STM32CubeMX, make sure that printf_config.h includes UART_HandleTypeDef and HAL_UART_Transmit().

4. Include all paths.
5. Initialize the UART handler calling initialize_uart_printf().
6. You can finally use printf().

1. First, you must redirect the printf() function to the UART. Please follow the guideline: How to use printf().
2. Add a preprocessor symbol: DEBUG_LEVEL=<verbose level>
3. Depending on your debug verbose level, the <verbose level> can be set from 0 to 3.

DEBUG_LEVEL=0 // Deactivates all debug messages.
DEBUG_LEVEL=1 // Only activates DEBUG_V(). DEBUG_VV() and DEBUG_VVV() doesn't print anything.
DEBUG_LEVEL=2 // Activates DEBUG_V() and DEBUG_VV().
DEBUG_LEVEL=3 // Activates all debug messages.

You may coded like this:

printf("Print something");

stdout is line buffered by default. Therefore, it doesn't prompt the text on the screen until a new line escape sequence (\n) met. Adding the \n at the end of the string resolves the issue.

printf("Print something\n");

However, the solution from the above forces to move the cursor to the next line. If you not happy with it, there is a great link that explains about stdout and how to print immediately. I would recommend 2 possible ways from it.

• Using fflush

printf("Print immediately");
fflush(stdout);

• Make stdout to 'no buffering'

setvbuf(stdout, NULL, _IONBF, 0); 
printf("Print immediately");

Simply check Use float with printf from newlib-nano (-u _printf_float) option in the project properties.

You must add -u _printf_float to the linker options (LDFLAGS) in the Makefile.