The problem that STM32 cannot use printf() in MDK-EEWORLD

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When debugging the STM32 board serial port with MDK, the printf() function was called to facilitate serial port debugging. However, after burning the .hex file into the board, it was found that the serial port could not receive any data. When emulating with Keil, the serial port can output correctly. I was a little puzzled, and then called the USART_SendData() function, and found that the serial port can receive correct data, proving that there is no problem with the serial port configuration. The problem should be with the printf() function. Referring to the printf example of ST company, data cannot be output on the serial port. It can be seen that it should be the problem of software configuration. Later, Baidu and the AVR forum found the answer.

If you are using MDK, please check "Use MicroLIB" in "Target"->"Code Generation" in the project properties.

After making the above settings and compiling, the serial port should output the correct data.

#ifndef __UART_INTERFACE_H
#define __UART_INTEFFACE_H

#include "stm32f10x_lib.h"
#include "stdio.h"

void UART_Init(unsigned long UART_baud); //Baud rate, such as 115200
int fputc(int ch, FILE *f);    //fputc redirection
int fgetc(FILE *f); //fgetc redirection

#endif

The following is part of the .C code, omitting the initialization part. I wrote it by myself.

int fputc(int ch, FILE *f)
{

  USART_SendData(USART1, (u8) ch);


  while(!(USART_GetFlagStatus(USART1, USART_FLAG_TXE) == SET))
  {
  }

  return ch;
}

int fgetc(FILE *f)
{

  while(!(USART_GetFlagStatus(USART1, USART_FLAG_RXNE) == SET))
  {
  }


  return (USART_ReceiveData(USART1));
}

Keywords：MDK STM32 printf() Reference address：The problem that STM32 cannot use printf() in MDK

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